Neuropeptide-induced hypothermia and the course of central nervous system disease mediated by temperature-sensitive mutants of vesicular stomatitis virus.

Mice inoculated with many temperature-sensitive (ts) vesicular stomatitis virus (VSV) mutants incur a less aggressive disease than mice infected with wild-type VSV. The normal body temperature of mice, 38 degrees C, is not a permissive temperature for replication of the temperature-sensitive VSV mutants in cell culture. To determine whether the body temperature of mice caused the alteration in disease states, a neuropeptide that induces hypothermia in rodents was injected into mice before their infection with a temperature-sensitive VSV mutant. Only 1.0 ng of the neuropeptide neurotensin, injected intracerebroventricularly, was required to lower the core temperatures of mice an average of 2.5 degrees C. A single injection of neurotensin before infection with tsG31 VSV (complementation group III) dramatically altered the course of disease. Without neurotensin only 3% of the mice infected with tsG31 VSV died, but when neurotensin was administered 24 h before the inoculation of the tsG31 VSV, 80% of the mice died. The course of disease in mice produced by infection with another temperature-sensitive VSV mutant, tsG11 VSV (complementation group I), also was altered when neurotensin was injected before inoculation of the virus. Instead of 3% of the mice dying as in a normal infection with tsG11 VSV, treatment with neurotensin before inoculation produced a rapidly fatal disease, killing 90% of the mice.