Serum IgG reactivity with 41-, 31-, and 28-kDa larval proteins of Strongyloides stercoralis in individuals with strongyloidiasis.

Proteins from a deoxycholate-soluble extract of Strongyloides stercoralis infective larvae were separated by SDS-PAGE, blotted onto nitrocellulose paper, and reacted with sera from individuals with confirmed S. stercoralis infections (n = 100), suspected S. stercoralis infections in whom no larvae could be detected (n = 27), and other nematode infections (40 with Wuchereria bancrofti, 20 with Onchocerca volvulus, 20 with Necator americanus, and 20 with mixed Ascaris lumbricoides and Trichuris trichiura infections). Immunodominant proteins of approximately 41, 31, and 28 kDa were recognized by IgG in 91%, 88%, and 90%, respectively, of sera from those with confirmed strongyloidiasis; in 100%, 100%, and 93% of sera from those with suspected strongyloidiasis; and in 9%, 12%, and 14% of sera from those infected with other nematodes. IgG reactivity to each of these proteins was a more specific means of immunodiagnosis than the currently used indirect ELISA; the methods were equally sensitive.