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Cloning and characterization of an Onchocerca volvulus specific DNA sequence
S E Meredith1, T R Unnasch, M Karam
1Department of Tropical Public Health, Boston, MA 02115.
Molecular and Biochemical Parasitology
|August 1, 1989
Summary
A novel DNA sequence, pOvs134, specifically detects Onchocerca volvulus, the parasite causing river blindness. This highly repeated sequence is sensitive enough to identify even a single larva, aiding in disease diagnosis.
Area of Science:
- Molecular parasitology
- Genomics
- Neglected tropical diseases
Background:
- Onchocerca volvulus is a filarial nematode responsible for onchocerciasis (river blindness).
- Accurate detection and diagnosis of O. volvulus infections are crucial for effective disease control programs.
Purpose of the Study:
- To identify and characterize a specific DNA sequence for the detection of Onchocerca volvulus.
- To evaluate the diagnostic potential of the identified sequence.
Main Methods:
- Genomic library screening using plasmid pUC9.
- Dot blot hybridization for species-specific detection.
- DNA sequencing to analyze repetitive elements.
Main Results:
- The cloned sequence pOvs134 specifically hybridizes to Onchocerca volvulus isolates from diverse geographic locations.
- pOvs134 does not cross-hybridize with related Onchocerca species, other filarial parasites, or host DNA.
- The sequence contains a highly repeated 149-bp element, with variants exhibiting different specificities.
- Dot blot hybridization with pOvs134 can detect as little as 250 pg of DNA, suggesting sensitivity for single larval stages.
Conclusions:
- pOvs134 represents a highly specific and sensitive DNA marker for Onchocerca volvulus.
- The 149-bp repeat sequence and its variants are abundant in the O. volvulus genome.
- This sequence holds promise for developing improved diagnostic tools for onchocerciasis.