Evaluation Of The Feasibility Of Monoclonal Antibodies Based Immunotherapy Against Enterovirus71(EV71) And Coxsackievirus A Type16(CA16)

Enterovirus71(EV71) and Coxackievirus A type16(CA16) are the major causative reagents of hand, foot and mouth disease (HFMD). In recent years, the incidence of HFMD, the numbers of severe cases and deaths were significantly increased in China, and have seriously endangered the health and safety of children, which have made it an ergent need to develop effective therapeutic drugs to control there infection and epidemic. Because of low toxicity and good specificity, monoclonal antibodies (MAb) are a potential candidate for the treatment of viral infection. Therefore, we aim to optimize the EV71mouse model and establish a stable CA16mouse model, use this model to evaluate and obtain therapeutic MAb with treatment potential to EV71or CA16infection, which will provide important foundations for the development of therapeutic drugs of EV71and CA16.This study firstly optimized the challenge method and challenge dose of the original EV71mouse model to achieve a stable100%mortality rate. Meanwhile using13clinical CA16isolates to infect1-day-old BABL/c mice, the result showed that most of the CA16virus were virulent to mice and neurological symptoms such as limb paralysis were also confirmed. Pathological analysis confirmed serious necrosis and inflammation in the brain and spinal cord, which was similar to the infection of CA16in human. So far, a CA16mouse model by challenging intragastrically1-day-old BALB/c mice with CA16is established. This laid the foundations for future research.Then identified a CA16neutralization MAb (nMAb)14B10by evaluating the in vivo treatment effect of two CA16nMAbs in CA16mouse model. Through evaluating the effect of different treatment times and treatment strategies after CA16infection, it was shown that using a single treatment method within2days after infection can effectively treat90%of the challenged mice. Significant treatment effect was also achieved using a continuous thrice treatment method on3days after infection, which was one day prior to the onset of illness in mice. Thus it has been confirmed that14B10 owed a good therapeutic effect for CA16infection.A nMAb of EV71, CT11F9, was identified by evaluating the in vivo treatment ability of13EV71nMAbs. The in vivo treatment results of CT11F9at different treatment time and treatment strategies showed that single-treatment can effectively cure EV71challenged mice utill3days post-infection; using a continuous thrice treatment protocol on4days post-infection when the mice start to perform illness, an increased survival rate was also achieved. Competitive ELISA also confirmed that CT11F9-recognized epitopes were immunodominant in humans. Thus it has been confirmed that CT11F9owed a good therapeutic effect for EV71infection.In summary, this research has optimized the established EV71mouse model and built up a stable CA16mouse model, then screened and obtained therapeutic antibody candidates of EV71and CA16. These studies will provide important data support and theoretical basis for the development of therapeutic antibodies of EV71and CA16.