A comparison of two populations of defective, interfering pseudorabies virus particles

The characteristics of two independently evolving populations of defective, interfering particles of pseudorabies virus passaged at high multiplicity of infection have been studied. Defective particles in both populations interfere with the growth of standard virus and contain DNA with a molecular weight similar to, or slightly smaller than, that of standard pseudorabies viral DNA. The two populations of defective virions differ with respect to the degree of reiteration, as well as with respect to the G + C content of their DNA. Interference by defective particles with the growth of standard virus is not correlated with a change in buoyant density of the DNA of these particles. Despite the difference in the composition of the DNA molecules of the two populations of defective virions, they behave similarly. Production of viral particles is reduced in cells coinfected with standard virus and either one of the two populations of defectives, as compared to cells infected with standard virus alone. Maturation of concatemeric nascent forms of viral DNA to unit size molecules is also delayed.