Detection of immunoglobulin M antibodies to P35 antigen of Toxoplasma gondii for serodiagnosis of recently acquired infection in pregnant women.
We examined the efficiency of detection of immunoglobulin M (IgM) antibodies to a 35-kDa antigen (P35) of Toxoplasma gondii for serodiagnosis of acute infection in pregnant women. A double-sandwich enzyme-linked immunosorbent assay (ELISA) with recombinant P35 antigen (P35-IgM-ELISA) was used for this purpose. On the basis of the clinical history and the combination of results from the toxoplasma serological profile (Sabin-Feldman dye test, conventional IgM and IgA ELISAs, and the differential agglutination test), the patients were classified into three groups: group I, status suggestive of recently acquired infection; group II, status suggestive of infection acquired in the distant past; group III, status suggestive of persisting IgM antibodies. Eighteen (90.0%) of 20 serum samples from group I patients were positive by the P35-IgM-ELISA, whereas none of the 33 serum samples from group II patients were positive. Only 4 (25.0%) of 16 serum samples from group III patients were positive by the P35-IgM-ELISA, whereas all these serum samples were positive by the conventional IgM ELISA. These results indicate that demonstration of IgM antibodies against P35 by the P35-IgM-ELISA is more specific for the acute stage of the infection than demonstration of IgM antibodies by the ELISA that uses a whole-lysate antigen preparation. Studies with sera obtained from four pregnant women who seroconverted (IgG and IgM antibodies) during pregnancy revealed that two of them became negative by the P35-IgM-ELISA between 4 and 6 months after seroconversion, whereas the conventional IgM ELISA titers remained highly positive. The P35-IgM-ELISA appears to be useful for differentiating recently acquired infection from those acquired in the distant past in pregnant women.
Suzuki
Y
Y
Department of Immunology and Infectious Diseases, Research Institute, Palo Alto Medical Foundation, Palo Alto, California 94301, USA. ysuzuki@leland.stanford.edu
Ramirez
R
R
Press
C
C
Li
S
S
Parmley
S
S
Thulliez
P
P
Remington
J S
JS
D000208:Acute Disease; D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood*; D000953:Antigens, Protozoan / Q000235:genetics / Q000276:immunology*; D002908:Chronic Disease; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005260:Female; D006801:Humans; D007075:Immunoglobulin M / Q000097:blood*; D011247:Pregnancy; D015597:Pregnancy Complications, Parasitic / Q000175:diagnosis* / Q000469:parasitology; D011994:Recombinant Proteins / Q000235:genetics / Q000276:immunology; D012698:Serologic Tests; D014122:Toxoplasma / Q000276:immunology*; D014123:Toxoplasmosis / Q000175:diagnosis* / Q000469:parasitology
D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan; D007075:Immunoglobulin M; D011994:Recombinant Proteins