[Co-expressed GP5 and M proteins of porcine reproductive and respiratory syndrome virus can form heterodimers].

In order to investigate the characterization of in vitro co-expressed GP5 and M proteins of porcine reproductive and respiratory syndrome virus (PRRSV), eukaryotic expression plasmids pCI-ORF5 (expressing GP5 protein alone), pCI-ORF6 (expressing M protein alone), and pCI-ORF5/ORF6 (co-expressing GP5 and M proteins) were constructed. After transient transfection, Western blot analysis under nonreducing condition demonstrated that co-expressed GP5 and M proteins could form disulfide-linked heterodimers (GP5-M) in transiently transfected BHK-21 cells. To further study the influence of GP5-M heterodimers formation on the subcellular localizations of GP5 or M proteins, green fluorescence protein (EGFP) and red fluorescence protein (RFP) were used as markers. The results of fluorescence distribution showed that co-expressed GP5-EGFP chimera and M-RFP chimera boosted the transport of GP5 from the endoplasmic reticulum (ER) to the Golgi complex, indicating that the formation of GP5-M heterodimers may be involved in posttranslational modification, transport, and subcellular localization of GP5. These results presented here lay foundation to further study the molecular mechanism of GP5-M heterodimer formation and its role in protective immunity of PRRSV.