• 1 June 1973
    • journal article
    • Vol. 54  (3) , 260-6
Abstract
A defence mechanism either differentially induced or resisted by a virulent (V13) or an avirulent (A7) strain of Semliki Forest virus, which might explain their different patterns of infection in mice, has not been detected in virus-free extracts of muscle, blood and spleen from mice infected with either strain. The extracts contained low levels of interferon which were probably unrelated to the different infection patterns. The pattern of infection of A7 in mice during the first few days was similar in normal and in x-irradiated mice and in the latter the brain infection did not resemble that for the fatal V13 infection in normal animals. A previous infection with A7 prevented replication of V13 in the brain to its usually high and fatal levels.