Immunoglobulin M antibodies are not specific for serodiagnosis of human toxocariasis

Abstract

Serodiagnosis of human toxocariasis is established by detecting serum anti-Toxocara IgG antibodies, but there is little knowledge regarding the reactivity of human IgM antibodies against the Toxocara antigens. In this study, we have evaluated the reactivity of IgM antibodies in sera from patients with toxocariasis, patients with other helminth infections, and healthy individuals, against Toxocara larval excretory-secretory (TES) antigens by enzyme-linked immunosorbent assay (ELISA) and Western blot (WB). Anti-Toxocara IgM were detected in 91.4% of sera from patients with toxocariasis, 76% of sera from patients with other helminth infections, and 45.3% of sera from healthy individuals when ELISA was used. Likewise, IgM antibodies were detected in 94.8% of sera from patients with toxocariasis, 65.3% of sera from patients with other helminth infections, and 41% of sera from healthy individuals when WB was used. This reactivity exhibited only a slight decrease when the TES antigens were deglycosylated, showing that not only glycosidic epitopes, but also peptide epitopes are involved in the recognition and binding of IgM antibodies during the immune response against the parasite. The results shown that IgM antibodies are not specific for serodiagnosis of human toxocariasis.

Human Toxocariasis: 2010 to 2020 Contributions from Brazilian Researchers

“…Roldán et al 71 showed that IgM antibodies used for the serodiagnosis of human toxocariasis showed low specificity, and Santos et al 72 found that Toxocara recombinant antigens developed with the use of the yeast Pichia pastoris instead of Escherichia coli showed low sensitivity for the immunodiagnosis of Toxocara infections. On the other hand, when Santos et al 73 previously used recombinant antigens of low molecular weight (30 kDa), they obtained better results, especially in surveys that included children.…”

“…In an attempt to improve the sensitivity and specificity of immunological tests for the diagnosis of human toxocariasis, several researchers sought to identify possible markers of infections and the immunodominant antigens of T. canis. 64,[66][67][68][69][70] Roldán et al 71 showed that IgM antibodies used for the serodiagnosis of human toxocariasis showed low specificity, and Santos et al 72 found that Toxocara recombinant antigens developed with the use of the yeast Pichia pastoris instead of Escherichia coli showed low sensitivity for the immunodiagnosis of Toxocara infections. On the other hand, when Santos et al 73 previously used recombinant antigens of low molecular weight (30 kDa), they obtained better results, especially in surveys that included children.…”

Toxocariasis in children with digestive system diseases

“…Serologic testing for antibodies against Toxocara is available . Only immunoglobulin G (IgG) is used because studies have shown that immunoglobulin M antibo dies are not specific for human toxocariasis [9]. While specific anti-Toxocara IgG antibodies against larvae excretory/secretory (E/S) antigens using enzyme immunoassay are widely used [1].…”