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Spencer Clinton JL, Hoornweg TE, Tan J, Peng R, Schaftenaar W, Rutten VPMG, de Haan CAM, Ling PD. The EEHV1A gH/gL complex elicits humoral and cell-mediated immune responses in mice. Vaccine 2024; 42:126227. [PMID: 39180978 DOI: 10.1016/j.vaccine.2024.126227] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2024] [Revised: 08/11/2024] [Accepted: 08/12/2024] [Indexed: 08/27/2024]
Abstract
Elephant endotheliotropic herpesvirus (EEHV) causes lethal hemorrhagic disease (HD) in Asian and African elephants. Although rapid detection of viremia and supportive treatments may improve survival rates, an effective vaccine would mitigate the devastating effects of this virus. In elephants, chronic infection with EEHV leads to adaptive immunity against glycoproteins gB and gH/gL, the core entry machinery for most herpesviruses. We previously evaluated two EEHV gB vaccines in mice but not a gH/gL vaccine. Here, we found that inoculation of mice with an adjuvanted EEHV gH/gL subunit vaccine induced a significant antibody response that was similar to the response observed in elephants chronically infected with EEHV. Moreover, the gH/gL heterodimer elicited polyfunctional T cells with a Th1 phenotype but no detectable Th2 response. These results suggest that gH/gL, possibly in combination with gB, may be suitable immunogens for a vaccine comprising herpesvirus glycoproteins that are known to mediate cell entry and infection.
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Affiliation(s)
- Jennifer L Spencer Clinton
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, 1 Baylor Plaza, MS: BCM-385, Houston, TX 77030, USA.
| | - Tabitha E Hoornweg
- Department of Biomolecular Health Sciences, Div of Infectious Diseases and Immunology, Fac of Veterinary Medicine, Utrecht University, Yalelaan 1, 3584, CL, Utrecht, Netherlands.
| | - Jie Tan
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, 1 Baylor Plaza, MS: BCM-385, Houston, TX 77030, USA.
| | - Rongsheng Peng
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, 1 Baylor Plaza, MS: BCM-385, Houston, TX 77030, USA.
| | - Willem Schaftenaar
- Veterinary Advisor EAZA Elephant TAG, Rotterdam Zoo, Blijdorplaan 8, 3041, JG, Rotterdam, Netherlands.
| | - Victor P M G Rutten
- Department of Biomolecular Health Sciences, Div of Infectious Diseases and Immunology, Fac of Veterinary Medicine, Utrecht University, Yalelaan 1, 3584, CL, Utrecht, Netherlands; Department of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, Pretoria, South Africa.
| | - Cornelis A M de Haan
- Department of Biomolecular Health Sciences, Div of Infectious Diseases and Immunology, Fac of Veterinary Medicine, Utrecht University, Yalelaan 1, 3584, CL, Utrecht, Netherlands.
| | - Paul D Ling
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, 1 Baylor Plaza, MS: BCM-385, Houston, TX 77030, USA.
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Abdelgawad A, Nascimento M, Prahl A, Flügger M, Szentiks CA, Holtze S, Hildebrandt TB, Trimpert J. Fatal infection caused by a genetically distinct elephant endotheliotropic herpesvirus type 5 in a captive Asian elephant in Germany. Virol J 2024; 21:221. [PMID: 39285293 PMCID: PMC11406788 DOI: 10.1186/s12985-024-02477-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2024] [Accepted: 08/20/2024] [Indexed: 09/19/2024] Open
Abstract
BACKGROUND Elephant endotheliotropic herpesvirus (EEHV) infection is the most common cause for lethal hemorrhagic disease in captive juvenile Asian elephants (Elephas maximus). Although EEHV1 is known as the most likely cause of fatal haemorrhagic disease in Asian elephants, EEHV5 was lately involved in lethal cases of haemorrhagic disease in captive elephants. CASE PRESENTATION Here we report the first death of a four-year old Asian elephant diagnosed with EEHV5 in Germany. Molecular diagnosis yielded detection of EEHV5 DNA in all tested tissues. Histopathological examination revealed typical features of hemorrhagic disease in all examined organs. EEHV5 was sequenced from total DNA isolated from heart tissue by Illumina and Nanopore sequencing. Sequencing data showed 3,881 variants, distributed across the entire genome, compared to the published EEHV5 sequence. CONCLUSIONS We have detected EEHV5 in a fatal disease case of a male Asian elephant. Whole genome sequencing revealed substantial differences of our DNA isolate compared to available EEHV5 sequences. This report of fatal haemorrhagic disease associated with EEHV5 infection should raise awareness for EEHV5 as an important elephant pathogen. Genome sequencing and downstream SNPs analysis will further encourage future research to understand genetic diversity, pathogenesis and virulence of EEHVs with respect to developing new diagnostic methods, prophylactic strategies, and implementation of surveillance and control measures.
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Affiliation(s)
- Azza Abdelgawad
- Institut für Virologie, Freie Universität Berlin, Robert-von-Ostertag-Str. 7-13, 14163, Berlin, Germany
| | - Mariana Nascimento
- Institut für Virologie, Freie Universität Berlin, Robert-von-Ostertag-Str. 7-13, 14163, Berlin, Germany
| | - Adriane Prahl
- Tierpark Hagenbeck Gem. GmbH, Lokstedter Grenzstraße 2, 22527, Hamburg, Germany
| | - Michael Flügger
- Tierpark Hagenbeck Gem. GmbH, Lokstedter Grenzstraße 2, 22527, Hamburg, Germany
| | - Claudia A Szentiks
- Leibniz-Institute for Zoo and Wildlife Research, Alfred-Kowalke-Strasse 17, 10315, Berlin, Germany
| | - Susanne Holtze
- Leibniz-Institute for Zoo and Wildlife Research, Alfred-Kowalke-Strasse 17, 10315, Berlin, Germany
| | - Thomas B Hildebrandt
- Leibniz-Institute for Zoo and Wildlife Research, Alfred-Kowalke-Strasse 17, 10315, Berlin, Germany
| | - Jakob Trimpert
- Institut für Virologie, Freie Universität Berlin, Robert-von-Ostertag-Str. 7-13, 14163, Berlin, Germany.
- Department of Diagnostic Medicine and Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS, USA.
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3
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Sharma K, Mathesh K, Janmeda P, Nautiyal S, Lakshmi PS, Subash A, Mahajan S, Agrawal R, Pawde AM, Sharma GK. Production and characterization of biologicals for disease diagnosis and pathological evaluation of elephant endotheliotropic herpesvirus (EEHV). J Virol Methods 2024; 329:114970. [PMID: 38830475 DOI: 10.1016/j.jviromet.2024.114970] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2024] [Revised: 05/30/2024] [Accepted: 05/30/2024] [Indexed: 06/05/2024]
Abstract
Elephant endotheliotropic herpesviruses (EEHV) belong to the family Herpesviridae and cause a highly fatal hemorrhagic infection in elephants. EEHV poses a global threat to the already endangered elephant population. Since EEHV is a non-cultivable virus, there is a scarcity of specific diagnostics, therapeutics, and vaccines. In this study, our objective was to develop biologicals for diagnosis and pathological studies against the most prevalent EEHV1A/1B. We expressed two truncated fragments of the DNA polymerase, glycoprotein B (gB), and glycoprotein (gL) of EEHV in the prokaryotic system. Hyperimmune serum against the purified antigens was raised in rabbits and guinea pigs. We validated the reactivity of this hyperimmune serum using western blotting, ELISA, and immune-histochemistry on known positive infected tissues. Samples collected from 270 animals across various states in India were evaluated with these biologicals. The raised antibodies successfully demonstrated virus in immune-cytochemistry. Additionally, all known positive samples consistently exhibited significant inhibition in the OD values when used in the competitive format of ELISA across all four antigens when compared to the serum collected from known negative animals. An apparent sero-prevalence of 10 % was observed in the randomly collected samples. In summary, our study successfully developed and validated biologicals that will be invaluable for EEHV diagnosis and control.
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Affiliation(s)
- Kirtika Sharma
- Centre for Wildlife Conservation Management and Disease Surveillance, ICAR-Indian Veterinary Research Institute, Izatnagar, Bareilly, Uttar Pradesh 243122, India
| | - Karikalan Mathesh
- Centre for Wildlife Conservation Management and Disease Surveillance, ICAR-Indian Veterinary Research Institute, Izatnagar, Bareilly, Uttar Pradesh 243122, India.
| | - Pracheta Janmeda
- Department of Bioscience and Biotechnology, Banasthali Vidyapith, Tonk, Rajasthan 304022, India
| | - Sushmita Nautiyal
- CADRAD, ICAR-Indian Veterinary Research Institute, Izatnagar, Bareilly, Uttar Pradesh 243122, India
| | - P Sree Lakshmi
- Centre for Wildlife Conservation Management and Disease Surveillance, ICAR-Indian Veterinary Research Institute, Izatnagar, Bareilly, Uttar Pradesh 243122, India
| | - Athira Subash
- Centre for Wildlife Conservation Management and Disease Surveillance, ICAR-Indian Veterinary Research Institute, Izatnagar, Bareilly, Uttar Pradesh 243122, India
| | - Sonalika Mahajan
- Biological Standardization Division, ICAR-Indian Veterinary Research Institute, Izatnagar, Bareilly, Uttar Pradesh 243122, India
| | - Ravikant Agrawal
- Biological Products Division, ICAR-Indian Veterinary Research Institute, Izatnagar, Bareilly, Uttar Pradesh 243122, India
| | - Abhijit M Pawde
- Centre for Wildlife Conservation Management and Disease Surveillance, ICAR-Indian Veterinary Research Institute, Izatnagar, Bareilly, Uttar Pradesh 243122, India
| | - Gaurav Kumar Sharma
- CADRAD, ICAR-Indian Veterinary Research Institute, Izatnagar, Bareilly, Uttar Pradesh 243122, India
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Sylvester H, Raines J, Burgdorf-Moisuk A, Connolly M, Wilson S, Ripple L, Rivera S, McCain S, Latimer E. SELECTED INSTANCES OF ELEPHANT ENDOTHELIOTROPIC HERPESVIRUS SHEDDING IN TRUNK SECRETIONS BY AFRICAN ELEPHANTS ( LOXODONTA AFRICANA) IN COMPARISON TO SHEDDING BY ASIAN ELEPHANTS ( ELEPHAS MAXIMUS). J Zoo Wildl Med 2024; 55:182-194. [PMID: 38453501 DOI: 10.1638/2022-0046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/21/2023] [Indexed: 03/09/2024] Open
Abstract
This study examined the viral shedding kinetics of elephant endotheliotropic herpesvirus (EEHV) in African elephants (Loxodonta africana) compared to viral shedding behavior in Asian elephants (Elephas maximus). Little is known about the transmission dynamics and epidemiology of this disease in African elephants. In light of recent clinical cases and mortalities, this paper aims to identify trends in viral biology. Trunk wash samples were collected from 22 African elephants from four North American zoological institutions that had recently experienced herd viremias or translocations. Processing of these samples included DNA extraction followed by qPCR to quantitate viral DNA load. The results were then compared with available literature that chronicled similar cases in Asian and African elephants. Minimal EEHV shedding was detected in response to varied herd translocations. Increased shedding was recorded in herds in which an elephant experienced an EEHV viremia when compared to baseline shedding. These index infections were followed by subsequent viremias in other elephants, although it is not known if these were recrudescence, transient controlled viremias, and/or primary infections via transmission to other elephants. When compared to historically published data, it was observed that EEHV3 cases in African elephants and EEHV1A cases in Asian elephants had consistently higher levels of viral DNA in the blood than were shed in trunk secretions, a fact that is seemingly inconsistent with such severe cases of disease and the high mortality rates associated with those respective types. The findings produced in this study highlight the need for more routine monitoring of viral shedding in African elephant herds to elucidate possible EEHV transmission and recrudescence factors for ex situ population management.
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Affiliation(s)
- Hannah Sylvester
- Smithsonian's National Zoo and Conservation Biology Institute, Washington, DC 20008, USA
| | | | | | | | | | | | | | | | - Erin Latimer
- Smithsonian's National Zoo and Conservation Biology Institute, Washington, DC 20008, USA,
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5
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Sittisak T, Guntawang T, Srivorakul S, Photichai K, Boonprasert K, Khammesri S, Chuammitri P, Thitaram C, Hsu WL, Thanawongnuwech R, Pringproa K. Response of elephant peripheral blood mononuclear cells when stimulated with elephant endotheliotropic herpesvirus glycoprotein B (EEHV-gB). Vet Immunol Immunopathol 2023; 258:110577. [PMID: 36867998 DOI: 10.1016/j.vetimm.2023.110577] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Revised: 02/10/2023] [Accepted: 02/26/2023] [Indexed: 03/05/2023]
Abstract
Elephant endotheliotropic herpesvirus-hemorrhagic disease (EEHV-HD) is the most highly fatal infectious disease among young Asian elephants. Despite the fact that antiviral therapy has been widely used, its therapeutic outcomes remain uncertain. Additionally, the virus has yet to be successfully cultivated in vitro in the process of develop viral envelope glycoproteins for vaccine design. The present study aims to investigate and evaluate EEHV1A glycoprotein B (gB) antigenic epitopes as potential candidates for further vaccine development. Epitopes of EEHV1A-gB were employed in in silico predictions and designed by using online antigenic predicting tools. Candidate genes were then constructed, transformed and expressed in the E. coli vectors prior to examine their potential for acceleration elephant immune responses in vitro. Elephant peripheral blood mononuclear cells (PBMCs) isolated from 16 healthy juvenile Asian elephants were investigated for their proliferative capability and cytokine responses after being stimulated with EEHV1A-gB epitopes. Exposure of elephant PBMCs to 20 µg/mL of gB for 72 h resulted in a significant proliferation of CD3 + cells when compared with the control group. Furthermore, proliferation of CD3 + cells was associated with a marked up-regulation of cytokine mRNA expression, involving IL-1β, IL-8, IL-12 and IFN-γ. It remains to be determined whether these candidate EEHV1A-gB epitopes could activate immune responses in animal models or elephants in vivo. Our potentially promising results demonstrate a degree of feasibility for the use of these gB epitopes in expanding EEHV vaccine development.
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Affiliation(s)
- Tidaratt Sittisak
- Department of Veterinary Biosciences and Veterinary Public Health, Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai 50100, Thailand
| | - Thunyamas Guntawang
- Department of Veterinary Biosciences and Veterinary Public Health, Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai 50100, Thailand
| | - Saralee Srivorakul
- Department of Veterinary Biosciences and Veterinary Public Health, Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai 50100, Thailand
| | - Kornravee Photichai
- Veterinary Diagnostic Center, Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai 50100, Thailand
| | - Khajohnpat Boonprasert
- Center of Excellence in Elephant and Wildlife Research, Chiang Mai University, Chiang Mai 50100, Thailand
| | - Siripat Khammesri
- Center of Excellence in Elephant and Wildlife Research, Chiang Mai University, Chiang Mai 50100, Thailand
| | - Phongsakorn Chuammitri
- Department of Veterinary Biosciences and Veterinary Public Health, Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai 50100, Thailand
| | - Chatchote Thitaram
- Center of Excellence in Elephant and Wildlife Research, Chiang Mai University, Chiang Mai 50100, Thailand; Department of Companion Animals and Wildlife Clinics, Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai 50100, Thailand
| | - Wei-Li Hsu
- Graduate Institute of Microbiology and Public Health, College of Veterinary Medicine, National Chung Hsing University, Taichung 402, Taiwan
| | - Roongroje Thanawongnuwech
- Department of Pathology, Faculty of Veterinary Sciences, Chulalongkorn University, Bangkok 10330, Thailand
| | - Kidsadagon Pringproa
- Department of Veterinary Biosciences and Veterinary Public Health, Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai 50100, Thailand; Center of Excellence in Elephant and Wildlife Research, Chiang Mai University, Chiang Mai 50100, Thailand.
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6
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Sree Lakshmi P, Karikalan M, Sharma GK, Sharma K, Chandra Mohan S, Rajesh Kumar K, Miachieo K, Kumar A, Gupta MK, Verma RK, Sahoo N, Saikumar G, Pawde AM. Pathological and molecular studies on elephant endotheliotropic herpesvirus haemorrhagic disease among captive and free-range Asian elephants in India. Microb Pathog 2023; 175:105972. [PMID: 36621697 DOI: 10.1016/j.micpath.2023.105972] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Revised: 12/19/2022] [Accepted: 01/03/2023] [Indexed: 01/07/2023]
Abstract
In the present research pathology and molecular diagnosis of elephant endotheliotropic herpes virus-haemorrhagic disease (EEHV-HD) among Asian elephants was studied. Out of 76 cases, 20 were positive for EEHV infection in PANPOL and POL1 based semi-nested PCR. Out of 20 samples, 10 samples were fatal cases of EEHV-HD while 10 were of either subclinical or latent infection. Acute onset haemorrhagic disease with EEHV-HD had anorexia, facial and neck swelling, cyanotic buccal mucosa and tongue, nasal and ocular discharge, and colic. The hallmark of gross finding in all cases were severe haemorrhagic lesions in the internal organs viz. cyanosis of tongue with multifocal petechial haemorrhages, diffuse epicardial and endocardial haemorrhages, swollen liver (rounded edges) with parenchymal haemorrhages, serosal and mucosal haemorrhages in gastrointestinal tract, congested kidneys with corticomedullary haemorrhages, highly congested meninges, and brain capillaries with haemorrhages. Microscopic findings in all the cases had severe vascular changes in the visceral organs. Microthrombi was present in the vasculature of tongue, heart, lung, liver, kidney, and brain. The endothelial lining of most of the blood vessels were swollen with apoptotic changes. Amphophilic to basophilic intranuclear inclusion bodies were observed in the endothelial cells. Immunostaining using anti-EEHV DNAPOL hyperimmune sera revealed intense positive signals in the endothelium of blood vessels and their walls. Quantification of viral load in necropsy tissue samples revealed highest in the heart (7.4 × 106/μg of sample) and least in the brain (9 × 103/μg of sample). The PCR amplicons from EEHV1 specific genes (POL1(U38) and TER were subjected to partial genome sequencing which had 99.9% similarity with the EEHV1A subtype. It was concluded that Asian elephants in India are latently infected for EEHV1 and in all the fatal EEHV-HD cases, EEHV1A subtype was the causative agent with characteristic pathomorphological changes in visceral organs.
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Affiliation(s)
- P Sree Lakshmi
- ICAR- Indian Veterinary Research Institute, Izatnagar, Bareilly, 243122, Uttar Pradesh, India
| | - M Karikalan
- ICAR- Indian Veterinary Research Institute, Izatnagar, Bareilly, 243122, Uttar Pradesh, India.
| | - Gaurav K Sharma
- ICAR- Indian Veterinary Research Institute, Izatnagar, Bareilly, 243122, Uttar Pradesh, India
| | - Kirtika Sharma
- ICAR- Indian Veterinary Research Institute, Izatnagar, Bareilly, 243122, Uttar Pradesh, India
| | - S Chandra Mohan
- ICAR- Indian Veterinary Research Institute, Izatnagar, Bareilly, 243122, Uttar Pradesh, India
| | - K Rajesh Kumar
- Veterinary Officer, Mudumalai Tiger Reserve, The Nigiris, Tamil Nadu, India
| | - Kenei Miachieo
- Sarguja Elephant Reserve, Ambikapur, Chhattisgarh, India
| | - Ajay Kumar
- Bhagwan Birsa Biological Park, Ranchi, Jharkhand, India
| | - M K Gupta
- Faculty of Veterinary Science & Animal Husbandry, Ranchi, Jharkhand, India
| | - Rakesh K Verma
- Sarguja Elephant Reserve, Ambikapur, Chhattisgarh, India
| | - Niranjana Sahoo
- Faculty of Veterinary Science & Animal Husbandry, OUAT, Odisha, India
| | - G Saikumar
- ICAR- Indian Veterinary Research Institute, Izatnagar, Bareilly, 243122, Uttar Pradesh, India
| | - A M Pawde
- ICAR- Indian Veterinary Research Institute, Izatnagar, Bareilly, 243122, Uttar Pradesh, India
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7
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DETECTION OF ELEPHANT ENDOTHELIOTROPIC HERPESVIRUS 1A IN ARCHIVAL TISSUE USING RNASCOPE ® IN SITU HYBRIDIZATION. J Zoo Wildl Med 2023; 53:661-669. [PMID: 36640067 DOI: 10.1638/2022-0042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/13/2022] [Indexed: 01/09/2023] Open
Abstract
Hemorrhagic disease due to elephant endotheliotropic herpesvirus infection (EEHV-HD) is an important cause of calf mortality in managed and free-ranging Asian (Elephas maximus) and African elephant (Loxodonta spp.) populations. Consequently, infection has profound implications for elephant population growth and sustainability. The mechanisms of disease caused by EEHV (i.e., infection, dissemination, shedding, latency) are relatively undefined, in part because of a lack of robust validated assays for detecting viral gene products in relevant samples. To address this issue, we used RNAscope® in situ hybridization (ISH) based on EEHV1A DNA polymerase and terminase genes to detect EEHV1A RNA in archival formalin-fixed, paraffin-embedded Asian elephant heart and tongue from PCR-confirmed cases (n = 4) of EEHV-HD and Asian elephants (n = 2) that died from other causes. EEHV1A-positive cases had positive hybridization signal in endothelial cell nuclei of both tissues for both DNA polymerase and terminase. EEHV-negative cases lacked signal. In positive cases, the number of positive nuclei was manually assessed to provide an estimate of the viral load and compare sensitivity of the two probes. In all cases, heart had greater signal than tongue for both probes (Wilcoxon rank test; P ≤ 0.01). Overall, terminase hybridization signal was greater than DNA polymerase signal (Wilcoxon rank test; P ≤ 0.01). Results indicate RNAscope ISH is a valuable tool for detection of EEHV in archival samples and for confirming infection. Additionally, the terminase gene is the optimal target and heart is preferable to tongue for detection in cases of EEHV-HD. Results will inform future investigations of viral tropism in EEHV-HD cases due to EEHV1A.
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8
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Yang N, Bao M, Zhu B, Shen Q, Guo X, Li W, Tang R, Zhu D, Tang Y, Phalen DN, Zhang L. Elephant Endotheliotropic Herpesvirus 1, 4 and 5 in China: Occurrence in Multiple Sample Types and Implications for Wild and Captive Population Surveillance. Viruses 2022; 14:v14020411. [PMID: 35216004 PMCID: PMC8875873 DOI: 10.3390/v14020411] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 02/13/2022] [Accepted: 02/15/2022] [Indexed: 02/05/2023] Open
Abstract
Elephant endotheliotropic herpesviruses (EEHVs) are important causes of death in both captive and wild Asian elephants (Elephas maximus). Nothing is known about the prevalence of EEHVs in wild or domestic elephants in China. To determine if EEHVs are present in elephants in China, 126 wild elephants from three populations and 202 captive individuals from zoos (n = 155) and the Wild Elephant Valley (n = 47) were screened using semi-nested polymerase chain reaction assays with EEHV-redundant and EEHV1/4/5-specific primers. EEHV1B and EEHV4 were detected in samples from both wild (EEHV1B:8/126; EEHV4:2/126) and captive (EEHV1B:5/155; EEHV4:9/155) elephants, while EEHV1A (six cases) and EEHV5 (one case) were only present in the captive elephants from the Wild Elephant Valley. EEHV1 was detected in blood and trunk and oral swabs; EEHV4 was detected in trunk and oral swabs as well as feces; EEHV5 was found in trunk and oral swabs. No significant age or sex association with EEHV1A, EEHV1B, or EEHV5 positivity was observed. An age association with EEHV4 positivity was found, with all unweaned elephants being EEHV4 positive, but an association with the sex of the elephant was not observed. These findings represent the first documentation of EEHV presence in captive and wild elephants in China. These findings also document EEHV1B and EEHV4 shedding in feces and demonstrate the utility of fecal screening as a tool for investigating EEHV4 infection in wild populations of elephants. It is recommended that EEHV testing be included in surveillance programs for captive and wild elephants in China.
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Affiliation(s)
- Nian Yang
- Key Laboratory for Biodiversity and Ecological Engineering of Ministry of Education, Department of Ecology, College of Life Sciences, Beijing Normal University, Beijing 100875, China; (N.Y.); (B.Z.); (R.T.); (D.Z.); (Y.T.)
| | - Mingwei Bao
- Wild Elephant Valley, Jinghong 666100, China;
| | - Biru Zhu
- Key Laboratory for Biodiversity and Ecological Engineering of Ministry of Education, Department of Ecology, College of Life Sciences, Beijing Normal University, Beijing 100875, China; (N.Y.); (B.Z.); (R.T.); (D.Z.); (Y.T.)
| | - Qingzhong Shen
- Ecotourism Management Institute of Yunnan Xishuangbanna National Nature Reserve, Jinghong 666100, China;
| | - Xianming Guo
- Research Institute of Xishuangbanna National Nature Reserve, Jinghong 666100, China;
| | - Wenwen Li
- Key Laboratory of Coastal Science and Integrated Management, First Institute of Oceanography, Ministry of Natural Resources, Qingdao 266061, China;
| | - Ruchun Tang
- Key Laboratory for Biodiversity and Ecological Engineering of Ministry of Education, Department of Ecology, College of Life Sciences, Beijing Normal University, Beijing 100875, China; (N.Y.); (B.Z.); (R.T.); (D.Z.); (Y.T.)
| | - Di Zhu
- Key Laboratory for Biodiversity and Ecological Engineering of Ministry of Education, Department of Ecology, College of Life Sciences, Beijing Normal University, Beijing 100875, China; (N.Y.); (B.Z.); (R.T.); (D.Z.); (Y.T.)
| | - Yinpu Tang
- Key Laboratory for Biodiversity and Ecological Engineering of Ministry of Education, Department of Ecology, College of Life Sciences, Beijing Normal University, Beijing 100875, China; (N.Y.); (B.Z.); (R.T.); (D.Z.); (Y.T.)
| | - David N. Phalen
- Sydney School of Veterinary Science, Faculty of Science, University of Sydney, Sydney, NSW 2006, Australia
- Schubot Exotic Bird Health Center, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, 701 Farm to Market 2818 Service Road, College Station, TX 77840, USA
- Correspondence: (D.N.P.); (L.Z.)
| | - Li Zhang
- Key Laboratory for Biodiversity and Ecological Engineering of Ministry of Education, Department of Ecology, College of Life Sciences, Beijing Normal University, Beijing 100875, China; (N.Y.); (B.Z.); (R.T.); (D.Z.); (Y.T.)
- Correspondence: (D.N.P.); (L.Z.)
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9
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Effects of between and within Herd Moves on Elephant Endotheliotropic Herpesvirus (EEHV) Recrudescence and Shedding in Captive Asian Elephants (Elephas maximus). Viruses 2022; 14:v14020229. [PMID: 35215824 PMCID: PMC8877707 DOI: 10.3390/v14020229] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Revised: 01/18/2022] [Accepted: 01/18/2022] [Indexed: 02/01/2023] Open
Abstract
Haemorrhagic disease associated with elephant endotheliotropic herpesvirus (Elephantid herpesvirus, EEHV) infections is the leading cause of death for Asian elephant (Elephas maximus) calves. This study assessed the effect of captive herd management on EEHV shedding, as evidence of latent infection reactivation, focusing on: (1) the influence of social change on the odds of recrudescence; (2) the respective effects of between and within herd moves; and (3) characteristics of recrudescent viral shedding. Trunk and conjunctival swabs (n = 165) were obtained from six elephants at an EAZA-accredited zoo, collected during a period of social stability, and at times of social change. Longitudinal sampling took place at times of moving two bulls out of the collection and one new bull into an adjacent enclosure to the cow herd (between herd moves), and during a period of mixing this new bull with the cow herd to facilitate mating (within herd moves). Quantitative PCR was employed to detect EEHV 1a/b, 4a/b, and EF–1–α (housekeeping gene). Generalised estimating equations determined EEHV recrudescence odds ratios (OR) and relative viral DNA load. Sixteen EEHV 1a/b shedding events occurred, but no EEHV 4a/b was detected. All management-derived social changes promoted recrudescence (social change OR = 3.27, 95% CI = 0.412–26, p = 0.262; and between herd moves OR = 1.6, 95% CI = 0.178−14.4, p = 0.675), though within herd movements posed the most significant increase of EEHV reactivation odds (OR = 6.86, 95% CI = 0.823−57.1, p = 0.075) and demonstrated the strongest relative influence (post hoc Tukey test p = 0.0425). Shedding onset and magnitude ranged from six to 54 days and from 3.59 to 11.09 ΔCts. Differing challenges are associated with between and within herd movements, which can promote recrudescence and should be considered an exposure risk to naïve elephants.
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Pharmacokinetics and analytical determination of acyclovir in Asian elephant calves ( Elephas maximus). Vet Anim Sci 2022; 15:100227. [PMID: 35024493 PMCID: PMC8724961 DOI: 10.1016/j.vas.2021.100227] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 12/09/2021] [Accepted: 12/22/2021] [Indexed: 12/04/2022] Open
Abstract
Pharmacokinetic and bioavailability data of acyclovir following intravenous and oral administration are reported for Asian elephant calves. Data represent the first comprehensive LC-MS/MS analysis of plasma acyclovir concentrations after i.v. and oral administration in elephants.
A therapeutic regimen that includes antiviral drugs is critical for the survival of Asian elephant (Elephas maximus) calves infected with elephant endotheliotropic herpesvirus hemorrhagic disease (EEHV-HD), with acyclovir showing considerable promise. The purpose of this study was to determine the pharmacokinetics and bioavailability of acyclovir following intravenous (IV) and oral (PO) administration in Asian elephants. A single dose of acyclovir (15 mg/kg, IV or 45 mg/kg, PO) was administered to four healthy elephant calves, with a minimum 2-week washout period between treatments. Serial plasma samples were collected after each injection for acyclovir analysis using a validated liquid chromatography-tandem mass spectrometry (LC-MS/MS) technique. Maximum plasma acyclovir concentrations were 27.02 ± 6.79 µg/mL at 0.94 ± 0.31 h after IV administration, and 1.45 ± 0.20 µg/mL at 3.00 ± 0.70 h after PO administration. The half-life of the elimination phase (T1/2) was 5.84 ± 0.74 and 8.74 ± 2.47 h after IV and PO administration, respectively. After IV administration, acyclovir concentrations were higher than the half-maximal inhibitory concentration (IC50) of those found for herpes simplex virus (HSV) 1 and 2 in humans, and equid alpha herpesvirus-1 (EHV-1) for at least 12 h. By contrast, the bioavailability of oral administration was low, only 6.03 ± 0.87%, so higher doses by that route likely are needed to be effective. Due to the high concentration of plasma acyclovir after IV administration, the dose may need to be adjusted to prevent any negative side effects.
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Key Words
- %CV, Mean precision
- AUC0-inf, Total area under the plasma concentration-time curve from time zero to infinity
- AUC0-t, Total area under the plasma concentration-time curve from time 0–48h
- Acyclovir
- Asian elephant
- Bioavailability
- Cl, Total clearance
- Cmax, Peak plasma concentration
- EEHV, Elephantendotheliotropic herpesviruses
- EEHV-HD, Elephant endotheliotropic herpesvirus hemorrhagic disease
- EHV, Equid alphaherpesvirus
- Elephant endotheliotropic herpesvirus (EEHV)
- F, Bioavailability
- HSV, Herpes simplex virus
- IV, Intravenous administration
- Kel, Elimination rate constant
- LC-MS/MS, Liquid chromatography-tandem mass spectrometry
- LLOQ, Lower limit of quantitation
- MAT, Mean absorption time
- MRM, Multiple reaction monitoring
- MRT, Mean residence time
- PO, Oral administration
- Pharmacokinetics
- QC, Quality control
- S/N, Signal to noise ratio
- T1/2, Elimination half-life
- Tmax, Time to reach peak plasma
- Vd(ss), Steady-state volume of distribution
- m/z, Mass-to-charge ratio
- r2, Coefficients of determination
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Primary Infection May Be an Underlying Factor Contributing to Lethal Hemorrhagic Disease Caused by Elephant Endotheliotropic Herpesvirus 3 in African Elephants ( Loxodonta africana). Microbiol Spectr 2021; 9:e0098321. [PMID: 34668724 PMCID: PMC8528115 DOI: 10.1128/spectrum.00983-21] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Distinct but related species of elephant endotheliotropic herpesviruses (EEHVs) circulate within Asian and African elephant populations. Primary infection with EEHVs endemic among Asian elephants can cause clinical illness and lethal EEHV hemorrhagic disease (EEHV-HD). The degree to which this occurs among African elephants has not been fully established. Recent cases of EEHV-HD caused by the EEHV3 species in African elephants housed in North American zoos has heightened concern about the susceptibility of this elephant species to EEHV-HD. In this study, we utilize the luciferase immunoprecipitation system (LIPS) to generate a serological assay specific for EEHV3 in African elephants by detecting antibodies against the EEHV3 E34 protein. The results showed that the majority of tested elephants from four separate and genetically unrelated herds, including five elephants that survived clinical illness associated with EEHV3, were positive for prior infection with EEHV3. However, African elephants who succumbed to EEHV3-HD were seronegative for EEHV3 prior to lethal infection. This supports the hypothesis that fatal EEHV-HD caused by EEHV3 is associated with primary infection rather than reactivation of latent virus. Lastly, we observed that African elephants, like Asian elephants, acquire abundant anti-EEHV antibodies prenatally and that anti-EEHV3 specific antibodies were either never detected or declined to undetectable levels in those animals that died from lethal disease following EEHV3 infection. IMPORTANCE Prior to 2019, only five cases of clinical disease from EEHV infection among African elephants had been documented. Since 2019, there have been at least seven EEHV-HD cases in North American zoos, resulting in three fatalities, all associated with EEHV3. Evidence is accumulating to suggest that EEHV-associated clinical illness and death among Asian elephants is due to primary infection and may be associated with waning anti-EEHV antibody levels in young elephants. The development of the EEHV3 serological test described in this study enabled us to confirm that similar dynamics may be contributing to EEHV-HD in African elephants. The ability to screen for EEHV immune status in African elephant calves will have a major impact on managing captive African elephant herds and will provide new tools for investigating and understanding EEHV in wild populations.
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12
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Yun Y, Sripiboon S, Pringproa K, Chuammitri P, Punyapornwithaya V, Boonprasert K, Tankaew P, Angkawanish T, Namwongprom K, Arjkumpa O, Brown JL, Thitaram C. Clinical characteristics of elephant endotheliotropic herpesvirus (EEHV) cases in Asian elephants ( Elephas maximus) in Thailand during 2006-2019. Vet Q 2021; 41:268-279. [PMID: 34511026 PMCID: PMC8475116 DOI: 10.1080/01652176.2021.1980633] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Background Elephant endotheliotropic herpesvirus causes a hemorrhagic disease (EEHV-HD) that is a major cause of death in juvenile Asian elephants with EEHV1 and EEHV4 being the most prevalent. Aim To perform a retrospective clinical data analysis. Methods Records of a total of 103 cases in Thailand confirmed by polymerase chain reaction (PCR) on blood and/or tissue samples. Results The severity of clinical signs varied among EEHV subtypes. EEHV1A was the most prevalent with 58%, followed by EEHV4 with 34%, EEHV1B with 5.8% and EEHV1&4 co-infection with 1.9%. Overall case fatality rate was 66%. When compared among subtypes, 100% case fatality rate was associated with EEHV1&4 co-infection, 83% with EEHV1B, 75% with EEHV1A, and the lowest at 40% for EEHV4. Calves 2- to 4-year old were in the highest age risk group and exhibited more severe clinical signs with the highest mortality. Majority of cases were found in weaned or trained claves and higher number of cases were observed in rainy season. A gender predilection could not be demonstrated. Severely affected elephants presented with thrombocytopenia, depletion of monocytes, lymphocytes and heterophils, a monocyte:heterophil (M:H) ratio lower than 2.37, hypoproteinemia (both albumin and globulin), severe grade of heterophil toxicity, and low red blood cell counts and pack cell volumes. Survival was not affected by antiviral drug treatment in the severely compromised animals. Conclusion Early detection by laboratory testing and aggressive application of therapies comprising of supportive and anti-viral treatment can improve survival outcomes of this disease.
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Affiliation(s)
- Yaoprapa Yun
- Faculty of Veterinary Medicine, Center of Elephant and Wildlife Research, Chiang Mai University (FVM-CMU), Chiang Mai, Thailand.,Graduate Program in Veterinary Science, Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai, Thailand
| | - Supaphen Sripiboon
- Faculty of Veterinary Medicine, Department of Large Animal and Wildlife Clinical Sciences, Kasetsart University (FVM-KU), Kamphaeng Saen Campus, Nakornpathom, Thailand
| | - Kidsadagon Pringproa
- Faculty of Veterinary Medicine, Department of Veterinary Biosciences and Public Health, Chiang Mai University, Chiang Mai, Thailand
| | - Phongsakorn Chuammitri
- Faculty of Veterinary Medicine, Department of Veterinary Biosciences and Public Health, Chiang Mai University, Chiang Mai, Thailand
| | - Veerasak Punyapornwithaya
- Faculty of Veterinary Medicine, Veterinary Public Health and Food Safety Centre for Asia Pacific, Chiang Mai University, Chiang Mai, Thailand
| | - Khajohnpat Boonprasert
- Faculty of Veterinary Medicine, Center of Elephant and Wildlife Research, Chiang Mai University (FVM-CMU), Chiang Mai, Thailand
| | - Pallop Tankaew
- Faculty of Veterinary Medicine, Center of Elephant and Wildlife Research, Chiang Mai University (FVM-CMU), Chiang Mai, Thailand
| | - Taweepoke Angkawanish
- Elephant Hospital, National Elephant Institute (NEI), Forest Industry Organization, Lampang, Thailand
| | - Kittikul Namwongprom
- Elephant Hospital, National Elephant Institute (NEI), Forest Industry Organization, Lampang, Thailand
| | - Orapun Arjkumpa
- Phra Nakhon Si Ayutthaya Provincial Livestock Office, Phra Nakhon Si Ayutthaya Province, Thailand
| | - Janine L Brown
- Faculty of Veterinary Medicine, Center of Elephant and Wildlife Research, Chiang Mai University (FVM-CMU), Chiang Mai, Thailand.,Center for Species Survival, Smithsonian Conservation Biology Institute (SCBI), Front Royal, VA, USA
| | - Chatchote Thitaram
- Faculty of Veterinary Medicine, Center of Elephant and Wildlife Research, Chiang Mai University (FVM-CMU), Chiang Mai, Thailand.,Department of Companion Animal and Wildlife Clinics, Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai, Thailand
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13
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Perrin KL, Kristensen AT, Bertelsen MF, Denk D. Retrospective review of 27 European cases of fatal elephant endotheliotropic herpesvirus-haemorrhagic disease reveals evidence of disseminated intravascular coagulation. Sci Rep 2021; 11:14173. [PMID: 34238966 PMCID: PMC8266883 DOI: 10.1038/s41598-021-93478-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2021] [Accepted: 06/25/2021] [Indexed: 02/06/2023] Open
Abstract
Elephant endotheliotropic herpesvirus haemorrhagic disease (EEHV-HD) is widely acknowledged as the most common cause of mortality in young Asian elephants (Elephas maximus) in captivity. The objective of the current study was to perform a blinded, retrospective pathology review of European EEHV-HD fatalities, constituting the largest systematic assessment of EEHV-HD pathology to date. Findings between viral genotypes were compared with the aim to investigate if disseminated intravascular coagulation (DIC) could be substantiated as a significant complicating factor, thereby increasing the understanding of disease pathophysiology. Immunohistochemical staining confirmed endothelial cell (EC) damage and the presence of EC intranuclear inclusion bodies, demonstrating a direct viral cytopathic effect. Microthrombi were observed in 63% of cases in several organs, including lungs, which, together with widespread haemorrhage and thrombocytopenia reported in EEHV-HD case reports, supports the presence of overt DIC as a serious haemostatic complication of active EEHV infection. Death was attributed to widespread vascular damage with multi-organ dysfunction, including severe acute myocardial haemorrhage and subsequent cardiac failure. Systemic inflammation observed in the absence of bacterial infection may be caused by cytokine release syndrome. Findings reinforce the necessity to investigate cytokine responses and haemostatic status during symptomatic and asymptomatic EEHV viraemia, to potentially support the use of anti-inflammatory treatment in conjunction with anti-viral therapy and cardiovascular support.
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Affiliation(s)
- K L Perrin
- Center for Zoo and Wild Animal Health, Copenhagen Zoo, Roskildevej 38, 2000, Frederiksberg, Denmark.
- The Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Dyrlægevej 16, 1870, Frederiksberg, Denmark.
| | - A T Kristensen
- The Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Dyrlægevej 16, 1870, Frederiksberg, Denmark
| | - M F Bertelsen
- Center for Zoo and Wild Animal Health, Copenhagen Zoo, Roskildevej 38, 2000, Frederiksberg, Denmark
| | - D Denk
- International Zoo Veterinary Group, Station House, Parkwood Street, Keighley, BD21 4NQ, UK
- Institute for Animal Pathology, Ludwig-Maximilians-University, Veterinärstr. 13, 80539, Munich, Germany
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14
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ACUTE HEMORRHAGIC DISEASE DUE TO ELEPHANT ENDOTHELIOTROPIC HERPESVIRUS 3A INFECTION IN FIVE AFRICAN ELEPHANTS ( LOXODONTA AFRICANA) AT ONE NORTH AMERICAN ZOOLOGICAL INSTITUTION. J Zoo Wildl Med 2021; 52:357-365. [PMID: 33827199 DOI: 10.1638/2020-0126] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/25/2020] [Indexed: 11/21/2022] Open
Abstract
Acute hemorrhagic disease caused by elephant endotheliotropic herpesvirus (EEHV) infection is well recognized as a major threat to young Asian elephants (Elephas maximus) but has been less frequently documented in African elephants (Loxodonta africana). This report describes five sequential cases of EEHV3A infection in African elephants in managed care at one institution. All elephants developed disease within a 4-mo period. The first two cases were 6.5- and 7.5-yr-old females that presented with depressed mentation, anorexia, hematuria, and diarrhea. Both elephants died within 48-72 hr of the onset of illness despite treatment. Postmortem findings included widespread edema, ascites, and extensive petechiae and ecchymoses on the heart, liver, and spleen and within the gastrointestinal and urogenital tracts. Histologic examination identified disseminated vascular necrosis with edema, hemorrhage, and rare endothelial cell intranuclear inclusions typical of herpesvirus in multiple organs. The third and fourth cases were a 13-yr-old male and a 12-yr-old female that presented with minimal to no clinical signs, but with marked changes in hematologic parameters and high viremia detected by quantitative polymerase chain reaction (qPCR). Both elephants survived the infection with early and aggressive treatment. The fifth case was a 37-yr-old female that presented with lethargy and a decreased appetite. Low viremia was detected by qPCR, and mild to moderate hematologic changes were noted. Early treatment resulted in a successful outcome. This case series documents the first known reports of clinical disease and fatality associated with EEHV3A in African elephants.
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15
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Oo ZM, Aung YH, Aung TT, San N, Tun ZM, Hayward GS, Zachariah A. Elephant Endotheliotropic Herpesvirus Hemorrhagic Disease in Asian Elephant Calves in Logging Camps, Myanmar. Emerg Infect Dis 2021; 26:63-69. [PMID: 31855135 PMCID: PMC6924905 DOI: 10.3201/eid2601.190159] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
In recent years, an alarming number of cases of lethal acute hemorrhagic disease have occurred in Asian elephant calves raised in logging camps in Myanmar. To determine whether these deaths were associated with infection by elephant endotheliotropic herpesvirus (EEHV), we conducted diagnostic PCR subtype DNA sequencing analysis on necropsy tissue samples collected from 3 locations. We found that EEHV DNA from 7 PCR loci was present at high levels in all 3 calves and was the same EEHV1A virus type that has been described in North America, Europe, and other parts of Asia. However, when analyzed over 5,610 bp, the strains showed major differences from each other and from all previously characterized EEHV1A strains. We conclude that these 3 elephant calves in Myanmar died from the same herpesvirus disease that has afflicted young Asian elephants in other countries over the past 20 years.
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16
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In vivo characterization of target cells for acute elephant endotheliotropic herpesvirus (EEHV) infection in Asian elephants (Elephas maximus). Sci Rep 2020; 10:11402. [PMID: 32647124 PMCID: PMC7347588 DOI: 10.1038/s41598-020-68413-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Accepted: 06/24/2020] [Indexed: 12/16/2022] Open
Abstract
Elephant endotheliotropic herpesvirus-hemorrhagic disease (EEHV-HD) is a dangerous viral infectious disease in young Asian elephants. Despite hypotheses underlying pathogenesis of the disease, it is unclear which cell types the virus targets during acute or persistent infections. This study investigated the tissues and target cells permissive for EEHV infection and replication in vivo. Rabbit polyclonal antibodies against the non-structural proteins of EEHV, DNA polymerase (EEHV DNAPol), were generated and validated. These were used to examine EEHV infection and replication in various tissues of acute EEHV-HD cases and compared to an EEHV-negative control. The results indicated that viral antigens were distributed throughout the epithelia of the alimentary tract and salivary glands, endothelia and smooth muscle cells, and monocytic lineage cells of the EEHV-infected elephants. Moreover, EEHV DNAPol proteins were also found in the bone marrow cells of the EEHV1A-HD and EEHV1A/4-HD cases. This study demonstrated for the first time the target cells that favor in vivo EEHV replication during acute infection, providing a promising foundation for investigating EEHV propagation in vitro.
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17
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Lethal Hemorrhagic Disease and Clinical Illness Associated with Elephant Endotheliotropic Herpesvirus 1 Are Caused by Primary Infection: Implications for the Detection of Diagnostic Proteins. J Virol 2020; 94:JVI.01528-19. [PMID: 31723022 PMCID: PMC7000966 DOI: 10.1128/jvi.01528-19] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Accepted: 10/17/2019] [Indexed: 12/21/2022] Open
Abstract
Whether clinical illness and deaths associated with elephant endotheliotropic herpesvirus (EEHV) infection result from primary infection or reactivation of latent virus is a longstanding question in the field. By applying a relatively new assay, the luciferase immunoprecipitation system (LIPS), combined with the genomic sequences of the viruses, we gained the insights and tools needed to resolve this issue. Our EEHV1-specific LIPS assay should be useful for assessing the vulnerability of elephant calves to infection with different EEHVs and evaluating antibody responses to anti-EEHV vaccines. A significant proportion of the Asian elephant population is under some form of human care. Hence, the ability to screen for EEHV immune status in elephant calves should have a major impact on the management of these animals worldwide. Elephant endotheliotropic herpesvirus (EEHV) can cause lethal hemorrhagic disease in juvenile Asian elephants, both in captivity and in the wild. Most deaths associated with the virus are caused by two chimeric variants of EEHV1 (EEHV1A and EEHV1B), while two other EEHVs endemic within Asian elephants (EEHV4 and EEHV5) have been recognized but cause death less often. Whether lethal EEHV infections are due to primary infection or reactivation of latent virus remains unknown, and knowledge of the anti-EEHV antibody levels in young elephants is limited. To close these gaps, we sought to develop a serologic assay capable of distinguishing among infections with different EEHVs using a luciferase immunoprecipitation system (LIPS) for antibody profiling and a panel of conserved EEHV recombinant proteins and proteins unique to EEHV1. The results showed that elephants dying from EEHV1 hemorrhagic disease or ill from EEHV infection were seronegative for the EEHV species that caused the disease or illness, indicating that the events were associated with primary infection rather than reactivation of latent virus. We also demonstrated that waning of EEHV1-specific antibodies can occur in the first 2 years of life, when a threshold protective level of antibody may be needed to prevent severe EEHV1-related disease. Use of the LIPS assay to identify putative “diagnostic” proteins would be a valuable asset in determining the EEHV immune status of young elephants and responses to candidate EEHV vaccines in the future. IMPORTANCE Whether clinical illness and deaths associated with elephant endotheliotropic herpesvirus (EEHV) infection result from primary infection or reactivation of latent virus is a longstanding question in the field. By applying a relatively new assay, the luciferase immunoprecipitation system (LIPS), combined with the genomic sequences of the viruses, we gained the insights and tools needed to resolve this issue. Our EEHV1-specific LIPS assay should be useful for assessing the vulnerability of elephant calves to infection with different EEHVs and evaluating antibody responses to anti-EEHV vaccines. A significant proportion of the Asian elephant population is under some form of human care. Hence, the ability to screen for EEHV immune status in elephant calves should have a major impact on the management of these animals worldwide.
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18
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Pavulraj S, Eschke K, Prahl A, Flügger M, Trimpert J, van den Doel PB, Andreotti S, Kaessmeyer S, Osterrieder N, Azab W. Fatal Elephant Endotheliotropic Herpesvirus Infection of Two Young Asian Elephants. Microorganisms 2019; 7:microorganisms7100396. [PMID: 31561506 PMCID: PMC6843339 DOI: 10.3390/microorganisms7100396] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Revised: 09/18/2019] [Accepted: 09/24/2019] [Indexed: 11/16/2022] Open
Abstract
Elephant endotheliotropic herpesvirus (EEHV) can cause a devastating haemorrhagic disease in young Asian elephants worldwide. Here, we report the death of two young Asian elephants after suffering from acute haemorrhagic disease due to EEHV-1A infection. We detected widespread distribution of EEHV-1A in various organs and tissues of the infected elephants. Enveloped viral particles accumulated within and around cytoplasmic electron-dense bodies in hepatic endothelial cells were detected. Attempts to isolate the virus on different cell cultures showed limited virus replication; however, late viral protein expression was detected in infected cells. We further showed that glycoprotein B (gB) of EEHV-1A possesses a conserved cleavage site Arg-X-Lys/Arg-Arg that is targeted by the cellular protease furin, similar to other members of the Herpesviridae. We have determined the complete 180 kb genome sequence of EEHV-1A isolated from the liver by next-generation sequencing and de novo assembly. As virus isolation in vitro has been unsuccessful and limited information is available regarding the function of viral proteins, we have attempted to take the initial steps in the development of suitable cell culture system and virus characterization. In addition, the complete genome sequence of an EEHV-1A in Europe will facilitate future studies on the epidemiology and diagnosis of EEHV infection in elephants.
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Affiliation(s)
- Selvaraj Pavulraj
- Institut für Virologie, Robert von Ostertag-Haus, Zentrum für Infektionsmedizin, Freie Universität Berlin, Robert-von-Ostertag-Str. 7-13, 14163 Berlin, Germany.
| | - Kathrin Eschke
- Institut für Virologie, Robert von Ostertag-Haus, Zentrum für Infektionsmedizin, Freie Universität Berlin, Robert-von-Ostertag-Str. 7-13, 14163 Berlin, Germany.
| | - Adriane Prahl
- Tierpark Hagenbeck gem. GmbH, Lokstedter Grenzstraße 2, 22527 Hamburg, Germany.
| | - Michael Flügger
- Tierpark Hagenbeck gem. GmbH, Lokstedter Grenzstraße 2, 22527 Hamburg, Germany.
| | - Jakob Trimpert
- Institut für Virologie, Robert von Ostertag-Haus, Zentrum für Infektionsmedizin, Freie Universität Berlin, Robert-von-Ostertag-Str. 7-13, 14163 Berlin, Germany.
| | - Petra B van den Doel
- ViroScience Lab, Erasmus Medical Center, Erasmus MC, Room Ee1714, dr. Molewaterplein 50, Rotterdam, 3015, GE, The Netherlands.
| | - Sandro Andreotti
- Department of Mathematics and Computer Science, Institute of Computer Science, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany.
| | - Sabine Kaessmeyer
- Department of Veterinary Medicine, Institute of Veterinary Anatomy, Freie Universität Berlin, Koserstraße 20, 14195 Berlin, Germany.
| | - Nikolaus Osterrieder
- Institut für Virologie, Robert von Ostertag-Haus, Zentrum für Infektionsmedizin, Freie Universität Berlin, Robert-von-Ostertag-Str. 7-13, 14163 Berlin, Germany.
| | - Walid Azab
- Institut für Virologie, Robert von Ostertag-Haus, Zentrum für Infektionsmedizin, Freie Universität Berlin, Robert-von-Ostertag-Str. 7-13, 14163 Berlin, Germany.
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19
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Srivorakul S, Guntawang T, Kochagul V, Photichai K, Sittisak T, Janyamethakul T, Boonprasert K, Khammesri S, Langkaphin W, Punyapornwithaya V, Chuammitri P, Thitaram C, Pringproa K. Possible roles of monocytes/macrophages in response to elephant endotheliotropic herpesvirus (EEHV) infections in Asian elephants (Elephas maximus). PLoS One 2019; 14:e0222158. [PMID: 31491031 PMCID: PMC6730851 DOI: 10.1371/journal.pone.0222158] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Accepted: 08/22/2019] [Indexed: 12/14/2022] Open
Abstract
Elephant endotheliotropic herpesvirus-hemorrhagic disease (EEHV-HD) is the primary cause of acute, highly fatal, hemorrhagic diseases in young Asian elephants. Although monocytopenia is frequently observed in EEHV-HD cases, the role monocytes play in EEHV-disease pathogenesis is unknown. This study seeks to explain the responses of monocytes/macrophages in the pathogenesis of EEHV-HD. Samples of blood, frozen tissues, and formalin-fixed, paraffin-embedded (FFPE) tissues from EEHV1A-HD, EEHV4-HD, co-infected EEHV1A and 4-HD, and EEHV-negative calves were analyzed. Peripheral blood mononuclear cells (PBMCs) from the persistent EEHV4-infected and EEHV-negative calves were also studied. The results showed increased infiltration of Iba-1-positive macrophages in the inflamed tissues of the internal organs of elephant calves with EEHV-HD. In addition, cellular apoptosis also increased in the tissues of elephants with EEHV-HD, especially in the PBMCs, compared to the EEHV-negative control. In the PBMCs of persistent EEHV4-infected elephants, cytokine mRNA expression was high, particularly up-regulation of TNF-α and IFN-γ. Moreover, viral particles were observed in the cytoplasm of the persistent EEHV4-infected elephant monocytes. Our study demonstrated for the first time that apoptosis of the PBMCs increased in cases of EEHV-HD. Furthermore, this study showed that monocytes may serve as a vehicle for viral dissemination during EEHV infection in Asian elephants.
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Affiliation(s)
- Saralee Srivorakul
- Veterinary Diagnostic Laboratory, Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai, Thailand
| | - Thunyamas Guntawang
- Department of Veterinary Biosciences and Veterinary Public Health, Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai, Thailand
| | - Varankpicha Kochagul
- Veterinary Diagnostic Laboratory, Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai, Thailand
| | - Kornravee Photichai
- Veterinary Diagnostic Laboratory, Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai, Thailand
| | - Tidaratt Sittisak
- Department of Veterinary Biosciences and Veterinary Public Health, Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai, Thailand
| | | | - Khajohnpat Boonprasert
- Center of Excellence in Elephant and Wildlife Research, Chiang Mai University, Chiang Mai, Thailand
| | | | | | - Veerasak Punyapornwithaya
- Department of Food Animal Clinic, Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai, Thailand
| | - Phongsakorn Chuammitri
- Department of Veterinary Biosciences and Veterinary Public Health, Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai, Thailand
| | - Chatchote Thitaram
- Center of Excellence in Elephant and Wildlife Research, Chiang Mai University, Chiang Mai, Thailand.,Department of Companion Animals and Wildlife Clinics, Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai, Thailand
| | - Kidsadagon Pringproa
- Department of Veterinary Biosciences and Veterinary Public Health, Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai, Thailand.,Center of Excellence in Elephant and Wildlife Research, Chiang Mai University, Chiang Mai, Thailand
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20
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Boonprasert K, Punyapornwithaya V, Tankaew P, Angkawanish T, Sriphiboon S, Titharam C, Brown JL, Somgird C. Survival analysis of confirmed elephant endotheliotropic herpes virus cases in Thailand from 2006 - 2018. PLoS One 2019; 14:e0219288. [PMID: 31276571 PMCID: PMC6611605 DOI: 10.1371/journal.pone.0219288] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2018] [Accepted: 06/20/2019] [Indexed: 11/19/2022] Open
Abstract
The elephant endotheliotropic herpesvirus (EEHV) has been a known cause of death of young elephants in Thailand for over a decade. In this study, we report on the demography, disease characteristics and mortality of 58 elephants with confirmed EEHV hemorrhagic disease between January 2006 and August 2018 using retrospective data subjected to survival analysis. Median age of EEHV presentation was 29 months, and the mortality rate was 68.97% with a median survival time of 36 h. Most EEHV cases occurred in the north of Thailand, the region where most of the country’s captive elephants reside. The hazard ratio analysis identified application of medical procedures and antiviral medications as being significant factors correlated to the risk of death. Our results indicate a need to focus EEHV monitoring efforts on young elephants and to follow current protocols that advise starting treatments before clinical signs appear.
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Affiliation(s)
| | - Veerasak Punyapornwithaya
- Center of Elephant and Wildlife Research, Chiang Mai University, Chiang Mai, Thailand
- Department of Food Animal Clinic, Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai, Thailand
| | - Pallop Tankaew
- Center of Elephant and Wildlife Research, Chiang Mai University, Chiang Mai, Thailand
| | - Taweepoke Angkawanish
- Elephant Hospital, National Elephant Institute, Forest Industry Organization, Lampang, Thailand
| | - Supaphen Sriphiboon
- Department of Large Animal and Wildlife Clinical Sciences, Faculty of Veterinary Medicine, Kasetsart University, Kamphaeng Saen Campus, Nakornpathom, Thailand
| | - Chatchote Titharam
- Center of Elephant and Wildlife Research, Chiang Mai University, Chiang Mai, Thailand
- Department of Companion Animal and Wildlife Clinics, Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai, Thailand
| | - Janine L. Brown
- Center for Species Survival, Smithsonian Conservation Biology Institute, Front Royal, Virginia, United State of America
| | - Chaleamchat Somgird
- Center of Elephant and Wildlife Research, Chiang Mai University, Chiang Mai, Thailand
- Department of Companion Animal and Wildlife Clinics, Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai, Thailand
- * E-mail:
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21
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Angkawanish T, Nielen M, Vernooij H, Brown JL, van Kooten PJS, van den Doel PB, Schaftenaar W, Na Lampang K, Rutten VPMG. Evidence of high EEHV antibody seroprevalence and spatial variation among captive Asian elephants (Elephas maximus) in Thailand. Virol J 2019; 16:33. [PMID: 30866975 PMCID: PMC6415343 DOI: 10.1186/s12985-019-1142-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Accepted: 03/04/2019] [Indexed: 11/25/2022] Open
Abstract
Background Elephant endotheliotropic herpesviruses (EEHV) can cause an acute highly fatal hemorrhagic disease in young Asian elephants (Elephas maximus), both ex situ and in situ. Amongst eight EEHV types described so far, type 1 (subtype 1A and 1B) is the predominant disease-associated type. Little is known about routes of infection and pathogenesis of EEHV, and knowledge of disease prevalence, especially in range countries, is limited. Methods A large cross-sectional serological survey was conducted in captive elephants (n = 994) throughout Thailand using an EEHV-1A glycoprotein B protein antigen specific antibody ELISA. Results Antibody seroprevalence was 42.3%, with 420 of 994 elephants testing positive. Associations between seropositivity and potential risk factors for EEHV infection were assessed and included: elephant age, sex, camp cluster size, management type (extensive versus intensive), sampling period (wet vs. dry season) and location of camp (region). Univariable regression analysis identified management system and region as risk factors for the presence of EEHV antibodies in elephants, with region being significant in the final multivariable regression model. Prevalence was highest in the North region of the country (49.4%). Conclusions This study produced baseline serological data for captive elephants throughout Thailand, and showed a significant EEHV burden likely to be maintained in the captive population. Electronic supplementary material The online version of this article (10.1186/s12985-019-1142-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Taweepoke Angkawanish
- Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 1, 3584, CL, Utrecht, The Netherlands. .,National Elephant Institute, Lampang-Chiangmai highway (km 28-29), Hangchart, Lampang, 52190, Thailand.
| | - Mirjam Nielen
- Department of Farm Animal Health, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands
| | - Hans Vernooij
- Department of Farm Animal Health, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands
| | - Janine L Brown
- Center for Species Survival, Smithsonian Conservation Biology Institute, Front Royal, Virginia, USA
| | - Peter J S van Kooten
- Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 1, 3584, CL, Utrecht, The Netherlands
| | | | | | - Kannika Na Lampang
- Department of Veterinary Bioscience and Veterinary Public Health, Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai, Thailand
| | - Victor P M G Rutten
- Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 1, 3584, CL, Utrecht, The Netherlands.,Department of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of Pretoria, Pretoria, South Africa
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22
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Bauer KL, Latimer E, Finnegan M. Long-term, intermittent, low-level elephant endotheliotropic herpesvirus 1A viremia in a captive Asian elephant calf. J Vet Diagn Invest 2018; 30:917-919. [PMID: 30264667 DOI: 10.1177/1040638718803138] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
A 2-y-old male Asian elephant ( Elephas maximus), with an elevated platelet count (1,100 × 109/L [1,100 × 103/mm3]), tested positive for elephant endotheliotropic herpesvirus 1A (EEHV-1A) on conventional PCR (cPCR) of EDTA whole blood. No clinical signs were ever reported and no treatment was administered, but low-level viremia persisted for 2.5 y based on results of cPCR and/or real-time PCR (rtPCR). Sequencing confirmed that the EEHV-1A detected was identical at the beginning through the end of the time period. No other elephants in the herd tested positive for EEHV-1 during this time period. Platelet counts remained elevated throughout the viremia and throughout the animal's life, and direct correlation between the elevated platelet counts and EEHV-1A viremia could not be confirmed. We document long-term, intermittent, low-level viremia of EEHV-1A and provide additional information to consider when determining if treatment is warranted in a case of EEHV infection.
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Affiliation(s)
- Kendra L Bauer
- Smithsonian Institution National Zoological Park, Smithsonian Conservation Biology Institute, Wildlife Health Sciences, Washington, DC (Bauer, Latimer).,Oregon Zoo, Portland, OR (Finnegan).,Houston Zoo, Houston, TX (Bauer)
| | - Erin Latimer
- Smithsonian Institution National Zoological Park, Smithsonian Conservation Biology Institute, Wildlife Health Sciences, Washington, DC (Bauer, Latimer).,Oregon Zoo, Portland, OR (Finnegan).,Houston Zoo, Houston, TX (Bauer)
| | - Mitch Finnegan
- Smithsonian Institution National Zoological Park, Smithsonian Conservation Biology Institute, Wildlife Health Sciences, Washington, DC (Bauer, Latimer).,Oregon Zoo, Portland, OR (Finnegan).,Houston Zoo, Houston, TX (Bauer)
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23
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Zachariah A, Sajesh PK, Santhosh S, Bathrachalam C, Megha M, Pandiyan J, Jishnu M, Kobragade RS, Long SY, Zong JC, Latimer EM, Heaggans SY, Hayward GS. Extended genotypic evaluation and comparison of twenty-two cases of lethal EEHV1 hemorrhagic disease in wild and captive Asian elephants in India. PLoS One 2018; 13:e0202438. [PMID: 30133540 PMCID: PMC6105008 DOI: 10.1371/journal.pone.0202438] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Accepted: 08/02/2018] [Indexed: 11/18/2022] Open
Abstract
Thirteen new lethal cases of acute hemorrhagic disease (HD) with typical histopathogical features were identified in young Asian elephants (Elephas maximus indicus) in India between 2013 and 2017. Eight occurred amongst free-ranging wild herds, with three more in camp-raised orphans and two in captive-born calves. All were confirmed to have high levels of Elephant Endotheliotropic Herpesvirus type 1A (EEHV1A) DNA detected within gross pathological lesions from necropsy tissue by multi-locus PCR DNA sequencing. The strains involved were all significantly different from one another and from nine previously described cases from Southern India (which included one example of EEHV1B). Overall, eight selected dispersed PCR loci totaling up to 6.1-kb in size were analyzed for most of the 22 cases, with extensive subtype clustering data being obtained at four hypervariable gene loci. In addition to the previously identified U48(gH-TK) and U51(vGPCR1) gene loci, these included two newly identified E5(vGPCR5) and E54(vOX2-1) loci mapping far outside of the classic EEHV1A versus EEHV1B subtype chimeric domains and towards the novel end segments of the genome that had not been evaluated previously. The high levels of genetic divergence and mosaic scrambling observed between adjacent loci match closely to the overall range of divergence found within 45 analyzed North American and European cases, but include some common relatively unique polymorphic features and preferred subtypes that appear to distinguish most but not all Indian strains from both those in Thailand and those outside range countries. Furthermore, more than half of the Indian cases studied here involved calves living within wild herds, whereas nearly all other cases identified in Asia so far represent rescued camp orphans or captive-born calves.
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Affiliation(s)
- A. Zachariah
- Department of Forests and Wildlife, Government of Kerala, Sultan Battery, Wayanad, India
| | - P. K. Sajesh
- SciGenom Research Foundation, Cheruthuruthy, Kerala, India
| | - S. Santhosh
- SciGenom Research Foundation, Cheruthuruthy, Kerala, India
| | | | - M. Megha
- SciGenom Research Foundation, Cheruthuruthy, Kerala, India
| | - J. Pandiyan
- AVC College, Mayiladuthurai, Tamilnadu, India
| | - M. Jishnu
- Department of Forests and Wildlife, Government of Kerala, Sultan Battery, Wayanad, India
| | - R. S. Kobragade
- Tadoba-Andhari Tiger Reserve, Chandrapur, Maharashtra, India
| | - S. Y. Long
- Viral Oncology Program, Department of Oncology, Johns Hopkins School of Medicine, Baltimore, MD, United States of America
| | - J-C Zong
- Viral Oncology Program, Department of Oncology, Johns Hopkins School of Medicine, Baltimore, MD, United States of America
| | - E. M. Latimer
- Wildlife Health Sciences, Smithsonian’s National Zoological Park, Washington, DC, United States of America
| | - S. Y. Heaggans
- Viral Oncology Program, Department of Oncology, Johns Hopkins School of Medicine, Baltimore, MD, United States of America
| | - G. S. Hayward
- Viral Oncology Program, Department of Oncology, Johns Hopkins School of Medicine, Baltimore, MD, United States of America
- * E-mail:
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24
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Kochakul V, Boonsri K, Tiwananthagorn S, Somgird C, Thitaram C, Pringproa K. Development of in situ hybridization for detection of elephant endotheliotropic herpesvirus in Asian elephants. J Vet Diagn Invest 2018; 30:628-632. [PMID: 29730973 DOI: 10.1177/1040638718773810] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Elephant endotheliotropic herpesvirus (EEHV) is one of the most important viral infectious diseases affecting the elephant population worldwide, especially juveniles and young adults. We developed a chromogenic in situ hybridization (ISH) test for detection of EEHV in Asian elephants ( Elephas maximus). Digoxigenin (DIG) DNA probes from the polymerase and terminase genes of EEHV were synthesized using a PCR DIG-labeling method, and detection of hybridized probe to target EEHV DNA was carried out by anti-DIG immunolabeling. Distribution of EEHV-1A and EEHV-4 genomes was found to be prominent in mononuclear phagocytic cells of spleen and endothelial cells of visceral organs. ISH enables the detection of EEHV infection and has applications in understanding pathogenesis of EEHV in Asian elephants.
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Affiliation(s)
- Varankpicha Kochakul
- Veterinary Diagnostic Laboratory (Kochakul, Boonsri), Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai, Thailand.,Department of Veterinary Biosciences and Veterinary Public Health (Tiwananthagorn, Pringproa), Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai, Thailand.,Department of Companion Animals and Wildlife Clinics (Somgird, Thitaram), Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai, Thailand.,Center of Excellence in Elephant Research and Education (Somgird, Thitaram, Pringproa), Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai, Thailand
| | - Kittikorn Boonsri
- Veterinary Diagnostic Laboratory (Kochakul, Boonsri), Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai, Thailand.,Department of Veterinary Biosciences and Veterinary Public Health (Tiwananthagorn, Pringproa), Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai, Thailand.,Department of Companion Animals and Wildlife Clinics (Somgird, Thitaram), Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai, Thailand.,Center of Excellence in Elephant Research and Education (Somgird, Thitaram, Pringproa), Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai, Thailand
| | - Saruda Tiwananthagorn
- Veterinary Diagnostic Laboratory (Kochakul, Boonsri), Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai, Thailand.,Department of Veterinary Biosciences and Veterinary Public Health (Tiwananthagorn, Pringproa), Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai, Thailand.,Department of Companion Animals and Wildlife Clinics (Somgird, Thitaram), Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai, Thailand.,Center of Excellence in Elephant Research and Education (Somgird, Thitaram, Pringproa), Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai, Thailand
| | - Chalermchart Somgird
- Veterinary Diagnostic Laboratory (Kochakul, Boonsri), Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai, Thailand.,Department of Veterinary Biosciences and Veterinary Public Health (Tiwananthagorn, Pringproa), Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai, Thailand.,Department of Companion Animals and Wildlife Clinics (Somgird, Thitaram), Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai, Thailand.,Center of Excellence in Elephant Research and Education (Somgird, Thitaram, Pringproa), Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai, Thailand
| | - Chatchote Thitaram
- Veterinary Diagnostic Laboratory (Kochakul, Boonsri), Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai, Thailand.,Department of Veterinary Biosciences and Veterinary Public Health (Tiwananthagorn, Pringproa), Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai, Thailand.,Department of Companion Animals and Wildlife Clinics (Somgird, Thitaram), Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai, Thailand.,Center of Excellence in Elephant Research and Education (Somgird, Thitaram, Pringproa), Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai, Thailand
| | - Kidsadagon Pringproa
- Veterinary Diagnostic Laboratory (Kochakul, Boonsri), Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai, Thailand.,Department of Veterinary Biosciences and Veterinary Public Health (Tiwananthagorn, Pringproa), Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai, Thailand.,Department of Companion Animals and Wildlife Clinics (Somgird, Thitaram), Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai, Thailand.,Center of Excellence in Elephant Research and Education (Somgird, Thitaram, Pringproa), Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai, Thailand
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25
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Production of antibody against elephant endotheliotropic herpesvirus (EEHV) unveils tissue tropisms and routes of viral transmission in EEHV-infected Asian elephants. Sci Rep 2018; 8:4675. [PMID: 29549315 PMCID: PMC5856810 DOI: 10.1038/s41598-018-22968-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Accepted: 03/05/2018] [Indexed: 01/06/2023] Open
Abstract
Elephant endotheliotropic herpesvirus (EEHV) is one of the most devastating viral infectious diseases in elephants worldwide. To date, it remains unclear how elephants get infected by the virus, where the virus persists, and what mechanisms drive the pathogenesis of the disease. The present study was aimed to develop an antibody against glycoprotein B (gB) of EEHV, investigate the EEHV tissue tropisms, and provide the possible routes of EEHV transmission in Asian elephants. Samples from elephant organs that had died from EEHV1A and EEHV4 infections, peripheral blood mononuclear cells (PBMC) from EEHV4- and non-EEHV-infected calves were used in this study. The results of western immunoblotting indicated that the antibody can be used for detection of gB antigens in both EEHV1A- and EEHV4-infected samples. Immunohistochemical detection indicated that the EEHV gB antigens were distributed mainly in the epithelial cells of the salivary glands, stomach and intestines. Immunofluorescence test of PBMC for EEHV gB in the EEHV4-infected calf indicated that the virus was observed predominantly in the mononuclear phagocytic cells. The findings in the present study unveil tissue tropisms in the EEHV1A- and EEHV4-infected calves and point out that saliva and intestinal content are likely sources for virus transmission in EEHV-infected Asian elephants.
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26
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Asian Elephant T Cell Responses to Elephant Endotheliotropic Herpesvirus. J Virol 2018; 92:JVI.01951-17. [PMID: 29263271 PMCID: PMC5827410 DOI: 10.1128/jvi.01951-17] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Accepted: 12/14/2017] [Indexed: 12/20/2022] Open
Abstract
Elephant endotheliotropic herpesvirus (EEHV) can cause lethal hemorrhagic disease in juvenile Asian elephants, an endangered species. One hypothesis to explain this vulnerability of some juvenile elephants is that they fail to mount an effective T cell response to the virus. To our knowledge, there have been no studies of Asian elephant T cell responses to EEHV. To address this deficiency, we validated the gamma interferon (IFN-γ) enzyme-linked immunospot assay for tracking antigen-directed T cell activity by monitoring rabies-specific responses in vaccinated elephants. In addition, we generated monoclonal antibodies to Asian elephant CD4 and CD8 to facilitate phenotypic T cell profiling. Using these tools, we screened healthy elephants with a history of EEHV infection for reactivity against nine EEHV proteins whose counterparts in other herpesviruses are known to induce T cell responses in their natural hosts. We identified glycoprotein B (gB) and the putative regulatory protein E40 as the most immunogenic T cell targets (IFN-γ responses in five of seven elephants), followed by the major capsid protein (IFN-γ responses in three of seven elephants). We also observed that IFN-γ responses were largely from CD4+ T cells. We detected no activity against the predicted major immediate early (E44) and large tegument (E34) proteins, both immunodominant T cell targets in humans latently infected with cytomegalovirus. These studies identified EEHV-specific T cells in Asian elephants for the first time, lending insight into the T cell priming that might be required to protect against EEHV disease, and will guide the design of effective vaccine strategies. IMPORTANCE Endangered Asian elephants are facing many threats, including lethal hemorrhagic disease from elephant endotheliotropic herpesvirus (EEHV). EEHV usually establishes chronic, benign infections in mature Asian elephants but can be lethal to juvenile elephants in captivity and the wild. It is the leading cause of death in captive Asian elephants in North America and Europe. Despite the availability of sensitive tests and protocols for treating EEHV-associated illness, these measures are not always effective. The best line of defense would be a preventative vaccine. We interrogated normal healthy elephants previously infected with EEHV for T cell responses to nine EEHV proteins predicted to induce cellular immune responses. Three proteins elicited IFN-γ responses, suggesting their potential usefulness as vaccine candidates. Our work is the first to describe T cell responses to a member of the proposed fourth subfamily of mammalian herpesviruses, the Deltaherpesvirinae, within a host species in the clade Afrotheria. An EEHV vaccine would greatly contribute to the health care of Asian and African elephants that are also susceptible to this disease.
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27
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Azab W, Damiani AM, Ochs A, Osterrieder N. Subclinical infection of a young captive Asian elephant with elephant endotheliotropic herpesvirus 1. Arch Virol 2017; 163:495-500. [PMID: 29094239 DOI: 10.1007/s00705-017-3628-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Accepted: 10/09/2017] [Indexed: 01/06/2023]
Abstract
Elephant endotheliotropic herpesviruses (EEHVs) are a continuous threat for young Asian elephants. We report a laboratory-confirmed infection of a 5-year-old female Asian elephant (AZ_2016) in the Berlin Zoologischer Garten. Initially, high EEHV-1 loads were detected in trunk swabs obtained from the young elephant during routine screening. The animal showed no clinical signs except for slight irritability. EEHV-1 was continuously shed for almost one year, with fluctuations in viral load from time to time. Our investigations highlight the continuous threat of EEHV-1 to young captive Asian elephants and stress the importance of routine monitoring of captive elephants to allow early detection of infection.
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Affiliation(s)
- Walid Azab
- Institut für Virologie, Robert von Ostertag-Haus, Zentrum für Infektionsmedizin, Freie Universität Berlin, Robert-von-Ostertag-Str. 7-13, 14163, Berlin, Germany.
| | - Armando Mario Damiani
- Institut für Virologie, Robert von Ostertag-Haus, Zentrum für Infektionsmedizin, Freie Universität Berlin, Robert-von-Ostertag-Str. 7-13, 14163, Berlin, Germany
- Instituto de Medicina y Biología Experimental de Cuyo IMBECU, CCT Mendoza-CONICET, Área de Química Biológica, Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, Mendoza, Argentina
| | - Andreas Ochs
- Zoologischer Garten Berlin AG, Hardenbergplatz 8, 10787, Berlin, Germany
| | - Nikolaus Osterrieder
- Institut für Virologie, Robert von Ostertag-Haus, Zentrum für Infektionsmedizin, Freie Universität Berlin, Robert-von-Ostertag-Str. 7-13, 14163, Berlin, Germany
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28
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Smith SD, Kawash JK, Karaiskos S, Biluck I, Grigoriev A. Evolutionary adaptation revealed by comparative genome analysis of woolly mammoths and elephants. DNA Res 2017; 24:359-369. [PMID: 28369217 PMCID: PMC5737375 DOI: 10.1093/dnares/dsx007] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2016] [Accepted: 03/15/2017] [Indexed: 12/19/2022] Open
Abstract
Comparative genomics studies typically limit their focus to single nucleotide variants (SNVs) and that was the case for previous comparisons of woolly mammoth genomes. We extended the analysis to systematically identify not only SNVs but also larger structural variants (SVs) and indels and found multiple mammoth-specific deletions and duplications affecting exons or even complete genes. The most prominent SV found was an amplification of RNase L (with different copy numbers in different mammoth genomes, up to 9-fold), involved in antiviral defense and inflammasome function. This amplification was accompanied by mutations affecting several domains of the protein including the active site and produced different sets of RNase L paralogs in four mammoth genomes likely contributing to adaptations to environmental threats. In addition to immunity and defense, we found many other unique genetic changes in woolly mammoths that suggest adaptations to life in harsh Arctic conditions, including variants involving lipid metabolism, circadian rhythms, and skeletal and body features. Together, these variants paint a complex picture of evolution of the mammoth species and may be relevant in the studies of their population history and extinction.
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Affiliation(s)
- Sean D Smith
- Department of Biology, Center for Computational and Integrative Biology, Rutgers University, Camden, NJ, USA
| | - Joseph K Kawash
- Department of Biology, Center for Computational and Integrative Biology, Rutgers University, Camden, NJ, USA
| | - Spyros Karaiskos
- Department of Biology, Center for Computational and Integrative Biology, Rutgers University, Camden, NJ, USA
| | - Ian Biluck
- Department of Biology, Center for Computational and Integrative Biology, Rutgers University, Camden, NJ, USA
| | - Andrey Grigoriev
- Department of Biology, Center for Computational and Integrative Biology, Rutgers University, Camden, NJ, USA
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29
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EPIDEMIOLOGIC EVALUATION OF ELEPHANT ENDOTHELIOTROPIC HERPESVIRUS 3B INFECTION IN AN AFRICAN ELEPHANT (LOXODONTA AFRICANA). J Zoo Wildl Med 2017; 48:335-343. [PMID: 28749266 DOI: 10.1638/2016-0063r.1] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
This epidemiologic study follows a 5-yr-old male African elephant ( Loxodonta africana ) during an episode of hemorrhagic disease (HD) due to elephant endotheliotropic herpesvirus 3B (EEHV3B) utilizing data from complete blood counts, electrophoresis and acute phase protein analysis, and polymerase chain reaction (PCR) of multiple body fluids during and after the clinical episode. The elephant presented with sudden onset of marked lethargy and inappetence followed by hypersalivation, hyperemia of the conjunctivae and focally on the tongue, and swellings on the head and ventrum. A moderate leukocytopenia with band neutrophilia, lymphopenia, monocytopenia, and thrombocytophilia was followed by a rise in all three cell types by day 10. Moderate increases in serum amyloid A and C-reactive protein were noted in the first weeks of illness. Conventional PCR of whole blood yielded a strong positive result for EEHV3B. Quantitative PCR revealed moderate viremia, which slowly returned to undetectable levels by day 35 of treatment. EEHV3B was shed in trunk wash samples starting at day 22 for 10 days at moderate levels, and then at low levels for up to 8.5 mo. All three female herd mates shed low levels of EEHV3B in trunk washes intermittently starting from day 28 of the calf's illness until over 7 mo afterward. The majority of saliva samples from the calf over the 8.5-mo period were also positive for EEHV3B. A subfraction of saliva samples from a female herdmate was positive from days 127-190 following disease onset in the calf. Four elephant gammaherpesviruses were detected sporadically from the calf and female herdmates during this same time period. Treatment was started at the onset of clinical signs and consisted of rectal and oral fluids and oral famciclovir. This is the first case of EEHV3B HD in an elephant species and the first thorough epidemiologic evaluation of EEHV HD in an African elephant.
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Barman NN, Choudhury B, Kumar V, Koul M, Gogoi SM, Khatoon E, Chakroborty A, Basumatary P, Barua B, Rahman T, Das SK, Kumar S. Incidence of elephant endotheliotropic herpesvirus in Asian elephants in India. Vet Microbiol 2017; 208:159-163. [PMID: 28888631 DOI: 10.1016/j.vetmic.2017.08.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2017] [Revised: 07/30/2017] [Accepted: 08/01/2017] [Indexed: 12/01/2022]
Abstract
Elephant endotheliotropic herpesviruses (EEHVs) are the cause of acute hemorrhagic disease in endangered Asian and African elephants. In the present study, we report the incidence of EEHV infection and associated mortality in the captive elephant of Assam, India. Our result showed the gross morphology and histopathological changes of EEHV infection in the elephant. Moreover, the phylogenetic analysis of the polymerase, helicase, and GPCR genes from the infected tissue samples suggested the presence of EEHV1A virus.
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Affiliation(s)
- Nagendra N Barman
- College of Veterinary Science, Assam Agricultural University, Khanapara, Guwahati, Assam, India
| | | | - Vishnu Kumar
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, Assam 781039, India
| | - Monika Koul
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, Assam 781039, India
| | - Sophia M Gogoi
- College of Veterinary Science, Assam Agricultural University, Khanapara, Guwahati, Assam, India
| | - Elina Khatoon
- College of Veterinary Science, Assam Agricultural University, Khanapara, Guwahati, Assam, India
| | - A Chakroborty
- College of Veterinary Science, Assam Agricultural University, Khanapara, Guwahati, Assam, India
| | | | - B Barua
- Veterinary officer, Government of Assam, India
| | - T Rahman
- College of Veterinary Science, Assam Agricultural University, Khanapara, Guwahati, Assam, India
| | - S K Das
- College of Veterinary Science, Assam Agricultural University, Khanapara, Guwahati, Assam, India
| | - Sachin Kumar
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, Assam 781039, India.
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Ackermann M, Hatt JM, Schetle N, Steinmetz H. Identification of shedders of elephant endotheliotropic herpesviruses among Asian elephants (Elephas maximus) in Switzerland. PLoS One 2017; 12:e0176891. [PMID: 28467495 PMCID: PMC5415103 DOI: 10.1371/journal.pone.0176891] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Accepted: 04/19/2017] [Indexed: 12/02/2022] Open
Abstract
Elephants, particularly Asian (Elephas maximus), are threatened by lethal elephant hemorrhagic disease (EHD) due to elephant endotheliotropic herpesviruses (EEHV). At least five of seven known EEHV types have been associated to EHD, with types 1, 4, and 5 predominantly affecting Asian elephants. In Switzerland, at least three Asian elephants have been lost due to EHD but nothing is known about the present EEHV1 circulation. Moreover, the prevalence of other EEHV types has never been assessed. Intermittent shedding of EEHV can be monitored through collecting trunk secretions and analyzing them by PCR methods that discriminate the different EEHV types. To identify EEHV shedders, seven of eight Asian elephants in a Swiss zoo were trained to provide trunk wash samples. These were collected at intervals over a period of four months and tested by PCR for presence of EEHV1 through 6. Moreover, the quality of each sample was assessed by testing for the elephant TNF-alpha gene. Overall, 57% of the samples were valid with five of seven participating elephants identified as EEHV shedders. Two of those shed virus only once, whereas the other three, all closely related among each other, shed virus on multiple occasions. One of the frequent shedders had been in very close contact to all of the three EHD victims. Therefore, we speculate that this particular animal may represent the virus source in all three cases. However, when subtyping was conducted, the presently circulating virus was identified as EEHV1B, while the virus subtype causing EHD had been 1A in all three cases. In addition to four animals excreting EEHV1, a recently introduced animal was observed to shed EEHV3/4. We suggest that the policy of trunk washing to identify and characterize EEHV-shedders is to be endorsed in zoos with ongoing or planned elephant breeding programs.
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Affiliation(s)
- Mathias Ackermann
- University of Zurich, Vetsuisse Faculty, Institute of Virology, Zurich, Switzerland
- * E-mail:
| | - Jean-Michel Hatt
- University of Zurich, Vetsuisse Faculty, Clinic for Zoo Animals, Exotic Pets and Wildlife, Zurich, Switzerland
| | - Nelli Schetle
- University of Zurich, Vetsuisse Faculty, Institute of Virology, Zurich, Switzerland
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Long SY, Latimer EM, Hayward GS. Review of Elephant Endotheliotropic Herpesviruses and Acute Hemorrhagic Disease. ILAR J 2016; 56:283-96. [PMID: 26912715 DOI: 10.1093/ilar/ilv041] [Citation(s) in RCA: 84] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
More than 100 young captive and wild Asian elephants are known to have died from a rapid-onset, acute hemorrhagic disease caused primarily by multiple distinct strains of two closely related chimeric variants of a novel herpesvirus species designated elephant endotheliotropic herpesvirus (EEHV1A and EEHV1B). These and two other species of Probosciviruses (EEHV4 and EEHV5) are evidently ancient and likely nearly ubiquitous asymptomatic infections of adult Asian elephants worldwide that are occasionally shed in trunk wash secretions. Although only a handful of similar cases have been observed in African elephants, they also have proved to harbor their own multiple and distinct species of Probosciviruses-EEHV2, EEHV3, EEHV6, and EEHV7-found in lung and skin nodules or saliva. For reasons that are not yet understood, approximately 20% of Asian elephant calves appear to be susceptible to the disease when primary infections are not controlled by normal innate cellular and humoral immune responses. Sensitive specific polymerase chain reaction (PCR) DNA blood tests have been developed, routine monitoring has been established, the complete large DNA genomes of each of the four Asian EEHV species have now been sequenced, and PCR gene subtyping has provided unambiguous evidence that this is a sporadic rather than epidemic disease that it is not being spread among zoos or other elephant housing facilities. Nevertheless, researchers have not yet been able to propagate EEHV in cell culture, determine whether or not human antiherpesvirus drugs are effective inhibitors, or develop serology assays that can distinguish between antibodies against the multiple different EEHV species.
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Affiliation(s)
- Simon Y Long
- Simon Y. Long, MS, VMD, is a pathology postdoctoral fellow in the Department of Molecular and Comparative Pathobiology and a graduate student under Dr. Gary S. Hayward in the graduate program in Cellular and Molecular Medicine at Johns Hopkins School of Medicine in Baltimore, Maryland. Erin M. Latimer, MS, is a research specialist and manager of the National Elephant Herpesvirus Laboratory at the Smithsonian's National Zoological Park in Washington, DC. Gary S. Hayward, PhD, is a professor in the Viral Oncology Program, Pharmacology and Molecular Sciences, and Pathology Departments at Johns Hopkins School of Medicine in Baltimore, Maryland
| | - Erin M Latimer
- Simon Y. Long, MS, VMD, is a pathology postdoctoral fellow in the Department of Molecular and Comparative Pathobiology and a graduate student under Dr. Gary S. Hayward in the graduate program in Cellular and Molecular Medicine at Johns Hopkins School of Medicine in Baltimore, Maryland. Erin M. Latimer, MS, is a research specialist and manager of the National Elephant Herpesvirus Laboratory at the Smithsonian's National Zoological Park in Washington, DC. Gary S. Hayward, PhD, is a professor in the Viral Oncology Program, Pharmacology and Molecular Sciences, and Pathology Departments at Johns Hopkins School of Medicine in Baltimore, Maryland
| | - Gary S Hayward
- Simon Y. Long, MS, VMD, is a pathology postdoctoral fellow in the Department of Molecular and Comparative Pathobiology and a graduate student under Dr. Gary S. Hayward in the graduate program in Cellular and Molecular Medicine at Johns Hopkins School of Medicine in Baltimore, Maryland. Erin M. Latimer, MS, is a research specialist and manager of the National Elephant Herpesvirus Laboratory at the Smithsonian's National Zoological Park in Washington, DC. Gary S. Hayward, PhD, is a professor in the Viral Oncology Program, Pharmacology and Molecular Sciences, and Pathology Departments at Johns Hopkins School of Medicine in Baltimore, Maryland
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Pursell T, Tan J, Peng R, Ling PD. Generation and validation of new quantitative real time PCR assays to detect elephant endotheliotropic herpesviruses 1A, 1B, and 4. J Virol Methods 2016; 237:138-142. [PMID: 27542531 DOI: 10.1016/j.jviromet.2016.08.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Revised: 06/24/2016] [Accepted: 08/14/2016] [Indexed: 10/21/2022]
Abstract
Elephant endotheliotropic herpesviruses (EEHVs) can cause fatal hemorrhagic disease in Asian and African elephants. There are quantitative real time PCR (qPCR) tests that can detect seven known EEHVs (1A, 1B, 2-6) in mucosal secretions, tissue isolates, and blood samples. However, current qPCR tests are unable to distinguish between EEHV 1A and 1B or 3 and 4. To address these inadequacies, new qPCR assays were generated and validated to specifically detect EEHV 1A, 1B, and 4. Each assay demonstrated robust efficiency, a broad linear range, and low intra- and inter-assay variability. Each also proved to be specific for its EEHV target when tested against known banked samples from past EEHV cases. The EEHV1A and 1B assays were then used to characterize an eight-week, low level EEHV1 viremic event in a young Asian elephant. These new tests will allow veterinarians and researchers to pinpoint the specific species causing infection more rapidly. They will also allow veterinarians and elephant keepers to better characterize the EEHV status of each animal within their herd leading to more informed management strategies.
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Affiliation(s)
- Taylor Pursell
- College of Veterinary Medicine, Texas A&M University, College Station, TX 77845, USA.
| | - Jie Tan
- Department of Molecular Virology and Microbiology, One Baylor Plaza, Baylor College of Medicine, Houston, TX 77030, USA.
| | - RongSheng Peng
- Department of Molecular Virology and Microbiology, One Baylor Plaza, Baylor College of Medicine, Houston, TX 77030, USA.
| | - Paul D Ling
- Department of Molecular Virology and Microbiology, One Baylor Plaza, Baylor College of Medicine, Houston, TX 77030, USA.
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Complete Genome Sequence of Elephant Endotheliotropic Herpesvirus 4, the First Example of a GC-Rich Branch Proboscivirus. mSphere 2016; 1:mSphere00081-15. [PMID: 27340695 PMCID: PMC4911795 DOI: 10.1128/msphere.00081-15] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Accepted: 05/09/2016] [Indexed: 01/25/2023] Open
Abstract
A novel group of mammalian DNA viruses called elephant endotheliotropic herpesviruses (EEHVs) belonging to the Proboscivirus genus has been associated with nearly 100 cases of highly lethal acute hemorrhagic disease in young Asian elephants worldwide. The complete 180-kb genomes of prototype strains from three AT-rich branch viruses, EEHV1A, EEHV1B, and EEHV5, have been published. However, less than 6 kb of DNA sequence each from EEHV3, EEHV4, and EEHV7 showed them to be a hugely diverged second major branch with GC-rich characteristics. Here, we determined the complete 206-kb genome of EEHV4(Baylor) directly from trunk wash DNA by next-generation sequencing and de novo assembly procedures. Among a total of 119 genes with an overall colinear organization similar to those of the AT-rich EEHVs, major features of EEHV4 include a family of 26 paralogous 7xTM and vGPCR-like genes plus 25 novel or missing genes. The genome also contains an unusual distribution of tracts of 5 to 11 successive A or T nucleotides in intergenic domains between the mostly much higher GC content protein coding regions. Furthermore, an extremely high GC-rich bias in the third wobble position of codons clearly delineates the coding regions for many but not all proteins. There are also two novel captured cellular genes, including a C-type lectin (vECTL) and an O-linked acetylglucosamine transferase (vOGT), as well as an unusually large and complex Ori-Lyt dyad symmetry domain. Finally, 30 kb from a second strain proved to include three small chimeric domains, indicating the existence of distinct EEHV4A and EEHV4B subtypes. IMPORTANCE Multiple species of herpesviruses from three different lineages of the Proboscivirus genus (EEHV1/6, EEHV2/5, and EEHV3/4/7) infect both Asian and African elephants, but lethal hemorrhagic disease is largely confined to Asian elephant calves and is predominantly associated with EEHV1. Milder disease caused by EEHV5 or EEHV4 is being increasingly recognized as well, but little is known about the latter, which is estimated to have diverged at least 35 million years ago from the others within a distinctive GC-rich branch of the Proboscivirus genus. Here, we have determined the complete genomic DNA sequence of a strain of EEHV4 obtained from a trunk wash sample collected from a surviving Asian elephant calf undergoing asymptomatic shedding during convalescence after an acute hemorrhagic disease episode. This represents the first example from among the three known GC-rich branch Proboscivirus species to be assembled and fully annotated. Several distinctive features of EEHV4 compared to AT-rich branch genomes are described.
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Comparison of the Gene Coding Contents and Other Unusual Features of the GC-Rich and AT-Rich Branch Probosciviruses. mSphere 2016; 1:mSphere00091-16. [PMID: 27340696 PMCID: PMC4911796 DOI: 10.1128/msphere.00091-16] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Accepted: 05/09/2016] [Indexed: 11/29/2022] Open
Abstract
Multiple species of herpesviruses from three different lineages of the Proboscivirus genus (EEHV1/6, EEHV2/5, and EEHV3/4/7) infect either Asian or African elephants, but the highly lethal hemorrhagic disease is largely confined to Asian elephant calves and is predominantly associated with EEHV1. In the accompanying paper [P. D. Ling et al., mSphere 1(3):e00081-15, http://dx.doi.org/10.1128/mSphere.00081-15], we report the complete 206-kb genome of EEHV4, the third different species causing disease in Asian elephants and the first example of a GC-rich branch proboscivirus. To gain insights into the nature and differential properties of these two very anciently diverged lineages of elephant herpesviruses, we describe here several additional unusual features found in the complete GC-rich genome of EEHV4 with particular emphasis on patterns of divergence as well as common unique features that are distinct from those of all other herpesviruses, such as the enlarged AT-rich intergenic domains and gene families, including the large number of vGPCR-like proteins. Nearly 100 cases of lethal acute hemorrhagic disease in young Asian elephants have been reported worldwide. All tested cases contained high levels of elephant endotheliotropic herpesvirus (EEHV) DNA in pathological blood or tissue samples. Seven known major types of EEHVs have been partially characterized and shown to all belong to the novel Proboscivirus genus. However, the recently determined 206-kb EEHV4 genome proved to represent the prototype of a GC-rich branch virus that is very distinct from the previously published 180-kb EEHV1A, EEHV1B, and EEHV5A genomes, which all fall within an alternative AT-rich branch. Although EEHV4 retains the large family of 7xTM and vGPCR-like genes, six are unique to either just one or the other branch. While both branches display a highly enriched distribution of A and T tracts in intergenic domains, they are generally much larger within the GC-rich branch. Both branches retain the vGCNT1 acetylglucosamine transferase and at least one vOX-2 gene, but the two branches differ by 25 genes overall, with the AT-rich branch encoding a fucosyl transferase (vFUT9) plus two or three more vOX2 proteins and an immunoglobulin-like gene family that are all absent from the GC-rich branch. Several envelope glycoproteins retain only 15 to 20% protein identity or less across the two branches. Finally, the two plausible predicted transcriptional regulatory proteins display no homology at all to those in the alpha-, beta-, or gammaherpesvirus subfamilies. These results reinforce our previous proposal that the probosciviruses should be designated a new subfamily of mammalian herpesviruses. IMPORTANCE Multiple species of herpesviruses from three different lineages of the Proboscivirus genus (EEHV1/6, EEHV2/5, and EEHV3/4/7) infect either Asian or African elephants, but the highly lethal hemorrhagic disease is largely confined to Asian elephant calves and is predominantly associated with EEHV1. In the accompanying paper [P. D. Ling et al., mSphere 1(3):e00081-15, 10.1128/mSphere.00081-15], we report the complete 206-kb genome of EEHV4, the third different species causing disease in Asian elephants and the first example of a GC-rich branch proboscivirus. To gain insights into the nature and differential properties of these two very anciently diverged lineages of elephant herpesviruses, we describe here several additional unusual features found in the complete GC-rich genome of EEHV4 with particular emphasis on patterns of divergence as well as common unique features that are distinct from those of all other herpesviruses, such as the enlarged AT-rich intergenic domains and gene families, including the large number of vGPCR-like proteins.
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CLINICAL INFECTION OF TWO CAPTIVE ASIAN ELEPHANTS (ELEPHAS MAXIMUS) WITH ELEPHANT ENDOTHELIOTROPIC HERPESVIRUS 1B. J Zoo Wildl Med 2016; 47:319-24. [PMID: 27010294 DOI: 10.1638/2015-0074.1] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The ability of prior infection from one elephant endotheliotropic herpesvirus (EEHV) type to protect against clinical or lethal infection from others remains an important question. This report describes viremia and subsequent shedding of EEHV1B in two juvenile 4-yr-old Asian elephants within 3 wk or 2 mo following significant infections caused by the rarely seen EEHV4. High levels of EEHV1B shedding were detected in the first elephant prior to emergence of infection and viremia in the second animal. The EEHV1B virus associated with both infections was identical to the strain causing infection in two herd mates previously. High EEHV viremia correlated with leukopenia and thrombocytopenia, which was followed by leukocytosis and thrombocytosis when clinical signs started to resolve. The observations from these cases should be beneficial for helping other institutions monitor and treat elephants infected with EEHV1, the most common virus associated with lethal hemorrhagic disease.
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CLINICAL INFECTION OF CAPTIVE ASIAN ELEPHANTS (ELEPHAS MAXIMUS) WITH ELEPHANT ENDOTHELIOTROPIC HERPESVIRUS 4. J Zoo Wildl Med 2016; 47:311-8. [PMID: 27010293 DOI: 10.1638/2015-0072.1] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Elephant endotheliotropic herpesvirus (EEHV) can cause lethal hemorrhagic disease in juvenile Asian elephants. A number of EEHV types and subtypes exist, where most deaths have been caused by EEHV1A and EEHV1B. EEHV4 has been attributed to two deaths, but as both diagnoses were made postmortem, EEHV4 disease has not yet been observed and recorded clinically. In this brief communication, two cases of EEHV4 infection in juvenile elephants at the Houston Zoo are described, where both cases were resolved following intensive treatment and administration of famciclovir. A quantitative real-time polymerase chain reaction detected EEHV4 viremia that correlated with clinical signs. High levels of EEHV4 shedding from trunk wash secretions of the first viremic elephant correlated with subsequent infection of the second elephant with EEHV4. It is hoped that the observations made in these cases--and the successful treatment regimen used--will help other institutions identify and treat EEHV4 infection in the future.
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Seilern-Moy K, Darpel K, Steinbach F, Dastjerdi A. Distribution and load of elephant endotheliotropic herpesviruses in tissues from associated fatalities of Asian elephants. Virus Res 2016; 220:91-6. [PMID: 27102836 DOI: 10.1016/j.virusres.2016.04.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Accepted: 04/14/2016] [Indexed: 11/15/2022]
Abstract
Elephant Endotheliotropic Herpesviruses (EEHVs) are the cause of a highly fatal haemorrhagic disease in elephants primarily affecting young Asian elephants (Elephas maximus) in both captivity and in the wild. The viruses have emerged as a significant threat to Asian elephant conservation, critically affecting overall sustainability of their population. So far insight into the pathogenesis of EEHV infections has been restricted to examination of EEHV-infected tissues. However, little is known about distribution and burden of the viruses within the organs of fatal cases, crucial elements in the understanding of the virus pathogenesis. This study was therefore undertaken to assess the extent of organ and cell involvement in fatal cases of EEHV-1A, 1B and 5 using a quantitative real-time PCR. EEHV-1 and 5 DNA were detectable in all the tissues examined, albeit with substantial differences in the viral DNA load. The highest EEHV-1A DNA load was observed in the liver, followed by the heart, thymus and tongue. EEHV-1B and 5 showed the highest DNA load in the heart, followed by tongue and liver. This study provides new insights into EEHV pathogenicity and has implications in choice of sample type for disease investigation and virus isolation.
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Affiliation(s)
- Katharina Seilern-Moy
- Animal and Plant Health Agency-Weybridge, New Haw, Addlestone, Surrey KT15 3NB, UK; Division of Microbial Sciences, Faculty of Health and Medical Sciences, University of Surrey, Guildford, Surrey GU2 7XH, UK
| | - Karin Darpel
- Division of Microbial Sciences, Faculty of Health and Medical Sciences, University of Surrey, Guildford, Surrey GU2 7XH, UK
| | - Falko Steinbach
- Animal and Plant Health Agency-Weybridge, New Haw, Addlestone, Surrey KT15 3NB, UK
| | - Akbar Dastjerdi
- Animal and Plant Health Agency-Weybridge, New Haw, Addlestone, Surrey KT15 3NB, UK.
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Detection of Quiescent Infections with Multiple Elephant Endotheliotropic Herpesviruses (EEHVs), Including EEHV2, EEHV3, EEHV6, and EEHV7, within Lymphoid Lung Nodules or Lung and Spleen Tissue Samples from Five Asymptomatic Adult African Elephants. J Virol 2015; 90:3028-43. [PMID: 26719245 DOI: 10.1128/jvi.02936-15] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2015] [Accepted: 12/23/2015] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED More than 80 cases of lethal hemorrhagic disease associated with elephant endotheliotropic herpesviruses (EEHVs) have been identified in young Asian elephants worldwide. Diagnostic PCR tests detected six types of EEHV in blood of elephants with acute disease, although EEHV1A is the predominant pathogenic type. Previously, the presence of herpesvirus virions within benign lung and skin nodules from healthy African elephants led to suggestions that African elephants may be the source of EEHV disease in Asian elephants. Here, we used direct PCR-based DNA sequencing to detect EEHV genomes in necropsy tissue from five healthy adult African elephants. Two large lung nodules collected from culled wild South African elephants contained high levels of either EEHV3 alone or both EEHV2 and EEHV3. Similarly, a euthanized U.S. elephant proved to harbor multiple EEHV types distributed nonuniformly across four small lung nodules, including high levels of EEHV6, lower levels of EEHV3 and EEHV2, and a new GC-rich branch type, EEHV7. Several of the same EEHV types were also detected in random lung and spleen samples from two other elephants. Sanger PCR DNA sequence data comprising 100 kb were obtained from a total of 15 different strains identified, with (except for a few hypervariable genes) the EEHV2, EEHV3, and EEHV6 strains all being closely related to known genotypes from cases of acute disease, whereas the seven loci (4.0 kb) obtained from EEHV7 averaged 18% divergence from their nearest relative, EEHV3. Overall, we conclude that these four EEHV species, but probably not EEHV1, occur commonly as quiescent infections in African elephants. IMPORTANCE Acute hemorrhagic disease characterized by high-level viremia due to infection by members of the Proboscivirus genus threatens the future breeding success of endangered Asian elephants worldwide. Although the genomes of six EEHV types from acute cases have been partially or fully characterized, lethal disease predominantly involves a variety of strains of EEHV1, whose natural host has been unclear. Here, we carried out genotype analyses by partial PCR sequencing of necropsy tissue from five asymptomatic African elephants and identified multiple simultaneous infections by several different EEHV types, including high concentrations in lymphoid lung nodules. Overall, the results provide strong evidence that EEHV2, EEHV3, EEHV6, and EEHV7 represent natural ubiquitous infections in African elephants, whereas Asian elephants harbor EEHV1A, EEHV1B, EEHV4, and EEHV5. Although a single case of fatal cross-species infection by EEHV3 is known, the results do not support the previous concept that highly pathogenic EEHV1A crossed from African to Asian elephants in zoos.
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van den Doel PB, Prieto VR, van Rossum-Fikkert SE, Schaftenaar W, Latimer E, Howard L, Chapman S, Masters N, Osterhaus ADME, Ling PD, Dastjerdi A, Martina B. A novel antigen capture ELISA for the specific detection of IgG antibodies to elephant endotheliotropic herpes virus. BMC Vet Res 2015; 11:203. [PMID: 26268467 PMCID: PMC4535388 DOI: 10.1186/s12917-015-0522-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Accepted: 07/31/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Elephants are classified as critically endangered animals by the International Union for Conservation of Species (IUCN). Elephant endotheliotropic herpesvirus (EEHV) poses a large threat to breeding programs of captive Asian elephants by causing fatal haemorrhagic disease. EEHV infection is detected by PCR in samples from both clinically ill and asymptomatic elephants with an active infection, whereas latent carriers can be distinguished exclusively via serological assays. To date, identification of latent carriers has been challenging, since there are no serological assays capable of detecting seropositive elephants. RESULTS Here we describe a novel ELISA that specifically detects EEHV antibodies circulating in Asian elephant plasma/serum. Approximately 80 % of PCR positive elephants display EEHV-specific antibodies. Monitoring three Asian elephant herds from European zoos revealed that the serostatus of elephants within a herd varied from non-detectable to high titers. The antibody titers showed typical herpes-like rise-and-fall patterns in time which occur in all seropositive animals in the herd more or less simultaneously. CONCLUSIONS This study shows that the developed ELISA is suitable to detect antibodies specific to EEHV. It allows study of EEHV seroprevalence in Asian elephants. Results confirm that EEHV prevalence among Asian elephants (whether captive-born or wild-caught) is high.
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Affiliation(s)
- Petra B van den Doel
- ViroScience Lab, Erasmus Medical Center, Erasmus MC, Room Ee1714, dr. Molewaterplein 50, 3015, GE, Rotterdam, The Netherlands.
| | | | | | | | - Erin Latimer
- Smithsonian Conservation Biology Institute, Smithsonian's National Zoo, Washington, DC, USA.
| | - Lauren Howard
- Department of Animal Health, Houston Zoo, Inc., Houston, TX, USA.
| | - Sarah Chapman
- East-Midland Zoological Society, Twycross Zoo, Warwickshire, UK.
| | - Nic Masters
- Veterinary Services, Zoological Society of London, London, UK.
| | - Albert D M E Osterhaus
- ViroScience Lab, Erasmus Medical Center, Erasmus MC, Room Ee1714, dr. Molewaterplein 50, 3015, GE, Rotterdam, The Netherlands. .,Artemis One Health Research Institute, Utrecht, The Netherlands.
| | - Paul D Ling
- Department of Molecular Virology and Microbiology, Baylor's College of Medicine, Houston, TX, USA.
| | | | - Byron Martina
- ViroScience Lab, Erasmus Medical Center, Erasmus MC, Room Ee1714, dr. Molewaterplein 50, 3015, GE, Rotterdam, The Netherlands. .,Artemis One Health Research Institute, Utrecht, The Netherlands.
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Houldcroft CJ, Breuer J. Tales from the crypt and coral reef: the successes and challenges of identifying new herpesviruses using metagenomics. Front Microbiol 2015; 6:188. [PMID: 25821447 PMCID: PMC4358218 DOI: 10.3389/fmicb.2015.00188] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Accepted: 02/20/2015] [Indexed: 12/14/2022] Open
Abstract
Herpesviruses are ubiquitous double-stranded DNA viruses infecting many animals, with the capacity to cause disease in both immunocompetent and immunocompromised hosts. Different herpesviruses have different cell tropisms, and have been detected in a diverse range of tissues and sample types. Metagenomics—encompassing viromics—analyses the nucleic acid of a tissue or other sample in an unbiased manner, making few or no prior assumptions about which viruses may be present in a sample. This approach has successfully discovered a number of novel herpesviruses. Furthermore, metagenomic analysis can identify herpesviruses with high degrees of sequence divergence from known herpesviruses and does not rely upon culturing large quantities of viral material. Metagenomics has had success in two areas of herpesvirus sequencing: firstly, the discovery of novel exogenous and endogenous herpesviruses in primates, bats and cnidarians; and secondly, in characterizing large areas of the genomes of herpesviruses previously only known from small fragments, revealing unexpected diversity. This review will discuss the successes and challenges of using metagenomics to identify novel herpesviruses, and future directions within the field.
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Affiliation(s)
- Charlotte J Houldcroft
- Infection, Inflammation and Rheumatology, Institute of Child Health, University College London , London, UK
| | - Judith Breuer
- Infection, Inflammation and Rheumatology, Institute of Child Health, University College London , London, UK ; Division of Infection and Immunity, University College London , London, UK
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Abstract
Elephant populations are under intense pressure internationally from habitat destruction and poaching for ivory and meat. They also face pressure from infectious agents, including elephant endotheliotropic herpesvirus 1 (EEHV1), which kills ~20% of Asian elephants (Elephas maximus) born in zoos and causes disease in the wild. EEHV1 is one of at least six distinct EEHV in a phylogenetic lineage that appears to represent an ancient but newly recognized subfamily (the Deltaherpesvirinae) in the family Herpesviridae.
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Comparative genome analysis of four elephant endotheliotropic herpesviruses, EEHV3, EEHV4, EEHV5, and EEHV6, from cases of hemorrhagic disease or viremia. J Virol 2014; 88:13547-69. [PMID: 25231309 DOI: 10.1128/jvi.01675-14] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED The genomes of three types of novel endotheliotropic herpesviruses (elephant endotheliotropic herpesvirus 1A [EEHV1A], EEHV1B, and EEHV2) associated with lethal hemorrhagic disease in Asian elephants have been previously well characterized and assigned to a new Proboscivirus genus. Here we have generated 112 kb of DNA sequence data from segments of four more types of EEHV by direct targeted PCR from blood samples or necropsy tissue samples from six viremic elephants. Comparative phylogenetic analysis of nearly 30 protein-encoding genes of EEHV5 and EEHV6 show that they diverge uniformly by nearly 20% from their closest relatives, EEHV2 and EEHV1A, respectively, and are likely to have similar overall gene content and genome organization. In contrast, seven EEHV3 and EEHV4 genes analyzed differ from those of all other EEHVs by 37% and have a G+C content of 63% compared to just 42% for the others. Three strains of EEHV5 analyzed clustered into two partially chimeric subgroups EEHV5A and EEHV5B that diverge by 19% within three small noncontiguous segments totaling 6.2 kb. We conclude that all six EEHV types should be designated as independent species within a proposed new fourth Deltaherpesvirinae subfamily of mammalian herpesviruses. These virus types likely initially diverged close to 100 million years ago when the ancestors of modern elephants split from all other placental mammals and then evolved into two major branches with high- or low-G+C content about 35 million years ago. Later additional branching events subsequently generated three paired sister taxon lineages of which EEHV1 plus EEHV6, EEHV5 plus EEHV2, and EEHV4 plus EEHV3 may represent Asian and African elephant versions, respectively. IMPORTANCE One of the factors threatening the long-term survival of endangered Asian elephants in both wild range countries and in captive breeding populations in zoos is a highly lethal hemorrhagic herpesvirus disease that has killed at least 70 young Asian elephants worldwide. The genomes of the first three types of EEHVs (or probosciviruses) identified have been partially characterized in the preceding accompanying paper (L. K. Richman, J.-C. Zong, E. M. Latimer, J. Lock, R. C. Fleischer, S. Y. Heaggans, and G. S. Hayward, J. Virol. 88:13523-13546, 2014, http://dx.doi.org/10.1128/JVI.01673-14). Here we have used PCR DNA sequence analysis from multiple segments of DNA amplified directly from blood or necropsy tissue samples of six more selected cases of hemorrhagic disease to partially characterize four other types of EEHVs from either Asian or African elephants. We propose that all six types and two chimeric subtypes of EEHV belong to multiple lineages of both AT-rich and GC-rich branches within a new subfamily to be named the Deltaherpesvirinae, which evolved separately from all other mammalian herpesviruses about100 million years ago.
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