Role of the immune response in recovery from Sindbis virus encephalitis in mice

The role of the immune response in recovery from acute encephalitis was studied by using a neuroadapted strain of Sindbis virus. Intracerebral inoculation of this virus caused fatal disease in weanling mice. Passive transfer of homologous immune serum protected mice, but transfer of immune spleen cells and lymph node cells failed to alter mortality. Transfers were made 24 hr after intracerebral infection of the recipient, when central nervous system infection was established. The protective factor in serum was present 7 days after donor infection, was specific for Sindbis virus, and appeared to be IgG; however, the protection did not correlate with virus-neutralizing activity.