A 10-Day-Old Murine Model of Coxsackievirus A6 Infection for the Evaluation of Vaccines and Antiviral Drugs.

Zaixue Jiang,Wenkuan Liu,Yaozhong Zhang,Xingui Tian,Baimao Zhong,Huayuan Lin,Xiaomei Lu,Rong Zhou,Qingqiu Cheng

doi:10.3389/fimmu.2021.665197

Abstract

Coxsackievirus A6 (CVA6) is recognized as a major enterovirus type that can cause severe hand, foot, and mouth disease and spread widely among children. Vaccines and antiviral drugs may be developed more effectively based on a stable and easy-to-operate CVA6 mouse infection model. In this study, a wild CVA6-W strain was sub-cultured in newborn mice of different ages (in days), for adaptation. Therefore, a CVA6-A mouse-adapted strain capable of stably infecting the mice was generated, and a fatal model was built. As the result indicated, CVA6-A could infect the 10-day-old mice to generate higher levels of IFN-γ, IL-6, and IL-10. The mice infected with CVA6-A were treated with IFN-α1b at a higher dose, with complete protection. Based on this strain, an animal model with active immunization was built to evaluate antiviral protection by active immunization. The three-day-old mice were pre-immunized with inactivated CVA6 thereby generating IgM and IgG antibodies within 7 days that enabled complete protection of the pre-immunized mice following the CVA6 virus challenge. There were eight mutations in the genome of CVA6-A than in that of CVA6-W, possibly attributed to the virulence of CVA6 in mice. Briefly, the CVA6 infection model of the 10-day-old mice built herein, may serve as an applicable preclinical evaluation model for CVA6 antiviral drugs and vaccine study.

Highlights

Hand, foot and mouth disease (HFMD) can jeopardize children’s health in the long term [1]
Coxsackievirus A6 (CVA6) was cultured in rhabdomyosarcoma cell line (RD cell), and the cytopathic effect (CPE) was monitored under the microscope every day for 2 to 4 days
The CCK8 detection kit was adopted to detect the survival rate of the cells, and the results indicated that the IFN-a1b of 0.1172 μg/ml can inhibit the infection of RD cells by CVA6 in vitro (Figure 5G)

Summary

Introduction

Foot and mouth disease (HFMD) can jeopardize children’s health in the long term [1]. Enterovirus 71 (EV71) was the main pathogen of HFMD, at previous studies [2]. Differential diagnoses of clinicians are more difficult to achieve as impacted by the possible similarity between the rash attributed to CVA6 in children and other exudative skin rash diseases, which causes children to developed serious complications [9]. There is no specific drug or vaccine to enable treatment or prevention of clinical CVA6 infection. Some antiviral drugs for treating CVA6, such as ribavirin, natural ingredients of herb, IFNa, and some vaccines for preventing CVA6 are under development [10,11,12,13]. Some candidates showed some effects in preventing and treating CVA6 infection, and suitable animal models are critical to the preclinical studies

Methods

Results

Conclusion