The pathomorphological patterns and the activity of serum interferon,
interleukin-1, tumor necrosis factor, natural killers, and proliferati
ve activity of lymphocytes were studied in BALB/c and C57B1/6 mice int
racerebrally infected with Machupo virus. The BALB/c mice showed 100 %
lethality at 8-9 days after inoculation while C57B1/6 mice were found
unsusceptible to Machupo virus inoculation by this route. The pathomo
rphological findings at the peak of clinical manifestations in BALB/c
mice revealed no organ whose functional deficiency could lead to the d
eath of the animals. Investigations of nonspecific immunity parameters
revealed a direct dependence between their high activity and suscepti
bility of the animals to Machupo virus infection. It is assumed that t
he endogenous shock due to the high activity of immune response mediat
ors is the cause of death in Machupo virus infection.