Related Experiment Video
Updated: Aug 24, 2026
Detecting the Lyme Disease Spirochete, Borrelia Burgdorferi, in Ticks Using Nested PCR
Published on: February 4, 2018
An oligonucleotide probe specific for Onchocerca volvulus
W Harnett1, A E Chambers, A Renz
1Division of Parasitology, National Institute for Medical Research, London, U.K.
Abstract:
A genomic DNA library of a Liberian strain of Onchocerca volvulus was prepared in the vector bacteriophage lambda gt10. The library was differentially screened by hybridisation with radiolabelled total DNA from the homologous parasite, two heterologous Onchocerca parasites (Onchocerca gibsoni and Onchocerca gutturosa) and human liver cells. A clone (C1A1) was isolated whose binding to O. volvulus DNA was at least 50 times stronger than to the other parasite DNA samples. No binding was observed with human DNA. The insert of C1A1 was subcloned into the filamentous phage vector M13 mp18 and sequenced. Two oligonucleotides, each corresponding to a unique region of 60 nucleotides (out of a total of 154) were synthesised and examined for hybridisation with three different geographical isolates of O. volvulus (including forest and savannah strains) and six other Onchocerca spp. One of the oligonucleotides (C1A1-2) was found to hybridise to the three O. volvulus isolates with an intensity in the region of 300 times greater than to any other Onchocerca spp. Since the other species include the two which may be most closely related to O. volvulus, i.e., O. gibsoni and Onchocerca ochengi, it is concluded that C1A1-2 is likely to represent a truly species-specific probe.
Insights
Researchers developed a species-specific DNA probe for Onchocerca volvulus, the parasite causing river blindness. This new probe, C1A1-2, accurately identifies O. volvulus DNA, aiding in disease diagnosis and control efforts.
Area of Science:
- Molecular Biology
- Parasitology
- Genetics
Background:
- Onchocerca volvulus is a parasitic nematode responsible for onchocerciasis (river blindness).
- Accurate identification of O. volvulus is crucial for disease control and epidemiological studies.
- Existing diagnostic methods may lack specificity or require complex procedures.
Purpose of the Study:
- To develop a highly specific molecular probe for the detection of Onchocerca volvulus.
- To identify unique genetic sequences for species-specific parasite identification.
Main Methods:
- Construction of a genomic DNA library from O. volvulus in a bacteriophage lambda gt10 vector.
- Differential screening of the library using homologous and heterologous parasite DNA, as well as human DNA.
- Subcloning and sequencing of a promising clone (C1A1).
- Synthesis and hybridization testing of oligonucleotides derived from the unique sequence with various Onchocerca species.
Main Results:
- Isolation of clone C1A1 with strong binding to O. volvulus DNA and no binding to human DNA.
- Identification of a 60-nucleotide unique region within the C1A1 insert.
- Development of oligonucleotide C1A1-2, which hybridized strongly (300x greater) to all tested O. volvulus isolates compared to other Onchocerca species.
- High specificity observed even against closely related species like O. gibsoni and O. ochengi.
Conclusions:
- The oligonucleotide C1A1-2 functions as a highly species-specific probe for Onchocerca volvulus.
- This probe has significant potential for accurate diagnosis and monitoring of onchocerciasis.
- The developed probe offers a valuable tool for epidemiological research and parasite control strategies.
Related Concept Videos
01:32PCR
03:31Labeling DNA Probes
Radioisotopes, fluorophores, or small molecule binding partners like biotin or digoxigenin, are the most widely used reporter tags for labeling DNA probes. These labels can be attached to the probe DNA molecule via...
02:57Southern Blot
Denatured DNA fragments must be transferred onto a carrier membrane from the gel to make it accessible to a probe - a small ssDNA fragment complementary to the target DNA...