Pathogenicity of Sendai virus in mice cage-mated with infectors and their offsprings.

Abstract

Sendai virus was first isolated from the tracheas and lungs of mice 1 to 2 days after cage-mating with infetctors, following by formation of lung consolidation in all mice examined 6 to 7 days. HI antibody was demonstrated in all mice 7 to 10 days, increasing in titers to 14 days. Isolation of the virus was negative from 12 days till 30 weeks when the experiments were terminated, except for some mice sacrificed 9 weeks which harbored the virus in their tracheas. HI antibody remained at high titers till the end of experiment and lung lesions persisted in more than a half of mice examined, although the affected area was localized around bronchioles in late stage of the infection. These findings were almost the same in both ddY and ICR strains of mice used, but a high mortality as 26.2 per cent was shown in ICR mice, being significantly different from 3.6 per cent in ddY mice. In offsprings from infected dams, maternal HI antibody of high titer was demonstrated at weaning, then it rapidly decreased to the lowest titer 7 to 14 weeks of age when the virus was isolated from the respiratory tracts of a few individuals. Thereafter the antibody titers increased again and isolation of the virus became negative. Detection rates of lung lesions were remarkably low in coraparison with those of their dams and neither death nor such clinical signs as ruffled fur and emaciation appeared.