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Construction of Onchocerca volvulus cDNA libraries and partial characterization of the cDNA for a major antigen
J E Donelson1, B O Duke, D Moser
1Department of Biochemistry, University of Iowa, Iowa City 52242.
Abstract:
Adult Onchocerca volvulus were isolated from nodules removed from onchocerciasis patients at four locations--two in the West African Sudan-savanna region (near Bamako, Mali, and Touboro, Cameroon), one in a West African forest region (Kumba, Cameroon) and one near Guatemala City, Guatemala. Four different cDNA expression libraries were constructed in bacteriophage lambda gt11 using poly(A)+ RNA from the adult female worms. Individual cDNA clones of single copy genes were used to compare the genomes of parasites from the different locales and to show that the haploid genome of O. volvulus is 1.5 x 10(8) base pairs. About 1 in 700 recombinant clones in each of the four amplified cDNA libraries produces a fusion protein recognized by pooled human anti-O. volvulus antisera. Partial sequence determination of a 2.0 kb cDNA clone for an O. volvulus protein that induces an immunodominant response in rabbits revealed that this antigen has sequence similarities with Caenorhabditis elegans myosin and with schistosome paramyosin (which confers partial protection against schistosome infection). The four cDNA libraries have been deposited with American Type Culture Collection (ATCC), 12301 Parklawn Drive, Rockville, MD 20852, U.S.A., for general distribution under ATCC Number 37509.
Insights
Researchers characterized adult Onchocerca volvulus worms from diverse geographic locations. They developed cDNA libraries to analyze parasite genomes and identified a potential antigen with similarities to myosin, offering insights into onchocerciasis.
Area of Science:
- Molecular Biology
- Parasitology
- Genomics
Background:
- Onchocerca volvulus is the causative agent of onchocerciasis, a debilitating neglected tropical disease.
- Understanding the genetic diversity and molecular characteristics of O. volvulus is crucial for developing effective control strategies.
Purpose of the Study:
- To construct and characterize cDNA expression libraries from adult Onchocerca volvulus worms collected from different geographical regions.
- To compare the genomes of O. volvulus parasites from various locales and estimate genome size.
- To identify potential antigens of O. volvulus that elicit an immune response.
Main Methods:
- Isolation of adult Onchocerca volvulus from nodules of infected patients in Mali, Cameroon, and Guatemala.
- Construction of four distinct cDNA expression libraries in bacteriophage lambda gt11.
- Screening of libraries using pooled human anti-O. volvulus antisera to identify reactive clones.
- Partial sequencing of a cDNA clone encoding an immunodominant antigen.
Main Results:
- The haploid genome size of O. volvulus was determined to be 1.5 x 10^8 base pairs.
- Approximately 1 in 700 recombinant clones produced fusion proteins recognized by human antisera.
- A 2.0 kb cDNA clone encoding an immunodominant antigen was partially sequenced, showing similarities to Caenorhabditis elegans myosin and schistosome paramyosin.
Conclusions:
- The study provides valuable molecular resources, including cDNA libraries, for further research into Onchocerca volvulus.
- The identified antigen may play a role in the host immune response and could be a target for diagnostics or vaccines.
- Genomic comparison suggests potential variations in O. volvulus populations across different regions.
