Published online by Cambridge University Press: 18 November 2009
It was possible to make a more critical study of immunity against A. suum by infecting pathogen-free, colostrum-deprived pigs produced by hysterectomy.
By means of the conglutinating complement absorption test, using a saline extract of worm as antigen, antibodies were first demonstrated in the circulation of three experimentally-infected pigs between the 10th and 13th days of infection, and were detected in the sera of two of them for at least 97 days.
The infections did not become patent, and no acquired immunity was shown by the pigs against a reinfection 97 days later. There was no evidence of an age immunity against migrant larvae.
A rise in serum antibody was observed, within seven days of infection, in six pigs aged between 10 weeks and 11 months, following a test dose of 500,000 eggs. Three suckling pigs, aged three weeks, did not respond serologically within seven days to the same test dose.