Establish Of An EV71 Infection ICR Mouse Model And Its Applicationes In Vaccine Evaluation

EV71 infections are generally mild, such as hand-foot-and-mouth disease (HFMD) and herpangina, but occasionally lead to severe diseases such as aseptic meningitis, brain stem encephalitis and poliomyelitis-like paralysis, with a significant morbidity and mortality mainly in infants and young children under 5 years old.Numerous large outbreaks of EV71 caused disease have occurred since it was first described in 1969. Since 1997, the outbreaks of EV71 infections have presented an ascensus tendency in Asia-Pacific regions. The epidemics of EV71 infection were reported firstly in 1980s and it was lasted for thirty years in mainland of China. In spring of 2009,40,000 of HFMD cases caused by EV71 were diagnosis in mainland of China, and 80 of them lead to serious symptoms. HFMD seems to come over the same time of this year. Until May the 4th,427,278 of HFMD cases were reported over the country, and 260 of them were dead. Most serious patients were under five years old and infected by EV71.Effective vaccines Development is considered as a first choice among all control measures, however, although several investigations have examined the feasibility of developing a useful vaccine for enterovirus, no vaccine for EV71 infection has been commercially available and the prevention of EV71 epidemics was only relying on public surveillance.The main reason is the failure of the building of a useful animal model. Altouth several animal models have been built to study the transmission and pathogenesis of EV71, there are no one could use to evaluate the vaccine, which was on the developing.In our study, EV71 strains isolated from patients of China were used to create possible animal models. Previous study suggesting that one day old ICR mouse was sensitive to virus, and intraperitoneal (IP) was the optimal infection rout. In the same time, one step RT-PCR, viral isolation, IFA and IEA methods have been developed. Furthermore, a mouse-adapted EV71 stain was derived from the fourth passage in mice muscle, designated as FuYang-0805a. We compared it with the parental EV71 strain and found that FuYang-0805a grew more rapidly, and was more cytotoxic in RD cell, and more virulent than the parental strain in one day old mice. The amino acid sequence diversity of parental and mouse-adapted EV71 strains was found too. With the developed virus detection methods and model estimate system we studied the clinical manifestation, etiology, viral molecular biology and pathology of this animal model, finding that specific pathologic changes were observed in infected mouse intestine, skeletal muscle and cardiac muscle, viral antigens were detected diffusely within the skeletal muscle fibers also. In this way, we have developed an ICR mouse model with this mouse-addapted EV71 strain.In summary, EV71 strains isolated from patients of China were first used in this animal infection experiment, finding that One day old ICR mouse was responsive. With the preparation of a mouse-addapted EV71 stain, virus infection ICR mouse model was established. On the same time, amount of virus detection methods were developed, especially the real-time quantitative RT-PCR technique with SYBR Green I. In the end, this model was succesfully used in evaluation of the subunit vaccine developed in our institute.