Simian hemorrhagic fever (SHF) virus is an unclassified togavirus which resembles most closely the flaviviruses in its mode of replication. Four strains of SHF virus have been identified. Two of the strains produce persistent infections in patas monkeys and the others, acute infections. All strains produce acute infections of monkeys of the genus Macaca which are nearly always fatal. Although SHF virus and flaviruses have many structural and morphogenetic similarities, they also differ considerably. By use of sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), we have obtained data which indicate that SHF virions contain five polypeptides. Flaviviruses have been reported to contain only three. Furhermore, by use of enzyme-linked immunosorbent assay (ELISA) we have found no antigenic relationship of SHF virus to flaviviruses, nor to members of the other currently recognized togavirus genera and to lactic dehydrogenase virus, a togavirus unclassified to genus.
