The Immune Effect Of The Novel Chitosan On Virus-Like Particles Of O Serotype Foot-and-Mouth Disease Virus

Foot and mouth disease(FMD),caused by a foot-and-mouth disease virus(FMDV),is an acute,febrile,highly pathogenic infectious disease,which mainly affects cloven hoofed animals such as pigs,cattle,sheep,camels,etc,cattle of whom are the most susceptible.FMD is mainly transmitted through the respiratory tract,and is mainly charactered by the vesicular lesion and fester on the oral mucosa,hoof,nose and skin of the breast,causing enormous economic loss for livestock production and global trade.Therefore,the effective prevention and control of foot and mouth disease and the final clearance,is one of the current research directions.In order to study the immune effect of the quaternized chitosan-gel microspheres on the VLPs,the VLPs of O type FMDV was expressed by Escherichia coli and was purified and assembled in vitro.Guinea pigs were immuned by VLPs emulsified by the quaternized chitosan microspheres(Chitosan A)and white oil mixed emulsion(Chitosan B).Using T lymphocyte proliferation,FMDV specific antibody level detection and protection rate after infection confirmed the immune effect of the quaternized chitosan-gel microspheres on FMD VLPs.Again through the pig animal model,FMDV specific antibody level,neutralizing antibody,cytokines and protection rate after infection,verify whether the quaternized chitosan-gel microspheres as adjuvants could enhance the immune response of FMD VLPs.These experiments proved that the VLPs of O type FMDV emulsified by both the quaternized chitosan-gel microspheres and routine adjuvant ISA201 induced high level FMDV specific antibody.In the proliferation of T lymphocytes the former was better than the latter,and the Chitosan B adjuvant group was better than Chitosan A adjuvant group,showing the quaternized chitosan-gel microspheres can enhance both humoral and cellular immune responses.The quaternized chitosan-gel microspheres as VLPs vaccine adjuvants can induce Th1 and Th2 immune responses,playing a stronger,more extensive cellular immune responses.The enhancement effect of the Chitosan B adjuvant is superior to Chitosan A adjuvant in both cellular immunity and humoral immunity.This study broadens the selection range of FMDV vaccine adjuvant and provides a new idea and theoretical basis for the quaternized chitosan-gel microspheres as an immunoenhancer of VLPs,therefore the quaternized chitosan-gel microspheres is a potential vaccine adjuvant.