Analysis of host genetic factors influencing African trypanosome species infection in a cohort of Tanzanian Bos indicus cattle
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Date
2011
Journal Title
Journal ISSN
Volume Title
Publisher
Elsevier
Abstract
Trypanosomosis caused by infection with protozoan parasites of the genus Trypanosoma is
a major health constraint to cattle production in many African countries. One hundred and
seventy one Bos indicus cattle from traditional pastoral Maasai (87) and more intensively
managed Boran (84) animals in Tanzania were screened by PCR for the presence of African
animal trypanosomes (Trypanosoma congolense, Trypanosoma vivax and Trypanosoma bru-
cei), using blood samples archived on FTA cards. All cattle screened for trypanosomes were
also genotyped at the highly polymorphic major histocompatibility complex (MHC) class II
DRB3 locus to investigate possible associations between host MHC and trypanosome infec-
tion. Overall, 23.4% of the 171 cattle tested positive for at least one of the three trypanosome
species. The prevalence of individual trypanosome species was 8.8% (T. congolense), 4.7% (T.
vivax) and 15.8% (T. brucei). The high prevalence of T. brucei compared with T. congolense and
T. vivax was unexpected as this species has previously been considered to be of lesser impor-
tance in terms of African bovine trypanosomosis. Significantly higher numbers of Maasai
cattle were infected with T. brucei (23.0%, p = 0.009) and T. congolense (13.8%, p = 0.019) com-
pared with Boran cattle (8.3% and 3.6%, respectively). Analysis of BoLA-DRB3 diversity in this
cohort identified extensive allelic diversity. Thirty-three BoLA-DRB3 PCR-RFLP defined alle-
les were identified. One allele (DRB3*15) was significantly associated with an increased risk
(odds ratio, OR = 2.71, p = 0.034) of T. brucei infection and three alleles (DRB3*35, *16 and
*23) were associated with increased risk of T. congolense infection. While further work is
required to dissect the role of these alleles in susceptibility to T. brucei and T. congolense
infections, this study demonstrates the utility of FTA archived blood samples in combined
molecular analyses of both host and pathogen.
Description
Keywords
African Animal trypanosomes, BOLA_DRB3, Bos indicus, Tanzania