title: A Neonatal Murine Model of Coxsackievirus A6 Infection for Evaluation of Antiviral and Vaccine Efficacy.
abstract: Hand, foot, and mouth disease (HFMD) is a global health concern. FamilyPicornaviridaemembers, particularly enterovirus A71 (EVA71) and coxsackievirus A16 (CVA16), are the primary etiological agents of HFMD; however, a third enterovirus A species, CVA6, has been recently associated with epidemic outbreaks. Study of the pathogenesis of CVA6 infection and development of antivirals and vaccines are hindered by a lack of appropriate animal models. We have developed and characterized a murine model of CVA6 infection that was employed to evaluate the antiviral activities of different drugs and the protective efficacies of CVA6-inactivated vaccines. Neonatal mice were susceptible to CVA6 infection via intramuscular inoculation, and the susceptibility of mice to CVA6 infection was age and dose dependent. Five-day-old mice infected with 105.550% tissue culture infective doses of the CVA6 WF057R strain consistently exhibited clinical signs, including reduced mobility, lower weight gain, and quadriplegia with significant pathology in the brain, hind limb skeletal muscles, and lungs of the infected mice in the moribund state. Immunohistochemical analysis and quantitative reverse transcription-PCR (qRT-PCR) analyses showed high viral loads (11 log10/mg) in skeletal muscle, and elevated levels of interleukin-6 (IL-6; >2,000 pg/ml) were associated with severe viral pneumonia and encephalitis. Ribavirin and gamma interferon administered prophylactically diminished CVA6-associated pathologyin vivo, and treatment with IL-6 accelerated the death of neonatal mice. Both specific anti-CVA6 serum and maternal antibody play important roles in controlling CVA6 infection and viral replication. Collectively, these findings indicate that this neonatal murine model will be invaluable in future studies to develop CVA6-specific antivirals and vaccines.IMPORTANCEAlthough coxsackievirus A6 (CVA6) infections are commonly mild and self-limiting, a small proportion of children may have serious complications, such as encephalitis, acute flaccid paralysis, and neurorespiratory syndrome, leading to fatalities. We have established a mouse model of CVA6 infection by inoculation of neonatal mice with a CVA6 clinical isolate that produced consistent pathological outcomes. Here, using this model of CVA6 infection, we found that high levels of IL-6 were associated with severe viral pneumonia and encephalitis, as in an evaluation of antiviral efficacyin vivo, IL-6 had no protective effect and instead accelerated death in neonatal mice. We demonstrated that, as antiviral drugs, both gamma interferon and ribavirin played important protective roles in the early stages of infection, with increased survival in treated neonatal mice challenged with CVA6. Moreover, active and passive immunization with the inactivated vaccines and anti-CVA6 serum also protected mice against homologous challenge infections.
authors.affiliation: Institute of Pathogen Biology, Taishan Medical College, Taian, Shandong, China.
authors.forename: Zhenjie
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: Institute of Pathogen Biology, Taishan Medical College, Taian, Shandong, China.|School of Public Health, Taishan Medical College, Taian, Shandong, China.
authors.forename: Zhaopeng
authors.initials: Z
authors.lastname: Dong
authors.affiliation: Taian Maternal and Child Care Hospital, Taian, Shandong, China.
authors.forename: Qingjuan
authors.initials: Q
authors.lastname: Wei
authors.affiliation: Global Station for Zoonosis Control, Global Institution for Collaborative Research and Education (GI-CoRE), Hokkaido University, Sapporo, Japan.|National Virus Reference Laboratory, University College Dublin, Dublin, Ireland.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Carr
authors.affiliation: Institute of Pathogen Biology, Taishan Medical College, Taian, Shandong, China.
authors.forename: Juan
authors.initials: J
authors.lastname: Li
authors.affiliation: Department of Viral Infectious Diseases Control and Prevention, Shandong Center for Disease Control and Prevention, Jinan, Shandong, China.
authors.forename: Shujun
authors.initials: S
authors.lastname: Ding
authors.affiliation: Beijing Institute of Microbiology and Epidemiology, Beijing, China.
authors.forename: Yigang
authors.initials: Y
authors.lastname: Tong
authors.affiliation: School of Public Health, Taishan Medical College, Taian, Shandong, China dli@tsmc.edu.cn shiwf@ioz.ac.cn.
authors.forename: Dong
authors.initials: D
authors.lastname: Li
authors.affiliation: Institute of Pathogen Biology, Taishan Medical College, Taian, Shandong, China dli@tsmc.edu.cn shiwf@ioz.ac.cn.
authors.forename: Weifeng
authors.identifier: http://orcid.org/0000-0002-8717-2942
authors.initials: W
authors.lastname: Shi
mesh_terms: D000818:Animals; D057134:Antibodies, Neutralizing / Q000276:immunology; D000914:Antibodies, Viral / Q000276:immunology / Q000627:therapeutic use*; D000998:Antiviral Agents / Q000627:therapeutic use*; D002478:Cells, Cultured; D002648:Child; D004195:Disease Models, Animal; D004660:Encephalitis / Q000821:virology; D029821:Enterovirus A, Human / Q000187:drug effects / Q000276:immunology* / Q000472:pathogenicity; D005260:Female; D006232:Hand, Foot and Mouth Disease / Q000188:drug therapy / Q000276:immunology* / Q000517:prevention & control* / Q000821:virology; D006801:Humans; D007116:Immunization, Passive / Q000379:methods*; D007371:Interferon-gamma / Q000097:blood / Q000627:therapeutic use*; D015850:Interleukin-6 / Q000097:blood / Q000494:pharmacology; D008168:Lung / Q000821:virology; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D018482:Muscle, Skeletal / Q000821:virology; D011024:Pneumonia, Viral / Q000821:virology; D012254:Ribavirin / Q000627:therapeutic use*; D014611:Vaccination; D015164:Vaccines, Inactivated / Q000276:immunology; D019562:Viral Load / Q000187:drug effects; D056189:Viral Tropism; D014765:Viral Vaccines / Q000276:immunology*
chemical_list: D057134:Antibodies, Neutralizing; D000914:Antibodies, Viral; D000998:Antiviral Agents; D015850:Interleukin-6; D015164:Vaccines, Inactivated; D014765:Viral Vaccines; C577686:interleukin-6, mouse; D012254:Ribavirin; D007371:Interferon-gamma
keywords: CVA6 infection; coxsackievirus; enterovirus; murine model