Construction of chimeric arteriviruses reveals that the ectodomain of the major glycoprotein is not the main determinant of equine arteritis virus tropism in cell culture

The recent development of arterivirus full-length cDNA clones makes possibl e the construction of chimeric arteriviruses for fundamental and applied st udies. Using an equine arteritis virus (EAV) infectious cDNA clone, we have engineered chimeras in which the ectodomains of the two major envelope pro teins, the glycoprotein GP(5) and the membrane protein M, were replaced by sequences from envelope proteins of related and unrelated RNA viruses. Usin g immunofluorescence microscopy, we monitored the transport of the hybrid G P(5) and M proteins to the Golgi complex, which depends on their heterodime rization and is a prerequisite for virus assembly. The only viable chimeras were those containing the GP(5) ectodomain from the porcine (PRRSV) or mou se (LDV) arteriviruses, which are both considerably smaller than the corres ponding sequence of EAV Although the two viable GP(5) chimeras were attenua ted, they were still able to infect baby hamster kidney (BHK-21) and rabbit kidney (RK-13) cells. These cells can be infected by EAV, but not by eithe r PRRSV or LDV This implies that the ectodomain of the major glycoprotein G P(5) which has been postulated to be involved in receptor recognition, is n ot the main determinant of EAV tropism in cell culture. (C) 2001 Academic P ress.