Ancient diversity and geographical sub-structuring in African buffalo Theileria parva populations revealed through metagenetic analysis of antigen-encoding loci.
Ancient diversity and geographical sub-structuring in African buffalo Theileria parva populations revealed through metagenetic analysis of antigen-encoding loci.
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DOI：
10.1016/j.ijpara.2017.10.006
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发表时间：
2018-03
影响因子：
4
通讯作者：
Weir W
中科院分区：
文献类型：
--
作者：
Hemmink JD;Sitt T;Pelle R;de Klerk-Lorist LM;Shiels B;Toye PG;Morrison WI;Weir W
牛源性小泰勒虫基因型高度多样。布法罗一贯表现出高度的多重感染。几种牛CD8 T细胞抗原在氨基酸水平上高度保守。肯尼亚和南非的寄生虫种群具有地理结构，但共享古老的多样性。数据表明，重组发挥了重要作用，在现场种群的多样性。目前使用一种感染和治疗方案，包括用三种寄生虫分离株的混合物感染并同时用土霉素治疗，以接种牛抗小泰勒虫。虽然疫苗接种在某些地区产生了高水平的保护，但在动物主要受到布法罗源寄生虫攻击的地区，几乎没有观察到保护。先前的一项研究涉及对一系列寄生虫分离株的两个抗原编码基因进行测序，表明这与水牛源T. parva。目前的研究着手扩展这些分析，通过应用高通量测序，从自然感染的布法罗离体样品，以确定在一组抗原编码基因的多样性程度。从两个群体的布法罗，一个在肯尼亚和其他在南非，样本进行了检查，调查的影响，地理距离的序列多样性的性质。结果揭示了一些重要的发现。首先，有一个可变程度的核苷酸序列的多样性，在所有的基因片段检查，多态性核苷酸的百分比范围从10%到69%。第二，在个体动物中发现每个基因的大量等位基因变体，表明多次感染事件。第三，尽管观察到核苷酸序列的多样性，但几种基因产物具有高度保守的氨基酸序列，因此代表了疫苗开发的潜在候选者。第四，虽然有令人信服的证据表明肯尼亚和南非T。在鉴定出细小寄生虫后，每个基因的分子变异分析显示，大部分潜在的核苷酸序列多态性在两个地区都是共同的，这表明寄生虫种群中这方面的遗传变异大部分出现在地理分离之前。
Buffalo-derived Theileria parva genotypes are highly diverse. Buffalo consistently exhibit a high multiplicity of infection. Several bovine CD8 T cell antigens are highly conserved at the amino acid level. Kenyan and South African parasite populations are geographically structured, but share ancient diversity. Data indicate that recombination plays a major role in generating diversity in field populations. An infection and treatment protocol involving infection with a mixture of three parasite isolates and simultaneous treatment with oxytetracycline is currently used to vaccinate cattle against Theileria parva. While vaccination results in high levels of protection in some regions, little or no protection is observed in areas where animals are challenged predominantly by parasites of buffalo origin. A previous study involving sequencing of two antigen-encoding genes from a series of parasite isolates indicated that this is associated with greater antigenic diversity in buffalo-derived T. parva. The current study set out to extend these analyses by applying high-throughput sequencing to ex vivo samples from naturally infected buffalo to determine the extent of diversity in a set of antigen-encoding genes. Samples from two populations of buffalo, one in Kenya and the other in South Africa, were examined to investigate the effect of geographical distance on the nature of sequence diversity. The results revealed a number of significant findings. First, there was a variable degree of nucleotide sequence diversity in all gene segments examined, with the percentage of polymorphic nucleotides ranging from 10% to 69%. Second, large numbers of allelic variants of each gene were found in individual animals, indicating multiple infection events. Third, despite the observed diversity in nucleotide sequences, several of the gene products had highly conserved amino acid sequences, and thus represent potential candidates for vaccine development. Fourth, although compelling evidence for population differentiation between the Kenyan and South African T. parva parasites was identified, analysis of molecular variance for each gene revealed that the majority of the underlying nucleotide sequence polymorphism was common to both areas, indicating that much of this aspect of genetic variation in the parasite population arose prior to geographic separation.
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影响因子：
4
作者：
Hemmink JD;Weir W;MacHugh ND;Graham SP;Patel E;Paxton E;Shiels B;Toye PG;Morrison WI;Pelle R
通讯作者：
Pelle R
DOI：
10.1073/pnas.1506468112
发表时间：
2015-09-22
影响因子：
11.1
作者：
Blake, Damer P.;Clark, Emily L.;Tomley, Fiona M.
通讯作者：
Tomley, Fiona M.
影响因子：
2.6
作者：
Chaisi, Mamohale E.;Collins, Nicola E.;Oosthuizen, Marinda C.
通讯作者：
Oosthuizen, Marinda C.
影响因子：
3.1
作者：
Graham, Simon P.;Pelle, Roger;Taracha, Evans L. N.
通讯作者：
Taracha, Evans L. N.
影响因子：
2.6
作者：
MARITIM, AC;YOUNG, AS;NGUMI, PN
通讯作者：
NGUMI, PN