Correlation between virus-cell receptor properties of alphaviruses in vitro and virulence in vivo.

Virulent and avirulent clones of Venezuelan, Western, and Eastern equine encephalitis viruses were examined for their in vitro attachment characteristics to the surface of cultured cell monolayers. These attachment characteristics were correlated with in vivo plasma clearance rates and virulence. For the clones investigated, avirulence correlated in vitro with attachment pH optima close to physiologic pH and in vivo with a rapid clearance from plasma. Conversely, virulent clones had lower in vitro attachment pH optima and low plasma clearances in vivo.