Secretory IgA responses in rats to antigens of various developmental stages ofNippostrongylus brasiliensis

Abstract

SummaryIntestinal and faecal IgA responses against different developmental stages ofNippostrongylus brasiliensiswere studied in Hooded Lister rats vaccinated subcutaneously with infective larvae or intragastrically with 4th-stage larvae, adult nematodes, adult worm somatic and metabolic antigens. It was found that intragastric administration of L4or adult worms produced as high resistance to challenge as normal infection. Oral vaccination with adult nematode excretory–secretory (ES) and somatic antigens produced 69 and 17% protection respectively. All vaccination regimes induced a considerable IgA response against somatic and metabolic antigens of the intestinal stages. However, no correlation could be seen between the IgA levels and degree of protection. Analysis of intestinal mucosal, intestinal contents and faecal IgA specific to larval or adult antigens suggests that the IgA is probably induced by antigen(s) common to all intestinal stages. Also secretory IgA responses against surface antigens of intestinal L4did not show stage specificity, although this was detected in sera.