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Isolation and characterization of expression cDNA clones encoding antigens of Onchocerca volvulus infective larvae
T R Unnasch1, M Y Gallin, P T Soboslay
1Department of Medicine, Case Western Reserve University, Cleveland, Ohio 44106.
Abstract:
The isolation of recombinant cDNA clones expressing antigens found in Onchocerca volvulus infective larvae is described. To isolate such clones, an expression cDNA library constructed from adult O. volvulus RNA was screened with antiserum raised against infective larvae. One clone, designated lambda RAL-1 was characterized further. The recombinant antigen produced by lambda RAL-1 stimulates proliferation of peripheral blood mononuclear cells from O. volvulus infected humans. Lambda RAL-1 is derived from a 1450 bases message that encodes a protein with an apparent molecular weight of 42,000 in adult O. volvulus. The inserted DNA of lambda RAL-1 contains an open reading frame of 1008 bp. The amino acid sequence predicted by this open reading frame contains three repeats of the sequence KKPEDWD. The identification of clones such as lambda RAL-1 will provide quantities of purified antigens sufficient to begin to study the immune response to and explore the development of immunity against the infectious form of the parasite.
Insights
Researchers isolated a recombinant cDNA clone, lambda RAL-1, expressing Onchocerca volvulus antigens. This clone
Area of Science:
- Parasitology
- Molecular Biology
- Immunology
Background:
- Onchocerca volvulus is a parasitic nematode causing onchocerciasis.
- Identifying antigens of infective larvae is crucial for understanding immunity.
Purpose of the Study:
- To isolate and characterize recombinant cDNA clones expressing Onchocerca volvulus antigens.
- To assess the immunogenicity of the expressed antigens.
Main Methods:
- Construction of a cDNA expression library from adult O. volvulus RNA.
- Screening the library using antiserum against infective larvae.
- Characterization of the positive clone lambda RAL-1.
Main Results:
- Isolation of lambda RAL-1, expressing a recombinant antigen.
- The antigen stimulated peripheral blood mononuclear cell proliferation in infected individuals.
- The clone is derived from a 1450-base message encoding a 42,000 MW protein.
Conclusions:
- Lambda RAL-1 expresses an immunogenic antigen from O. volvulus infective larvae.
- This provides a source of purified antigens for studying immune responses.
- Facilitates research into immunity against the parasite's infectious stage.
