Antibodies to bacterial vaccines demonstrating specificity for human choriogonadotropin (hCG) and immunochemical detection of hCG-like factor in subcellular bacterial fractions.

Investigations were done to determine whether vaccines prepared with chemically killed Staphylococcus haemolyticus RU1 and Streptococcus bovis AV46 (bacteria that have been demonstrated to express human choriogonadotropin [hCG]-like material on their surface) elicited antibodies in rabbits with specificity for hCG determinants. In addition, the anatomical locus of the hCG-like factor was determined by separation of bacterial subcellular fractions. The results demonstrated that these bacterial vaccines elicited antibodies immunologically similar to those antibodies produced in response to the whole human trophoblastic hormone, a similarity extending even to cross-reactivity with human luteinizing hormone. The bacterial hCG-like material appeared to be localized in the membranes of the cell wall, and most was present in the soluble membranous and cytoplasmic constituents. Its expression in bacteria was a strain characteristic and not a species characteristic.