Molecular characterization of bovine trypanosomes from the Kachia Grazing Reserve, north-west Nigeria

Abstract

Primers (Kin 1 and Kin 2) designed to amplify the internal transcribed spacer1 (ITS1) of ribosomal deoxyribonucleic acid (rDNA) and serve as a universal diagnostic test for all pathogenic trypanosomes were further evaluated for polymerise chain reaction (PCR) diagnosis and characterization of liveestock trypanosomes. Blood samples collected from 121 cattle and 3 sheep from the Kachia Grazing Reserve, north-west Nigeria in February 2005 were examined for the presence of trypanosomes using the Buffy coat technique and Giemsathin bloodfilms. 36 cattle were found positive for trypanosomes: 33 with Trypanosoma vivax, 2 with T. congolense and one mixed infection of T. congolense and T. vivax; in sheep 2 of T. vivax and one T. brucei infection. DNA extracted from all positive samples and 86 negative samples were subjected to PCR amplification using the ITS1
primers. The PCR assay allowed detection and characterization of three Trypanosoma livestock species namely T. vivax, 13 of 33 was positive; T. congolense forest, 1 of 2 and 1 T. b. brucei. The sizes of base pairs were 147 bp, 710 bp and 480 bp. respectively. The one mixed infection was detected the way it was as T. congolense and T. vivax plus another mixed infection of T. congolense and T. vivax, which was not revealed by the buffy coat. In the 86- trypanosome negative samples, 82 (95.3%) were still negative while 4 (4.7% were detected with T. vivax infection. Overall, the sensitivity of the ITS1 primers PCR detection
was 42.9% and specificity 95.3%. The study concludes that the ITS1 primers are adequate for type characterization of livestock trypanosomes through a single PCR, thus saving cost. For diagnostic purposes, improvement in primer designs for enhancing T. vivax detection in field samples is suggested.

Keywords: polymerase chain reaction, primers (Kin 1 and Kin 2), internal transcribed spacer 1(ITS1), ribosomal DNA, African
animal trypanosomes.

Nigerian Journal of Parasitology Vol. 29 (2) 2008: pp. 98-102