MUCOSAL IMMUNE-RESPONSES IN CALVES ORALLY VACCINATED WITH A LIVE AUXOTROPHIC AROA SALMONELLA-DUBLIN STRAIN

The mucosal immune responses were studied in two calves orally vaccina ted with the live aroA mutant strain, Salmonella dublin SL5631, and in two non-vaccinated control calves. Intestinal secretions were collect ed through a permanent fistula in place during a 5-week period. Vaccin ated calves responded with high IgM and IgA titres against the S. dubl in lipopolysaccharide. Both IgA and the IgM titres appeared already af ter 3 days and IgM somewhat earlier than the IgA titres. Both antibody titres remained high for 2 weeks after the third and final vaccine do se. The calves also showed marked T-cell responses in lymphocytes coll ected from mesenterial lymph nodes and the spleen.