Comparison of capsid polypeptides of group B coxsackieviruses and polypeptide synthesis in infected cells

Capsid polypeptides of all six types (B1--6) of group B coxsackieviruses were compared by high-resolution gel electrophoresis, and synthesis of protein and RNA in B4- or B5-infected HeLa cells was analyzed. Four polypeptides, VP1--4; were detected in each type. Another polypeptide, VP0, slightly larger than VP1; was also detected in trace amounts in some types. VP1--3 showed different but characteristic molecular weights (VP1, 34,500 to 37,000; VP2, 31,000 to 36,000; VP3, 26,000 to 32,500), and presented well-defined and reproducible differences in electrophoretic mobility. Virus-specific protein synthesis began while host protein synthesis was declining, increased during the ensuing period, and declined in late infection. A number of virus-specific proteins with molecular weights from 23,500 to > 92,500 were detected in the host cytoplasm. At least three of these proteins were also present in the nucleus. The kinetics of processing of virus-specific proteins were examined by pulse-chase experiments in B5-infected cells. The relative intensities of ( super(35)S)-methionine-labeled polypeptides suggest that a number of smaller, stable chains (MW 23,500 to 38,000) are generated by cleavage of a precursor polypeptide (MW 92,500 to 100,000).