COINFECTION WITH A RHABDOVIRUS - VESICULAR STOMATITIS-VIRUS OF INDIANA AND NEW-JERSEY SEROTYPES

Abstract

Coinfection of hamster cells with vesicular stomatitis virus (VSV) of Indiana [In] and New Jersey [Nj] serotypes were performed. Thermosensitive mutants (ts) of VSV Indiana and the wild type strain (+) of New Jersey were used. Harvests and titrations were made at permissive (PT) and nonpermissive (NPT) temperatures. The harvest was mainly composed of one parental-like infectious particles. The dominance of 1 serotype over the other was a function of the relative multiplicity of the 2 viruses; the presence of a thermosensitive lesion imparts a disadvantage to the corresponding serotype. Non parental-like particles were also detected. As expected, these particles were detected only in 2 conditions. When harvest was performed at NPT and titrations allowed at PT, most of the infectious particles (i.e., twin particles) resistant to anti-Nj serum developed a plaque (i.e., mixed-plaque) containing virions of both serotypes: Indiana (ts) and New Jersey (+). After sonication or EDTA treatment of the harvest, prior to titrations, nor more mixed-plaques were formed. Examination of the harvest by EM showed that 7-17% of the particles formed aggregates; therefore, the twin-particles are apparently aggregates. When harvest was performed at PT and titrations allowed at NPT, 1% of the wild type infectious particles was resistant to anti-Nj serum even though it was of Nj genotype. It was inactivated by a mixture of anti-Nj and anti-In sera and therefore behaved as pseudotypes. But since twin particles, when plated at NPT, would give rise to an homogenous progeny from New Jersey (+), they could be confused with pseudotypes. Under those conditions there is no absolute evidence that phenotypic mixing really occurs between VSV of Indiana and New Jersey serotypes.