Resistance against migrating Ascaris suum larvae in pigs immunized with infective eggs or adult worm antigens

Resistance to Ascal is suum infections was investigated in 8- and 15-week-o ld Iberian pigs. Groups of 3 or 5 pigs were immunized weekly for 6 weeks wi th antigens of adult A. suum: a 97 kDa body wall (BW) fraction, a 42 kDa fr action of pseudocoelomic fluid (PF) or a 14 kDa PF-fraction; or were inocul ated with increasing doses of infective eggs (500-20 000), with or without abbreviation by pyrantel pamoate. All immunized pigs and unimmunized contro l pigs, were challenged with 10 000 infective eggs 7 days after the last im munization. The number of liver lesions and lung larvae was substantially l ower in the older pigs than in the younger ones 7 days after challenge, but the resistance in immunized pigs of both age groups was similar in compari son to the challenge controls of the same age. The highest degree of resist ance against lung larvae was observed in pigs immunized with A. suum eggs ( 97-99%). The pigs immunized with the 11 kDa and 42 kDa PF-fractions were al so well protected (67-93%), while no protection was produced by the 97 kDa BW fraction (0-49 %,). The reduction of white spots following immunization was less evident, with a maximum of 82%, reduction in egg-inoculated young pigs.