IDENTIFICATION OF ORTHOPOXVIRUSES BY POLYACRYLAMIDE-GEL ELECTROPHORESIS OF INTRACELLULAR POLYPEPTIDES .1. 4 MAJOR GROUPINGS

Orthopoxviruses were compared by means of their late intracellular polypeptides (ICPs). HeLa cells were labeled with [35S]methionine at 16 hr after infection and the ICPs were analysed by SDS-polyacrylamide gel electrophoresis and autoradiography. Time course and pulse-chase studies confirmed the significance of the differences observed. ICPs in three regions of the gels (MW 177,000, 96-103,000, and 15,500) permitted an initial grouping of the 24 viruses examined into four main groups (cowpox, monkeypox, vaccinia, and variola-related viruses). Only cowpox-like viruses had a prominent ICP of MW 177,000, and only monkeypox-like viruses had a heavily labeled ICP of MW 15,500. Viruses in these two groups appeared to have only a single ICP in the 96-103,000 region (MW, 98,000). By contrast, vaccinia-like viruses and variola-like viruses had two ICPs in this region but were distinguished because the ICPs of vaccinia were of higher molecular weight and were apparently reversed with repect to those of variola-like viruses. This was supported by the disappearance on chase of the lower MW vaccinia ICP and the higher MW variola ICP. The significance of these results and their use in the identification of orthopoxvirus isolates, particularly whitepox viruses, has been discussed. © 1979.