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 research article describes the creation of chimeric arteriviruses to study the role of the major glycoprotein ectodomain in equine arteritis virus (EAV) cell culture tropism. The findings suggest that the ectodomain is not the primary determinant of EAV’s tropism.

Research Methodology

The researchers used a distinct method for their study:

• The full-length cDNA clones of arteriviruses were utilized to create chimeric arteriviruses. These chimeras were created using an equine arteritis virus (EAV) infectious cDNA clone.
• The ectodomains of the two major envelope proteins, glycoprotein GP(5) and the membrane protein M, were replaced with sequences derived from envelope proteins of related and unrelated RNA viruses.
• Using immunofluorescence microscopy, the transport of the hybrid GP(5) and M proteins to the Golgi complex was monitored. Their heterodimerization influenced this transport, which is a crucial step for virus assembly.

Results and Findings

The researchers were able to obtain significant results:

• The chimeras containing the GP(5) ectodomain from porcine (PRRSV) or mouse (LDV) arteriviruses were the only viable ones. The sequences from these arteriviruses were considerably smaller than the corresponding sequence of EAV.
• Even though the successful GP(5) chimeras were weakened, they could still infect baby hamster kidney (BHK-21) and rabbit kidney (RK-13) cells. These cells are susceptible to EAV infection, but not to either PRRSV or LDV.

Conclusion

In conclusion, the major glycoprotein GP(5)’s ectodomain, previously hypothesized to involve receptor recognition is not the main determinant of EAV tropism in cell culture. This conclusion is based on the observation that chimeras could infect cell types usually not susceptible to their original viruses, implying other factors beyond the GP(5) ectodomain determine EAV tropism.