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Characterization of a variant tandem repeat from Sudanese Onchocerca volvulus. Trop Med Parasitol 1993 Jun;44(2):113-5



Pubmed ID



Strategies for detection and control of onchocerciasis in Africa have included identification of DNA probes and PCR target sequences for sensitive and specific detection of parasites. To evaluate the applicability of published PCR and DNA probe based methods for the study of onchocerciasis in Sudan, we collected adult O. volvulus from geographically distinct regions of Sudan (700 miles apart), Abu Hamed (northern desert) and Raja (southwestern savannah), and we examined the similarities between Sudanese O. volvulus repeats and published versions of the repeat from West African O. volvulus. Amplification of DNA extracted from the Raja O. volvulus strain predictably generated a ladder of products, multiples of the base 150 bp repeat, as has been reported from West Africa. However, amplification of DNA from the Abu Hamed O. volvulus isolate resulted in a series of doublets. The unexpected DNA fragments thus amplified differed in size from the base 150 bp unit by approximately 50 base pairs and was most clearly visualized at 150-200 base pairs. DNA sequence analysis of the amplified repeats in the isolate of O. volvulus from Abu Hamed revealed a variant of the 150 bp tandem repeat which contained an extra 49 bp. The additional 49 bp contained two short repeats of 21 bp and 10 bp, corresponding to bases 99-119 and 128-137 respectively, of the known 150 bp O. volvulus repeat. This work demonstrates a variant of the O. volvulus 150 bp tandem repeat, which easily distinguishes Raja and Abu Hamed isolates of O. volvulus, and which has potential value for differentiating Abu Hamed strains of O. volvulus from other strains in East Africa.

Author List

Kron MA, Ali MH


Michael Kron MD Director, Professor in the Medicine department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Base Sequence
Blotting, Southern
DNA Probes
Electrophoresis, Agar Gel
Genetic Variation
Molecular Sequence Data
Onchocerca volvulus
Polymerase Chain Reaction
Repetitive Sequences, Nucleic Acid
Sequence Homology, Nucleic Acid
jenkins-FCD Prod-482 91ad8a360b6da540234915ea01ff80e38bfdb40a