Comparison of central nervous system disease produced by wild-type and temperature-sensitive mutants of vesicular stomatitis virus

The pathogenicity of infection produced following intracerebral (i.c.) inoculation of wild-type vesicular stomatitis virus (VSV) or temperature-sensitive (ts) mutants of VSV was compared. ts mutants used were ts 31 (VSV complementation group II) and ts 41 (VSV complementation group IV). The i.c. injection of wild-type VSV in weanling Swiss mice produced a rapidly fatal encephalitis with death of mice in 2 to 3 days. Histopathologically, such mice exhibited minimal changes of encephalitis on light microscopy. In contrast to the highly virulent, rapidly fatal central nervous system (CNS) infection seen after i.c. inoculation of wild-type VSV, infection with ts 31 VSV produced a more slowly progressive CNS infection characterized by hind limb paralysis and death 6 to 9 days after infection. Histopathologically, CNS infection with ts 31 is associated with previously unreported extensive spongiform changes in the gray matter of the spinal cord. The inoculation of ts 41 i.c., on the other hand, did not result in either clinical illness or histopathological changes in the spinal cords or brains of infected mice. The absence of clinical and histopathological lesions following i.c. infection of ts 41 VSV suggests that the capacity to alter the pathogenesis of VSV CNS infection may be a function of only certain ts mutants of VSV.