RDD基序对口蹄疫Asia1型毒株感染力的影响

不同型口蹄疫病毒1D蛋白的βG和βH链之间都含有一个高度保守的RGD基序,其结合细胞受体,起始病毒感染.但本文通过对Asia1型FMDV的1D序列分析证实,田间毒株含有RGD和RDD基序(RGD中的G突变为D)的两种类型毒株.通过反向遗传技术制备了分别含有RGD和RDD基序的两种病毒,测定其生物学特性,并通过细胞感染力和乳鼠致病力比较这两种病毒感染力的差别.结果表明,含有RGD和RDD的毒株都具有感染性,含有RDD毒株的细胞感染力和乳鼠致病力比含RGD的高10倍左右,为进一步阐明RDD基序Asia1毒株的感染机制的分子基础奠定必要的基础.

Infectivity of Asia1 type foot-and-mouth disease virus was increased via an alternative RDD motif

The amino acid sequence motif Arg-Gly-Asp (RGD), located in the surface-exposed βG-βH loop of the 1D protein of different serotypes and subtypes of foot-and-mouth disease virus (FMDV), is highly conserved and participates in binding of FMDV to susceptible cells. Previous sequence analyses of the 1D-encoding region of a FMDV serotype Asia1 field isolates from China indicated the presence of an alternative RDD motif instead of the conserved βG-βH loop RGD. The role of the RGD and RDD sequences in virus infection was investigated by recovering viruses with the βG-βH loop RGD (named rRGD-Asia1) and a RDD tripeptide (named rRDD-Asia1), respectively, using a genome-length infectious chimeric cDNA clone. The results show that the infectivity of the rRDD-Asia1 virus for baby hamster kidney cells (BHK-21) and baby hamsters was higher as 10 times. These results also demonstrate that field isolates with RGD and an alternative RDD receptor recognition site have infectivity, and RDD motif can increase the infectivity of the viruses. The study lays a foundation for further study of the existence of other receptor molecules and alternative mechanisms for FMDV entry into cells.