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Nair N, Osterhaus ADME, Rimmelzwaan GF, Prajeeth CK. Rift Valley Fever Virus-Infection, Pathogenesis and Host Immune Responses. Pathogens 2023; 12:1174. [PMID: 37764982 PMCID: PMC10535968 DOI: 10.3390/pathogens12091174] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Revised: 09/09/2023] [Accepted: 09/14/2023] [Indexed: 09/29/2023] Open
Abstract
Rift Valley Fever Virus is a mosquito-borne phlebovirus causing febrile or haemorrhagic illness in ruminants and humans. The virus can prevent the induction of the antiviral interferon response through its NSs proteins. Mutations in the NSs gene may allow the induction of innate proinflammatory immune responses and lead to attenuation of the virus. Upon infection, virus-specific antibodies and T cells are induced that may afford protection against subsequent infections. Thus, all arms of the adaptive immune system contribute to prevention of disease progression. These findings will aid the design of vaccines using the currently available platforms. Vaccine candidates have shown promise in safety and efficacy trials in susceptible animal species and these may contribute to the control of RVFV infections and prevention of disease progression in humans and ruminants.
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Wichgers Schreur PJ, Bird BH, Ikegami T, Bermúdez-Méndez E, Kortekaas J. Perspectives of Next-Generation Live-Attenuated Rift Valley Fever Vaccines for Animal and Human Use. Vaccines (Basel) 2023; 11:vaccines11030707. [PMID: 36992291 DOI: 10.3390/vaccines11030707] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 03/10/2023] [Accepted: 03/14/2023] [Indexed: 03/31/2023] Open
Abstract
Live-attenuated Rift Valley fever (RVF) vaccines transiently replicate in the vaccinated host, thereby effectively initiating an innate and adaptive immune response. Rift Valley fever virus (RVFV)-specific neutralizing antibodies are considered the main correlate of protection. Vaccination with classical live-attenuated RVF vaccines during gestation in livestock has been associated with fetal malformations, stillbirths, and fetal demise. Facilitated by an increased understanding of the RVFV infection and replication cycle and availability of reverse genetics systems, novel rationally-designed live-attenuated candidate RVF vaccines with improved safety profiles have been developed. Several of these experimental vaccines are currently advancing beyond the proof-of-concept phase and are being evaluated for application in both animals and humans. We here provide perspectives on some of these next-generation live-attenuated RVF vaccines and highlight the opportunities and challenges of these approaches to improve global health.
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Affiliation(s)
- Paul J Wichgers Schreur
- Department of Virology and Molecular Biology, Wageningen Bioveterinary Research, Wageningen University & Research, 8221 RA Lelystad, The Netherlands
- BunyaVax B.V., 8221 RA Lelystad, The Netherlands
| | - Brian H Bird
- One Health Institute, School of Veterinary Medicine, University of California, Davis, CA 95616, USA
| | - Tetsuro Ikegami
- Department of Pathology, The University of Texas Medical Branch at Galveston, Galveston, TX 77555, USA
- The Sealy Institute for Vaccine Sciences, The University of Texas Medical Branch at Galveston, Galveston, TX 77555, USA
- The Center for Biodefense and Emerging Infectious Diseases, The University of Texas Medical Branch at Galveston, Galveston, TX 77555, USA
| | - Erick Bermúdez-Méndez
- Department of Virology and Molecular Biology, Wageningen Bioveterinary Research, Wageningen University & Research, 8221 RA Lelystad, The Netherlands
- Laboratory of Virology, Wageningen University & Research, 6708 PB Wageningen, The Netherlands
| | - Jeroen Kortekaas
- Department of Virology and Molecular Biology, Wageningen Bioveterinary Research, Wageningen University & Research, 8221 RA Lelystad, The Netherlands
- Laboratory of Virology, Wageningen University & Research, 6708 PB Wageningen, The Netherlands
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Ayers VB, Huang YJS, Dunlop JI, Kohl A, Brennan B, Higgs S, Vanlandingham DL. Immunogenicity of a Candidate Live Attenuated Vaccine for Rift Valley Fever Virus with a Two-Segmented Genome. Viral Immunol 2023; 36:33-40. [PMID: 36399689 PMCID: PMC9885543 DOI: 10.1089/vim.2022.0104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Rift Valley fever virus (RVFV) is an emerging arbovirus that affects both ruminants and humans. RVFV causes severe and recurrent outbreaks in Africa and the Arabian Peninsula with a significant risk for emergence into new locations. Although there are a variety of RVFV veterinary vaccines for use in endemic areas, there is currently no licensed vaccine for human use; therefore, there is a need to develop and assess new vaccines. Herein, we report a live-attenuated recombinant vaccine candidate for RVFV, based on the previously described genomic reconfiguration of the conditionally licensed MP12 vaccine. There are two general strategies used to develop live-attenuated RVFV vaccines, one being serial passage of wild-type RVFV strains to select attenuated mutants such as Smithburn, Clone 13, and MP12 vaccine strains. The second strategy has utilized reverse genetics to attenuate RVFV strains by introducing deletions or insertions within the viral genome. The novel candidate vaccine characterized in this report contains a two-segmented genome that lacks the medium viral segment (M) and two virulence genes (nonstructural small and nonstructural medium). The vaccine candidate, named r2segMP12, was evaluated for the production of neutralizing antibodies to RVFV in outbred CD-1 mice. The immune response induced by the r2segMP12 vaccine candidate was directly compared to the immune response induced by the rMP12 parental strain vaccine. Our study demonstrated that a single immunization with the r2segMP12 vaccine candidate at 105 plaque-forming units elicited a higher neutralizing antibody response than the rMP12 vaccine at the same vaccination titer without the need for a booster.
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Affiliation(s)
- Victoria B. Ayers
- Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, Kansas, USA.,Biosecurity Research Institute, Kansas State University, Manhattan, Kansas, USA
| | - Yan-Jang S. Huang
- Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, Kansas, USA.,Biosecurity Research Institute, Kansas State University, Manhattan, Kansas, USA
| | - James I. Dunlop
- MRC-University of Glasgow Centre for Virus Research, Glasgow, United Kingdom
| | - Alain Kohl
- MRC-University of Glasgow Centre for Virus Research, Glasgow, United Kingdom
| | - Benjamin Brennan
- MRC-University of Glasgow Centre for Virus Research, Glasgow, United Kingdom
| | - Stephen Higgs
- Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, Kansas, USA.,Biosecurity Research Institute, Kansas State University, Manhattan, Kansas, USA
| | - Dana L. Vanlandingham
- Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, Kansas, USA.,Biosecurity Research Institute, Kansas State University, Manhattan, Kansas, USA.,Address correspondence to: Dr. Dana L. Vanlandingham, Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS 66506, USA
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4
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Evaluations of rationally designed rift valley fever vaccine candidate RVax-1 in mosquito and rodent models. NPJ Vaccines 2022; 7:109. [PMID: 36131104 PMCID: PMC9492667 DOI: 10.1038/s41541-022-00536-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2022] [Accepted: 09/01/2022] [Indexed: 12/14/2022] Open
Abstract
Rift Valley fever (RVF) is a mosquito-borne zoonosis endemic to Africa and the Arabian Peninsula, which causes large outbreaks among humans and ruminants. Single dose vaccinations using live-attenuated RVF virus (RVFV) support effective prevention of viral spread in endemic countries. Due to the segmented nature of RVFV genomic RNA, segments of vaccine strain-derived genomic RNA could be incorporated into wild-type RVFV within co-infected mosquitoes or animals. Rationally designed vaccine candidate RVax-1 displays protective epitopes fully identical to the previously characterized MP-12 vaccine. Additionally, all genome segments of RVax-1 contribute to the attenuation phenotype, which prevents the formation of pathogenic reassortant strains. This study demonstrated that RVax-1 cannot replicate efficiently in orally fed Aedes aegypti mosquitoes, while retaining strong immunogenicity and protective efficacy in an inbred mouse model, which were indistinguishable from the MP-12 vaccine. These findings support further development of RVax-1 as the next generation MP-12-based vaccine for prevention of Rift Valley fever in humans and animals.
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Stoek F, Rissmann M, Ulrich R, Eiden M, Groschup MH. Black rats (Rattus rattus) as potential reservoir hosts for Rift Valley fever phlebovirus: Experimental infection results in viral replication and shedding without clinical manifestation. Transbound Emerg Dis 2022; 69:1307-1318. [PMID: 33794070 DOI: 10.1111/tbed.14093] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Revised: 03/05/2021] [Accepted: 03/29/2021] [Indexed: 12/01/2022]
Abstract
Rift Valley fever phlebovirus (RVFV) is an arthropod-borne virus that can cause severe disease in ruminants and humans. Epidemics occur mainly after heavy rainfall, which leads to a significant increase in the occurrence of RVFV-transmitting mosquitoes. During inter-epidemic periods, the virus is assumed to be maintained between mosquitoes, susceptible livestock and yet unknown wildlife. The widespread rodent Rattus rattus (black rat) has been suspected to be involved in RVFV maintenance. In order to elucidate its susceptibility and thus its possible role in the transmission cycle of the virus, an experimental infection study was performed. Black rats were subcutaneously infected with highly virulent RVFV strain 35/74 and euthanized on days 3, 14 and 28 post-infection. Additional black rats served as non-infected contact animals. The infected black rats showed high susceptibility to RVFV infection. Generation of RVFV-neutralizing antibodies was found, and the rats developed viraemias lasting up to 17 days. Viral RNA was found in tissues until the last day of the experiment. However, neither a clinical manifestation nor virus-induced histopathological lesions were observed in any rat. These findings indicate the persistence of RVFV in black rats without affecting the animals. In contact animals, no evidence of horizontal RVFV transmission was found, although the co-housed infected rats showed oral, rectal and conjunctival RVFV shedding. Results of this study point to an involvement of black rats in the RVFV transmission cycle, and further studies are needed to investigate their potential role in the maintenance of the virus.
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Affiliation(s)
- Franziska Stoek
- Institute of Novel and Emerging Infectious Diseases, Friedrich-Loeffler-Institut, Greifswald-Insel Riems, Germany
| | - Melanie Rissmann
- Institute of Novel and Emerging Infectious Diseases, Friedrich-Loeffler-Institut, Greifswald-Insel Riems, Germany
- Department of Viroscience, Erasmus MC, Rotterdam, Netherlands
| | - Reiner Ulrich
- Department of Experimental Animal Facilities and Biorisk Management, Friedrich-Loeffler-Institut, Greifswald-Insel Riems, Germany
- Faculty of Veterinary Medicine, Institute of Veterinary-Pathology, Universität Leipzig, Leipzig, Germany
| | - Martin Eiden
- Institute of Novel and Emerging Infectious Diseases, Friedrich-Loeffler-Institut, Greifswald-Insel Riems, Germany
| | - Martin H Groschup
- Institute of Novel and Emerging Infectious Diseases, Friedrich-Loeffler-Institut, Greifswald-Insel Riems, Germany
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Further Characterization of Rio Grande Virus and Potential for Cross Reactivity with Rift Valley Fever Virus Assays. Viruses 2021; 13:v13091719. [PMID: 34578299 PMCID: PMC8471117 DOI: 10.3390/v13091719] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 08/17/2021] [Accepted: 08/26/2021] [Indexed: 11/17/2022] Open
Abstract
Phleboviruses (genus Phlebovirus, family Phenuiviridae) are emerging pathogens of humans and animals. Sand-fly-transmitted phleboviruses are found in Europe, Africa, the Middle East, and the Americas, and are responsible for febrile illness and nervous system infections in humans. Rio Grande virus (RGV) is the only reported phlebovirus in the United States. Isolated in Texas from southern plains woodrats, RGV is not known to be pathogenic to humans or domestic animals, but serologic evidence suggests that sheep (Ovis aries) and horses (Equus caballus) in this region have been infected. Rift Valley fever virus (RVFV), a phlebovirus of Africa, is an important pathogen of wild and domestic ruminants, and can also infect humans with the potential to cause severe disease. The introduction of RVFV into North America could greatly impact U.S. livestock and human health, and the development of vaccines and countermeasures is a focus of both the CDC and USDA. We investigated the potential for serologic reagents used in RVFV diagnostic assays to also detect cells infected with RGV. Western blots and immunocytochemistry assays were used to compare the antibody detection of RGV, RVFV, and two other New World phlebovirus, Punta Toro virus (South and Central America) and Anhanga virus (Brazil). Antigenic cross-reactions were found using published RVFV diagnostic reagents. These findings will help to inform test interpretation to avoid false positive RVFV diagnoses that could lead to public health concerns and economically costly agriculture regulatory responses, including quarantine and trade restrictions.
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Monath TP, Kortekaas J, Watts DM, Christofferson RC, Desiree LaBeaud A, Gowen B, Peters CJ, Smith DR, Swanepoel R, Morrill JC, Ksiazek TG, Pittman PR, Bird BH, Bettinger G. Theoretical risk of genetic reassortment should not impede development of live, attenuated Rift Valley fever (RVF) vaccines commentary on the draft WHO RVF Target Product Profile. Vaccine X 2020; 5:100060. [PMID: 32337506 PMCID: PMC7176985 DOI: 10.1016/j.jvacx.2020.100060] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Revised: 03/08/2020] [Accepted: 03/21/2020] [Indexed: 11/29/2022] Open
Abstract
WHO published draft Target Product Profiles (TPPs) for Rift Valley Fever virus (RVFV) vaccines. The TPPs contain restrictive requirements aimed at reducing the risk of genetic reassortment. We find no evidence for reassortment despite use of live RVFV vaccines. If genetic reassortment occurred with wild-type RVFV it would be of no consequence. The hypothetical risks of reassortment do not outweigh the benefits of vaccination
In November 2019, The World Health Organization (WHO) issued a draft set of Target Product Profiles (TPPs) describing optimal and minimally acceptable targets for vaccines against Rift Valley fever (RVF), a Phlebovirus with a three segmented genome, in both humans and ruminants. The TPPs contained rigid requirements to protect against genomic reassortment of live, attenuated vaccines (LAVs) with wild-type RVF virus (RVFV), which place undue constraints on development and regulatory approval of LAVs. We review the current LAVs in use and in development, and conclude that there is no evidence that reassortment between LAVs and wild-type RVFV has occurred during field use, that such a reassortment event if it occurred would have no untoward consequence, and that the TPPs should be revised to provide a more balanced assessment of the benefits versus the theoretical risks of reassortment.
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Affiliation(s)
- Thomas P Monath
- Managing Partner and Chief Scientific Officer, Crozet BioPharma LLC, Devens, MA, USA
| | - Jeroen Kortekaas
- Professor of Veterinary Arbovirology, Department of Virology, Wageningen Bioveterinary Research, Lelystad, the Netherlands
| | - Douglas M Watts
- Executive Director of Vet Services, and Director of Biosafety Level 3 Laboratory and Co-Director of BBRC Infectious Disease and Immunology, University of Texas at El Paso, El Paso, TX, USA
| | - Rebecca C Christofferson
- Pathobiological Sciences, Louisiana State University, School of Veterinary Medicine, Baton Rouge, LA, USA
| | - Angelle Desiree LaBeaud
- Professor of Pediatrics (Infectious Diseases), Stanford University School of Medicine, Senior Fellow at the Woods Institute for the Environment and Professor of Health Research and Policy (Epidemiology) at the Lucile Salter Packard Children's Hospital, Stanford, CA, USA
| | | | - Clarence J Peters
- Professor (Emeritus) Departments of Microbiology & Immunology and Pathology Director (Emeritus) for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, TX, USA
| | - Darci R Smith
- Immunodiagnostics Department, Naval Medical Research Center, Biological Defense Research Directorate, Fort Detrick, MD, USA
| | - Robert Swanepoel
- Department of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, Gauteng, South Africa
| | - John C Morrill
- Department of Pathology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Thomas G Ksiazek
- Department of Pathology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Phillip R Pittman
- U.S. Army Medical Research Institute of Infectious Diseases, Medical Research and Materiel Command, Fort Detrick, Frederick, MD, USA
| | - Brian H Bird
- Viral Special Pathogens Branch, Division of High-Consequence Pathogens and Pathology, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, GA, USA.,University of California, Davis, One Health Institute, School of Veterinary Medicine, Davis 956164, CA, USA
| | - George Bettinger
- USAID Rift Valley Fever Vaccine Project at The University of Texas at El Paso, El Paso, TX, USA
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Abstract
Introduction: Rift Valley fever (RVF) outbreaks can cause devastating economic loss and public health concerns. RVF virus (RVFV: genus Phlebovirus family Phenuiviridae) is transmitted by mosquitoes, causes abortion in sheep, cattle, and goats, and severe diseases in humans including hemorrhagic fever, encephalitis, or retinitis. RVFV has spread from sub-Saharan Africa into Madagascar, Egypt, Saudi Arabia, and Yemen.Area covered: There are a few licensed veterinary RVF vaccines in endemic countries, whereas no licensed RVF vaccines are available for human use. There are two Investigational New Drug (IND) RVF candidate vaccines used in clinical trials. This review will discuss the development of two IND vaccines for RVF over the past 20-40 years, and further innovation for future RVF vaccines applicable for the use in endemic areas.Expert opinion: Vaccination for human RVF can protect at-risk personnel against severe RVF illness. Formalin-inactivated RVF candidate vaccine requires three doses to induce protective immunity, whereas the live-attenuated MP-12 candidate vaccine retains strong immunogenicity. Further innovation in safety, immunogenicity, and thermostability will facilitate future RVF vaccines for humans.
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Affiliation(s)
- Tetsuro Ikegami
- Department of Pathology, The University of Texas Medical Branch, Galveston, TX, USA.,Sealy Center for Vaccine Development, The University of Texas Medical Branch, Galveston, TX, USA.,Center for Biodefense and Emerging Infectious Diseases, The University of Texas Medical Branch, Galveston, TX, USA
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Lorenzo G, López-Gil E, Ortego J, Brun A. Efficacy of different DNA and MVA prime-boost vaccination regimens against a Rift Valley fever virus (RVFV) challenge in sheep 12 weeks following vaccination. Vet Res 2018; 49:21. [PMID: 29467018 PMCID: PMC5822472 DOI: 10.1186/s13567-018-0516-z] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2017] [Accepted: 02/01/2018] [Indexed: 12/15/2022] Open
Abstract
The aim of this work was to evaluate the immunogenicity and efficacy of DNA and MVA vaccines encoding the RVFV glycoproteins Gn and Gc in an ovine model of RVFV infection. Adult sheep of both sexes were challenged 12 weeks after the last immunization and clinical, virological, biochemical and immunological consequences, were analyzed. Strategies based on immunization with homologous DNA or heterologous DNA/MVA prime-boost were able to induce a rapid in vitro neutralizing antibody response as well as IFNγ production after in vitro virus specific re-stimulation. In these animals we observed reduced viremia levels and less clinical signs when compared with mock-immunized controls. In contrast, sheep inoculated with a homologous MVA prime-boost showed increased viremia correlating with the absence of detectable neutralizing antibody responses, despite of inducing cellular responses after the last immunization. However, faster induction of neutralizing antibodies and IFNγ production after challenge were found in this group when compared to the mock vaccinated group, indicative of a primed immune response. In conclusion, these results suggest that vaccination strategies based on DNA priming were able to mount and maintain specific anti-RVFV glycoprotein immune responses upon homologous or heterologous booster doses, warranting further optimization in large animal models of infection.
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Affiliation(s)
- Gema Lorenzo
- Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Centro de Investigación en Sanidad Animal (CISA), Valdeolmos, 28130, Madrid, Spain
| | - Elena López-Gil
- Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Centro de Investigación en Sanidad Animal (CISA), Valdeolmos, 28130, Madrid, Spain
| | - Javier Ortego
- Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Centro de Investigación en Sanidad Animal (CISA), Valdeolmos, 28130, Madrid, Spain
| | - Alejandro Brun
- Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Centro de Investigación en Sanidad Animal (CISA), Valdeolmos, 28130, Madrid, Spain.
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Attenuation and protective efficacy of Rift Valley fever phlebovirus rMP12-GM50 strain. Vaccine 2017; 35:6634-6642. [PMID: 29061350 DOI: 10.1016/j.vaccine.2017.10.036] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Revised: 09/20/2017] [Accepted: 10/12/2017] [Indexed: 11/24/2022]
Abstract
Rift Valley fever (RVF) is a mosquito-borne zoonotic disease endemic to Africa and the Arabian Peninsula that affects sheep, cattle, goats, camels, and humans. Effective vaccination of susceptible ruminants is important for the prevention of RVF outbreaks. Live-attenuated RVF vaccines are in general highly immunogenic in ruminants, whereas residual virulence might be a concern for vulnerable populations. It is also important for live-attenuated strains to encode unique genetic markers for the differentiation from wild-type RVFV strains. In this study, we aimed to strengthen the attenuation profile of the MP-12 vaccine strain via the introduction of 584 silent mutations. To minimize the impact on protective efficacy, codon usage and codon pair bias were not de-optimized. The resulting rMP12-GM50 strain showed 100% protective efficacy with a single intramuscular dose, raising a 1:853 mean titer of plaque reduction neutralization test. Moreover, outbred mice infected with one of three pathogenic reassortant ZH501 strains, which encoded rMP12-GM50 L-, M-, or S-segments, showed 90%, 50%, or 30% survival, respectively. These results indicate that attenuation of the rMP12-GM50 strain is significantly attenuated via the L-, M-, and S-segments. Recombinant RVFV vaccine strains encoding similar silent mutations will be also useful for the surveillance of reassortant strains derived from vaccine strains in endemic countries.
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Risk analysis of inter-species reassortment through a Rift Valley fever phlebovirus MP-12 vaccine strain. PLoS One 2017; 12:e0185194. [PMID: 28926632 PMCID: PMC5604998 DOI: 10.1371/journal.pone.0185194] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2017] [Accepted: 09/07/2017] [Indexed: 11/20/2022] Open
Abstract
Rift Valley fever (RVF) is a mosquito-borne zoonotic disease endemic to Africa and the Arabian Peninsula. The causative agent, Rift Valley fever phlebovirus (RVFV), belongs to the genus Phlebovirus in the family Phenuiviridae and causes high rates of abortions in ruminants, and hemorrhagic fever, encephalitis, or blindness in humans. Viral maintenance by mosquito vectors has led to sporadic RVF outbreaks in ruminants and humans in endemic countries, and effective vaccination of animals and humans may minimize the impact of this disease. A live-attenuated MP-12 vaccine strain is one of the best characterized RVFV strains, and was conditionally approved as a veterinary vaccine in the U.S. Live-attenuated RVF vaccines including MP-12 strain may form reassortant strains with other bunyavirus species. This study thus aimed to characterize the occurrence of genetic reassortment between the MP-12 strain and bunyavirus species closely related to RVFV. The Arumowot virus (AMTV) and Gouleako goukovirus (GOLV), are transmitted by mosquitoes in Africa. The results of this study showed that GOLV does not form detectable reassortant strains with the MP-12 strain in co-infected C6/36 cells. The AMTV also did not form any reassortant strains with MP-12 strain in co-infected C6/36 cells, due to the incompatibility among N, L, and Gn/Gc proteins. A lack of reassortant formation could be due to a functional incompatibility of N and L proteins derived from heterologous species, and due to a lack of packaging via heterologous Gn/Gc proteins. The MP-12 strain did, however, randomly exchange L-, M-, and S-segments with a genetic variant strain, rMP12-GM50, in culture cells. The MP-12 strain is thus unlikely to form any reassortant strains with AMTV or GOLV in nature.
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Lokugamage N, Ikegami T. Genetic stability of Rift Valley fever virus MP-12 vaccine during serial passages in culture cells. NPJ Vaccines 2017; 2:20. [PMID: 29167748 PMCID: PMC5627234 DOI: 10.1038/s41541-017-0021-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Revised: 05/24/2017] [Accepted: 06/06/2017] [Indexed: 12/15/2022] Open
Abstract
Rift Valley fever (RVF) is a mosquito-borne zoonotic disease endemic to Africa which affects both ruminants and humans. RVF causes serious damage to the livestock industry and is also a threat to public health. The Rift Valley fever virus has a segmented negative-stranded RNA genome consisting of Large (L)-, Medium (M)-, and Small (S)-segments. The live-attenuated MP-12 vaccine is immunogenic in livestock and humans, and is conditionally licensed for veterinary use in the U.S. The MP-12 strain encodes 23 mutations (nine amino acid substitutions) and is attenuated through a combination of mutations in the L-, M-, and S-segments. Among them, the M-U795C, M-A3564G, and L-G3104A mutations contribute to viral attenuation through the L- and M-segments. The M-U795C, M-A3564G, L-U533C, and L-G3750A mutations are also independently responsible for temperature-sensitive (ts) phenotype. We hypothesized that a serial passage of the MP-12 vaccine in culture cells causes reversions of the MP-12 genome. The MP-12 vaccine and recombinant rMP12-ΔNSs16/198 were serially passaged 25 times. Droplet digital PCR analysis revealed that the reversion occurred at L-G3750A during passages of MP-12 in Vero or MRC-5 cells. The reversion also occurred at M-A3564G and L-U533C of rMP12-ΔNSs16/198 in Vero cells. Reversion mutations were not found in MP-12 or the variant, rMP12-TOSNSs, in the brains of mice with encephalitis. This study characterized genetic stability of the MP-12 vaccine and the potential risk of reversion mutation at the L-G3750A ts mutation after excessive viral passages in culture cells.
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Affiliation(s)
- Nandadeva Lokugamage
- Department of Pathology, The University of Texas Medical Branch at Galveston, 301 University Blvd., Galveston, TX 77555 USA
| | - Tetsuro Ikegami
- Department of Pathology, The University of Texas Medical Branch at Galveston, 301 University Blvd., Galveston, TX 77555 USA
- The Sealy Center for Vaccine Development, The University of Texas Medical Branch at Galveston, 301 University Blvd., Galveston, TX 77555 USA
- The Center for Biodefense and Emerging Infectious Diseases, The University of Texas Medical Branch at Galveston, 301 University Blvd., Galveston, TX 77555 USA
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14
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Ikegami T. Rift Valley fever vaccines: an overview of the safety and efficacy of the live-attenuated MP-12 vaccine candidate. Expert Rev Vaccines 2017; 16:601-611. [PMID: 28425834 DOI: 10.1080/14760584.2017.1321482] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
INTRODUCTION Rift Valley fever (RVF) is a mosquito-borne zoonotic viral disease endemic to Africa and the Arabian Peninsula. High rates of abortion among infected ruminants and hemorrhagic fever in infected humans are major public health concerns. Commercially available veterinary RVF vaccines are important for preventing the spread of the Rift Valley fever virus (RVFV) in endemic countries; however, RVFV outbreaks continue to occur frequently in endemic countries in the 21st century. In the U.S., the live-attenuated MP-12 vaccine has been developed for both animal and human vaccination. This vaccine strain is well attenuated, and a single dose induces neutralizing antibodies in both ruminants and humans. Areas covered: This review describes scientific evidences of MP-12 vaccine efficacy and safety, as well as MP-12 variants recently developed by reverse genetics, in comparison with other RVF vaccines. Expert commentary: The containment of active RVF outbreaks and long-term protection from RVF exposure to infected mosquitoes are important goals for RVF vaccination. MP-12 vaccine will allow immediate vaccination of susceptible animals in case of an unexpected RVF outbreak in the U.S., whereas MP-12 vaccine may be also useful for the RVF control in endemic regions.
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Affiliation(s)
- Tetsuro Ikegami
- a Department of Pathology, Sealy Center for Vaccine Development, Center for Biodefense and Emerging Infectious Diseases , The University of Texas Medical Branch , Galveston , TX , USA
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Rissmann M, Ulrich R, Schröder C, Hammerschmidt B, Hanke D, Mroz C, Groschup MH, Eiden M. Vaccination of alpacas against Rift Valley fever virus: Safety, immunogenicity and pathogenicity of MP-12 vaccine. Vaccine 2016; 35:655-662. [PMID: 28012779 DOI: 10.1016/j.vaccine.2016.12.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Revised: 11/25/2016] [Accepted: 12/01/2016] [Indexed: 02/07/2023]
Abstract
Rift Valley fever (RVF) is an emerging zoonosis of major public health concern in Africa and Arabia. Previous outbreaks attributed camelids a significant role in the epidemiology of Rift Valley fever virus (RVFV), making them an important target species for vaccination. Using three alpacas as model-organisms for dromedary camels, the safety, immunogenicity and pathogenicity of the MP-12 vaccine were evaluated in this study. To compare both acute and subacute effects, animals were euthanized at 3 and 31days post infection (dpi). Clinical monitoring, analysis of liver enzymes and hematological parameters demonstrated the tolerability of the vaccine, as no significant adverse effects were observed. Comprehensive analysis of serological parameters illustrated the immunogenicity of the vaccine, eliciting high neutralizing antibody titers and antibodies targeting different viral antigens. RVFV was detected in serum and liver of the alpaca euthanized 3dpi, whereas no virus was detectable at 31dpi. Viral replication was confirmed by detection of various RVFV-antigens in hepatocytes by immunohistochemistry and the presence of mild multifocal necrotizing hepatitis. In conclusion, results indicate that MP-12 is a promising vaccine candidate but still has a residual pathogenicity, which requires further investigation.
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Affiliation(s)
- M Rissmann
- Institute of Novel and Emerging Infectious Diseases, Friedrich-Loeffler-Institut, Greifswald-Insel Riems, Germany
| | - R Ulrich
- Department of Experimental Animal Facilities and Biorisk Management, Friedrich-Loeffler-Institut, Greifswald-Insel Riems, Germany
| | - C Schröder
- Department of Experimental Animal Facilities and Biorisk Management, Friedrich-Loeffler-Institut, Greifswald-Insel Riems, Germany
| | - B Hammerschmidt
- Department of Experimental Animal Facilities and Biorisk Management, Friedrich-Loeffler-Institut, Greifswald-Insel Riems, Germany
| | - D Hanke
- Institute of Diagnostic Virology, Friedrich-Loeffler-Institut, Greifswald-Insel Riems, Germany
| | - C Mroz
- Institute of Novel and Emerging Infectious Diseases, Friedrich-Loeffler-Institut, Greifswald-Insel Riems, Germany
| | - M H Groschup
- Institute of Novel and Emerging Infectious Diseases, Friedrich-Loeffler-Institut, Greifswald-Insel Riems, Germany
| | - M Eiden
- Institute of Novel and Emerging Infectious Diseases, Friedrich-Loeffler-Institut, Greifswald-Insel Riems, Germany.
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Yamaoka S, Ebihara H. The two faces of Rift Valley fever virus virulence factor NSs: The development of a vaccine and the elucidation of pathogenesis. Virulence 2016; 7:856-859. [PMID: 27432532 DOI: 10.1080/21505594.2016.1213938] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Affiliation(s)
- Satoko Yamaoka
- a Molecular Virology and Host-Pathogen Interaction Unit, Laboratory of Virology, Division of Intramural Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health , Hamilton , MT , USA
| | - Hideki Ebihara
- a Molecular Virology and Host-Pathogen Interaction Unit, Laboratory of Virology, Division of Intramural Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health , Hamilton , MT , USA
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Ly HJ, Ikegami T. Rift Valley fever virus NSs protein functions and the similarity to other bunyavirus NSs proteins. Virol J 2016; 13:118. [PMID: 27368371 PMCID: PMC4930582 DOI: 10.1186/s12985-016-0573-8] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Accepted: 06/23/2016] [Indexed: 12/31/2022] Open
Abstract
Rift Valley fever is a mosquito-borne zoonotic disease that affects both ruminants and humans. The nonstructural (NS) protein, which is a major virulence factor for Rift Valley fever virus (RVFV), is encoded on the S-segment. Through the cullin 1-Skp1-Fbox E3 ligase complex, the NSs protein promotes the degradation of at least two host proteins, the TFIIH p62 and the PKR proteins. NSs protein bridges the Fbox protein with subsequent substrates, and facilitates the transfer of ubiquitin. The SAP30-YY1 complex also bridges the NSs protein with chromatin DNA, affecting cohesion and segregation of chromatin DNA as well as the activation of interferon-β promoter. The presence of NSs filaments in the nucleus induces DNA damage responses and causes cell-cycle arrest, p53 activation, and apoptosis. Despite the fact that NSs proteins have poor amino acid similarity among bunyaviruses, the strategy utilized to hijack host cells are similar. This review will provide and summarize an update of recent findings pertaining to the biological functions of the NSs protein of RVFV as well as the differences from those of other bunyaviruses.
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Affiliation(s)
- Hoai J Ly
- Department of Pathology, The University of Texas Medical Branch at Galveston, Galveston, TX, USA
| | - Tetsuro Ikegami
- Department of Pathology, The University of Texas Medical Branch at Galveston, Galveston, TX, USA. .,The Sealy Center for Vaccine Development, The University of Texas Medical Branch at Galveston, Galveston, TX, USA. .,The Center for Biodefense and Emerging Infectious Diseases, The University of Texas Medical Branch at Galveston, Galveston, TX, USA.
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Nishiyama S, Slack OAL, Lokugamage N, Hill TE, Juelich TL, Zhang L, Smith JK, Perez D, Gong B, Freiberg AN, Ikegami T. Attenuation of pathogenic Rift Valley fever virus strain through the chimeric S-segment encoding sandfly fever phlebovirus NSs or a dominant-negative PKR. Virulence 2016; 7:871-881. [PMID: 27248570 DOI: 10.1080/21505594.2016.1195528] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Abstract
Rift Valley fever is a mosquito-borne zoonotic disease affecting ruminants and humans. Rift Valley fever virus (RVFV: family Bunyaviridae, genus Phlebovirus) causes abortions and fetal malformations in ruminants, and hemorrhagic fever, encephalitis, or retinitis in humans. The live-attenuated MP-12 vaccine is conditionally licensed for veterinary use in the US. However, this vaccine lacks a marker for the differentiation of vaccinated from infected animals (DIVA). NSs gene is dispensable for RVFV replication, and thus, rMP-12 strains lacking NSs gene is applicable to monitor vaccinated animals. However, the immunogenicity of MP-12 lacking NSs was not as high as parental MP-12. Thus, chimeric MP-12 strains encoding NSs from either Toscana virus (TOSV), sandfly fever Sicilian virus (SFSV) or Punta Toro virus Adames strain (PTA) were characterized previously. Although chimeric MP-12 strains are highly immunogenic, the attenuation through the S-segment remains unknown. Using pathogenic ZH501 strain, we aimed to demonstrate the attenuation of ZH501 strain through chimeric S-segment encoding either the NSs of TOSV, SFSV, PTA, or Punta Toro virus Balliet strain (PTB). In addition, we characterized rZH501 encoding a human dominant-negative PKR (PKRΔE7), which also enhances the immunogenicity of MP-12. Study done on mice revealed that attenuation of rZH501 occurred through the S-segment encoding either PKRΔE7 or SFSV NSs. However, rZH501 encoding either TOSV, PTA, or PTB NSs in the S-segment uniformly caused lethal encephalitis. Our results indicated that the S-segments encoding PKRΔE7 or SFSV NSs are attenuated and thus applicable toward next generation MP-12 vaccine candidates that encode a DIVA marker.
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Affiliation(s)
- Shoko Nishiyama
- a Department of Pathology , The University of Texas Medical Branch at Galveston , Galveston , TX , USA
| | - Olga A L Slack
- a Department of Pathology , The University of Texas Medical Branch at Galveston , Galveston , TX , USA
| | - Nandadeva Lokugamage
- a Department of Pathology , The University of Texas Medical Branch at Galveston , Galveston , TX , USA
| | - Terence E Hill
- a Department of Pathology , The University of Texas Medical Branch at Galveston , Galveston , TX , USA
| | - Terry L Juelich
- a Department of Pathology , The University of Texas Medical Branch at Galveston , Galveston , TX , USA.,b Galveston National Laboratory, The University of Texas Medical Branch at Galveston , Galveston , TX , USA
| | - Lihong Zhang
- a Department of Pathology , The University of Texas Medical Branch at Galveston , Galveston , TX , USA.,b Galveston National Laboratory, The University of Texas Medical Branch at Galveston , Galveston , TX , USA
| | - Jennifer K Smith
- a Department of Pathology , The University of Texas Medical Branch at Galveston , Galveston , TX , USA.,b Galveston National Laboratory, The University of Texas Medical Branch at Galveston , Galveston , TX , USA
| | - David Perez
- a Department of Pathology , The University of Texas Medical Branch at Galveston , Galveston , TX , USA
| | - Bin Gong
- a Department of Pathology , The University of Texas Medical Branch at Galveston , Galveston , TX , USA.,b Galveston National Laboratory, The University of Texas Medical Branch at Galveston , Galveston , TX , USA.,c The Center for Biodefense and Emerging Infectious Diseases, The University of Texas Medical Branch at Galveston , Galveston , TX , USA
| | - Alexander N Freiberg
- a Department of Pathology , The University of Texas Medical Branch at Galveston , Galveston , TX , USA.,b Galveston National Laboratory, The University of Texas Medical Branch at Galveston , Galveston , TX , USA.,c The Center for Biodefense and Emerging Infectious Diseases, The University of Texas Medical Branch at Galveston , Galveston , TX , USA.,d The Sealy Center for Vaccine Development, The University of Texas Medical Branch at Galveston , Galveston , TX , USA
| | - Tetsuro Ikegami
- a Department of Pathology , The University of Texas Medical Branch at Galveston , Galveston , TX , USA.,c The Center for Biodefense and Emerging Infectious Diseases, The University of Texas Medical Branch at Galveston , Galveston , TX , USA.,d The Sealy Center for Vaccine Development, The University of Texas Medical Branch at Galveston , Galveston , TX , USA
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Mutational Analysis of the Rift Valley Fever Virus Glycoprotein Precursor Proteins for Gn Protein Expression. Viruses 2016; 8:v8060151. [PMID: 27231931 PMCID: PMC4926171 DOI: 10.3390/v8060151] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Revised: 05/17/2016] [Accepted: 05/19/2016] [Indexed: 01/17/2023] Open
Abstract
The Rift Valley fever virus (RVFV) M-segment encodes the 78 kD, NSm, Gn, and Gc proteins. The 1st AUG generates the 78 kD-Gc precursor, the 2nd AUG generates the NSm-Gn-Gc precursor, and the 3rd AUG makes the NSm’-Gn-Gc precursor. To understand biological changes due to abolishment of the precursors, we quantitatively measured Gn secretion using a reporter assay, in which a Gaussia luciferase (gLuc) protein is fused to the RVFV M-segment pre-Gn region. Using the reporter assay, the relative expression of Gn/gLuc fusion proteins was analyzed among various AUG mutants. The reporter assay showed efficient secretion of Gn/gLuc protein from the precursor made from the 2nd AUG, while the removal of the untranslated region upstream of the 2nd AUG (AUG2-M) increased the secretion of the Gn/gLuc protein. Subsequently, recombinant MP-12 strains encoding mutations in the pre-Gn region were rescued, and virological phenotypes were characterized. Recombinant MP-12 encoding the AUG2-M mutation replicated slightly less efficiently than the control, indicating that viral replication is further influenced by the biological processes occurring after Gn expression, rather than the Gn abundance. This study showed that, not only the abolishment of AUG, but also the truncation of viral UTR, affects the expression of Gn protein by the RVFV M-segment.
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Nishiyama S, Ikegami T. Temperature-sensitive mutations for live-attenuated Rift Valley fever vaccines: implications from other RNA viruses. Front Microbiol 2015; 6:787. [PMID: 26322023 PMCID: PMC4531298 DOI: 10.3389/fmicb.2015.00787] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Accepted: 07/20/2015] [Indexed: 11/13/2022] Open
Abstract
Rift Valley fever (RVF) is a mosquito-borne zoonotic disease endemic to the African continent. RVF is characterized by high rate of abortions in ruminants and hemorrhagic fever, encephalitis, or blindness in humans. RVF is caused by the Rift Valley fever virus (RVFV: genus Phlebovirus, family Bunyaviridae). Vaccination is the only known effective strategy to prevent the disease, but there are no licensed RVF vaccines available for humans. A live-attenuated vaccine candidate derived from the wild-type pathogenic Egyptian ZH548 strain, MP-12, has been conditionally licensed for veterinary use in the U.S. MP-12 displays a temperature-sensitive (ts) phenotype and does not replicate at 41°C. The ts mutation limits viral replication at a specific body temperature and may lead to an attenuation of the virus. Here we will review well-characterized ts mutations for RNA viruses, and further discuss the potential in designing novel live-attenuated vaccines for RVF.
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Affiliation(s)
- Shoko Nishiyama
- Department of Pathology, The University of Texas Medical Branch at Galveston, Galveston, TX USA
| | - Tetsuro Ikegami
- Department of Pathology, The University of Texas Medical Branch at Galveston, Galveston, TX USA ; Sealy Center for Vaccine Development, The University of Texas Medical Branch at Galveston, Galveston, TX USA ; Center for Biodefense and Emerging Infectious Diseases, The University of Texas Medical Branch at Galveston, Galveston, TX USA
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