Partially purified leaf extracts of Melia azedarach L. inhibit tacaribe virus growth in neonatal mice

Neonatal mice, inoculated intraperitoneally with 103 PFU of Tacaribe virus, died after developing a typical encephalitis. The administration of partially purified extracts of Melia azedarach L. (Ma) fresh green leaves, in seven doses by the same route, reduced virus spread which normally involves the kidneys, liver and brain. Mortality fell to 50% in treated mice and viral titres in brain were at least 3 logs lower than those of untreated mice. Surviving mice mounted a humoral immune response. High levels of neutralizing antibodies were present up to 60 days post‐infection when the animals were killed. Ma administration exerts a marked decrease in circulating interferon levels of infected mice. Thus, at day 6 post‐infection the amount of acid resistant interferon in treated animals was eight times lower than in those untreated.