Cobra venom factor abrogates passive humoral resistance to syphilitic infection in hamsters.

Cobra venom factor, an agent commonly used to deplete complement, lowered the resistance of hamsters to infection with Treponema pallidum subsp. endemicum , as shown by a more rapid development of cutaneous lesions in infected animals treated with cobra venom factor than in infected, untreated animals. Cobra venom factor also abrogated the passive transfer of resistance by injection of serum from syphilitic immune hamsters. These results indicate that complement influences the pathogenesis of treponemal infection.