Caractères biologiques de souches du virus de l'influenza adaptées à 29 °C et à 41 °C

Abstract

Two mouse-adapted influenza virus strains were adapted to growth at 29 °C by a gradual lowering of the temperature of incubation in embryonated eggs. The growth of these two cold variants was completely inhibited at 41 °C. The cold and hot variants showed no significant difference in rise in the infectious titer in the mouse lung but a marked reduction in mortality and pathological response was observed with the cold variants, while good antibody response was stimulated in both cases. The cold variants were better interferon inducers in chick embryo. However, neither cold nor hot variants induced more than detectable amounts of interferon in blood, spleen, or lungs of infected mice. These cold variants possess many characteristics suitable for an effective live virus vaccine.