Integrin sub-unit expression in cell cultures used for the diagnosis of foot-and-mouth disease

The ability to propagate foot-and-mouth disease virus (FMDV) plays an important role in laboratory diagnosis and the production of vaccines to control the spread of the disease. Many established cell lines suffer from poor sensitivity for isolating virus from field samples. One possible factor that limits sensitivity to FMDV is the lack of expression of surface integrins, the primary class of cell receptor used by FMDV to initiate infection. In this study we have sequenced cDNAs encoding these molecules for pigs and subsequently developed quantitative real-time reverse transcription (RT)-PCR assays to quantify underlying mRNA transcription of integrin molecules. These novel assays were used together with flow-cytometry to determine cell surface expression and of 4 different cell culture systems. These studies have identified a clear correlation of sensitivity to FMDV with expression of integrins αVβ6 and αVβ8. In contrast, cell surface expression of αVβ3 or mRNA for the β1, β3 or β5 subunits did not appear to contribute to sensitivity of cells to FMDV. These findings confirm the requirement for αV6 and αVβ8 as receptors for isolating FMDV from clinical samples and provide important tools and information for the rational design of recombinant cell lines containing these ligands for improved FMDV diagnosis and vaccine production.