To identify Trichinella
antigens suitable for high-specificity and high-sensitivity serodiagnosis of
human trichinellosis, we evaluated assays using four
antigens: (i) crude first-stage larval extract (CLE), (ii) O-deglycosylated CLE, (iii)
tyvelose-bearing
antigens (Trichinella spiralis larva group 1 [TSL-1]
antigens) purified by US4 affinity chromatography and coupled directly to
enzyme-linked
immunosorbent assay (ELISA) plates (pTSL-1 antigens), and (iv) TSL-1
antigens immobilized on ELISA plates with the
monoclonal antibody (MAb) US4 (cTSL-1 antigens). Assays using these
antigens were compared by analysis of sera from healthy individuals (n = 224) (group 1), individuals with noninfectious intestinal pathologies (n = 114) (group 2), individuals with other
parasitic infections (n = 107) (group 3), and individuals with confirmed
trichinellosis (n = 42) (group 4). Our results indicate that capture ELISA using cTSL-1
antigens is the most effective method for serodiagnosis of
human trichinellosis; this was the only method showing 100% specificity and 100% sensitivity at the patent stage of the
infection, and it was also the most sensitive for sera obtained prior to patency in indirect immunofluorescence (IIF). Indirect ELISA with pTSL-1
antigens was also 100% specific but was slightly less sensitive, particularly with sera obtained before IIF patency. Inhibition ELISA with MAb US4 indicated (i) that in Trichinella-infected patients the immune response to TSL-1
antigens is directed mostly against
tyvelose-containing
epitopes (mean of 84.2% of total anti-TSL-1
immunoglobulin G1 [
IgG1] antibody response [range, 51.3 to 97.6%]) and (ii) that in most individuals a large proportion of anti-CLE
IgG1 antibodies (mean, 49.5%; range, 7.3 to 92.6%) are directed against
tyvelose epitopes.