Genetic evolutionary characteristics for piroplasm infection in equines in Qinghai Province

doi:10.12140/j.issn.1000-7423.2025.03.005

Abstract

Abstract:

Objective To investigate the prevalence of tick-borne piroplasm infections and the genetic evolutionary characteristics in equines in selected areas of Qinghai Province, so as to provide insights into management of equine piroplasmosis in Qinghai Province. Methods The blood samples were collected from free range equines in four cities (prefectures) of Haidong, Xining, Haixi and Haibei in Qinghai Province from March 2023 to July 2024. Genomic DNA was extracted from blood samples and the 18S rRNA gene was amplified using nested PCR assay. The obtained gene sequence was subjected to homology alignment and analysis using the NCBI BLAST program. Haplotype analysis was performed using the software DNASP 6, and a haplotype network diagram was plotted using PopArt. The sequences of Theileria equi genotypes A to E and Babesia caballi genotypes A to C were selected from GenBank as reference sequences, and a phylogenetic tree was built using the maximum likelihood estimation with the software MEGA 6.0. Results The prevalence of piroplasm infections infection was 47.73% (84/176) in 176 blood samples from free-ranging equines, and the prevalence rates of T. equi and B. caballi infections were 47.16% (83/176) and 0.57% (1/176), respectively. A total of 16 haplotypes were identified in the 83 sequences of T. equi, with a haplotype diversity of 0.450 and a nucleotide diversity of 0.026 43, and H1 was the dominant haplotype of T. equi (73.49%, 61/83), followed by H5 haplotype (9.64%, 8/83), and the remaining 14 haplotypes (H2 to H4, H6 to H16) each accounted for 1.20% (1/83). Phylogenetic analysis showed that the gene sequences of T. equi haplotypes H5, H8 to H14, H16 were clustered together with T. equi genotype A (GenBank accession numbers: JX177672 and MT463613) in GenBank into the same clade, and the remaining 7 haplotypes were clustered together with T. equi genotype B (GenBank accession numbers: EU642507 and AB515310) into the same clade, while the gene sequences of B. caballi and B. caballi genotype A (GenBank accession numbers: EU642512, KJ787774, AY309995, AB734392, MH651219, MH651220 and JX049130) in GenBank were clustered into the same clade. Conclusion T. equi and B. caballi are piroplasm species infecting equines in selected areas of Qinghai Province, with a high prevalence rate of infections. The prevalent genotypes are T. equi genotypes A and B and B. caballi genotype A, with T. equi genotype B as the dominant genotype.

Key words: Piroplasma infection, Equine, Haplotype, Genetic evolution, Qinghai

CLC Number:

R531

LI Zhi, MENG Ru, HAN Yuan, YUAN Qing, HUANG Ying, DUO Hong, FU Yong. Genetic evolutionary characteristics for piroplasm infection in equines in Qinghai Province[J]. CHINESE JOURNAL OF PARASITOLOGY AND PARASITIC DISEASES, 2025, 43(3): 335-339.

Figures/Tables 4

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地区 Area	样品数/份 No. samples	宿主 Host	马梨形虫感染率/% Infection rate of equine piroplasms/%
地区 Area	样品数/份 No. samples	宿主 Host	马泰勒虫 T. equi	驽巴贝虫 B. caballi
海东 Haidong	83	马 Horse	86.75%（72/83）	0
西宁 Xining	50	驴 Donkey	0	0
海北 Haibei	14	马 Horse	8/14	1/14
海西 Haixi	29	马 Horse	5.08%（3/29）	0
合计 Total	176		47.16%（83/176）	0.57%（1/176）