Phenotypic Mixing of Vesicular Stomatitis Virus with HVJ (Sendai Virus)

ABSTRACTVesicular stomatitis virus (VSV) plaque‐forming virions obtained from mixed infection of HeLa cells with VSV and HVJ (Sendai virus) were shown to contain two types of phenotypically mixed virions: virions doubly neutralizable with both anti‐VSV and anti‐HVJ antisera (up to 15%), and virions which could be neutralized only with anti‐HVJ serum and not with anti‐VSV serum (up to 0.3%). No evidence for genetic recombination was obtained between these two viruses. Phenotypically mixed virions could adsorb to and elute from chiken erythrocytes, and bullet‐shaped virions, typical of VSV, were found to be adsorbed to chicken erythrocytes in electron microscopy. Neuraminidase activity was detected in the virions specifically sedimented with anti‐VSV serum. From these findings, phenotypically mixed virions were suggested to contain hemagglutinin and neuraminidase of HVJ in the envelope. In sucrose gradient centrifugation, phenotypically mixed virions enclosed within HVJ antigens sedimented slightly faster than standard HVJ.