title: Two genotypic groups of morphologically similar fish trypanosomes from the Okavango Delta, Botswana.
abstract: Blood smears and blood lysate samples from freshwater fishes captured in the Okavango Delta, Botswana, were examined to determine whether their trypanosomes were all Trypanosoma mukasai, a species of supposed broad host specificity and widespread existence across Africa. Trypanosomes and/or babesiosomes occurred in 20/32 blood smears, and morphometric analysis of trypanosomes from 13/32 smears showed features suggestive of T. mukasai, including nuclear indices consistently >1. In 16/32 blood lysate samples from which DNA was extracted, trypanosome DNA was detected in 12/16 by PCR (polymerase chain reaction), using trypanosome-specific ssu rRNA gene primers. Two samples positive for trypanosomes in blood smears yielded no amplifiable trypanosome DNA, but 4 samples with no detectable infection in blood smears were positive for trypanosome DNA, suggesting an overall trypanosome prevalence rate of 17/32 (53%) among fishes and demonstrating the value of PCR in trypanosome recognition. Cloning and sequencing of the 12 amplified fragments revealed 2 genotypic groups among these fish trypanosomes. Group 1 trypanosomes were from cichlids and 3 families of catfishes, Group 2 from 2 types of catfishes. Sequence comparison showed that the consensus Group 1 sequence was most similar to that of Trypanosoma cobitis, representing European fish trypanosomes of the carassii type, while the consensus Group 2 sequence showed similarity with a trypanosome sequence from another African catfish, Clarias angolensis. It was concluded that the identification of T. mukasai remains a problem, but at least 2 genotypic groups of trypanosomes occur in Okavango Delta fishes, and catfishes in this region appear to contain both types.
authors.affiliation: School of Life Sciences, Kingston University, Kingston upon Thames, UK. ajdavies.russell@kingston.ac.uk
authors.forename: Angela J
authors.initials: AJ
authors.lastname: Davies
authors.forename: Wendy
authors.initials: W
authors.lastname: Gibson
authors.forename: Vanessa
authors.initials: V
authors.lastname: Ferris
authors.forename: Linda
authors.initials: L
authors.lastname: Basson
authors.forename: Nico J
authors.initials: NJ
authors.lastname: Smit
mesh_terms: D000818:Animals; D001483:Base Sequence; D001902:Botswana; D017931:DNA Primers; D005399:Fishes / Q000469:parasitology*; D005838:Genotype; D008969:Molecular Sequence Data; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D013045:Species Specificity; D014345:Trypanosoma / Q000166:cytology* / Q000235:genetics*
chemical_list: D017931:DNA Primers