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Davis EH, Wang B, White M, Huang YJS, Sarathy VV, Wang T, Bourne N, Higgs S, Barrett ADT. Impact of yellow fever virus envelope protein on wild-type and vaccine epitopes and tissue tropism. NPJ Vaccines 2022; 7:39. [PMID: 35322047 PMCID: PMC8942996 DOI: 10.1038/s41541-022-00460-6] [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: 04/27/2021] [Accepted: 02/16/2022] [Indexed: 12/04/2022] Open
Abstract
The envelope (E) protein of flaviviruses is functionally associated with viral tissue tropism and pathogenicity. For yellow fever virus (YFV), viscerotropic disease primarily involving the liver is pathognomonic for wild-type (WT) infection. In contrast, the live-attenuated vaccine (LAV) strain 17D does not cause viscerotropic disease and reversion to virulence is associated with neurotropic disease. The relationship between structure-function of the E protein for WT strain Asibi and its LAV derivative 17D strain is poorly understood; however, changes to WT and vaccine epitopes have been associated with changes in virulence. Here, a panel of Asibi and 17D infectious clone mutants were generated with single-site mutations at the one membrane residue and each of the eight E protein amino acid substitutions that distinguish the two strains. The mutants were characterized with respect to WT-specific and vaccine-specific monoclonal antibodies (mAbs) binding to virus plus binding of virus to brain, liver, and lung membrane receptor preparations (MRPs) generated from AG129 mice. This approach shows that amino acids in the YFV E protein domains (ED) I and II contain the WT E protein epitope, which overlap with those that mediate YFV binding to mouse liver. Furthermore, amino acids in EDIII associated with the vaccine epitope overlap with those that facilitate YFV binding mouse brain MRPs. Taken together, these data suggest that the YFV E protein is a key determinant in the phenotype of WT and 17D vaccine strains of YFV.
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Affiliation(s)
- Emily H Davis
- Department of Pathology, University of Texas Medical Branch (UTMB), Galveston, TX, USA.,Sealy Institute for Vaccine Sciences, UTMB, Galveston, TX, USA
| | - Binbin Wang
- Department of Pathology, University of Texas Medical Branch (UTMB), Galveston, TX, USA
| | | | - Yan-Jang S Huang
- Biosecurity Research Institute, Kansas State University, Manhattan, KS, USA.,Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS, USA.,Center on Emerging and Zoonotic Infectious Diseases, College of Veterinary Medicine, Kansas State University, Manhattan, KS, USA
| | - Vanessa V Sarathy
- Department of Pathology, University of Texas Medical Branch (UTMB), Galveston, TX, USA.,Sealy Institute for Vaccine Sciences, UTMB, Galveston, TX, USA
| | - Tian Wang
- Department of Pathology, University of Texas Medical Branch (UTMB), Galveston, TX, USA.,Sealy Institute for Vaccine Sciences, UTMB, Galveston, TX, USA
| | - Nigel Bourne
- Sealy Institute for Vaccine Sciences, UTMB, Galveston, TX, USA.,Department of Pediatrics, UTMB, Galveston, TX, USA
| | - Stephen Higgs
- Biosecurity Research Institute, Kansas State University, Manhattan, KS, USA.,Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS, USA.,Center on Emerging and Zoonotic Infectious Diseases, College of Veterinary Medicine, Kansas State University, Manhattan, KS, USA
| | - Alan D T Barrett
- Department of Pathology, University of Texas Medical Branch (UTMB), Galveston, TX, USA. .,Sealy Institute for Vaccine Sciences, UTMB, Galveston, TX, USA.
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2
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Hu T, Wu Z, Wu S, Chen S, Cheng A. The key amino acids of E protein involved in early flavivirus infection: viral entry. Virol J 2021; 18:136. [PMID: 34217298 PMCID: PMC8254458 DOI: 10.1186/s12985-021-01611-2] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Accepted: 06/29/2021] [Indexed: 02/11/2023] Open
Abstract
Flaviviruses are enveloped viruses that infect multiple hosts. Envelope proteins are the outermost proteins in the structure of flaviviruses and mediate viral infection. Studies indicate that flaviviruses mainly use envelope proteins to bind to cell attachment receptors and endocytic receptors for the entry step. Here, we present current findings regarding key envelope protein amino acids that participate in the flavivirus early infection process. Among these sites, most are located in special positions of the protein structure, such as the α-helix in the stem region and the hinge region between domains I and II, motifs that potentially affect the interaction between different domains. Some of these sites are located in positions involved in conformational changes in envelope proteins. In summary, we summarize and discuss the key envelope protein residues that affect the entry process of flaviviruses, including the process of their discovery and the mechanisms that affect early infection.
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Affiliation(s)
- Tao Hu
- Research Center of Avian Disease, College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang District, Chengdu, 611130, Sichuan, China
| | - Zhen Wu
- Research Center of Avian Disease, College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang District, Chengdu, 611130, Sichuan, China
| | - Shaoxiong Wu
- Research Center of Avian Disease, College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang District, Chengdu, 611130, Sichuan, China
| | - Shun Chen
- Research Center of Avian Disease, College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang District, Chengdu, 611130, Sichuan, China. .,Institute of Preventive Veterinary Medicine, College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang District, Chengdu, 611130, Sichuan, China. .,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Wenjiang District, Chengdu, 611130, Sichuan, China.
| | - Anchun Cheng
- Research Center of Avian Disease, College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang District, Chengdu, 611130, Sichuan, China. .,Institute of Preventive Veterinary Medicine, College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang District, Chengdu, 611130, Sichuan, China. .,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Wenjiang District, Chengdu, 611130, Sichuan, China.
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3
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Fiacre L, Pagès N, Albina E, Richardson J, Lecollinet S, Gonzalez G. Molecular Determinants of West Nile Virus Virulence and Pathogenesis in Vertebrate and Invertebrate Hosts. Int J Mol Sci 2020; 21:ijms21239117. [PMID: 33266206 PMCID: PMC7731113 DOI: 10.3390/ijms21239117] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Revised: 11/23/2020] [Accepted: 11/26/2020] [Indexed: 12/12/2022] Open
Abstract
West Nile virus (WNV), like the dengue virus (DENV) and yellow fever virus (YFV), are major arboviruses belonging to the Flavivirus genus. WNV is emerging or endemic in many countries around the world, affecting humans and other vertebrates. Since 1999, it has been considered to be a major public and veterinary health problem, causing diverse pathologies, ranging from a mild febrile state to severe neurological damage and death. WNV is transmitted in a bird–mosquito–bird cycle, and can occasionally infect humans and horses, both highly susceptible to the virus but considered dead-end hosts. Many studies have investigated the molecular determinants of WNV virulence, mainly with the ultimate objective of guiding vaccine development. Several vaccines are used in horses in different parts of the world, but there are no licensed WNV vaccines for humans, suggesting the need for greater understanding of the molecular determinants of virulence and antigenicity in different hosts. Owing to technical and economic considerations, WNV virulence factors have essentially been studied in rodent models, and the results cannot always be transported to mosquito vectors or to avian hosts. In this review, the known molecular determinants of WNV virulence, according to invertebrate (mosquitoes) or vertebrate hosts (mammalian and avian), are presented and discussed. This overview will highlight the differences and similarities found between WNV hosts and models, to provide a foundation for the prediction and anticipation of WNV re-emergence and its risk of global spread.
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Affiliation(s)
- Lise Fiacre
- UMR 1161 Virology, ANSES, INRAE, ENVA, ANSES Animal Health Laboratory, EURL for Equine Diseases, 94704 Maisons-Alfort, France; (L.F.); (J.R.); (G.G.)
- CIRAD, UMR ASTRE, F-97170 Petit Bourg, Guadeloupe, France; (N.P.); (E.A.)
- ASTRE, University Montpellier, CIRAD, INRAE, F-34398 Montpellier, France
| | - Nonito Pagès
- CIRAD, UMR ASTRE, F-97170 Petit Bourg, Guadeloupe, France; (N.P.); (E.A.)
- ASTRE, University Montpellier, CIRAD, INRAE, F-34398 Montpellier, France
| | - Emmanuel Albina
- CIRAD, UMR ASTRE, F-97170 Petit Bourg, Guadeloupe, France; (N.P.); (E.A.)
- ASTRE, University Montpellier, CIRAD, INRAE, F-34398 Montpellier, France
| | - Jennifer Richardson
- UMR 1161 Virology, ANSES, INRAE, ENVA, ANSES Animal Health Laboratory, EURL for Equine Diseases, 94704 Maisons-Alfort, France; (L.F.); (J.R.); (G.G.)
| | - Sylvie Lecollinet
- UMR 1161 Virology, ANSES, INRAE, ENVA, ANSES Animal Health Laboratory, EURL for Equine Diseases, 94704 Maisons-Alfort, France; (L.F.); (J.R.); (G.G.)
- Correspondence: ; Tel.: +33-1-43967376
| | - Gaëlle Gonzalez
- UMR 1161 Virology, ANSES, INRAE, ENVA, ANSES Animal Health Laboratory, EURL for Equine Diseases, 94704 Maisons-Alfort, France; (L.F.); (J.R.); (G.G.)
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4
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Mandary MB, Masomian M, Ong SK, Poh CL. Characterization of Plaque Variants and the Involvement of Quasi-Species in a Population of EV-A71. Viruses 2020; 12:E651. [PMID: 32560288 PMCID: PMC7354493 DOI: 10.3390/v12060651] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 05/15/2020] [Accepted: 05/20/2020] [Indexed: 12/13/2022] Open
Abstract
Viral plaque morphologies in human cell lines are markers for growth capability and they have been used to assess the viral fitness and selection of attenuated mutants for live-attenuated vaccine development. In this study, we investigate whether the naturally occurring plaque size variation reflects the virulence of the variants of EV-A71. Variants of two different plaque sizes (big and small) from EV-A71 sub-genotype B4 strain 41 were characterized. The plaque variants displayed different in vitro growth kinetics compared to the parental wild type. The plaque variants showed specific mutations being present in each variant strain. The big plaque variants showed four mutations I97L, N104S, S246P and N282D in the VP1 while the small plaque variants showed I97T, N237T and T292A in the VP1. No other mutations were detected in the whole genome of the two variants. The variants showed stable homogenous small plaques and big plaques, respectively, when re-infected in rhabdomyosarcoma (RD) and Vero cells. The parental strain showed faster growth kinetics and had higher viral RNA copy number than both the big and small plaque variants. Homology modelling shows that both plaque variants have differences in the structure of the VP1 protein due to the presence of unique spontaneous mutations found in each plaque variant This study suggests that the EV-A71 sub-genotype B4 strain 41 has at least two variants with different plaque morphologies. These differences were likely due to the presence of spontaneous mutations that are unique to each of the plaque variants. The ability to maintain the respective plaque morphology upon passaging indicates the presence of quasi-species in the parental population.
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Affiliation(s)
- Madiiha Bibi Mandary
- Centre for Virus and Vaccine Research, School of Science and Technology, Sunway University, Kuala Lumpur, Selangor 47500, Malaysia; (M.B.M.); (M.M.)
| | - Malihe Masomian
- Centre for Virus and Vaccine Research, School of Science and Technology, Sunway University, Kuala Lumpur, Selangor 47500, Malaysia; (M.B.M.); (M.M.)
| | - Seng-Kai Ong
- Department of Biological Science, School of Science and Technology, Sunway University, Kuala Lumpur, Selangor 47500, Malaysia;
| | - Chit Laa Poh
- Centre for Virus and Vaccine Research, School of Science and Technology, Sunway University, Kuala Lumpur, Selangor 47500, Malaysia; (M.B.M.); (M.M.)
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5
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Davis EH, Barrett ADT. Structure-Function of the Yellow Fever Virus Envelope Protein: Analysis of Antibody Epitopes. Viral Immunol 2019; 33:12-21. [PMID: 31682201 DOI: 10.1089/vim.2019.0107] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Yellow fever virus (YFV) is the prototype member of the genus Flavivirus, which contains more than 60 positive-sense, single-stranded RNA viruses, many of which are considered public health threats. YF disease is controlled by a live attenuated vaccine, 17D, which was generated empirically through serial passage of the wild-type (WT) strain Asibi in chicken tissue. The vaccine, which has been used for over 80 years, is considered to be one of the safest and most effective live attenuated vaccines. It has been shown that the humoral immune response is essential to a positive disease outcome during infection. As such, the neutralizing antibody response and its correlation to long-term protection are a critical measure of 17D efficacy. The primary target of these antibodies is the envelope (E) protein, which is the major component of the virion. Monoclonal antibodies can distinguish WT strain Asibi and vaccine strain 17D by many different measures, including physical binding, hemagglutination inhibition, neutralization, and passive protection. This makes the WT-vaccine pair ideal candidates to study the structure-function relationship of the E protein in the attenuation and immunogenicity of flaviviruses. In this study, we provide an overview of structure-function of YFV E protein and its involvement in protective immunity.
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Affiliation(s)
- Emily H Davis
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas.,Sealy Institute for Vaccine Sciences, University of Texas Medical Branch, Galveston, Texas
| | - Alan D T Barrett
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas.,Sealy Institute for Vaccine Sciences, University of Texas Medical Branch, Galveston, Texas
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6
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Chen T, He X, Zhang P, Yuan Y, Lang X, Yu J, Qin Z, Li X, Zhang Q, Zhu L, Zhang B, Wu Q, Zhao W. Research advancements in the neurological presentation of flaviviruses. Rev Med Virol 2019; 29:e2021. [PMID: 30548722 PMCID: PMC6590462 DOI: 10.1002/rmv.2021] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Revised: 07/27/2018] [Accepted: 10/26/2018] [Indexed: 12/25/2022]
Abstract
Owing to the large-scale epidemic of Zika virus disease and its association with microcephaly, properties that allow flaviviruses to cause nervous system diseases are an important area of investigation. At present, although potential pathogenic mechanisms of flaviviruses in the nervous system have been examined, they have not been completely elucidated. In this paper, we review the possible mechanisms of blood-brain barrier penetration, the pathological effects on neurons, and the association between virus mutations and neurotoxicity. A hypothesis on neurotoxicity caused by the Zika virus is presented. Clarifying the mechanisms of virulence of flaviviruses will be helpful in finding better antiviral drugs and optimizing the treatment of symptoms.
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Affiliation(s)
- Tingting Chen
- Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public HealthSouthern Medical UniversityGuangzhouChina
| | - Xiaoen He
- Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public HealthSouthern Medical UniversityGuangzhouChina
| | - Peiru Zhang
- Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public HealthSouthern Medical UniversityGuangzhouChina
| | - Yawen Yuan
- Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public HealthSouthern Medical UniversityGuangzhouChina
| | - Xinyue Lang
- Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public HealthSouthern Medical UniversityGuangzhouChina
| | - Jianhai Yu
- Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public HealthSouthern Medical UniversityGuangzhouChina
| | - Zhiran Qin
- Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public HealthSouthern Medical UniversityGuangzhouChina
| | - Xujuan Li
- Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public HealthSouthern Medical UniversityGuangzhouChina
| | - Qiwei Zhang
- Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public HealthSouthern Medical UniversityGuangzhouChina
| | - Li Zhu
- Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public HealthSouthern Medical UniversityGuangzhouChina
| | - Bao Zhang
- Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public HealthSouthern Medical UniversityGuangzhouChina
| | - Qinghua Wu
- Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public HealthSouthern Medical UniversityGuangzhouChina
| | - Wei Zhao
- Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public HealthSouthern Medical UniversityGuangzhouChina
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7
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Calvert AE, Dixon KL, Piper J, Bennett SL, Thibodeaux BA, Barrett ADT, Roehrig JT, Blair CD. A humanized monoclonal antibody neutralizes yellow fever virus strain 17D-204 in vitro but does not protect a mouse model from disease. Antiviral Res 2016; 131:92-9. [PMID: 27126613 PMCID: PMC4899248 DOI: 10.1016/j.antiviral.2016.04.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Revised: 04/20/2016] [Accepted: 04/23/2016] [Indexed: 01/29/2023]
Abstract
The yellow fever virus (YFV) vaccine 17D-204 is considered safe and effective, yet rare severe adverse events (SAEs), some resulting in death, have been documented following vaccination. Individuals exhibiting post-vaccinal SAEs are ideal candidates for antiviral monoclonal antibody (MAb) therapy; the time until appearance of clinical signs post-exposure is usually short and patients are quickly hospitalized. We previously developed a murine-human chimeric monoclonal antibody (cMAb), 2C9-cIgG, reactive with both virulent YFV and 17D-204, and demonstrated its ability to prevent and treat YF disease in both AG129 mouse and hamster models of infection. To counteract possible selection of 17D-204 variants that escape neutralization by treatment with a single MAb (2C9-cIgG), we developed a second cMAb, 864-cIgG, for use in combination with 2C9-cIgG in post-vaccinal therapy. MAb 864-cIgG recognizes/neutralizes only YFV 17D-204 vaccine substrain and binds to domain III (DIII) of the viral envelope protein, which is different from the YFV type-specific binding site of 2C9-cIgG in DII. Although it neutralized 17D-204 in vitro, administration of 864-cIgG had no protective capacity in the interferon receptor-deficient AG129 mouse model of 17D-204 infection. The data presented here show that although DIII-specific 864-cIgG neutralizes virus infectivity in vitro, it does not have the ability to abrogate disease in vivo. Therefore, combination of 864-cIgG with 2C9-cIgG for treatment of YF vaccination SAEs does not appear to provide an improvement on 2C9-cIgG therapy alone.
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MESH Headings
- Animals
- Antibodies, Monoclonal, Humanized/immunology
- Antibodies, Monoclonal, Humanized/therapeutic use
- Antibodies, Neutralizing/immunology
- Antibodies, Neutralizing/therapeutic use
- Antibodies, Viral/immunology
- Antibodies, Viral/therapeutic use
- Disease Models, Animal
- Humans
- Immunization, Passive
- Mice
- Neutralization Tests
- Receptors, Interferon/deficiency
- Receptors, Interferon/genetics
- Viral Envelope Proteins/immunology
- Viral Envelope Proteins/metabolism
- Yellow Fever/immunology
- Yellow Fever/prevention & control
- Yellow Fever/therapy
- Yellow Fever Vaccine/adverse effects
- Yellow Fever Vaccine/immunology
- Yellow fever virus/immunology
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Affiliation(s)
- Amanda E Calvert
- Division of Vector-Borne Diseases, U.S. Centers for Disease Control and Prevention, Fort Collins, CO, 80521, USA
| | - Kandice L Dixon
- Division of Vector-Borne Diseases, U.S. Centers for Disease Control and Prevention, Fort Collins, CO, 80521, USA
| | - Joseph Piper
- Arthropod-borne and Infectious Diseases Laboratory, Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, CO, 80523-1692, USA
| | - Susan L Bennett
- Arthropod-borne and Infectious Diseases Laboratory, Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, CO, 80523-1692, USA
| | - Brett A Thibodeaux
- Arthropod-borne and Infectious Diseases Laboratory, Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, CO, 80523-1692, USA
| | - Alan D T Barrett
- Department of Pathology and Sealy Center for Vaccine Development, University of Texas-Medical Branch, Galveston, TX, 77555, USA
| | - John T Roehrig
- Division of Vector-Borne Diseases, U.S. Centers for Disease Control and Prevention, Fort Collins, CO, 80521, USA
| | - Carol D Blair
- Arthropod-borne and Infectious Diseases Laboratory, Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, CO, 80523-1692, USA.
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9
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A High-Performance Multiplex Immunoassay for Serodiagnosis of Flavivirus-Associated Neurological Diseases in Horses. BIOMED RESEARCH INTERNATIONAL 2015; 2015:678084. [PMID: 26457301 PMCID: PMC4589573 DOI: 10.1155/2015/678084] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Accepted: 05/12/2015] [Indexed: 12/21/2022]
Abstract
West Nile virus (WNV), Japanese encephalitis virus (JEV), and tick-borne encephalitis virus (TBEV) are flaviviruses responsible for severe neuroinvasive infections in humans and horses. The confirmation of flavivirus infections is mostly based on rapid serological tests such as enzyme-linked immunosorbent assays (ELISAs). These tests suffer from poor specificity, mainly due to antigenic cross-reactivity among flavivirus members. Robust diagnosis therefore needs to be validated through virus neutralisation tests (VNTs) which are time-consuming and require BSL3 facilities. The flavivirus envelope (E) glycoprotein ectodomain is composed of three domains (D) named DI, DII, and DIII, with EDIII containing virus-specific epitopes. In order to improve the serological differentiation of flavivirus infections, the recombinant soluble ectodomain of WNV E (WNV.sE) and EDIIIs (rEDIIIs) of WNV, JEV, and TBEV were synthesised using the Drosophila S2 expression system. Purified antigens were covalently bonded to fluorescent beads. The microspheres coupled to WNV.sE or rEDIIIs were assayed with about 300 equine immune sera from natural and experimental flavivirus infections and 172 nonimmune equine sera as negative controls. rEDIII-coupled microspheres captured specific antibodies against WNV, TBEV, or JEV in positive horse sera. This innovative multiplex immunoassay is a powerful alternative to ELISAs and VNTs for veterinary diagnosis of flavivirus-related diseases.
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10
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Kim YI, Murphy R, Majumdar S, Harrison LG, Aitken J, DeVincenzo JP. Relating plaque morphology to respiratory syncytial virus subgroup, viral load, and disease severity in children. Pediatr Res 2015; 78:380-8. [PMID: 26107392 PMCID: PMC4589428 DOI: 10.1038/pr.2015.122] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Accepted: 03/26/2015] [Indexed: 12/23/2022]
Abstract
BACKGROUND Viral culture plaque morphology in human cell lines are markers for growth capability and cytopathic effect, and have been used to assess viral fitness and select preattenuation candidates for live viral vaccines. We classified respiratory syncytial virus (RSV) plaque morphology and analyzed the relationship between plaque morphology as compared to subgroup, viral load and clinical severity of infection in infants and children. METHODS We obtained respiratory secretions from 149 RSV-infected children. Plaque morphology and viral load was assessed within the first culture passage in HEp-2 cells. Viral load was measured by polymerase chain reaction (PCR), as was RSV subgroup. Disease severity was determined by hospitalization, length of stay, intensive care requirement, and respiratory failure. RESULTS Plaque morphology varied between individual subjects; however, similar results were observed among viruses collected from upper and lower respiratory tracts of the same subject. Significant differences in plaque morphology were observed between RSV subgroups. No correlations were found among plaque morphology and viral load. Plaque morphology did not correlate with disease severity. CONCLUSION Plaque morphology measures parameters that are viral-specific and independent of the human host. Morphologies vary between patients and are related to RSV subgroup. In HEp-2 cells, RSV plaque morphology appears unrelated to disease severity in RSV-infected children.
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Affiliation(s)
- Young-In Kim
- grid.267301.10000 0004 0386 9246Department of Pediatrics, University of Tennessee Health Science Center, Memphis, Tennessee ,grid.413728.b0000 0004 0383 6997Children’s Foundation Research Institute at Le Bonheur Children’s Hospital, Memphis, Tennessee
| | - Ryan Murphy
- grid.267301.10000 0004 0386 9246Department of Pediatrics, University of Tennessee Health Science Center, Memphis, Tennessee ,grid.413728.b0000 0004 0383 6997Children’s Foundation Research Institute at Le Bonheur Children’s Hospital, Memphis, Tennessee
| | - Sirshendu Majumdar
- grid.267301.10000 0004 0386 9246Department of Pediatrics, University of Tennessee Health Science Center, Memphis, Tennessee ,grid.413728.b0000 0004 0383 6997Children’s Foundation Research Institute at Le Bonheur Children’s Hospital, Memphis, Tennessee
| | - Lisa G. Harrison
- grid.267301.10000 0004 0386 9246Department of Pediatrics, University of Tennessee Health Science Center, Memphis, Tennessee ,grid.413728.b0000 0004 0383 6997Children’s Foundation Research Institute at Le Bonheur Children’s Hospital, Memphis, Tennessee
| | - Jody Aitken
- grid.413728.b0000 0004 0383 6997Children’s Foundation Research Institute at Le Bonheur Children’s Hospital, Memphis, Tennessee
| | - John P. DeVincenzo
- grid.267301.10000 0004 0386 9246Department of Pediatrics, University of Tennessee Health Science Center, Memphis, Tennessee ,grid.413728.b0000 0004 0383 6997Children’s Foundation Research Institute at Le Bonheur Children’s Hospital, Memphis, Tennessee ,grid.267301.10000 0004 0386 9246Department of Microbiology, Immunology and Biochemistry, University of Tennessee Health Science Center, Memphis, Tennessee
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11
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Beasley DWC, McAuley AJ, Bente DA. Yellow fever virus: genetic and phenotypic diversity and implications for detection, prevention and therapy. Antiviral Res 2014; 115:48-70. [PMID: 25545072 DOI: 10.1016/j.antiviral.2014.12.010] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Revised: 12/05/2014] [Accepted: 12/11/2014] [Indexed: 11/28/2022]
Abstract
Yellow fever virus (YFV) is the prototypical hemorrhagic fever virus, yet our understanding of its phenotypic diversity and any molecular basis for observed differences in disease severity and epidemiology is lacking, when compared to other arthropod-borne and haemorrhagic fever viruses. This is, in part, due to the availability of safe and effective vaccines resulting in basic YFV research taking a back seat to those viruses for which no effective vaccine occurs. However, regular outbreaks occur in endemic areas, and the spread of the virus to new, previously unaffected, areas is possible. Analysis of isolates from endemic areas reveals a strong geographic association for major genotypes, and recent epidemics have demonstrated the emergence of novel sequence variants. This review aims to outline the current understanding of YFV genetic and phenotypic diversity and its sources, as well as the available animal models for characterizing these differences in vivo. The consequences of genetic diversity for detection and diagnosis of yellow fever and development of new vaccines and therapeutics are discussed.
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Affiliation(s)
- David W C Beasley
- Department of Microbiology and Immunology, University of Texas Medical Branch, 301 University Blvd., Galveston, TX 77555, United States; Sealy Center for Vaccine Development, University of Texas Medical Branch, 301 University Blvd., Galveston, TX 77555, United States; Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, 301 University Blvd., Galveston, TX 77555, United States; Institute for Human Infections and Immunity, University of Texas Medical Branch, 301 University Blvd., Galveston, TX 77555, United States.
| | - Alexander J McAuley
- Department of Microbiology and Immunology, University of Texas Medical Branch, 301 University Blvd., Galveston, TX 77555, United States
| | - Dennis A Bente
- Department of Microbiology and Immunology, University of Texas Medical Branch, 301 University Blvd., Galveston, TX 77555, United States; Sealy Center for Vaccine Development, University of Texas Medical Branch, 301 University Blvd., Galveston, TX 77555, United States; Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, 301 University Blvd., Galveston, TX 77555, United States; Institute for Human Infections and Immunity, University of Texas Medical Branch, 301 University Blvd., Galveston, TX 77555, United States
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12
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13
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Monath TP. Review of the risks and benefits of yellow fever vaccination including some new analyses. Expert Rev Vaccines 2012; 11:427-448. [DOI: 10.1586/erv.12.6] [Citation(s) in RCA: 88] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/30/2023]
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14
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Neuroadapted yellow fever virus strain 17D: a charged locus in domain III of the E protein governs heparin binding activity and neuroinvasiveness in the SCID mouse model. J Virol 2008; 82:12510-9. [PMID: 18842715 DOI: 10.1128/jvi.00458-08] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
A molecular clone of yellow fever virus (YFV) strain 17D was used to identify critical determinants of mouse neuroinvasiveness previously localized to domain III of the neuroadapted SPYF-MN virus envelope protein. Three candidate virulence substitutions (305F-->V, 326K-->E, and 380R-->T) were individually evaluated for their roles in this phenotype in a SCID mouse model. The virus containing a glutamic acid residue at position 326 of the envelope protein (326E) caused rapidly lethal encephalitis, with a mortality rate and average survival time resembling those of the parental SPYF-MN virus. Determinants at positions 380 (380T) and 305 (305V) did not independently affect neuroinvasiveness. Testing a panel of viruses with various amino acid substitutions at position 326 revealed that attenuation of neuroinvasiveness required a positively charged residue (lysine or arginine) at this position. Molecular-modeling studies suggest that residues 326 and 380 contribute to charge clusters on the lateral surface of domain III that constitute putative heparin binding sites, as confirmed by studies of heparin inhibition of plaque formation. The neuroinvasiveness of YFVs in the SCID model correlated inversely with sensitivity to heparin. These findings establish that residue 326 in domain III of the E protein is a critical determinant of YFV neuroinvasiveness in the SCID mouse model. Together with modeling of domain III from virulent YFV strains, the data suggest that heparin binding activity involving lysine at position 326 may be a modulator of YFV virulence phenotypes.
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15
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E protein domain III determinants of yellow fever virus 17D vaccine strain enhance binding to glycosaminoglycans, impede virus spread, and attenuate virulence. J Virol 2008; 82:6024-33. [PMID: 18400851 DOI: 10.1128/jvi.02509-07] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The yellow fever virus (YFV) 17D strain is one of the most effective live vaccines for human use, but the in vivo mechanisms for virulence attenuation of the vaccine and the corresponding molecular determinants remain elusive. The vaccine differs phenotypically from wild-type YFV by the loss of viscerotropism, despite replicative fitness in cell culture, and genetically by 20 amino acid changes predominantly located in the envelope (E) protein. We show that three residues in E protein domain III inhibit spread of 17D in extraneural tissues and attenuate virulence in type I/II interferon-deficient mice. One of these residues (Arg380) is a dominant glycosaminoglycan-binding determinant, which mainly accounts for more rapid in vivo clearance of 17D from the bloodstream in comparison to 17D-derived variants with wild-type-like E protein. While other mutations will account for loss of neurotropism and phenotypic stability, the described impact of E protein domain III changes on virus dissemination and virulence is the first rational explanation for the safety of the 17D vaccine in humans.
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16
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Genetic determinants of Sindbis virus mosquito infection are associated with a highly conserved alphavirus and flavivirus envelope sequence. J Virol 2007; 82:2966-74. [PMID: 18160430 DOI: 10.1128/jvi.02060-07] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Wild-type Sindbis virus (SINV) strain MRE16 efficiently infects Aedes aegypti midgut epithelial cells (MEC), but laboratory-derived neurovirulent SINV strain TE/5'2J infects MEC poorly. SINV determinants for MEC infection have been localized to the E2 glycoprotein. The E2 amino acid sequences of MRE16 and TE/5'2J differ at 60 residue sites. To identify the genetic determinants of MEC infection of MRE16, the TE/5'2J virus genome was altered to contain either domain chimeras or more focused nucleotide substitutions of MRE16. The growth patterns of derived viruses in cell culture were determined, as were the midgut infection rates (MIR) in A. aegypti mosquitoes. The results showed that substitutions of MRE16 E2 aa 95 to 96 and 116 to 119 into the TE/5'2J virus increased MIR both independently and in combination with each other. In addition, a unique PPF/.GDS amino acid motif was located between these two sites that was found to be a highly conserved sequence among alphaviruses and flaviviruses but not other arboviruses.
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17
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van Marle G, Antony J, Ostermann H, Dunham C, Hunt T, Halliday W, Maingat F, Urbanowski MD, Hobman T, Peeling J, Power C. West Nile virus-induced neuroinflammation: glial infection and capsid protein-mediated neurovirulence. J Virol 2007; 81:10933-49. [PMID: 17670819 PMCID: PMC2045515 DOI: 10.1128/jvi.02422-06] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
West Nile virus (WNV) infection causes neurological disease at all levels of the neural axis, accompanied by neuroinflammation and neuronal loss, although the underlying mechanisms remain uncertain. Given the substantial activation of neuroinflammatory pathways observed in WNV infection, we hypothesized that WNV-mediated neuroinflammation and cell death occurred through WNV infection of both glia and neurons, which was driven in part by WNV capsid protein expression. Analysis of autopsied neural tissues from humans with WNV encephalomyelitis (WNVE) revealed WNV infection of both neurons and glia. Upregulation of proinflammatory genes, CXCL10, interleukin-1beta, and indolamine-2',3'-deoxygenase with concurrent suppression of the protective astrocyte-specific endoplasmic reticulum stress sensor gene, OASIS (for old astrocyte specifically induced substance), was evident in WNVE patients compared to non-WNVE controls. These findings were supported by increased ex vivo expression of these proinflammatory genes in glia infected by WNV-NY99. WNV infection caused endoplasmic reticulum stress gene induction and apoptosis in neurons but did not affect glial viability. WNV-infected astrocytic cells secreted cytotoxic factors, which caused neuronal apoptosis. The expression of the WNV-NY99 capsid protein in neurons and glia by a Sindbis virus-derived vector (SINrep5-WNVc) caused neuronal death and the release of neurotoxic factors by infected astrocytes, coupled with proinflammatory gene induction and suppression of OASIS. Striatal implantation of SINrep5-WNV(C) induced neuroinflammation in rats, together with the induction of CXCL10 and diminished OASIS expression, compared to controls. Moreover, magnetic resonance neuroimaging showed edema and tissue injury in the vicinity of the SINrep5-WNVc implantation site compared to controls, which was complemented by neurobehavioral abnormalities in the SINrep5-WNVc-implanted animals. These studies underscore the important interactions between the WNV capsid protein and neuroinflammation in the pathogenesis of WNV-induced neurological disorders.
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Affiliation(s)
- Guido van Marle
- Departments of Microbiology and Infectious Diseases, University of Calgary, Calgary, Alberta, Canada
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Jia Y, Moudy RM, Dupuis AP, Ngo KA, Maffei JG, Jerzak GVS, Franke MA, Kauffman EB, Kramer LD. Characterization of a small plaque variant of West Nile virus isolated in New York in 2000. Virology 2007; 367:339-47. [PMID: 17617432 PMCID: PMC2190729 DOI: 10.1016/j.virol.2007.06.008] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2007] [Revised: 04/07/2007] [Accepted: 06/07/2007] [Indexed: 11/29/2022]
Abstract
A small-plaque variant (SP) of West Nile virus (WNV) was isolated in Vero cell culture from kidney tissue of an American crow collected in New York in 2000. The in vitro growth of the SP and parental (WT) strains was characterized in mammalian (Vero), avian (DF-1 and PDE), and mosquito (C6/36) cells. The SP variant replicated less efficiently than did the WT in Vero cells. In avian cells, SP growth was severely restricted at high temperatures, suggesting that the variant is temperature sensitive. In mosquito cells, growth of SP and WT was similar, but in vivo in Culex pipiens (L.) there were substantial differences. Relative to WT, SP exhibited reduced replication following intrathoracic inoculation and lower infection, dissemination, and transmission rates following oral infection. Analysis of the full length sequence of the SP variant identified sequence differences which led to only two amino acid substitutions relative to WT, prM P54S and NS2A V61A.
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Affiliation(s)
- Yongqing Jia
- The Arbovirus Laboratories, Wadsworth Center, New York State Department of Health, Slingerlands, New York 12159
| | - Robin M. Moudy
- The Arbovirus Laboratories, Wadsworth Center, New York State Department of Health, Slingerlands, New York 12159
| | - Alan P. Dupuis
- The Arbovirus Laboratories, Wadsworth Center, New York State Department of Health, Slingerlands, New York 12159
| | - Kiet A. Ngo
- The Arbovirus Laboratories, Wadsworth Center, New York State Department of Health, Slingerlands, New York 12159
| | - Joseph G. Maffei
- The Arbovirus Laboratories, Wadsworth Center, New York State Department of Health, Slingerlands, New York 12159
| | - Greta V. S. Jerzak
- The Arbovirus Laboratories, Wadsworth Center, New York State Department of Health, Slingerlands, New York 12159
| | - Mary A. Franke
- The Arbovirus Laboratories, Wadsworth Center, New York State Department of Health, Slingerlands, New York 12159
| | - Elizabeth B. Kauffman
- The Arbovirus Laboratories, Wadsworth Center, New York State Department of Health, Slingerlands, New York 12159
| | - Laura D. Kramer
- The Arbovirus Laboratories, Wadsworth Center, New York State Department of Health, Slingerlands, New York 12159
- Department of Biomedical Sciences, School of Public Health, State University of New York at Albany, Albany, New York 12201
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19
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McElroy KL, Tsetsarkin KA, Vanlandingham DL, Higgs S. Characterization of an infectious clone of the wild-type yellow fever virus Asibi strain that is able to infect and disseminate in mosquitoes. J Gen Virol 2005; 86:1747-1751. [PMID: 15914853 DOI: 10.1099/vir.0.80746-0] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Infectious clone technology provides an opportunity to study the molecular basis of arthropod-virus interactions in detail. This study describes the development of an infectious clone of the prototype yellow fever virus Asibi strain (YFV-As) with the purpose of identifying sequences or domains that influence infection dynamics in the mosquito vector. The full-length cDNA of YFV-As virus was produced from RT-PCR products of parental viral RNA. These were cloned into a low-copy-number plasmid previously used to develop the YFV-17D infectious clone (pACNR/FLYF-17D). Virus recovered from the infectious clone exhibited biological characteristics similar to those of the parental YFV-As, including replication kinetics, reactivity to flavivirus cross-reactive and YFV-specific antibodies and infection and dissemination rates in Aedes aegypti, the principal mosquito vector of YFV. These data provide the basis for future studies with chimeric Asibi/17D viruses to identify the determinants of vaccine attenuation in the vector.
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Affiliation(s)
- Kate L McElroy
- Department of Pathology, University of Texas Medical Branch, Keiller 2.104, 301 University Boulevard, Galveston, TX 77555-0609, USA
| | - Konstantin A Tsetsarkin
- Department of Pathology, University of Texas Medical Branch, Keiller 2.104, 301 University Boulevard, Galveston, TX 77555-0609, USA
| | - Dana L Vanlandingham
- Department of Pathology, University of Texas Medical Branch, Keiller 2.104, 301 University Boulevard, Galveston, TX 77555-0609, USA
| | - Stephen Higgs
- Department of Pathology, University of Texas Medical Branch, Keiller 2.104, 301 University Boulevard, Galveston, TX 77555-0609, USA
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Vlaycheva L, Nickells M, Droll DA, Chambers TJ. Neuroblastoma cell-adapted yellow fever virus: mutagenesis of the E protein locus involved in persistent infection and its effects on virus penetration and spread. J Gen Virol 2005; 86:413-421. [PMID: 15659761 DOI: 10.1099/vir.0.80314-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Persistent infection of mouse neuroblastoma NB41A3 cells with yellow fever 17D virus generates viral variants which exhibit defective cell penetration, poor cell-to-cell spread, small plaque size and reduced growth efficiency, caused by substitution of glycine for aspartic acid or glutamic acid at positions 360 and 362 in the envelope protein. These positions occur within a charge cluster, Asp360-Asp361-Glu362, located in domain III, near its interface with domain I. To characterize further the molecular basis for the variant phenotype, a series of mutant viruses containing substitutions at position 360, 361 and 362, were studied for effects on the cell culture properties typical of the neuroblastoma-adapted variant. Most substitutions at position 360 gave rise to viruses that were very defective in cell penetration, growth efficiency and cell-to-cell spread, whereas substitution with glutamic acid yielded a virus indistinguishable from parental yellow fever 17D. Substitution with lysine was not tolerated and substitution with asparagine resulted in frequent wild-type revertants. A glycine residue was not tolerated at position 361, but substitution at 362 yielded a small plaque virus, similar to the effect of substitution at position 360. These data indicate that the yellow fever virus E protein contains a locus within domain III where a negative-charge cluster is important for optimal function of this domain in virus-cell interactions beyond the stage of virus attachment. Modelling predictions suggest that the mutations alter the local properties of the loop within domain III, and may compromise interactions of this domain with an adjacent region of domain I during conformational changes that occur in the E protein in association with virus entry.
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Affiliation(s)
- Leonssia Vlaycheva
- Department of Molecular Microbiology and Immunology, St Louis University Health Sciences Center, 1402 South Grand Avenue, St Louis, MO 63104, USA
| | - Michael Nickells
- Department of Molecular Microbiology and Immunology, St Louis University Health Sciences Center, 1402 South Grand Avenue, St Louis, MO 63104, USA
| | - Deborah A Droll
- Department of Molecular Microbiology and Immunology, St Louis University Health Sciences Center, 1402 South Grand Avenue, St Louis, MO 63104, USA
| | - Thomas J Chambers
- Department of Molecular Microbiology and Immunology, St Louis University Health Sciences Center, 1402 South Grand Avenue, St Louis, MO 63104, USA
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Vlaycheva L, Nickells M, Droll DA, Chambers TJ. Yellow fever 17D virus: pseudo-revertant suppression of defective virus penetration and spread by mutations in domains II and III of the E protein. Virology 2004; 327:41-9. [PMID: 15327896 DOI: 10.1016/j.virol.2004.06.015] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2004] [Revised: 04/22/2004] [Accepted: 06/03/2004] [Indexed: 10/26/2022]
Abstract
A yellow fever (YFV) 17D virus variant, which causes persistent infection of mouse neuroblastoma cells associated with defective cell penetration and small plaque size, yielded plaque-revertant viruses from cells transfected with viral transcripts encoding the adaptive mutation (Gly360 in the E protein). Reconstruction of a plaque-purified revertant which contained Gly360 and additional substitutions (Asn for Lys303 and Val for Ala261) yielded a virus whose infectious center size, growth efficiency, and cell penetration rate similar to the parental YF5.2iv virus, whereas viruses with Asn303 or Val261 alone with Gly360 yielded either a small-plaque virus or a parental revertant. These data indicate that the YFV E protein is subject to suppression of mutations in domain III that are deleterious for viral entry and spread by a second-site mutation in domain II. Position 261 lies within the hydrophobic ligand-binding pocket at the domain I-II interface, a site believed to be involved in the hinge-like conformational change of domain II during activation of membrane fusion-activity. Results of this study provide genetic data consistent with findings on flavivirus structure and implicate domain III in functions beyond simply cell surface attachment.
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Affiliation(s)
- Leonssia Vlaycheva
- Department of Molecular Microbiology and Immunology, Saint Louis University Health Sciences Center, St. Louis, MO 63104, USA
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Charlier N, Molenkamp R, Leyssen P, Paeshuyse J, Drosten C, Panning M, De Clercq E, Bredenbeek PJ, Neyts J. Exchanging the yellow fever virus envelope proteins with Modoc virus prM and E proteins results in a chimeric virus that is neuroinvasive in SCID mice. J Virol 2004; 78:7418-26. [PMID: 15220415 PMCID: PMC434118 DOI: 10.1128/jvi.78.14.7418-7426.2004] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A chimeric flavivirus infectious cDNA was constructed by exchanging the premembrane (prM) and envelope (E) genes of the yellow fever virus vaccine strain 17D (YF17D) with the corresponding genes of Modoc virus (MOD). This latter virus belongs to the cluster of the "not-known vector" flaviviruses and is, unlike YF17D, neuroinvasive in SCID mice. Replication of in vitro-transcribed RNA from this chimeric flavivirus was shown by [(3)H]uridine labeling and RNA analysis. Expression of the MOD prM and E proteins was monitored by radioimmunoprecipitation and revealed that the MOD proteins were correctly and efficiently produced from the chimeric precursor protein. The MOD E protein was shown to be N-linked glycosylated, whereas prM, as predicted from the genome sequence, did not contain N-linked carbohydrates. In Vero cells, the chimeric virus replicated with a similar efficiency as the parental viruses, although it formed smaller plaques than YF17D and MOD. In SCID mice that had been infected intraperitoneally with the chimeric virus, the viral load increased steadily until death. The MOD/YF virus, like MOD from which it had acquired the prM and E structural proteins, but unlike YF, proved neuroinvasive in SCID mice. Animals developed neurological symptoms about 15 days after inoculation and died shortly thereafter. The distribution of MOD/YF RNA in the brain of infected mice was similar to that observed in MOD-infected mice. The observations provide compelling evidence that the determinants of neuroinvasiveness of flaviviruses are entirely located in the envelope proteins prM and E.
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Affiliation(s)
- Nathalie Charlier
- Rega Institute for Medical Research, Minderbroedersstraat 10, B-3000 Leuven, Belgium.
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