Cryo-Microtome sections of coproculture larvae of Strongyloides stercoralis and Strongyloides ratti as antigen sources for the immunodiagnosis of human strongyloidiasis

Abstract

Cryo-microtome sections of larvae of Strongyloides stercoralis and S. ratti respectively obtained from human and rat feces cultures, were used as antigens. Fluoresceinate conjugates against human IgG were employed at the ideal titer of 10 for S. stercoralis and 100 for S. ratti. The sensitivity of the indirect immunofluorescence reaction (IIF) was 94.4% and 92.5% and the specificity 94.2% and 97.1% for the two specific larval antigens, respectively. Sera from 123 persons (54 from carriers of S. stercoralis infections and 69 from controls) were submitted to the reaction. The titers of different sera varied from 20 to 2560. There was a significant linear correlation (r = 0.85 p < or = 0.001) between the antibodies from the two species of larval antigens. We conclude that both antigens may be used in the IIF reaction for the diagnosis of human strongyloidiasis. Due to the feasibility of safe and low-cost mass production of S. ratti larvae in the laboratory with a considerable economy of conjugate, their utilization in the serum diagnosis of human strongyloidiasis is recommended.

Strongyloides venezuelensis alkaline extract for the diagnosis of human strongyloidiasis by enzyme-linked immunosorbent assay

“…Complementary tests for the diagnosis and the monitoring of the immune response in this parasitosis have been developed. However, the major limitation for the standardization of immunological methods is the difficulty in obtaining large amount of S. stercoralis larvae (Sato et al 1995, Costa-Cruz et al 1997.The aim of this study was to diagnose human strongyloidiasis by enzyme-linked immunosorbent assay (ELISA) using alkaline extract of S. venezuelensis filariform larvae. The study received approval from the Ethical Committee of the Federal University of Uberlândia.…”

“…Complementary tests for the diagnosis and the monitoring of the immune response in this parasitosis have been developed. However, the major limitation for the standardization of immunological methods is the difficulty in obtaining large amount of S. stercoralis larvae (Sato et al 1995, Costa-Cruz et al 1997.…”

Strongyloides ratti antigenic components recognized by IgE antibodies in immunoblotting as an additional tool for improving the immunodiagnosis in human strongyloidiasis

“…However, one of the most important limitations for immunodiagnosis in strongyloidiasis is the difficulty for obtaining S. stercoralis filariform larvae. Thus, studies have been conduced using heterologous antigen of filariform larvae from Strongyloides ratti and Strongyloides venezuelensis in the development of serological methods (Grove & Blair 1981, Costa-Cruz et al 1997, Machado et al 2001. The aim of this study was to evaluate IgE antibody response in human strongyloidiasis by immunoblotting using S. ratti saline extract as heterologous antigen and to compare it with ELISA-IgE results.…”

Heterologous antigen extract in ELISA for the detection of human IgE anti-Strongyloides stercoralis

“…The majority of the cases are underdiagnosed due to the lack of defined symptoms, thus contributing for the infection dissemination, particularly in tropical and subtropical countries 9 . The difficult mass production of S. stercoralis larvae, with the involved risk of infectivity for laboratory technicians, can be avoided because of the feasibility of safe and easy mass production of S. ratti larvae, an adequate substitute antigen, as proven in our previous studies using indirect immunofluorescence reaction 7 .…”

“…As Strongyloides ratti is readily maintained in laboratory rats it may represent a practical source of antigen. Immunological tests using S. stercoralis and S. ratti third-stage filariform larvae have shown comparable results 7,14,27 .…”