Nehra Anil Kumar, Kumari Ansu, Kundave V R, Vohra Sukhdeep, Ram Hira
Department of Veterinary Parasitology, Lala Lajpat Rai University of Veterinary and Animal Sciences, Hisar, Haryana 125004, India.
Department of Veterinary Medicine, Lala Lajpat Rai University of Veterinary and Animal Sciences, Hisar, Haryana 125004, India.
Infect Genet Evol. 2022 Apr;99:105252. doi: 10.1016/j.meegid.2022.105252. Epub 2022 Feb 17.
The present study was conducted to elucidate the population genetic diversity and haplotype network of Theileria annulata based on all available nearly complete 18S rRNA gene sequences in the GenBank™. In total, 52 sequences of the nuclear 18S rRNA gene used to assess the relationship of T. annulata with their country of origin identified 34 haplotypes. Haplotype 4 was widespread, occurring in India, China, Turkey and Iran, while the remaining haplotypes were singleton and unique to one country. Haplotype 4 displayed numerous single haplotypes around it and the stellate shape of the network suggested a rapid population expansion. India exhibited the largest number of haplotypes (h = 25) followed by Turkey (h = 6), China (h = 4), and Iran and Italy (h = 1). No geographical clustering of haplotypes was recorded. Nucleotide diversity was the highest in the Turkish followed by the Indian and Chinese populations. Similarly, haplotype diversity was the highest in China followed by Turkey, and the lowest in India. The overall dataset exhibited a low nucleotide diversity (0.00253 ± 0.00035), but high haplotype diversity (0.917 ± 0.034). It suggested the presence of only minor differences (01-11 nucleotide) between haplotypes which was also evident from the haplotype network. A high level of genetic diversity was documented within the Indian, Chinese and Turkish populations of T. annulata, whereas little genetic differentiation was noticed among these populations with a very high level of gene flow. Analysis of molecular variance (AMOVA) of T. annulata sequences revealed higher genetic variation within countries (83.58%) as compared to the variation among countries (16.42%). Neutrality indices, viz., Tajima's D, Fu and Li's F, Fu's F, and R along with the unimodal mismatch distributions demonstrated a recent population expansion of T. annulata in India and the overall dataset. However, the non-significant values of Tajima's D, Fu and Li's F, and Fu's F for the Chinese population along with a bimodal mismatch distribution signified a constant population size. For the Turkish population, the neutrality and mismatch distribution tests either indicated a constant or a slight increase in population size. The present study provides novel insights into the population genetics and haplotype network of T. annulata based on the 18S rRNA gene for the first time.
本研究旨在基于GenBank™中所有可用的近乎完整的18S rRNA基因序列，阐明环形泰勒虫的群体遗传多样性和单倍型网络。总共使用52条核18S rRNA基因序列来评估环形泰勒虫与其原产国之间的关系，共鉴定出34个单倍型。单倍型4分布广泛，出现在印度、中国、土耳其和伊朗，而其余单倍型均为单例且每个国家独有。单倍型4周围有许多单一单倍型，网络的星状形状表明群体迅速扩张。印度的单倍型数量最多（h = 25），其次是土耳其（h = 6）、中国（h = 4）以及伊朗和意大利（h = 1）。未观察到单倍型的地理聚类现象。土耳其群体的核苷酸多样性最高，其次是印度和中国群体。同样，中国群体的单倍型多样性最高，其次是土耳其，印度最低。总体数据集显示出较低的核苷酸多样性（0.00253±0.00035），但单倍型多样性较高（0.917±0.034）。这表明单倍型之间仅存在微小差异（01 - 11个核苷酸），这从单倍型网络中也很明显。在环形泰勒虫的印度、中国和土耳其群体中记录到高水平的遗传多样性，而这些群体之间几乎没有遗传分化，基因流水平非常高。对环形泰勒虫序列的分子方差分析（AMOVA）显示，与国家间的变异（16.42%）相比，国家内的遗传变异更高（83.58%）。中性指数，即Tajima's D、Fu和Li's F、Fu's F以及R，连同单峰错配分布表明，印度和总体数据集中环形泰勒虫最近出现了群体扩张。然而，中国群体的Tajima's D、Fu和Li's F以及Fu's F的非显著值以及双峰错配分布表明群体大小恒定。对于土耳其群体，中性和错配分布测试要么表明群体大小恒定，要么略有增加。本研究首次基于18S rRNA基因对环形泰勒虫的群体遗传学和单倍型网络提供了新的见解。
