基于印度牛只中Tams1基因的环形泰勒虫分子流行病学及基因型多样性
Molecular Epidemiology and Genotypic Diversity of Theileria annulata among Bovines Based Upon Tams1 Gene in India.
作者信息
Malik Rashmi, Maharana Biswa Ranjan, Ganguly Anita, Vohra Sukhdeep, Kumar Binod, Kumar Ankit, Singh Harpreet, Potliya Sandeep, Khanna Sujoy, Sahu Subhasish
机构信息
Haryana Pashu Vigyan Kendra, Lala Lajpat Rai University of Veterinary and Animal Sciences, Uchani, Karnal, 132001, Haryana, India.
Lala Lajpat Rai University of Veterinary and Animal Sciences, Hisar, 125001, Haryana, India.
出版信息
Acta Parasitol. 2025 Apr 3;70(2):81. doi: 10.1007/s11686-025-01014-1.
PURPOSE
Bovine theileriosis, caused by Theileria annulata, presents a significant economic challenge to India's livestock industry. This study investigates the molecular epidemiology of T. annulata in bovine populations from Haryana, India, focusing on the genetic diversity of the Tams1 gene (785 bp).
METHODS
The prevalence of T. annulata was evaluated in 800 blood samples using microscopy and PCR techniques, specifically targeting SSU rRNA and Tams1 genes. Genetic diversity among T. annulata isolates was analyzed through DNA sequencing and phylogenetic studies. Additionally, the impact of various risk factors on T. annulata infection was assessed.
RESULTS
Microscopy revealed that 29.25% (117/400) of cattle and 2.75% (11/400) of buffalo were detected positive for Theileria spp. in Giemsa-stained blood smears. The Theileria genus-specific primers amplified a 1098 bp fragment of the SSU rRNA gene in 39.5% (158/400) cattle and 6% (24/400) buffalo. The T. annulata-specific PCR targeting the partial Tams1 gene revealed a prevalence rate of 37% (148/400) in cattle and 3.5% (14/400) in buffalo. A genetic analysis of the Tams1 gene in 389 sequences, including 14 T. annulata isolates from Haryana (8 from cattle, 6 from buffaloes), revealed significant variation within Indian T. annulata parasites. Analysis of Tams1 gene sequences (389 from 16 countries) revealed 35 haplotypes globally, with four identified from the 14 isolates sequenced in this study. Nucleotide homology among 14 northern Indian isolates ranged from 89.46-100%, compared to a broader range of 78.42-100% when global sequences were included. Among 35 haplotypes, Hap_1 is the most dominant and shows geographic clustering. Globally, low genetic distance (Fst < 0.15) and high gene flow (Nm > 1) were observed among the five populations (South Asia, East Asia, West Asia, Europe, and Africa), suggesting minimal genetic differentiation among T. annulata populations. Negative values in Tajima' s D (-1.21941) and Li's F (-2.97801) tests suggest recent population expansion. Risk factors such as age, sex, and host species are significantly associated with T. annulata infection.
CONCLUSION
This study offers comprehensive insights into T. annulata genetic diversity, population structure, and haplotype networks using the Tams1 gene.
目的
由环形泰勒虫引起的牛泰勒虫病给印度的畜牧业带来了重大经济挑战。本研究调查了印度哈里亚纳邦牛群中环形泰勒虫的分子流行病学，重点关注Tams1基因（785 bp）的遗传多样性。
方法
使用显微镜检查和PCR技术对800份血样进行环形泰勒虫流行率评估，具体针对小亚基核糖体RNA（SSU rRNA）和Tams1基因。通过DNA测序和系统发育研究分析环形泰勒虫分离株之间的遗传多样性。此外，评估了各种风险因素对环形泰勒虫感染的影响。
结果
显微镜检查显示，在吉姆萨染色的血涂片中，29.25%（117/400）的牛和2.75%（11/400）的水牛检测出泰勒虫属阳性。泰勒虫属特异性引物在39.5%（158/400）的牛和6%（24/400）的水牛中扩增出了1098 bp的SSU rRNA基因片段。针对部分Tams1基因的环形泰勒虫特异性PCR显示，牛的流行率为37%（148/400），水牛为3.5%（14/400）。对389个序列中的Tams1基因进行遗传分析，其中包括来自哈里亚纳邦的14株环形泰勒虫分离株（8株来自牛，6株来自水牛），结果显示印度环形泰勒虫寄生虫存在显著变异。对Tams1基因序列（来自16个国家的389个序列）的分析显示，全球共有35个单倍型，本研究测序的14个分离株中鉴定出4个。印度北部14个分离株之间的核苷酸同源性范围为89.46%-100%，而纳入全球序列时范围更广，为78.42%-100%。在35个单倍型中，Hap_1最为占主导且呈现地理聚类。在全球范围内，五个种群（南亚、东亚、西亚、欧洲和非洲）之间观察到低遗传距离（Fst < 0.15）和高基因流（Nm > 1），这表明环形泰勒虫种群之间的遗传分化最小。Tajima's D（-1.21941）和Li's F（-2.97801）检验的负值表明近期种群扩张。年龄、性别和宿主物种等风险因素与环形泰勒虫感染显著相关。
结论
本研究利用Tams1基因对环形泰勒虫的遗传多样性、种群结构和单倍型网络提供了全面的见解。
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