Enhancement of Rubella Virus Replication in Swine Testicle Cells by Co-Infection with Hog Cholera Virus

Abstract

Rubella virus readily replicated in primary culture of swine testicle cells. Cells cultured 1 or more days when infected with the virus supported better viral growth with higher peak titer than those infected at the time of cell seeding. In these cell cultures rubella virus replication was enhanced significantly by co-infection with hog cholera virus given either simultaneously with or a few days before or after rubella virus. Culture fluids always showed higher infectivity titers than cells. Production of rubella virus hemagglutinin was also markedly enhanced. Identification of the viruses grown in double infected cells was confirmed by the neutralization and hemagglutination inhibition tests. Rubella virus strains induced little or weak cytopathic effect in cells uninfected with hog cholera virus, but some strains induced marked cytopathic effect in hog cholera infected cells. Unlike rubella virus, replication of hog cholera virus was little affected by rubella virus.