Use of the Sindbis replicon system for expression of LaCrosse virus envelope proteins in mosquito cells

The Sindbis replicon expression system was used to express La Crosse (LAC) virus envelope glycoprotein genes in both mammalian and mosquito cell culture. Replicon expressed LAC proteins had correct molecular mass (Mr) and were antigenically similar to wild type LAC envelope proteins. In addition, LAC G1 and G2 proteins colocalized when expressed from separate constructs in both mammalian and mosquito cells suggesting that they were trafficked through the cell similarly to wild type LAC proteins. A truncated form of the G1 protein was secreted from mosquito cells when expressed alone. The truncated G1 protein was also secreted from mosquito cells when expressed with the G2 protein, but to a lesser extent than when expressed alone, suggesting that the G2 protein sequestered G1 protein intracellularly. The Sindbis replicon system is a powerful tool for the study of LAC virus protein maturation within mosquito cells and mosquitoes.