Structural proteins of Tacaribe and Tamiami virions.

Tacaribe and Tamiami viruses were grown in BHK-21 monolayers and purified by centrifugation in combination glycerol-tartrate gradients followed by sucrose gradient centrifugation. The major polypeptides of Tacaribe and Tamiami virions were shown to differ from those of Pichinde virions when suitably labeled preparations of the three viruses were coelectrophoresed in SDS-polyacrylamide gels. Tacaribe and Tamiami virions each contained two major polypeptides, a nonglycosylated protein of molecular weight 68,000 and 66,000, respectively, and a single glycoprotein size-class of molecular weight 42,000 and 44,000, respectively. The nonglycosylated protein is associated with the viral RNA in a nucleoprotein structure which can be isolated by equilibrium centrifugation in CsCl. The glycoproteins were selectively removed from virions by chymotrypsin treatment, which produces essentially spikeless particles. Tacaribe and Tamiami virions also contain a minor polypeptide species of molecular weight 79,000 and 77,000, respectively.