Construction of a full-length infectious cDNA clone of inter-genotypic chimeric foot-and-mouth disease virus

Abstract:

Abstract:［Objective］A series of type O foot-and-mouth disease (FMD) outbreaks occurred in China seriously affect development of Chinese husbandry． Its causative agent—type O foot-and-mouth disease virus (FMDV) has been evolved three topotypes: Cathay，Middle East-South Asia and Southeast Asia，specifically，the viruses of Cathay topotype are highly adapted to pig，representing the biggest threat on Chinese pig industry． The available FMD vaccine in China provides insufficient protection against some arising viruses of Chathay topotype，which exert important obstacle to control porcinophilic FMD epidemics in China． To develop vaccine candidate with characteristics of good immunogenicity and broad spectrotype，a full-length infectious cDNA clone of inter-genotypic chimeric FMDV was constructed，which replaced part VP3 and VP1 gene of O/HN /93 strain with the corresponding to the variants of Cathay topotype (mainly replaced the B-C and G-H loop of structure protein VP1)．［Methods］ Linearized recombinant plasmid and plasmid expressing T7 RNA polymerase were cotransfected into BHK-21 cells to rescue the chimeric virus in vivo．［Result］The transfected cells showed apparent cytopathic effects (CPE) after 36 h post-transfection． The rescued virus was checked by RT-PCR，indirect immunofluorescence，electron microscope． Results show that chimeric FMDV was successfully rescued in vivo．The study of sulk mice pathogenicity show chimeric FMDV has attenuated pathogenicity for suckling mice compared with its parental virus.［Conclusion］ The construction of inter-genotypic chimeric FMDV will lay the basis for developing novel vaccine against FMD.