Early diagnosis of Schistosoma mansoni in mice using assays directed against cercarial antigens isolated by hydrophobic chromatography.
Two diagnostic assays are described for the early diagnosis of acute schistosomiasis, using a defined cercarial antigen preparation obtained by hydrophobic chromatography. Circulating IgM antibodies against this antigen fraction could be detected by ELISA as early as 1 wk after exposure in experimentally infected mice; IgM levels against other antigens and IgG levels against all the preparations examined were not significantly elevated until approximately 4-5 wk postinfection. Circulating antigen was detected as early as 3 days after exposure by a competitive inhibition ELISA using rabbit serum prepared against the cercarial antigen; antigen levels in the serum of mice with a 100-worm infection were found to exceed 100 ng/ml. Studies using sera from infected humans indicate that the assay can also recognize chronic S. mansoni, S. haematobium or S. japonicum infections. In a very limited field study, the specificity of the circulating antigen assay with regard to other helminthic infections was found to be 85%; sensitivity 100%. Preliminary characterization of the relevant antigen indicates that it is a relatively hydrophobic polypeptide with a molecular weight of approximately 41,000 daltons. The implications of these findings with regard to the treatment of travelers or the conduct of seroepidemiological studies in endemic areas are discussed.
D000818:Animals; D000947:Antigens, Helminth / Q000032:analysis* / Q000276:immunology / Q000302:isolation & purification; D002845:Chromatography; D004797:Enzyme-Linked Immunosorbent Assay; D005188:False Negative Reactions; D005189:False Positive Reactions; D006801:Humans; D007074:Immunoglobulin G / Q000032:analysis; D007075:Immunoglobulin M / Q000032:analysis*; D051379:Mice; D008970:Molecular Weight; D012550:Schistosoma mansoni / Q000276:immunology*; D012555:Schistosomiasis mansoni / Q000175:diagnosis* / Q000276:immunology
D000947:Antigens, Helminth; D007074:Immunoglobulin G; D007075:Immunoglobulin M