Glycoprotein-mediated biological properties of a host range mutant of Junin virus

The biological properties mediated by the main envelope glycoprotein (GP1) of a mouse-attenuated mutant of Junin virus, named Cl67, were investigated in comparison with its parental strain XJCl3. In contrast to the parental strain, this mutant was unable to multiply in primary cultures of mouse embryo fibroblasts (MEFs). Impairment of Cl67 multiplication was associated with a lack of virus binding to MEF, probably due to an altered interaction between GP1 and cellular receptors. Antigenic and immunogenic characterization of GP1, performed by neutralization assays, demonstrated that, under certain conditions, polyclonal and monoclonal antibodies exhibited differential affinity and specificity for each virus. Cl67-infected Vero cells showed a marked pH-dependent fusion capability, suggesting more efficient low pH triggering of fusion by mutant virus GP1 in comparison with the parental strain.