Objective: Foot-and-Mouth Disease Virus (FMDV) initiates infection by binding to integrin receptors via a highly conserved Arg-Gly-Asp (RGD) sequence found in the G-H loop of the structural protein VP1. However, FMDV is an RNA virus, which harbors the evolutionary potential to render the RGD motif dispensable upon changes in constant environment. We studied mutation of RGD motif upon short-time passages FMDV Asial/JS/China/2005 field strain in different host.
Methods: VP1 gene was amplified from Asial/JS/China/05 field strain, the fourth passage virus in sulking mice (MF4) of the above strain and the virus isolated from a pig housing with cattle inoculated with the above strain followed eight passages in BHK-21 cell (PBF8) by RT-PCR, and the VP1 genes were sequenced and their deduced amino acid sequences were compared with each other.
Result: Dominant population with RGD and Arg-Ser-Asp (RSD) receptor recognition site motif was generated after four passages of Asial/JS/China/2005 field virus in sulking mice and another dominant population with Arg-Asp-Asp (RDD) motif was produced after eight passages the virus isolated from housing pig with cattle inoculated with the above field strain.
Conclusion: This study indicated that the dominant FMDV virus populations with RSD or RDD receptor binding site instead of original RGD motif were produced upon short-time evolution of FMDV field isolates with RGD motif in different environment. These studies not only increase number of viable mutants with substitutions in the RGD region, but also these profoundly altered, but viable, mutants with different receptor recognition site will provide useful tools for studies of cell recognition by FMDV and host tropism modifications.