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McGinnes Cullen L, Luo B, Wen Z, Zhang L, Durr E, Morrison TG. The Respiratory Syncytial Virus (RSV) G Protein Enhances the Immune Responses to the RSV F Protein in an Enveloped Virus-Like Particle Vaccine Candidate. J Virol 2023; 97:e0190022. [PMID: 36602367 PMCID: PMC9888267 DOI: 10.1128/jvi.01900-22] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Accepted: 12/14/2022] [Indexed: 01/06/2023] Open
Abstract
Respiratory syncytial virus (RSV) is a serious human respiratory pathogen, but no RSV vaccine has been licensed. Many vaccine candidates are focused on the viral F protein since the F protein is more conserved than the viral G protein across RSV strains and serotypes; thus, the F protein is thought more likely to induce a broader range of protection from infection. However, it is the G protein that binds the likely receptor, CX3CR1, in lung ciliated epithelial cells, raising the question of the importance of the G protein in vaccine candidates. Using virus-like particle (VLP) vaccine candidates, we have directly compared VLPs containing only the prefusion F protein (pre-F), only the G protein, or both glycoproteins. We report that VLPs containing both glycoproteins bind to anti-F-protein-specific monoclonal antibodies differently than do VLPs containing only the prefusion F protein. In RSV-naive cotton rats, VLPs assembled with only the pre-F protein stimulated extremely weak neutralizing antibody (NAb) titers, as did VLPs assembled with G protein. However, VLPs assembled with both glycoproteins stimulated quite robust neutralizing antibody titers, induced improved protection of the animals from RSV challenge compared to pre-F VLPs, and induced significantly higher levels of antibodies specific for F protein antigenic site 0, site III, and the AM14 binding site than did VLPs containing only the pre-F protein. These results indicate that assembly of pre-F protein with G protein in VLPs further stabilized the prefusion conformation or otherwise altered the conformation of the F protein, increasing the induction of protective antibodies. IMPORTANCE Respiratory syncytial virus (RSV) results in significant disease in infants, young children, and the elderly. Thus, development of an effective vaccine for these populations is a priority. Most ongoing efforts in RSV vaccine development have focused on the viral fusion (F) protein; however, the importance of the inclusion of G in vaccine candidates is unclear. Here, using virus-like particles (VLPs) assembled with only the F protein, only the G protein, or both glycoproteins, we show that VLPs assembled with both glycoproteins are a far superior vaccine in a cotton rat model compared with VLPs containing only F protein or only G protein. The results show that the presence of G protein in the VLPs influences the conformation of the F protein and the immune responses to F protein, resulting in significantly higher neutralizing antibody titers and better protection from RSV challenge. These results suggest that inclusion of G protein in a vaccine candidate may improve its effectiveness.
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Affiliation(s)
- Lori McGinnes Cullen
- Department of Microbiology and Physiological Systems, Program in Immunology and Microbiology, University of Massachusetts Chan Medical School, Worcester, Massachusetts, USA
| | - Bin Luo
- Pharmacology, Merck & Co., Inc., West Point, Pennsylvania, USA
| | - Zhiyun Wen
- Infectious Diseases and Vaccines Discovery, Merck & Co., Inc., West Point, Pennsylvania, USA
| | - Lan Zhang
- Infectious Diseases and Vaccines Discovery, Merck & Co., Inc., West Point, Pennsylvania, USA
| | - Eberhard Durr
- Infectious Diseases and Vaccines Discovery, Merck & Co., Inc., West Point, Pennsylvania, USA
| | - Trudy G. Morrison
- Department of Microbiology and Physiological Systems, Program in Immunology and Microbiology, University of Massachusetts Chan Medical School, Worcester, Massachusetts, USA
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2
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Long-Term Infection and Pathogenesis in a Novel Mouse Model of Human Respiratory Syncytial Virus. Viruses 2022; 14:v14081740. [PMID: 36016362 PMCID: PMC9415064 DOI: 10.3390/v14081740] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Revised: 07/30/2022] [Accepted: 08/03/2022] [Indexed: 11/24/2022] Open
Abstract
Intensive efforts have been made to develop models of hRSV infection or disease using various animals. However, the limitations such as semi-permissiveness and short duration of infection have impeded their applications in both the pathogenesis of hRSV and therapeutics development. Here, we present a mouse model based on a Rag2 gene knockout using CRISPR/Cas9 technology. Rag2−/− mice sustained high viral loads upon intranasal inoculation with hRSV. The average peak titer rapidly reached 1 × 109.8 copies/g and 1c106 TCID50 in nasal cavity, as well as 1 × 108 copies/g and 1 × 105 TCID50 in the lungs up to 5 weeks. Mild interstitial pneumonia, severe bronchopneumonia, elevated cytokines and NK cells were seen in Rag2−/− mice. A humanized monoclonal antibody showed strong antiviral activity in this animal model, implying that Rag2−/− mice that support long-term stable infection are a useful tool for studying the transmission and pathogenesis of human RSV, as well as evaluating therapeutics.
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3
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Bergeron HC, Tripp RA. Immunopathology of RSV: An Updated Review. Viruses 2021; 13:2478. [PMID: 34960746 PMCID: PMC8703574 DOI: 10.3390/v13122478] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Revised: 12/06/2021] [Accepted: 12/08/2021] [Indexed: 12/14/2022] Open
Abstract
RSV is a leading cause of respiratory tract disease in infants and the elderly. RSV has limited therapeutic interventions and no FDA-approved vaccine. Gaps in our understanding of virus-host interactions and immunity contribute to the lack of biological countermeasures. This review updates the current understanding of RSV immunity and immunopathology with a focus on interferon responses, animal modeling, and correlates of protection.
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Affiliation(s)
| | - Ralph A. Tripp
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA 30602, USA;
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4
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Martinez ME, Niewiesk S, La Perle KMD. Cotton Rat Placenta Anatomy and Fc Receptor Expression and Their Roles in Maternal Antibody Transfer. Comp Med 2020; 70:510-519. [PMID: 33121562 DOI: 10.30802/aalas-cm-20-000040] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Respiratory syncytial virus (RSV) is the leading cause of bronchiolitis and viral pneumonia in infants and young children worldwide. Currently no vaccine is available to prevent RSV infection, but virus-neutralizing monoclonal antibodies can be given prophylactically, emphasizing the protective potential of antibodies. One concept of RSV vaccinology is mothers' immunization to induce high antibody titers, leading to passive transfer of high levels of maternal antibody to the fetus through the placenta and to the neonate through colostrum. Cotton rats are an excellent small animal model for RSV infection and have been used to test maternal immunization. To mechanistically understand antibody transfer in the cotton rat model, we characterized the cotton rat placenta and Fc receptor localization. Placentas from cotton rats at midgestation (approximately day 14) and at late gestation (approximately day 25) and neonatal (younger than 1 wk) gastrointestinal tracts were collected for light microscopy, immunohistochemistry, and transmission electron microscopy. The cotton rat placenta is hemotrichorial and has 5 distinct layers: decidua, junctional zone, labyrinth, chorionic plate, and yolk sac. Consistent with the transfer of maternal antibodies, the majority of the Fc receptors are present in the yolk sac endoderm and fetal capillary endothelium of the chorionic plate, involving 10% of the cells within the labyrinth. In addition, Fc receptors are present on duodenal and jejunal enterocytes in cotton rats, similar to humans, mice, and rats. These findings provide the structural basis for the pre- and postnatal transfer of maternal antibodies described in cotton rats.
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Affiliation(s)
- Margaret E Martinez
- Department of Veterinary Biosciences, Ohio State University, Columbus, Ohio;,
| | - Stefan Niewiesk
- Department of Veterinary Biosciences, Ohio State University, Columbus, Ohio
| | - Krista M D La Perle
- Department of Veterinary Biosciences, Ohio State University, Columbus, Ohio; Comparative Pathology and Mouse Phenotyping Shared Resource, Ohio State University, Columbus, Ohio
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5
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Schultheis K, Pugh HM, Oh J, Nguyen J, Yung B, Reed C, Cooch N, Chen J, Yan J, Muthumani K, Humeau LM, Weiner DB, Broderick KE, Smith TRF. Active immunoprophylaxis with a synthetic DNA-encoded monoclonal anti-respiratory syncytial virus scFv-Fc fusion protein confers protection against infection and durable activity. Hum Vaccin Immunother 2020; 16:2165-2175. [PMID: 32544376 PMCID: PMC7553682 DOI: 10.1080/21645515.2020.1748979] [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] [Indexed: 11/13/2022] Open
Abstract
Respiratory Syncytial virus (RSV) is a major threat to many vulnerable populations. There are currently no approved vaccines, and RSV remains a high unmet global medical need. Here we describe the employment of a novel synthetic DNA-encoded antibody technology platform to develop and deliver an engineered human DNA-encoded monoclonal antibody (dMAbTM) targeting the fusion protein (F) of RSV as a new approach to prevention or therapy of at risk populations. In in vivo models, a single administration of synthetic DNA-encoding the single-chain fragment variable-constant fragment (scFv-Fc) RSV-F dMAb resulted in robust and durable circulating levels of a functional antibody systemically and in mucosal tissue. In cotton rats, which are the gold-standard animals to model RSV infection, we observed sustained scFv-Fc RSV-F dMAb in the sera and lung-lavage samples, demonstrating the potential for both long-lasting immunity to RSV and effective biodistribution. The scFv-Fc RSV-F dMAb harbored in the sera exhibited RSV antigen-specific binding and potent viral neutralizing activity. Importantly, in vivo delivery of synthetic DNA-encoding, the scFv-Fc RSV-F dMAb protected animals against viral challenge. Our findings support the significance of dMAbs as a potential platform technology for durable protection against RSV disease.
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Affiliation(s)
| | - Holly M Pugh
- Inovio Pharmaceuticals , Plymouth Meeting, PA, USA
| | - Janet Oh
- Inovio Pharmaceuticals , Plymouth Meeting, PA, USA
| | | | - Bryan Yung
- Inovio Pharmaceuticals , Plymouth Meeting, PA, USA
| | - Charles Reed
- Inovio Pharmaceuticals , Plymouth Meeting, PA, USA
| | - Neil Cooch
- Inovio Pharmaceuticals , Plymouth Meeting, PA, USA
| | - Jing Chen
- Inovio Pharmaceuticals , Plymouth Meeting, PA, USA
| | - Jian Yan
- Inovio Pharmaceuticals , Plymouth Meeting, PA, USA
| | - Kar Muthumani
- Vaccine & Immunotherapy Center, The Wistar Institute , Philadelphia, PA, USA
| | | | - David B Weiner
- Vaccine & Immunotherapy Center, The Wistar Institute , Philadelphia, PA, USA
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6
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Martinez ME, Harder OE, Rosas LE, Joseph L, Davis IC, Niewiesk S. Pulmonary function analysis in cotton rats after respiratory syncytial virus infection. PLoS One 2020; 15:e0237404. [PMID: 32776985 PMCID: PMC7416943 DOI: 10.1371/journal.pone.0237404] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Accepted: 07/25/2020] [Indexed: 01/31/2023] Open
Abstract
The cotton rat (Sigmodon hispidus) is an excellent small animal model for human respiratory viral infections such as human respiratory syncytial virus (RSV) and human metapneumovirus (HMPV). These respiratory viral infections, as well as other pulmonary inflammatory diseases such as asthma, are associated with lung mechanic disturbances. So far, the pathophysiological effects of viral infection and allergy on cotton rat lungs have not been measured, although this information might be an important tool to determine the efficacy of vaccine and drug candidates. To characterize pulmonary function in the cotton rat, we established forced oscillation technique in uninfected, RSV infected and HDM sensitized cotton rats, and characterized pulmonary inflammation, mucus production, pulmonary edema, and oxygenation. There was a gender difference after RSV infection, with females demonstrating airway hyper-responsiveness while males did not. Female cotton rats 2dpi had a mild increase in pulmonary edema (wet: dry weight ratios). At day 4 post infection, female cotton rats demonstrated mild pulmonary inflammation, no increase in mucus production or reduction in oxygenation. Pulmonary function was not significantly impaired after RSV infection. In contrast, cotton rats sensitized to HDM demonstrated airway hyper-responsiveness with a significant increase in pulmonary inflammation, increase in baseline tissue damping, and a decrease in baseline pulmonary compliance. In summary, we established baseline data for forced oscillation technique and other respiratory measures in the cotton rat and used it to analyze respiratory diseases in cotton rats.
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Affiliation(s)
- Margaret E. Martinez
- Department of Veterinary Biosciences, College of Veterinary Medicine, The Ohio State University, Columbus, Ohio, United States of America
| | - Olivia E. Harder
- Department of Veterinary Biosciences, College of Veterinary Medicine, The Ohio State University, Columbus, Ohio, United States of America
| | - Lucia E. Rosas
- Department of Veterinary Biosciences, College of Veterinary Medicine, The Ohio State University, Columbus, Ohio, United States of America
| | - Lisa Joseph
- Department of Veterinary Biosciences, College of Veterinary Medicine, The Ohio State University, Columbus, Ohio, United States of America
| | - Ian C. Davis
- Department of Veterinary Biosciences, College of Veterinary Medicine, The Ohio State University, Columbus, Ohio, United States of America
| | - Stefan Niewiesk
- Department of Veterinary Biosciences, College of Veterinary Medicine, The Ohio State University, Columbus, Ohio, United States of America
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7
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Sitthicharoenchai P, Alnajjar S, Ackermann MR. A model of respiratory syncytial virus (RSV) infection of infants in newborn lambs. Cell Tissue Res 2020; 380:313-324. [PMID: 32347384 PMCID: PMC7223741 DOI: 10.1007/s00441-020-03213-w] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Accepted: 04/01/2020] [Indexed: 12/29/2022]
Abstract
Many animal models have been established for respiratory syncytial virus (RSV) infection of infants with the purpose of studying the pathogenesis, immunological response, and pharmaceutical testing and the objective of finding novel therapies and preventive measures. This review centers on a neonatal lamb model of RSV infection that has similarities to RSV infection of infants. It includes a comprehensive description of anatomical and immunological similarities between ovine and human lungs along with comparison of pulmonary changes and immune responses with RSV infection. These features make the newborn lamb an effective model for investigating key aspects of RSV infection in infants. The importance of RSV lamb model application in preclinical therapeutic trials and current updates on new studies with the RSV-infected neonatal lamb are also highlighted.
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Affiliation(s)
- Panchan Sitthicharoenchai
- Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA USA
| | - Sarhad Alnajjar
- Department of Veterinary Pathology, College of Veterinary Medicine, University of Baghdad, Baghdad, Iraq
- LambCure LLC, Corvallis, OR USA
| | - Mark R. Ackermann
- LambCure LLC, Corvallis, OR USA
- Department of Biomedical Sciences and Oregon Veterinary Diagnostic Laboratory, Carlson College of Veterinary Medicine, Oregon State University, Corvallis, OR USA
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8
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Espeseth AS, Cejas PJ, Citron MP, Wang D, DiStefano DJ, Callahan C, Donnell GO, Galli JD, Swoyer R, Touch S, Wen Z, Antonello J, Zhang L, Flynn JA, Cox KS, Freed DC, Vora KA, Bahl K, Latham AH, Smith JS, Gindy ME, Ciaramella G, Hazuda D, Shaw CA, Bett AJ. Modified mRNA/lipid nanoparticle-based vaccines expressing respiratory syncytial virus F protein variants are immunogenic and protective in rodent models of RSV infection. NPJ Vaccines 2020; 5:16. [PMID: 32128257 PMCID: PMC7021756 DOI: 10.1038/s41541-020-0163-z] [Citation(s) in RCA: 104] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Accepted: 01/17/2020] [Indexed: 12/31/2022] Open
Abstract
The RSV Fusion (F) protein is a target for neutralizing antibody responses and is a focus for vaccine discovery; however, the process of RSV entry requires F to adopt a metastable prefusion form and transition to a more stable postfusion form, which displays less potent neutralizing epitopes. mRNA vaccines encode antigens that are translated by host cells following vaccination, which may allow conformational transitions similar to those observed during natural infection to occur. Here we evaluate a panel of chemically modified mRNA vaccines expressing different forms of the RSV F protein, including secreted, membrane associated, prefusion-stabilized, and non-stabilized structures, for conformation, immunogenicity, protection, and safety in rodent models. Vaccination with mRNA encoding native RSV F elicited antibody responses to both prefusion- and postfusion-specific epitopes, suggesting that this antigen may adopt both conformations in vivo. Incorporating prefusion stabilizing mutations further shifts the immune response toward prefusion-specific epitopes, but does not impact neutralizing antibody titer. mRNA vaccine candidates expressing either prefusion stabilized or native forms of RSV F protein elicit robust neutralizing antibody responses in both mice and cotton rats, similar to levels observed with a comparable dose of adjuvanted prefusion stabilized RSV F protein. In contrast to the protein subunit vaccine, mRNA-based vaccines elicited robust CD4+ and CD8+ T-cell responses in mice, highlighting a potential advantage of the technology for vaccines requiring a cellular immune response for efficacy.
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Affiliation(s)
- Amy S. Espeseth
- ID/Vaccines Discovery, Merck & Co., Inc., Kenilworth, NJ USA
| | - Pedro J. Cejas
- ID/Vaccines Discovery, Merck & Co., Inc., Kenilworth, NJ USA
| | | | - Dai Wang
- ID/Vaccines Discovery, Merck & Co., Inc., Kenilworth, NJ USA
| | | | - Cheryl Callahan
- ID/Vaccines Discovery, Merck & Co., Inc., Kenilworth, NJ USA
| | | | | | - Ryan Swoyer
- ID/Vaccines Discovery, Merck & Co., Inc., Kenilworth, NJ USA
| | - Sinoeun Touch
- ID/Vaccines Discovery, Merck & Co., Inc., Kenilworth, NJ USA
| | - Zhiyun Wen
- ID/Vaccines Discovery, Merck & Co., Inc., Kenilworth, NJ USA
| | | | - Lan Zhang
- ID/Vaccines Discovery, Merck & Co., Inc., Kenilworth, NJ USA
| | | | - Kara S. Cox
- ID/Vaccines Discovery, Merck & Co., Inc., Kenilworth, NJ USA
| | - Daniel C. Freed
- ID/Vaccines Discovery, Merck & Co., Inc., Kenilworth, NJ USA
| | - Kalpit A. Vora
- ID/Vaccines Discovery, Merck & Co., Inc., Kenilworth, NJ USA
| | | | | | | | - Marian E. Gindy
- Pharmaceutical Science, Merck & Co., Inc., Kenilworth, NJ USA
| | | | - Daria Hazuda
- ID/Vaccines Discovery, Merck & Co., Inc., Kenilworth, NJ USA
| | | | - Andrew J. Bett
- ID/Vaccines Discovery, Merck & Co., Inc., Kenilworth, NJ USA
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9
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Blanco JCG, Fernando LR, Zhang W, Kamali A, Boukhvalova MS, McGinnes-Cullen L, Morrison TG. Alternative Virus-Like Particle-Associated Prefusion F Proteins as Maternal Vaccines for Respiratory Syncytial Virus. J Virol 2019; 93:e00914-19. [PMID: 31511382 PMCID: PMC6854499 DOI: 10.1128/jvi.00914-19] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Accepted: 09/03/2019] [Indexed: 01/09/2023] Open
Abstract
Maternal vaccination may be the most effective and safest approach to the protection of infants from respiratory syncytial virus (RSV) infection, a severe acute lower respiratory tract disease in infants and young children worldwide. We previously compared five different virus-like particle (VLP)-associated, mutation-stabilized prefusion F (pre-F) proteins, including the prototype DS-Cav1 F VLPs. We showed that alternative versions of prefusion F proteins have different conformations and induce different populations of anti-F protein antibodies. Two of these alternative pre-F VLPs, the UC-2 F and UC-3 F VLPs, stimulated in mice higher titers of neutralizing antibodies than DS-Cav1 F VLPs (M. L. Cullen, R. M. Schmidt, M. G. Torres, A. A. Capoferri, et al., Vaccines 7:21-41, 2019, https://doi.org/10.3390/vaccines7010021). Here we describe a comparison of these two pre-F VLPs with DS-Cav1 F VLPs as maternal vaccines in cotton rats and report that UC-3 F VLPs significantly increased the neutralizing antibody (NAb) titers in pregnant dams compared to DS-Cav1 F VLPs. The neutralizing antibody titers in the sera of the offspring of the dams immunized with UC-3 F VLPs were significantly higher than those in the sera of the offspring of dams immunized with DS-Cav1 VLPs. This increase in serum NAb titers translated to a 6- to 40-fold lower virus titer in the lungs of the RSV-challenged offspring of dams immunized with UC-3 F VLPs than in the lungs of the RSV-challenged offspring of dams immunized with DS-Cav1 F VLPs. Importantly, the offspring of UC-3 F VLP-immunized dams showed significant protection from lung pathology and from induction of inflammatory lung cytokine mRNA expression after RSV challenge. Immunization with UC-3 F VLPs also induced durable levels of high-titer neutralizing antibodies in dams.IMPORTANCE Respiratory syncytial virus (RSV) is a significant human pathogen severely impacting neonates and young children, but no vaccine exists to protect this vulnerable population. Furthermore, direct vaccination of neonates is likely ineffective due to the immaturity of their immune system, and neonate immunization is potentially unsafe. Maternal vaccination may be the best and safest approach to the protection of neonates through the passive transfer of maternal neutralizing antibodies in utero to the fetus after maternal immunization. Here we report that immunization of pregnant cotton rats, a surrogate model for human maternal immunization, with novel RSV virus-like particle (VLP) vaccine candidates containing stabilized prefusion RSV F proteins provides significant levels of protection of the offspring of immunized dams from RSV challenge. We also found that antibodies induced by VLPs containing different versions of the prefusion F protein varied by 40-fold in the extent of protection provided to the offspring of vaccinated dams upon RSV challenge.
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Affiliation(s)
| | | | - Wei Zhang
- Sigmovir Biosystems Inc., Rockville, Maryland, USA
| | - Arash Kamali
- Sigmovir Biosystems Inc., Rockville, Maryland, USA
| | | | - Lori McGinnes-Cullen
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, Massachusetts, USA
| | - Trudy G Morrison
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, Massachusetts, USA
- Program in Microbiology and Immunology, University of Massachusetts Medical School, Worcester, Massachusetts, USA
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10
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Schneider-Ohrum K, Snell Bennett A, Rajani GM, Hostetler L, Maynard SK, Lazzaro M, Cheng LI, O'Day T, Cayatte C. CD4 + T Cells Drive Lung Disease Enhancement Induced by Immunization with Suboptimal Doses of Respiratory Syncytial Virus Fusion Protein in the Mouse Model. J Virol 2019; 93:e00695-19. [PMID: 31092578 PMCID: PMC6639276 DOI: 10.1128/jvi.00695-19] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Accepted: 05/08/2019] [Indexed: 12/23/2022] Open
Abstract
Respiratory syncytial virus (RSV) infection of seronegative children previously immunized with formalin-inactivated (FI) RSV has been associated with serious enhanced respiratory disease (ERD). The phenomenon was reproduced in the cotton rat and the mouse, and both preclinical models have been routinely used to evaluate the safety of new RSV vaccine candidates. More recently, we demonstrated that immunizations with suboptimal doses of the RSV fusion (F) antigen, in its post- or prefusion conformation, and in the presence of a Th1-biasing adjuvant, unexpectedly led to ERD in the cotton rat model. To assess if those observations are specific to the cotton rat and to elucidate the mechanism by which vaccination with low antigen doses can drive ERD post-RSV challenge, we evaluated RSV post-F antigen dose de-escalation in BALB/c mice in the presence of a Th1-biasing adjuvant. While decreasing antigen doses, we observed an increase in lung inflammation associated with an upregulation of proinflammatory cytokines. The amplitude of the lung histopathology was comparable to that of FI-RSV-induced ERD, confirming the observations made in the cotton rat. Importantly, depletion of CD4+ T cells prior to viral challenge completely abrogated ERD, preventing proinflammatory cytokine upregulation and the infiltration of T cells, neutrophils, eosinophils, and macrophages into the lung. Overall, low-antigen-dose-induced ERD resembles FI-RSV-induced ERD, except that the former appears in the absence of detectable levels of viral replication and in the context of a Th1-biased immune response. Taken together, our observations reinforce the recent concept that vaccines developed for RSV-naïve individuals should be systematically tested under suboptimal dosing conditions.IMPORTANCE RSV poses a significant health care burden and is the leading cause of serious lower-respiratory-tract infections in young children. A formalin-inactivated RSV vaccine developed in the 1960s not only showed a complete lack of efficacy against RSV infection but also induced severe lung disease enhancement in vaccinated children. Since then, establishing safety in preclinical models has been one of the major challenges to RSV vaccine development. We recently observed in the cotton rat model that suboptimal immunizations with RSV fusion protein could induce lung disease enhancement. In the present study, we extended suboptimal dosing evaluation to the mouse model. We confirmed the induction of lung disease enhancement by vaccinations with low antigen doses and dissected the associated immune mechanisms. Our results stress the need to evaluate suboptimal dosing for any new RSV vaccine candidate developed for seronegative infants.
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Affiliation(s)
| | - Angie Snell Bennett
- Department of Infectious Disease/Vaccines, MedImmune, Gaithersburg, Maryland, USA
| | | | - Leigh Hostetler
- Laboratory Animal Resources, MedImmune, Gaithersburg, Maryland, USA
| | - Sean K Maynard
- Department of Infectious Disease/Vaccines, MedImmune, Gaithersburg, Maryland, USA
| | - Michelle Lazzaro
- Department of Infectious Disease/Vaccines, MedImmune, Gaithersburg, Maryland, USA
| | - Lily I Cheng
- Pathology Department, MedImmune, Gaithersburg, Maryland, USA
| | - Terrence O'Day
- Statistical Sciences, MedImmune, Gaithersburg, Maryland, USA
| | - Corinne Cayatte
- Department of Infectious Disease/Vaccines, MedImmune, Gaithersburg, Maryland, USA
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11
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Altamirano-Lagos MJ, Díaz FE, Mansilla MA, Rivera-Pérez D, Soto D, McGill JL, Vasquez AE, Kalergis AM. Current Animal Models for Understanding the Pathology Caused by the Respiratory Syncytial Virus. Front Microbiol 2019; 10:873. [PMID: 31130923 PMCID: PMC6510261 DOI: 10.3389/fmicb.2019.00873] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Accepted: 04/04/2019] [Indexed: 12/14/2022] Open
Abstract
The human respiratory syncytial virus (hRSV) is the main etiologic agent of severe lower respiratory tract infections that affect young children throughout the world, associated with significant morbidity and mortality, becoming a serious public health problem globally. Up to date, no licensed vaccines are available to prevent severe hRSV-induced disease, and the generation of safe-effective vaccines has been a challenging task, requiring constant biomedical research aimed to overcome this ailment. Among the difficulties presented by the study of this pathogen, it arises the fact that there is no single animal model that resembles all aspects of the human pathology, which is due to the specificity that this pathogen has for the human host. Thus, for the study of hRSV, different animal models might be employed, depending on the goal of the study. Of all the existing models, the murine model has been the most frequent model of choice for biomedical studies worldwide and has been of great importance at contributing to the development and understanding of vaccines and therapies against hRSV. The most notable use of the murine model is that it is very useful as a first approach in the development of vaccines or therapies such as monoclonal antibodies, suggesting in this way the direction that research could have in other preclinical models that have higher maintenance costs and more complex requirements in its management. However, several additional different models for studying hRSV, such as other rodents, mustelids, ruminants, and non-human primates, have been explored, offering advantages over the murine model. In this review, we discuss the various applications of animal models to the study of hRSV-induced disease and the advantages and disadvantages of each model, highlighting the potential of each model to elucidate different features of the pathology caused by the hRSV infection.
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Affiliation(s)
- María José Altamirano-Lagos
- Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Millennium Institute on Immunology and Immunotherapy, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Fabián E. Díaz
- Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Millennium Institute on Immunology and Immunotherapy, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Miguel Andrés Mansilla
- Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Millennium Institute on Immunology and Immunotherapy, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Daniela Rivera-Pérez
- Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Millennium Institute on Immunology and Immunotherapy, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Daniel Soto
- Sección Biotecnología, Instituto de Salud Pública de Chile, Santiago, Chile
| | - Jodi L. McGill
- Department of Veterinary Microbiology and Preventive Medicine, Iowa State University, Ames, IA, United States
| | - Abel E. Vasquez
- Sección Biotecnología, Instituto de Salud Pública de Chile, Santiago, Chile
- Facultad de Medicina y Ciencia, Universidad San Sebastián, Providencia, Santiago, Chile
| | - Alexis M. Kalergis
- Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Millennium Institute on Immunology and Immunotherapy, Pontificia Universidad Católica de Chile, Santiago, Chile
- Departamento de Endocrinología, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
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12
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Sealy RE, Jones BG, Surman SL, Penkert RR, Pelletier S, Neale G, Hurwitz JL. Will Attention by Vaccine Developers to the Host's Nuclear Hormone Levels and Immunocompetence Improve Vaccine Success? Vaccines (Basel) 2019; 7:vaccines7010026. [PMID: 30818795 PMCID: PMC6466149 DOI: 10.3390/vaccines7010026] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Revised: 02/16/2019] [Accepted: 02/21/2019] [Indexed: 01/18/2023] Open
Abstract
Despite extraordinary advances in fields of immunology and infectious diseases, vaccine development remains a challenge. The development of a respiratory syncytial virus vaccine, for example, has spanned more than 50 years of research with studies of more than 100 vaccine candidates. Dozens of attractive vaccine products have entered clinical trials, but none have completed the path to licensing. Human immunodeficiency virus vaccine development has proven equally difficult, as there is no licensed product after more than 30 years of pre-clinical and clinical research. Here, we examine vaccine development with attention to the host. We discuss how nuclear hormones, including vitamins and sex hormones, can influence responses to vaccines. We show how nuclear hormones interact with regulatory elements of immunoglobulin gene loci and how the deletion of estrogen response elements from gene enhancers will alter patterns of antibody isotype expression. Based on these findings, and findings that nuclear hormone levels are often insufficient or deficient among individuals in both developed and developing countries, we suggest that failed vaccine studies may in some cases reflect weaknesses of the host rather than the product. We encourage analyses of nuclear hormone levels and immunocompetence among study participants in clinical trials to ensure the success of future vaccine programs.
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Affiliation(s)
- Robert E Sealy
- Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, TN 38105, USA.
| | - Bart G Jones
- Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, TN 38105, USA.
| | - Sherri L Surman
- Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, TN 38105, USA.
| | - Rhiannon R Penkert
- Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, TN 38105, USA.
| | - Stephane Pelletier
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA.
| | - Geoff Neale
- The Hartwell Center for Bioinformatics & Biotechnology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA.
| | - Julia L Hurwitz
- Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, TN 38105, USA.
- Department of Microbiology, Immunology and Biochemistry, University of Tennessee Health Science Center, Memphis, TN 38163, USA.
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13
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Russell MS, Muralidharan A, Larocque L, Cao J, Deschambault Y, Varga J, Thulasi Raman SN, Li X. Identification and characterisation of the CD40-ligand of Sigmodon hispidus. PLoS One 2018; 13:e0199067. [PMID: 30052641 PMCID: PMC6063397 DOI: 10.1371/journal.pone.0199067] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Accepted: 07/14/2018] [Indexed: 11/18/2022] Open
Abstract
Cotton rats are an important animal model to study infectious diseases. They have demonstrated higher susceptibility to a wider variety of human pathogens than other rodents and are also the animal model of choice for pre-clinical evaluations of some vaccine candidates. However, the genome of cotton rats remains to be fully sequenced, with much fewer genes cloned and characterised compared to other rodent species. Here we report the cloning and characterization of CD40 ligand, whose human and murine counterparts are known to be expressed on a range of cell types including activated T cells and B cells, dendritic cells, granulocytes, macrophages and platelets and exerts a broad array of immune responses. The cDNA for cotton rat CD40L we isolated is comprised of 1104 nucleotides with an open reading frame (ORF) of 783bp coding for a 260 amino acid protein. The recombinant cotton rat CD40L protein was recognized by an antibody against mouse CD40L. Moreover, it demonstrated functional activities on immature bone marrow dendritic cells by upregulating surface maturation markers (CD40, CD54, CD80, and CD86), and increasing IL-6 gene and protein expression. The availability of CD40L gene identity could greatly facilitate mechanistic research on pathogen-induced-immunopathogenesis and vaccine-elicited immune responses.
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Affiliation(s)
- Marsha S. Russell
- Centre for Biologics Evaluation, Biologics and Genetic Therapies Directorate, HPFB, Health Canada and WHO Collaborating Center for Standardization and Evaluation of Biologicals, Ottawa, Ontario, Canada
| | - Abenaya Muralidharan
- Centre for Biologics Evaluation, Biologics and Genetic Therapies Directorate, HPFB, Health Canada and WHO Collaborating Center for Standardization and Evaluation of Biologicals, Ottawa, Ontario, Canada
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Canada
| | - Louise Larocque
- Centre for Biologics Evaluation, Biologics and Genetic Therapies Directorate, HPFB, Health Canada and WHO Collaborating Center for Standardization and Evaluation of Biologicals, Ottawa, Ontario, Canada
| | - Jingxin Cao
- National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba, Canada
| | - Yvon Deschambault
- National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba, Canada
| | - Jessie Varga
- National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba, Canada
| | - Sathya N. Thulasi Raman
- Centre for Biologics Evaluation, Biologics and Genetic Therapies Directorate, HPFB, Health Canada and WHO Collaborating Center for Standardization and Evaluation of Biologicals, Ottawa, Ontario, Canada
| | - Xuguang Li
- Centre for Biologics Evaluation, Biologics and Genetic Therapies Directorate, HPFB, Health Canada and WHO Collaborating Center for Standardization and Evaluation of Biologicals, Ottawa, Ontario, Canada
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Canada
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14
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Abstract
Host-derived “danger-associated molecular patterns” (DAMPs) contribute to innate immune responses and serve as markers of disease progression and severity for inflammatory and infectious diseases. There is accumulating evidence that generation of DAMPs such as oxidized phospholipids and high-mobility-group box 1 (HMGB1) during influenza virus infection leads to acute lung injury (ALI). Treatment of influenza virus-infected mice and cotton rats with the Toll-like receptor 4 (TLR4) antagonist Eritoran blocked DAMP accumulation and ameliorated influenza virus-induced ALI. However, changes in systemic HMGB1 kinetics during the course of influenza virus infection in animal models and humans have yet to establish an association of HMGB1 release with influenza virus infection. To this end, we used the cotton rat model that is permissive to nonadapted strains of influenza A and B viruses, respiratory syncytial virus (RSV), and human rhinoviruses (HRVs). Serum HMGB1 levels were measured by an enzyme-linked immunosorbent assay (ELISA) prior to infection until day 14 or 18 post-infection. Infection with either influenza A or B virus resulted in a robust increase in serum HMGB1 levels that decreased by days 14 to 18. Inoculation with the live attenuated vaccine FluMist resulted in HMGB1 levels that were significantly lower than those with infection with live influenza viruses. RSV and HRVs showed profiles of serum HMGB1 induction that were consistent with their replication and degree of lung pathology in cotton rats. We further showed that therapeutic treatment with Eritoran of cotton rats infected with influenza B virus significantly blunted serum HMGB1 levels and improved lung pathology, without inhibiting virus replication. These findings support the use of drugs that block HMGB1 to combat influenza virus-induced ALI. Influenza virus is a common infectious agent causing serious seasonal epidemics, and there is urgent need to develop an alternative treatment modality for influenza virus infection. Recently, host-derived DAMPs, such as oxidized phospholipids and HMGB1, were shown to be generated during influenza virus infection and cause ALI. To establish a clear link between influenza virus infection and HMGB1 as a biomarker, we have systematically analyzed temporal patterns of serum HMGB1 release in cotton rats infected with nonadapted strains of influenza A and B viruses and compared these patterns with a live attenuated influenza vaccine and infection by other respiratory viruses. Towards development of a new therapeutic modality, we show herein that blocking serum HMGB1 levels by Eritoran improves lung pathology in influenza B virus-infected cotton rats. Our study is the first report of systemic HMGB1 as a potential biomarker of severity in respiratory virus infections and confirms that drugs that block virus-induced HMGB1 ameliorate ALI.
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15
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de Waal L, Smits SL, Veldhuis Kroeze EJB, van Amerongen G, Pohl MO, Osterhaus ADME, Stittelaar KJ. Transmission of Human Respiratory Syncytial Virus in the Immunocompromised Ferret Model. Viruses 2018; 10:E18. [PMID: 29301313 PMCID: PMC5795431 DOI: 10.3390/v10010018] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Revised: 12/27/2017] [Accepted: 12/30/2017] [Indexed: 12/26/2022] Open
Abstract
Human respiratory syncytial virus (HRSV) causes substantial morbidity and mortality in vulnerable patients, such as the very young, the elderly, and immunocompromised individuals of any age. Nosocomial transmission of HRSV remains a serious challenge in hospital settings, with intervention strategies largely limited to infection control measures, including isolation of cases, high standards of hand hygiene, cohort nursing, and use of personal protective equipment. No vaccines against HRSV are currently available, and treatment options are largely supportive care and expensive monoclonal antibody or antiviral therapy. The limitations of current animal models for HRSV infection impede the development of new preventive and therapeutic agents, and the assessment of their potential for limiting HRSV transmission, in particular in nosocomial settings. Here, we demonstrate the efficient transmission of HRSV from immunocompromised ferrets to both immunocompromised and immunocompetent contact ferrets, with pathological findings reproducing HRSV pathology in humans. The immunocompromised ferret-HRSV model represents a novel tool for the evaluation of intervention strategies against nosocomial transmission of HRSV.
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Affiliation(s)
- Leon de Waal
- Viroclinics Biosciences BV, Rotterdam 3029 AK, The Netherlands.
| | - Saskia L Smits
- Viroclinics Biosciences BV, Rotterdam 3029 AK, The Netherlands.
| | - Edwin J B Veldhuis Kroeze
- Viroclinics Biosciences BV, Rotterdam 3029 AK, The Netherlands.
- Department of Viroscience, Erasmus MC, Rotterdam 3015 CN, The Netherlands.
| | | | - Marie O Pohl
- Viroclinics Biosciences BV, Rotterdam 3029 AK, The Netherlands.
| | - Albert D M E Osterhaus
- Viroclinics Biosciences BV, Rotterdam 3029 AK, The Netherlands.
- Research Centre for Emerging Infections and Zoonoses, University of Veterinary Medicine Hannover, 30559 Hannover, Germany.
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16
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Patel MC, Pletneva LM, Boukhvalova MS, Vogel SN, Kajon AE, Blanco JCG. Immunization with Live Human Rhinovirus (HRV) 16 Induces Protection in Cotton Rats against HRV14 Infection. Front Microbiol 2017; 8:1646. [PMID: 28912760 PMCID: PMC5583225 DOI: 10.3389/fmicb.2017.01646] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Accepted: 08/15/2017] [Indexed: 11/13/2022] Open
Abstract
Human rhinoviruses (HRVs) are the main cause of cold-like illnesses, and currently no vaccine or antiviral therapies against HRVs are available to prevent or mitigate HRV infection. There are more than 150 antigenically heterogeneous HRV serotypes, with ∼90 HRVs belonging to major group species A and B. Development of small animal models that are susceptible to infection with major group HRVs would be beneficial for vaccine research. Previously, we showed that the cotton rat (Sigmodon hispidus) is semi-permissive to HRV16 (major group, species HRV-A virus) infection, replicating in the upper and lower respiratory tracts with measurable pathology, mucus production, and expression of inflammatory mediators. Herein, we report that intranasal infection of cotton rats with HRV14 (major group, species HRV-B virus) results in isolation of infectious virus from the nose and lung. Similar to HRV16, intramuscular immunization with live HRV14 induces homologous protection that correlated with high levels of serum neutralizing antibodies. Vaccination and challenge experiments with HRV14 and HRV16 to evaluate the development of cross-protective immunity demonstrate that intramuscular immunization with live HRV16 significantly protects animals against HRV14 challenge. Determination of the immunological mechanisms involved in heterologous protection and further characterization of infection with other major HRV serotypes in the cotton rat could enhance the robustness of the model to define heterotypic relationships between this diverse group of viruses and thereby increase its potential for development of a multi-serotype HRV vaccine.
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Affiliation(s)
- Mira C Patel
- Sigmovir Biosystems, Inc., RockvilleMD, United States
| | | | | | - Stefanie N Vogel
- University of Maryland School of Medicine, BaltimoreMD, United States
| | - Adriana E Kajon
- Infectious Disease Program, Lovelace Respiratory Research Institute, AlbuquerqueNM, United States
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17
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Hanson JM, Anderson LJ, Williams CM, Jorquera P, Tripp RA. Passive narcosis for anesthesia induction in cotton rats (Sigmodon hispidus). Lab Anim (NY) 2017; 45:333-7. [PMID: 27551803 DOI: 10.1038/laban.1084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Accepted: 06/15/2016] [Indexed: 11/09/2022]
Abstract
Cotton rats (Sigmodon hispidus) are widely used as animal models for infectious disease and immunological research. They emulate many aspects of human disease pathogenesis, and the introduction of cotton rat-specific immunological reagents, cell lines and sequencing of relevant genes have all helped to increase the popularity of this disease model. However, the use of cotton rats is problematic owing to their propensity for aggressive responses when handled, which can lead to escape, increased stress to the animals, and bites to staff. When cotton rats are co-housed, which is recommended under current social housing guidelines, these risks are increased. Here, we describe a method of isoflurane anesthesia induction in the home cage that reduces the risk of animal escape, minimizes stress during induction, and provides additional safety for staff. The method uses inexpensive materials that are widely available and can be easily disinfected. Our method also eliminates the need for expensive and cumbersome machines traditionally used with anesthetic chambers, and uses a minimal amount of inhalant anesthetic, saving resources and protecting staff from inhalation of leaked gas.
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Affiliation(s)
- Jarod M Hanson
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, Georgia
| | - Lydia J Anderson
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, Georgia
| | - Colin M Williams
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, Georgia
| | - Patricia Jorquera
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, Georgia
| | - Ralph A Tripp
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, Georgia
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18
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Immunization with Low Doses of Recombinant Postfusion or Prefusion Respiratory Syncytial Virus F Primes for Vaccine-Enhanced Disease in the Cotton Rat Model Independently of the Presence of a Th1-Biasing (GLA-SE) or Th2-Biasing (Alum) Adjuvant. J Virol 2017; 91:JVI.02180-16. [PMID: 28148790 DOI: 10.1128/jvi.02180-16] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Accepted: 01/23/2017] [Indexed: 12/14/2022] Open
Abstract
Respiratory syncytial virus (RSV) infection of children previously immunized with a nonlive, formalin-inactivated (FI)-RSV vaccine has been associated with serious enhanced respiratory disease (ERD). Consequently, detailed studies of potential ERD are a critical step in the development of nonlive RSV vaccines targeting RSV-naive children and infants. The fusion glycoprotein (F) of RSV in either its postfusion (post-F) or prefusion (pre-F) conformation is a target for neutralizing antibodies and therefore an attractive antigen candidate for a pediatric RSV subunit vaccine. Here, we report the evaluation of RSV post-F and pre-F in combination with glucopyranosyl lipid A (GLA) integrated into stable emulsion (SE) (GLA-SE) and alum adjuvants in the cotton rat model. Immunization with optimal doses of RSV F antigens in the presence of GLA-SE induced high titers of virus-neutralizing antibodies and conferred complete lung protection from virus challenge, with no ERD signs in the form of alveolitis. To mimic a waning immune response, and to assess priming for ERD under suboptimal conditions, an antigen dose de-escalation study was performed in the presence of either GLA-SE or alum. At low RSV F doses, alveolitis-associated histopathology was unexpectedly observed with either adjuvant at levels comparable to FI-RSV-immunized controls. This occurred despite neutralizing-antibody titers above the minimum levels required for protection and with no/low virus replication in the lungs. These results emphasize the need to investigate a pediatric RSV vaccine candidate carefully for priming of ERD over a wide dose range, even in the presence of strong neutralizing activity, Th1 bias-inducing adjuvant, and protection from virus replication in the lower respiratory tract.IMPORTANCE RSV disease is of great importance worldwide, with the highest burden of serious disease occurring upon primary infection in infants and children. FI-RSV-induced enhanced disease, observed in the 1960s, presented a major and ongoing obstacle for the development of nonlive RSV vaccine candidates. The findings presented here underscore the need to evaluate a nonlive RSV vaccine candidate during preclinical development over a wide dose range in the cotton rat RSV enhanced-disease model, as suboptimal dosing of several RSV F subunit vaccine candidates led to the priming for ERD. These observations are relevant to the validity of the cotton rat model itself and to safe development of nonlive RSV vaccines for seronegative infants and children.
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19
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Taylor G. Animal models of respiratory syncytial virus infection. Vaccine 2017; 35:469-480. [PMID: 27908639 PMCID: PMC5244256 DOI: 10.1016/j.vaccine.2016.11.054] [Citation(s) in RCA: 129] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Revised: 10/12/2016] [Accepted: 11/16/2016] [Indexed: 11/26/2022]
Abstract
Human respiratory syncytial virus (hRSV) is a major cause of respiratory disease and hospitalisation of infants, worldwide, and is also responsible for significant morbidity in adults and excess deaths in the elderly. There is no licensed hRSV vaccine or effective therapeutic agent. However, there are a growing number of hRSV vaccine candidates that have been developed targeting different populations at risk of hRSV infection. Animal models of hRSV play an important role in the preclinical testing of hRSV vaccine candidates and although many have shown efficacy in preclinical studies, few have progressed to clinical trials or they have had only limited success. This is, at least in part, due to the lack of animal models that fully recapitulate the pathogenesis of hRSV infection in humans. This review summarises the strengths and limitations of animal models of hRSV, which include those in which hRSV is used to infect non-human mammalian hosts, and those in which non-human pneumoviruses, such as bovine (b)RSV and pneumonia virus of mice (PVM) are studied in their natural host. Apart from chimpanzees, other non-human primates (NHP) are only semi-permissive for hRSV replication and experimental infection with large doses of virus result in little or no clinical signs of disease, and generally only mild pulmonary pathology. Other animal models such as cotton rats, mice, ferrets, guinea pigs, hamsters, chinchillas, and neonatal lambs are also only semi-permissive for hRSV. Nevertheless, mice and cotton rats have been of value in the development of monoclonal antibody prophylaxis for infants at high risk of severe hRSV infection and have provided insights into mechanisms of immunity to and pathogenesis of hRSV. However, the extent to which they predict hRSV vaccine efficacy and safety is unclear and several hRSV vaccine candidates that are completely protective in rodent models are poorly effective in chimpanzees and other NHP, such as African Green monkeys. Furthermore, interpretation of findings from many rodent and NHP models of vaccine-enhanced hRSV disease has been confounded by sensitisation to non-viral antigens present in the vaccine and challenge virus. Studies of non-human pneumoviruses in their native hosts are more likely to reflect the pathogenesis of natural hRSV infection, and experimental infection of calves with bRSV and of mice with PVM result in clinical disease and extensive pulmonary pathology. These animal models have not only been of value in studies on mechanisms of immunity to and the pathogenesis of pneumovirus infections but have also been used to evaluate hRSV vaccine concepts. Furthermore, the similarities between the epidemiology of bRSV in calves and hRSV in infants and the high level of genetic and antigenic similarity between bRSV and hRSV, make the calf model of bRSV infection a relevant model for preclinical evaluation of hRSV vaccine candidates which contain proteins that are conserved between hRSV and bRSV.
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Affiliation(s)
- Geraldine Taylor
- The Pirbright Institute, Ash Road, Pirbright, Woking Surrey GU24 0NF, United Kingdom.
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20
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Patel MC, Wang W, Pletneva LM, Rajagopala SV, Tan Y, Hartert TV, Boukhvalova MS, Vogel SN, Das SR, Blanco JCG. Enterovirus D-68 Infection, Prophylaxis, and Vaccination in a Novel Permissive Animal Model, the Cotton Rat (Sigmodon hispidus). PLoS One 2016; 11:e0166336. [PMID: 27814404 PMCID: PMC5096705 DOI: 10.1371/journal.pone.0166336] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Accepted: 10/26/2016] [Indexed: 12/17/2022] Open
Abstract
In recent years, there has been a significant increase in detection of Enterovirus D-68 (EV-D68) among patients with severe respiratory infections worldwide. EV-D68 is now recognized as a re-emerging pathogen; however, due to lack of a permissive animal model for EV-D68, a comprehensive understanding of the pathogenesis and immune response against EV-D68 has been hampered. Recently, it was shown that EV-D68 has a strong affinity for α2,6-linked sialic acids (SAs) and we have shown previously that α2,6-linked SAs are abundantly present in the respiratory tract of cotton rats (Sigmodon hispidus). Thus, we hypothesized that cotton rats could be a potential model for EV-D68 infection. Here, we evaluated the ability of two recently isolated EV-D68 strains (VANBT/1 and MO/14/49), along with the historical prototype Fermon strain (ATCC), to infect cotton rats. We found that cotton rats are permissive to EV-D68 infection without virus adaptation. The different strains of EV-D68 showed variable infection profiles and the ability to produce neutralizing antibody (NA) upon intranasal infection or intramuscular immunization. Infection with the VANBT/1 resulted in significant induction of pulmonary cytokine gene expression and lung pathology. Intramuscular immunization with live VANBT/1 or MO/14/49 induced strong homologous antibody responses, but a moderate heterologous NA response. We showed that passive prophylactic administration of serum with high content of NA against VANBT/1 resulted in an efficient antiviral therapy. VANBT/1-immunized animals showed complete protection from VANBT/1 challenge, but induced strong pulmonary Th1 and Th2 cytokine responses and enhanced lung pathology, indicating the generation of exacerbated immune response by immunization. In conclusion, our data illustrate that the cotton rat is a powerful animal model that provides an experimental platform to investigate pathogenesis, immune response, anti-viral therapies and vaccines against EV-D68 infection.
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Affiliation(s)
- Mira C. Patel
- Sigmovir Biosystems Inc., Rockville, Maryland, United States of America
- Department of Microbiology and Immunology, University of Maryland, Baltimore, Maryland, United States of America
| | - Wei Wang
- Infectious Diseases Group, J. Craig Venter Institute, Rockville, Maryland, United States of America
| | | | - Seesandra V. Rajagopala
- Infectious Diseases Group, J. Craig Venter Institute, Rockville, Maryland, United States of America
| | - Yi Tan
- Infectious Diseases Group, J. Craig Venter Institute, Rockville, Maryland, United States of America
| | - Tina V. Hartert
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | | | - Stefanie N. Vogel
- Department of Microbiology and Immunology, University of Maryland, Baltimore, Maryland, United States of America
| | - Suman R. Das
- Infectious Diseases Group, J. Craig Venter Institute, Rockville, Maryland, United States of America
- * E-mail: (JCGB); (SRD)
| | - Jorge C. G. Blanco
- Sigmovir Biosystems Inc., Rockville, Maryland, United States of America
- * E-mail: (JCGB); (SRD)
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21
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Ruckwardt TJ, Morabito KM, Graham BS. Determinants of early life immune responses to RSV infection. Curr Opin Virol 2016; 16:151-157. [PMID: 26986236 DOI: 10.1016/j.coviro.2016.01.003] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Accepted: 01/07/2016] [Indexed: 12/17/2022]
Abstract
Respiratory syncytial virus causes significant morbidity and mortality in both developed and developing countries, and a vaccine that adequately protects from severe disease remains an important unmet need. RSV disease has an inordinate impact on the very young, and the physical and immunological immaturity of early life complicates vaccine design. Defining and targeting the functional capacities of early life immune responses and controlling responses during primary antigen exposure with selected vaccine delivery approaches will be important for protecting infants by active immunization. Alternatively, vaccination of older children and pregnant mothers may ameliorate disease burden indirectly until infants reach about six months of age, when they can generate more effective anti-RSV immune responses.
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Affiliation(s)
- Tracy J Ruckwardt
- Vaccine Research Center, National Institute of Allergy and Infectious Disease, National Institutes of Health, Bethesda, MD, USA.
| | - Kaitlyn M Morabito
- Vaccine Research Center, National Institute of Allergy and Infectious Disease, National Institutes of Health, Bethesda, MD, USA
| | - Barney S Graham
- Vaccine Research Center, National Institute of Allergy and Infectious Disease, National Institutes of Health, Bethesda, MD, USA
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22
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Blanco JCG, Pletneva LM, Oue RO, Patel MC, Boukhvalova MS. Maternal transfer of RSV immunity in cotton rats vaccinated during pregnancy. Vaccine 2015; 33:5371-5379. [PMID: 26335771 PMCID: PMC5155338 DOI: 10.1016/j.vaccine.2015.08.071] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Revised: 08/07/2015] [Accepted: 08/24/2015] [Indexed: 11/18/2022]
Abstract
Respiratory Syncytial Virus (RSV) is the leading cause of pneumonia and bronchiolitis in infants, resulting in significant morbidity and mortality worldwide. There is currently no RSV vaccine. Although maternal serum antibodies against RSV are efficiently transferred through placenta protecting human infants from RSV-induced disease, this protection is short-lived and the methods for extending and augmenting protection are not known. The objective of this study was to develop an animal model of maternal RSV vaccination using the Sigmodon hispidus cotton rat. Naïve or RSV-primed female cotton rats were inoculated with live RSV and set in breeding pairs. Antibody transfer to the litters was quantified and the offspring were challenged with RSV at different ages for analysis of protection against viral replication and lung inflammation. There was a strong correlation between RSV-neutralizing antibody (NA) titers in cotton rat mothers and their pups, which also correlated with protection of litters against virus challenge. Passive protection was short-lived and strongly reduced in animals at 4 weeks after birth. Protection of litters was significantly enhanced by inoculating mothers parenterally with live RSV and inversely correlated with the expression of lung cytokines and pathology. Importantly, vaccination and boosting of naïve mothers with the live RSV produced the highest levels of NAs. We conclude that maternal vaccination against RSV in the cotton rat can be used to define vaccine preparations that could improve preexistent immunity and induce subsequent transfer of efficient immunity to infants.
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Affiliation(s)
- Jorge C G Blanco
- Sigmovir Biosystems Inc., 9610 Medical Center Drive, Suite 100, Rockville, MD 20850, United States.
| | - Lioubov M Pletneva
- Sigmovir Biosystems Inc., 9610 Medical Center Drive, Suite 100, Rockville, MD 20850, United States
| | - Raymonde O Oue
- Sigmovir Biosystems Inc., 9610 Medical Center Drive, Suite 100, Rockville, MD 20850, United States
| | - Mira C Patel
- Sigmovir Biosystems Inc., 9610 Medical Center Drive, Suite 100, Rockville, MD 20850, United States; University of Maryland School of Medicine, Baltimore, MD 21101, United States
| | - Marina S Boukhvalova
- Sigmovir Biosystems Inc., 9610 Medical Center Drive, Suite 100, Rockville, MD 20850, United States
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23
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Krarup A, Truan D, Furmanova-Hollenstein P, Bogaert L, Bouchier P, Bisschop IJM, Widjojoatmodjo MN, Zahn R, Schuitemaker H, McLellan JS, Langedijk JPM. A highly stable prefusion RSV F vaccine derived from structural analysis of the fusion mechanism. Nat Commun 2015; 6:8143. [PMID: 26333350 PMCID: PMC4569726 DOI: 10.1038/ncomms9143] [Citation(s) in RCA: 235] [Impact Index Per Article: 26.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2015] [Accepted: 07/23/2015] [Indexed: 11/12/2022] Open
Abstract
Respiratory syncytial virus (RSV) causes acute lower respiratory tract infections and is the leading cause of infant hospitalizations. Recently, a promising vaccine antigen based on the RSV fusion protein (RSV F) stabilized in the native prefusion conformation has been described. Here we report alternative strategies to arrest RSV F in the prefusion conformation based on the prevention of hinge movements in the first refolding region and the elimination of proteolytic exposure of the fusion peptide. A limited number of unique mutations are identified that stabilize the prefusion conformation of RSV F and dramatically increase expression levels. This highly stable prefusion RSV F elicits neutralizing antibodies in cotton rats and induces complete protection against viral challenge. Moreover, the structural and biochemical analysis of the prefusion variants suggests a function for p27, the excised segment that precedes the fusion peptide in the polypeptide chain. Respiratory syncytial virus (RSV) is a highly contagious childhood pathogen of the respiratory tract for which no vaccine is currently available. Here the authors present a strategy to stabilize the RSV F protein in a prefusion conformation that can elicit a strong protective immune response in animal models.
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Affiliation(s)
- Anders Krarup
- Janssen Infectious Diseases and Vaccines, Archimedesweg 4-6, Leiden 2333 CN, The Netherlands
| | - Daphné Truan
- Janssen Infectious Diseases and Vaccines, Archimedesweg 4-6, Leiden 2333 CN, The Netherlands
| | | | - Lies Bogaert
- Janssen Infectious Diseases and Vaccines, Archimedesweg 4-6, Leiden 2333 CN, The Netherlands
| | - Pascale Bouchier
- Janssen Infectious Diseases and Vaccines, Archimedesweg 4-6, Leiden 2333 CN, The Netherlands
| | - Ilona J M Bisschop
- Janssen Infectious Diseases and Vaccines, Archimedesweg 4-6, Leiden 2333 CN, The Netherlands
| | - Myra N Widjojoatmodjo
- Janssen Infectious Diseases and Vaccines, Archimedesweg 4-6, Leiden 2333 CN, The Netherlands
| | - Roland Zahn
- Janssen Infectious Diseases and Vaccines, Archimedesweg 4-6, Leiden 2333 CN, The Netherlands
| | - Hanneke Schuitemaker
- Janssen Infectious Diseases and Vaccines, Archimedesweg 4-6, Leiden 2333 CN, The Netherlands
| | - Jason S McLellan
- Department of Biochemistry, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire 03755-3844, USA
| | - Johannes P M Langedijk
- Janssen Infectious Diseases and Vaccines, Archimedesweg 4-6, Leiden 2333 CN, The Netherlands
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24
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Sacco RE, Durbin RK, Durbin JE. Animal models of respiratory syncytial virus infection and disease. Curr Opin Virol 2015; 13:117-22. [PMID: 26176495 DOI: 10.1016/j.coviro.2015.06.003] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Accepted: 06/10/2015] [Indexed: 01/05/2023]
Abstract
The study of human respiratory syncytial virus pathogenesis and immunity has been hampered by its exquisite host specificity, and the difficulties encountered in adapting this virus to a murine host. The reasons for this obstacle are not well understood, but appear to reflect, at least in part, the inability of the virus to block the interferon response in any but the human host. This review addresses some of the issues encountered in mouse models of respiratory syncytial virus infection, and describes the advantages and disadvantages of alternative model systems.
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Affiliation(s)
- Randy E Sacco
- Ruminant Diseases and Immunology Research Unit, National Animal Disease Center, USDA, Agricultural Research Service, Ames, IA, United States
| | - Russell K Durbin
- Center for Immunity and Inflammation, Rutgers, The State University of New Jersey, New Jersey Medical School, Newark, NJ, United States
| | - Joan E Durbin
- Center for Immunity and Inflammation, Rutgers, The State University of New Jersey, New Jersey Medical School, Newark, NJ, United States; Department of Pathology, Rutgers, The State University of New Jersey, New Jersey Medical School, Newark, NJ, United States.
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25
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Pierantoni A, Esposito ML, Ammendola V, Napolitano F, Grazioli F, Abbate A, del Sorbo M, Siani L, D’Alise AM, Taglioni A, Perretta G, Siccardi A, Soprana E, Panigada M, Thom M, Scarselli E, Folgori A, Colloca S, Taylor G, Cortese R, Nicosia A, Capone S, Vitelli A. Mucosal delivery of a vectored RSV vaccine is safe and elicits protective immunity in rodents and nonhuman primates. Mol Ther Methods Clin Dev 2015; 2:15018. [PMID: 26015988 PMCID: PMC4441047 DOI: 10.1038/mtm.2015.18] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Accepted: 03/20/2015] [Indexed: 01/27/2023]
Abstract
Respiratory Syncytial Virus (RSV) is a leading cause of severe respiratory disease in infants and the elderly. No vaccine is presently available to address this major unmet medical need. We generated a new genetic vaccine based on chimpanzee Adenovirus (PanAd3-RSV) and Modified Vaccinia Ankara RSV (MVA-RSV) encoding the F, N, and M2-1 proteins of RSV, for the induction of neutralizing antibodies and broad cellular immunity. Because RSV infection is restricted to the respiratory tract, we compared intranasal (IN) and intramuscular (M) administration for safety, immunogenicity, and efficacy in different species. A single IN or IM vaccination completely protected BALB/c mice and cotton rats against RSV replication in the lungs. However, only IN administration could prevent infection in the upper respiratory tract. IM vaccination with MVA-RSV also protected cotton rats from lower respiratory tract infection in the absence of detectable neutralizing antibodies. Heterologous prime boost with PanAd3-RSV and MVA-RSV elicited high neutralizing antibody titers and broad T-cell responses in nonhuman primates. In addition, animals primed in the nose developed mucosal IgA against the F protein. In conclusion, we have shown that our vectored RSV vaccine induces potent cellular and humoral responses in a primate model, providing strong support for clinical testing.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | - Alessandra Taglioni
- Cellular Biology and Neurobiology Institute (IBCN) National Research Council of Italy, Rome, Italy
| | - Gemma Perretta
- Cellular Biology and Neurobiology Institute (IBCN) National Research Council of Italy, Rome, Italy
| | | | | | | | | | | | | | | | | | - Riccardo Cortese
- ReiThera Srl, Rome, Italy (former Okairos Srl)
- Keires AG, Basel, Switzerland
| | - Alfredo Nicosia
- ReiThera Srl, Rome, Italy (former Okairos Srl)
- CEINGE, Naples, Italy
- Department of Molecular Medicine and Medical Biotechnology, University Federico II, Naples, Italy
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26
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Cuddington B, Verschoor M, Mossman K. Handling of the cotton rat in studies for the pre-clinical evaluation of oncolytic viruses. J Vis Exp 2014:e52232. [PMID: 25490047 DOI: 10.3791/52232] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Oncolytic viruses are a novel anticancer therapy with the ability to target tumor cells, while leaving healthy cells intact. For this strategy to be successful, recent studies have shown that involvement of the host immune system is essential. Therefore, oncolytic virotherapy should be evaluated within the context of an immunocompetent model. Furthermore, the study of antitumor therapies in tolerized animal models may better recapitulate results seen in clinical trials. Cotton rats, commonly used to study respiratory viruses, are an attractive model to study oncolytic virotherapy as syngeneic models of mammary carcinoma and osteosarcoma are well established. However, there is a lack of published information on the proper handling procedure for these highly excitable rodents. The handling and capture approach outlined minimizes animal stress to facilitate experimentation. This technique hinges upon the ability of the researcher to keep calm during handling and perform procedures in a timely fashion. Finally, we describe how to prepare cotton rat mammary tumor cells for consistent subcutaneous tumor formation, and how to perform intratumoral and intraperitoneal injections. These methods can be applied to a wide range of studies furthering the development of the cotton rat as a relevant pre-clinical model to study antitumor therapy.
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Affiliation(s)
- Breanne Cuddington
- Department of Pathology and Molecular Medicine, McMaster Immunology Research Centre, Institute for Infectious Disease Research, McMaster University
| | - Meghan Verschoor
- Department of Pathology and Molecular Medicine, McMaster Immunology Research Centre, Institute for Infectious Disease Research, McMaster University
| | - Karen Mossman
- Department of Pathology and Molecular Medicine, McMaster Immunology Research Centre, Institute for Infectious Disease Research, McMaster University;
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27
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Rational design of human metapneumovirus live attenuated vaccine candidates by inhibiting viral mRNA cap methyltransferase. J Virol 2014; 88:11411-29. [PMID: 25056882 DOI: 10.1128/jvi.00876-14] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED The paramyxoviruses human respiratory syncytial virus (hRSV), human metapneumovirus (hMPV), and human parainfluenza virus type 3 (hPIV3) are responsible for the majority of pediatric respiratory diseases and inflict significant economic loss, health care costs, and emotional burdens. Despite major efforts, there are no vaccines available for these viruses. The conserved region VI (CR VI) of the large (L) polymerase proteins of paramyxoviruses catalyzes methyltransferase (MTase) activities that typically methylate viral mRNAs at positions guanine N-7 (G-N-7) and ribose 2'-O. In this study, we generated a panel of recombinant hMPVs carrying mutations in the S-adenosylmethionine (SAM) binding site in CR VI of L protein. These recombinant viruses were specifically defective in ribose 2'-O methylation but not G-N-7 methylation and were genetically stable and highly attenuated in cell culture and viral replication in the upper and lower respiratory tracts of cotton rats. Importantly, vaccination of cotton rats with these recombinant hMPVs (rhMPVs) with defective MTases triggered a high level of neutralizing antibody, and the rats were completely protected from challenge with wild-type rhMPV. Collectively, our results indicate that (i) amino acid residues in the SAM binding site in the hMPV L protein are essential for 2'-O methylation and (ii) inhibition of mRNA cap MTase can serve as a novel target to rationally design live attenuated vaccines for hMPV and perhaps other paramyxoviruses, such as hRSV and hPIV3. IMPORTANCE Human paramyxoviruses, including hRSV, hMPV, and hPIV3, cause the majority of acute upper and lower respiratory tract infections in humans, particularly in infants, children, the elderly, and immunocompromised individuals. Currently, there is no licensed vaccine available. A formalin-inactivated vaccine is not suitable for these viruses because it causes enhanced lung damage upon reinfection with the same virus. A live attenuated vaccine is the most promising vaccine strategy for human paramyxoviruses. However, it remains a challenge to identify an attenuated virus strain that has an optimal balance between attenuation and immunogenicity. Using reverse genetics, we generated a panel of recombinant hMPVs that were specifically defective in ribose 2'-O methyltransferase (MTase) but not G-N-7 MTase. These MTase-defective hMPVs were genetically stable and sufficiently attenuated but retained high immunogenicity. This work highlights a critical role of 2'-O MTase in paramyxovirus replication and pathogenesis and a new avenue for the development of safe and efficacious live attenuated vaccines for hMPV and other human paramyxoviruses.
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