This project deals with both the laboratory and clinical aspects of infection caused by the intestinal nematode, Strongyloides stercoralis. The laboratory research involves analysis and characterization of parasite antigens. The clinical studies focus upon the immune response of infected individuals, and factors that influence the immune response. For certain purposes experimental infections are carried out in the jird (Meriones unguiculaius). The diagnosis of chronic strongyloides infection is often difficult because excretion of larvae is scanty and intermittent. Therefore, an ELISA type of serologic test is useful in identifying individuals who harbor the parasite. But this serologic test is available only in specialized laboratories and availability of the antigen is limited. For these reasons, a cDNA library was prepared from infective (L3) larvae of the parasite, and several recombinant clones were identified by screening the library with immune serum of patients. Some of the clones, alone or in combination, can be used as diagnostic antigens in an ELISA test. Since some of the recombinant antigens are reactive with parasite-specific serum IgE, it may be possible to use them in an immediate hypersensitivity skin test. Several systems for expression of recombinant proteins, including yeast cells, are used. Brazilian patients with all combinations of infection with S. stercoralis and HTLV-1 retrovirus are studied to determine cytokine responses of peripheral blood mononuclear cells (PBMCs) to S.stercoralis antigen and mitogens. Blood samples are also obtained to check HTLV-1 and strongyloides serology, as well as serum IgE levels. PBMCs are also cultured and treated with special reagents so they can be fixed and frozen for analysis of intracellular cytokines.
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|Mitre, Edward; Thompson, Robert W; Carvalho, Edgar M et al. (2003) Majority of interferon-gamma-producing CD4+ cells in patients infected with human T cell lymphotrophic virus do not express tax protein. J Infect Dis 188:428-32|
|Ravi, Varatharajalu; Ramachandran, Srinivasan; Thompson, Robert W et al. (2002) Characterization of a recombinant immunodiagnostic antigen (NIE) from Strongyloides stercoralis L3-stage larvae. Mol Biochem Parasitol 125:73-81|
|Neva, F A; Gam, A A; Maxwell, C et al. (2001) Skin test antigens for immediate hypersensitivity prepared from infective larvae of Strongyloides stercoralis. Am J Trop Med Hyg 65:567-72|
|Carvalho, E M; Bacellar, O; Porto, A F et al. (2001) Cytokine profile and immunomodulation in asymptomatic human T-lymphotropic virus type 1-infected blood donors. J Acquir Immune Defic Syndr 27:1-6|
|Porto, A F; Oliveira Filho, J; Neva, F A et al. (2001) Influence of human T-cell lymphocytotropic virus type 1 infection on serologic and skin tests for strongyloidiasis. Am J Trop Med Hyg 65:610-3|
|Porto, A F; Neva, F A; Bittencourt, H et al. (2001) HTLV-1 decreases Th2 type of immune response in patients with strongyloidiasis. Parasite Immunol 23:503-7|