Correlation between gut hypersensitivity and resistance to Trichostrongylus colubriformis infection of outbred and inbred lines of guinea pigs.

The relationship between gut sensitivity and immunity to challenge infection was examined in outbred and inbred guinea pig lines. Primary infections terminated at 3,6,9 or 13 days and multiple infections of 3 days' duration confirmed the importance of direct gut stimulation and the period of exposure in the induction of immunity and gut hypersensitivity. The studies with the multiple 3-day infections confirmed that the third-stage larvae alone are capable of inducing strong protective immunity and showed that this is accompanied by pronounced gut sensitivity to parasite extracts and secretions. Finally, two inbred guinea pig lines selected for enhanced resistance or susceptibility to T. colubriformis infection displayed corresponding high or low capacities to mount hypersensitivity reactions following a single truncated 3-day primary infection.