Lack of a significant systemic immune response in pigs experimentally infected with Serpulina piwsicou

摘要

Porcine intestinal spirochaetosis (PIS) is a diarrhoeal disease resulting from colonisation by the spirochaete Serpulina pilosicoli. Little is known about immunity in this infection. Individual animals may be colonised for extended periods of time,and the disease in infected piggeries appears to occur sporadically Pig infected with PIS suffer from decreased growth rates, poor feed conversion, and weight loss. This experiment was conducted fo determine whether infected pigs developed circulating antibodies to the spirochaete, and to evaluate the effect of vaccination. Two groups of weaner pigs were used. Six pigs were vaccinated intramuscularly, twice at a three week interval, with a bacterin containing 10~(10) cells of S. pilosicoli strain 95/1000, inactivated in formalin, and emulsified in Freund's incomplete adjuvant. The other group of eight pigs were not vaccinated. All pigs were challenged orally on three successive days with broth cultures of S. pilosicoli strain 95/1000 (10~(10) cells/day), ten days after the second vaccination. The clinical condition of the pigs was monitored daily, and colonisation was determined by faecal culture and histological analysis at post-mortem 2-3 weeks post-infection.