The effect of adjuvant and specific or non-specific vaccination on development of protective immunity of rabbits against Trichostrongylus colubriformis infection.

Adult New Zealand rabbits were vaccinated subcutaneously with one dose of 100 micrograms adult nematode phosphate buffered saline-soluble proteins (PBS-ASP, groups I and II), a detergent-soluble fraction of adult somatic proteins (DS-ASP, group III) or three doses of 1 mg normal rabbit serum proteins (group IV). Injections of the immunogens in groups II, III and IV were accompanied with beryllium hydroxide, Be(OH)2 as an adjuvant. Vaccinated rabbits and also those of group V (naive) were challenged orally with 10,000 infective larvae of T. colubriformis 14 days after antigen injection and necropsied 2 weeks later. A single dose of PBS-ASP induced 33.5% protection when the antigen was given alone (group I) and 69.4% when injected with Be(OH)2 (group II). A detergent-soluble fraction of ASP given with the adjuvant provided 87.2% protection (group III), whilst non-specific vaccination with serum proteins plus Be(OH)2 elicited 99% protection (group IV). Mesenteric lymph node leukocyte responses were measured using a leukocyte migration inhibition assay. A significant response was observed only in group IV. In ELISA tests IgA antibodies specific to PBS-ASP reached the highest level in the intestinal mucosa of groups I and II and in the bile of groups I and III. Antibody levels of IgG isotype were similar in the intestinal mucosa of all the immunized groups. Nematode antigen was detected using a 'sandwich' ELISA method in faecal protein extracts of rabbits of groups II and III on days 2-6 after challenge.

Influence of adjuvants on immunity in rabbits vaccinated with infective larval somatic proteins of Trichostrongylus colubriformis.

Adult New Zealand rabbits were vaccinated at 2-week intervals with three doses of 100 micrograms of infective larval somatic proteins (L3SP) administered subcutaneously with Freund's complete adjuvant (FCA) or beryllium hydroxide and then challenged orally with 10,000 L3. Groups of rabbits immunized orally with three doses of 5000 or 2000 L3 served as vaccination controls. Intestinal worm burdens on Day 21 after challenge revealed that beryllium hydroxide effectively potentiates the protective immunogenicity of L3SP. The level of protection obtained using the beryllium adjuvant (94.8%) was nearly as high as that in rabbits immunized with three doses of 5000 L3 (99.8%). Rabbits vaccinated using FCA showed very poor immunity (29.5%). Local and systemic antibody levels detected by radioimmunoprecipitation tests using 125I-L3SP showed very little correlation with the degree of protection. The beryllium hydroxide-treated group demonstrated significantly higher bile IgA antibody levels than other experimental rabbits. FCA-treated rabbits developed a much higher serum precipitating antibody response, detectable using gel double diffusion tests, than the beryllium group. Also, mucosal IgA antibody levels detected on Day 21 after challenge were significantly higher in the FCA group than in other groups.

Surface antigens of Obeliscoides cuniculi inducing local and systemic humoral responses in infected rabbits.

125I-radiolabelled surface proteins of various developmental stages of Obeliscoides cuniculi were used to analyze serum and gastrointestinal immunoglobulin responses of the host to primary infection with 10,000 larvae of the nematode, using a radioimmunoprecipitation method. Serum IgM, IgA, and IgG antibodies reacted mostly with infective larval and adult nematodal surface proteins. The highest binding activity was shown by IgG against the surface of infective larvae on days 56 and 86 after infection. Local (gastric mucosal) antibodies were also predominantly directed against surface antigens of infective larvae and adults, although considerable binding of the fourth-stage larval surface proteins by gastric mucosal IgG occurred 35 days after infection. Physicochemical analysis of the radiolabelled surface antigens revealed that the strongest antigenicity was found in proteins with molecular weights of 40,000 and 145,000. Nonspecific binding demonstrated in our tests by infective larval surface proteins was associated with particles with a molecular weight of 550,000.

Inhibition phenomena mechanisms in experimental obeliscoidosis in rabbits. II. Local and systemic antibody responses.

A series of experiments was carried out using adult outbred Polish race rabbits of both sexes infected, during spring or autumn, with 10,000 larvae of Obeliscoides cuniculi, either fresh or stored at 4 degrees C. Extracts of mucosal proteins and bile were collected at postmortem 6 or 12 weeks after infection. Antibody levels were determined in antisera, bile and stomach mucosa by haemagglutination and precipitation tests. Local antibody responses were demonstrated in the stomach and bile, and reactions were obtained with the tissue fluids by haemagglutination and precipitation tests with worm antigens and ES products. Additionally, some specific immunological response was observed in the circulation during the primary infection. These results suggest a clear-cut relationship between increased levels of these antibodies and either larval inhibition or worm expulsion during O. cuniculi infections.

Enteral and parenteral responses in mice after primary infection with Trichinella spiralis (Nematoda).

Enteral and enteral-parenteral infections were produced with T. spiralis in albino, Swiss Webster, outbred mice. Primary enteral infections abbreviated with thiabendazole stimulated inflammatory changes in Peyer's patches and the lamina propria of the small intestine of mice. These changes were accompanied by increased IgA in the intestinal luminal wash. Primary enteral-parenteral infections similarly stimulated the gut, and, in addition, the spleen. Splenic stimulation resulted in production of IgG1, and IgG2 antibodies specific for T. spiralis L3.