Immunity to Trichinella spiralis transferred by serum from vaccinated mice not protected by immunization

Serum antibody responses to infection with the intestinal helminth Trichinella spiralis in mice remain at low levels for the first ten to 12 days, slowly increasing to high titres around day 20. It is thought that antibody, therefore, has a limited role in the primary immune response raised against this infection and this is confirmed by the inability of primary infection serum to transfer immunity adoptively. High-responder NIH and low-responder B10 mice were vaccinated with T.spiralis antigen in Freund's complete adjuvant prior to challenge. This procedure conferred significant protection on NIH mice but not B10. Sera from these mice were transferred into recipients before and during challenge infection. Significant levels of protection were obtained in both strains with both homologous and heterologous sera, even though vaccination itself had not resulted in protection of the B10 donor mice. These data indicate that the B10 strain is potentially capable of making a protective immune response against the intestinal phase of T.spiralis.