Antibody-mediated protection of guinea-pigs against infection with Treponema pallidum.

The results of this study demonstrate that passive transfer of immune serum containing high titres of treponemal antibody into normal guinea-pigs significantly lowered the percentage of animals developing chancre-like lesions, but did not prevent the dissemination of organisms into the draining lymph nodes after these recipients were challenged with virulent treponemes. Similar levels of partial protection against cutaneous syphilitic infection occurred in guinea-pigs receiving partially purified anti-treponemal immunoglobulins, while immune serum depleted of IgG by treatment with Protein A was totally unprotective. Western blotting analysis revealed the presence of several Treponema pallidum polypeptides detectable by immune guinea-pig IgG. These findings provide direct evidence to suggest that syphilitic infection induces the formation of serum factors, residing primarily in the IgG fraction of immune serum, that are capable of providing a limited form of resistance to symptomatic disease.