Natural IgM antibodies in sera from various animals but not the cat kill Toxoplasma gondii by activating the classical complement pathway.
Sera from swine, rabbit, and dog, that had never been exposed to Toxoplasma gondii, demonstrated significant killing of T. gondii tachyzoites in vitro, while cat serum did not. Swine and rabbit sera contained natural IgM antibody against the tachyzoites, and the classical complement pathway was activated by the binding of natural IgM antibody to the tachyzoites, leading to lysis. Anti-T. gondii antibodies, induced in swine or cat infected with T. gondii, had no killing effect by themselves but killed the tachyzoites in the presence of swine complement. However, the anti-T. gondii antibodies of swine or cat demonstrated a very low killing effect in the presence of cat complement. This suggests that T. gondii tachyzoites have an evasion mechanism to prevent lysis which is specific for cat complement.
Kaneko
Y
Y
Department of Global Agricultural Sciences, Graduate School of Agricultural and Life Sciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
Takashima
Y
Y
Xuaun
X
X
Igarashi
I
I
Nagasawa
H
H
Mikami
T
T
Otsuka
H
H
D000818:Animals; D000913:Antibodies, Protozoan / Q000276:immunology; D001770:Blood Bactericidal Activity / Q000276:immunology; D002415:Cats / Q000276:immunology* / Q000469:parasitology; D002614:Chelating Agents / Q000494:pharmacology; D015922:Complement C1q / Q000276:immunology; D003171:Complement Pathway, Classical / Q000276:immunology; D004285:Dogs / Q000276:immunology* / Q000469:parasitology; D004533:Egtazic Acid / Q000494:pharmacology; D007075:Immunoglobulin M / Q000276:immunology*; D009500:Neutralization Tests / Q000662:veterinary; D011817:Rabbits / Q000276:immunology* / Q000469:parasitology; D013047:Specific Pathogen-Free Organisms; D013552:Swine / Q000276:immunology* / Q000469:parasitology; D014122:Toxoplasma / Q000254:growth & development / Q000276:immunology*; D014124:Toxoplasmosis, Animal / Q000276:immunology*
D000913:Antibodies, Protozoan; D002614:Chelating Agents; D007075:Immunoglobulin M; D004533:Egtazic Acid; D015922:Complement C1q