Potential immunological markers for diagnosis and therapeutic assessment of toxocariasis

Abstract

SUMMARYIn human toxocariasis, there are few approaches using immunological markers for diagnosis and therapeutic assessment. An immunoblot (IB) assay using excretory-secretory Toxocara canis antigen was standardized for monitoring IgG, IgE and IgA antibodies in 27 children with toxocariasis (23 visceral, three mixed visceral and ocular, and one ocular form) for 22-116 months after chemotherapy. IB sensitivity was 100% for IgG antibodies to bands of molecular weight [29][30][31][32][33][34][35][36][37][38][48][49][50][51][52][53][54] >205 kDa,[48][49][50][51][52][53][54] > 205 kDa, and 65.4% for IgA to 29-38, 48-54, 81-93 kDa. Candidates for diagnostic markers should be IgG antibodies to bands of low molecular weight (29-38 and 48-54 kDa). One group of patients presented the same antibody reactivity to all bands throughout the follow-up study; in the other group, antibodies decayed partially or completely to some or all bands, but these changes were not correlated with time after chemotherapy. Candidates for monitoring patients after chemotherapy may be IgG antibodies to > 205 kDa fractions, IgA to 29-38, 48-54, 81-93 kDa and IgE to 95-121 kDa. Further identification of antigen epitopes related to these markers will allow the development of sensitive and specific immunoassays for the diagnosis and therapeutic assessment of toxocariasis.

Anti-Toxocara spp. antibodies in an adult healthy population: serosurvey and risk factors in Southeast Brazil

“…Viable larvae may persist in tissues and excrete/secrete antigens for several years, and no simple method is available to confirm parasite death even after chemotherapy. As a consequence, a single-sample IgG-ELISA titre cannot distinguish between past and current infections [28] . Another relevant question to our study is whether the infection was acquired in the household or occurred due to the type of work performed by the individuals.…”

Immunodiagnosis of Human Toxocariasis

“…IgG antibodies to >205 kDa fractions, IgA to 29-38, 48-54, 81-93 kDa and IgE to 95-121 kDa were suggested as candidates for monitoring the treatment. Further identification of antigen epitopes related to these markers will allow the development of sensitive and specific immunoassays for the diagnosis and therapeutic assessment of toxocariasis (Rubinsky-Elefant et al, 2011).…”

“…Nowadays, Immunoblot assay is useful to confirm any positive serum by the ELISA test (where pre-absorption is not carried out) in patients with suspected toxocariasis (Magnaval et al, 1991;Rubinsky-Elefant et al, 2011).…”

“…In order to give an idea of how to develop an immunoblot assay using TES antigens to detect specific IgG antibodies, we describe a protocol developed by , however, we recommend to revise in detail other procedures described by other authors (Magnaval et al, 1991;Nunes et al, 1997;Rubinsky-Elefant et al, 2011).…”

“…Many authors usually have used 10% or 12% resolving polyacrylamide gels (Magnaval et al, 1991;Elefant et al, 2006), but others prefer use gradient resolving gels, such as 5-15% (Nunes et al, 1997;Rubinsky-Elefant et al, 2011) or 4-16% ). The relative molecular weight (MW) of the TES antigens may be calculated by using the wide-range molecular weight markers that are commercially available.…”