Study On The Immunogenicity And Protective Efficacy Of EV71,CA16,CA10,CA6 Quadrivalent VP1 Protein Vaccine Candidate

Background Hand,foot,and mouth disease(HFMD)is a global health concern.Enterovirus A71(EV71)and coxsackievirusA16(CA16),are the primary etiological agents of HFMD.However,the proportion of HFMD caused by CA6 has been increasing in recent years.Study of the pathogenesis of CVA6 infection and development of antivirals and vaccines are hindered by a lack of appropriate animal models.In this paper,7-day-old ICR mice were infected with CA6 virus to establish a mouse infection model.Methods CA6 was subcultured in 10-day-old ICR mice for three times to obtain mouse adaptive strain MP3.7-day-old ICR mice were infected with 2×105TCID50 CA6 adaptive strain by intraperitoneal injection(i.p.).The clinical symptoms were observed,and the changes of viral load and pathology in each tissue were detected.Results Mice infected with CA6 showed symptoms of decreased mobility,weight gain loss and hindlimb paralysis,and eventually died.In the pathological results,it was found that there were pathological injuries in muscle,thymus,heart,spleen and brain of mice,among which the muscle demonstrated the most severe pathological injury.Conclusions In this study,an animal model of CA6 infection with ICR was successfully established,which laid a foundation for the pathogenesis of CA6 infection and the research and development of antiviral drugs and vaccines.Background Hand,foot and mouth disease(HFMD)mainly affects children under the age of 5.Because HFMD is caused by a group of enteroviruses,several vaccine researches in the direction of HFMD are in progress,with most of the strategies focusing on a single causative agent,and the development of a multivalent HFMD vaccine could be the best strategy.In this study,we prepared a quadrivalent VP1 protein vaccine candidate against EV71,CA16,CA10 and CA6.This vaccine was then injected into mice to examine immune activities and to evaluate safety.Methods Prepare quadrivalent VP 1 protein vaccine candidate and immunize ICR mice,virus-specific antibodies and their neutralizing activities were analyzed,and virus-specific T cell immune responses and changes in cytokines were assessed.Furthermore,passive immunoprotective effects passed from immunized mothers to their neonatal offspring were evaluated with in vivo infection experiments.Results The quadrivalent VP 1 protein vaccine candidate continuously induced virus-specific IgGs and IgMs,which had the ability to neutralize the viruses.In addition to inducing virus-specific humoral immunity,the quadrivalent VP1 protein vaccine candidate activated the virus-specific T cell response as well.The vaccine candidate also provided passive immunity to neonatal mice against EV71 and CA6 infection.Additionally,inflammatory cytokines maintain a relatively stable level during the immune process.Conclusions The quadrivalent VP1 protein vaccine candidate was effective against EV71,CA16,CA10 and CA6 challenge,and could therefore be useful for the development of multivalent HFMD vaccines.