SPECIFIC ANTIBODY TO HAEMOPHILUS-SOMNUS IN THE BOVINE UTERUS FOLLOWING INTRAMUSCULAR IMMUNIZATION

Sources of anti-Haemophilus somnus antibody in bovine uterine secretio ns following intramuscular immunization and subsequent intrauterine in oculation of killed H. somnus were investigated. Holstein cattle (n = 21) were immunized with a 270-kDa outer membrane protein from H. somnu s (omp-270) by intramuscular injection. At estrus, the cattle were giv en an intrauterine inoculum of a heat-killed suspension of a homologou s strain of H. somnus containing omp-270 (n = 7), a heterologous strai n of H. somnus lacking omp-270 (n = 7), or phosphate-buffered saline ( n = 7). Uterine secretions were sampled by saline lavage immediately p rior to inoculation and at 6, 24, 48, 72, 96, and 120 h after inoculat ion. Immunoglobulin G subclass 1 (IgG1) and IgG2 antibody specific for omp-270 were detectable in estrous uterine secretions of all systemic ally immunized cattle from which an adequate sample was obtained. IgM antibody specific for omp-270 was detected in serum following immuniza tion but was not consistently detected in the uterine secretions of an y animal. IgA antibody specific for omp-270 was not detectable in eith er serum or uterine secretions following immunization or intrauterine inoculation. Ratios of antibody to immunoglobulin and ratios of immuno globulin to albumin in serum and uterine secretions indicated that abo ut half the IgG1 and essentially all the IgG2 in secretions originated in the serum. Relative titers of IgG1 and IgG2 omp-270-specific antib odies in the uterine lumen and serum gave no evidence for selective tr ansport of either subclass from serum into local secretions. Neither h eterologous nor homologous intrauterine inocula detectably altered the serum contribution to antibody in uterine secretions within the sampl ing period. On the basis of these results, development of a systemic I gG2 antibody response may provide the basis for local immunological pr otection in the bovine reproductive tract.