Variations On The Major Functional Genes Of Persistent Isolates Of Foot-and-Mouth Disease Virus From Yaks

This is the first time in our country to construct animal model of FMDV persistent infection, five yaks were infected with the oringinal strain Akesu/58 that the full-length genome has known by puncturing in the tongue, then Oesophageal-Pharyngeal(O/P) fluid and serum were collected and detected, lasting 12 months. Towards the positive samples, by RT-PCR, molecular cloning, sequencing and biologic software, VP1, L and 3ABC genes sequences were achieved and analyzed. The results showed that the five infected yaks were in carrier state, but persistent time was various because of individual difference among them. VP1, L and 3 ABC genes of persistence strains had incoordinate variation and VP1 gene was the most evident. The central tripeptide of binding cell receptor in these strains was Arg-Gly-Asp(RGD) instead of Ser-Gly-Asp(SGD) in oringinal strain. This may be the result of adaptive mutation. As for different hosts, 3 ABC, especially 3 A gene, varied obviously and its variation contributed to the changes in the hosts of virus. In addition, the comparison of the result of RT-RCR and non-structural (NS) protein antibody in serum showed that the higher NS protein antibody was, the more possible persistent infection was, but there was not linear relationship between them.