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Strain differentiation of Onchocerca volvulus from Uganda using DNA probes
P Fischer1, J Bamuhiiga, A H Kilian
1Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany.
Parasitology
|April 1, 1996
Summary
DNA analysis revealed that the Onchocerca volvulus parasite in Uganda differs genetically from West African strains. This finding challenges the existing forest/savannah classification for this parasite in Uganda.
Area of Science:
- Molecular Biology
- Parasitology
- Genetics
Background:
- Onchocerca volvulus is a parasitic nematode causing onchocerciasis.
- Geographic classification of O. volvulus into forest and savannah forms is established in West Africa.
- The applicability of this classification to O. volvulus in other regions, like Uganda, requires investigation.
Purpose of the Study:
- To genetically characterize Onchocerca volvulus from Uganda using molecular techniques.
- To compare the genetic profile of Ugandan O. volvulus with West African strains.
- To evaluate the suitability of the forest/savannah classification for Ugandan O. volvulus.
Main Methods:
- Polymerase chain reaction (PCR) amplification of a 150 bp tandem repeat.
- Non-radioactive DNA hybridization using a digoxigenin-labeled oligonucleotide probe specific for the O. volvulus forest form.
- Nested PCR with primers derived from the forest form-specific DNA sequence.
- Morphometric analysis of microfilariae length.
Main Results:
- DNA hybridization confirmed the presence of the O. volvulus forest form in Liberia, Ghana, Benin, and Cameroon, but not in Uganda.
- Nested PCR results corroborated the hybridization findings, differentiating Ugandan O. volvulus.
- Morphometric studies showed distinct microfilariae length differences between Ugandan and West African O. volvulus, particularly the savannah form from Burkina Faso.
Conclusions:
- The genetic and morphometric data suggest that Ugandan O. volvulus is distinct from West African forms.
- The established forest/savannah classification system for O. volvulus from West Africa is not applicable to the Simulium neavei-transmitted O. volvulus found in Uganda.