Study On HFMD Pathogen Spectrum Of Jiangsu Province And Preliminary Establishment Of Moxi B3 Vaccine Evaluation Mouse Model

Hand, foot and mouth disease(HFMD) is a common acute infectious disease in infants and childern. In recent years, HFMD is widespread in the world, especially in Asia-Pacific region. Enterovirus(EV) is the major pathogen which can cause HFMD. Among them, Enterovirus A71(EV-A71) and Coxsackievirus A16(CV-A16) draw more attention for causing HFMD outbreaks in many countries or regions. However, there are still many questions need to be answered to facilitate disease control and vaccine development: 1. Clarification of the incidence and disease spectrum is important for the evaluation of the disease burden and formulation of the prevention and control strategies, while there is lack of researches on HFMD incidence currently; 2. Genetic variations in enteroviruses can easily occur during circulation, which may complicate clinical manifestations. So it is necessary to analyze the genetic evolutionary characteristics of EV-A71, CV-A16 and other EVs; 3. EV-B viruses can easily cause viral myocarditis, encephalitis and other severe clinical symptoms besides HFMD. However, there are no successful vaccines. Researches on CV-B3 animal model and vaccine could contribute to viral myocarditis prevention.Focusing on the above problems on HFMD etiology and CV-B3 vaccinology, this research studied the pathogen spectrum and incidence of HFMD in Jiangsu Province with methods which combined active surveillance with case reports. Genetical characteristics of the major pathogens have been analyzed, a CV-B3 animal model has been established, and preliminarily studies on the protective effect of an inactivated vaccine have also been done. The main contents of this research are as follows:1. The two-year prospective cohort study has been carried out in the popu lation of 9442 volunteers recruited in phase â…¢ clinical trial of EV-A71 vaccine in Jiangsu Province. The incidence of HFMD in 2012-2013 was 150.9/1000, which was achieved by active surveillance. The incidences of the top five ente roviruses are CV-A16(54.5/1000), CV-B3(14.2/1000), CV-A10(8.5/1000), EVA71(5.9/1000) and CV-A6(5.7/1000). The pathogen spectrum of HFMD in 2012-2013 was composed of CV-A16(36.1%), CV-B3(9.3%), CV-A10(5.6%), CV-A6(3.7%), E9(3.1%), EV-A71(2.2%), CV-A2/CV-A12/CV-A22/CV-A14/E16(1.9%), CV-A8/CV-A9/E3/E11/E24(1.2%), CV-A1/CV-A4/CV-B5/CV-A21/E6/E18/E19(0.6%), untyped EVs(8.6%) and non-EVs(25.0%).2. The incidence of HFMD in 2013-2014 was 29.9/1000, which was achie ved by case reports. The incidences of the top five enteroviruses are EV-A71(4.2/1000), CV-A16(1.2/1000), CV-A22(1.1/1000), CV-A6(0.9/1000), CV-A24(0.7/1000). The pathogen spectrum of HFMD in 2013-2014 was composed of EV-A71(14.2%), CV-A16(3.9%), CV-A22(3.5%), CV-A6(2.8%), CV-A24(2.5%), CV-A10/CV-B3/E6(2.1%), CV-B5(1.8%), E9(1.4%), CV-A9/CV-B4(1.1%), CV-B2/E1/E11(0.7%), CV-A1/CV-A2/CV-A20/E3/E7/E15/E16/E21/E25/ EV-B69/EV-C99(0.4%), untyped EVs(6.4%) and non-EVs(51.8%). Streptococcus and human herpesvirus 5 were detected in the non-EVs samples with high positive rate by deep sequencing, and the constituent ratio of HFMD were 27.9% and 47.8%, respectively.3. The major pathogens circulated during the two-year monitoring period were isolated and the evolution characteristics of EV-A71, CV-A16, CV-A6, CV-A10 and CV-B3 were analyzed. The EV-A71 strains of two different branches of C4 a sub-genotype co-circulated in Jiangsu Province in 2012-2014. There were some differences between the CV-A16 strains in 2013 and the ones in 2012, which belonged to different branches of B2 a sub-genotype. CV-A6 strains of F2 and F3 sub-genotypes co-circulated in 2012, while the strains in 2013 were mainly F3 strains. The CV-A10 strains circulated in 2012 belonged to genotype C and D. The CV-B3 strains in 2012 belonged to two different branches of D2 sub-genotype.4. A mouse model was initially established based on the high pathogenicity CV-B3 strain(286/CV-B3), and the protective effect of a CV-B3 inactivated vaccine was evaluated by this mouse model. It was found that the inactivated vaccine showed good protective effect inmice when challenged by 286/CV-B3.In summary, the pathogen spectrum and incidence of HFMD in Jiangsu Province in 2012-2014 were obtained. It indicated that CV-B3 and CV-A6 might need be incorporated into multiple HFMD vaccine for the high ratio in spectrum and the serious pathogenicity. To break the bottlenecks in the research on CV-B3 vaccine, a animal model suitable for CV-B3 vaccine evaluation was initially established, the protective effect of CV-B3 inactivated vaccine was evaluated, which provided the foundation for the prevention and control of HFMD and the development of CV-B3 vaccines.