Molecular detection and genetic characteristics of Babesia gibsoni in dogs in Shaanxi Province, China

Wen-Ping Guo,Meng Su,Guang-Cheng Xie,Dan Li,Rui Jian,Luan-Ying Du

doi:10.1186/s13071-020-04232-w

Abstract

BackgroundSeveral members of genus Babesia are important pathogens causing babesiosis in dogs. In China, at least five Babesia species have been described in dogs or ticks. This study sought to determine the prevalence and molecular characteristics of various Babesia spp. in dogs in cities in Shaanxi Province in China, including Xi’an and Hanzhong.MethodsA total of 371 blood samples were collected from pet dogs presenting to veterinary clinics in the cities of Xi’an and Hanzhong in Shaanxi, China. Babesia spp. DNA was detected via amplification of partial 18S rRNA genes by semi-nested PCR. Almost full-length 18S rRNA, ITS, partial TRAP and complete cytb genes were recovered for analysis of the genetic characteristics and relationships with known isolates.ResultsA single species, Babesia gibsoni, was identified in dogs in Xi’an and Hanzhong. Consistently, B. gibsoni was also detected in 14 ticks collected from positive dogs. Sequence similarities and phylogenetic analysis suggested that the isolates identified herein showed a closer genetic relationship with isolates from East Asian countries rather than India, Bangladesh, or the USA. Sequence analysis based on tandem repeat analysis of the TRAP gene further revealed that specific haplotypes were circulating in both Xi’an and Hanzhong, with no specific regionality. In addition, 10.9% of all isolates with atovaquone (ATV)-resistance were identified because of M121I mutation in the deduced cytb protein.ConclusionsThis study revealed a high prevalence rate of Babesia infection. Babesia gibsoni was the only Babesia species identified in cases of canine babesiosis in the cities of Xi’an and Hanzhong cities in Shaanxi, China. In addition, the TRAP gene presented high genetic diversity across isolates. Such information is useful for elucidating the epidemiological characteristics of canine babesiosis, as well as the overall genetic diversity of Babesia spp. circulating in dog populations in Shaanxi Province.

Highlights

Several members of genus Babesia are important pathogens causing babesiosis in dogs
Babesia gibsoni was the only Babesia species identified in cases of canine babesiosis in the cities of Xi’an and Hanzhong cities in Shaanxi, China
The thrombospondin-related adhesive protein (TRAP) gene presented high genetic diversity across isolates. Such information is useful for elucidating the epide‐ miological characteristics of canine babesiosis, as well as the overall genetic diversity of Babesia spp. circulating in dog populations in Shaanxi Province

Summary

Introduction

In China, at least five Babesia species have been described in dogs or ticks. Babesiosis refers to a serious, worldwide, tick-borne hemoprotozoan disease caused by various Babesia spp. These Babesia spp. are classified as either large (3–5 μm). The clinical signs of canine babesiosis are similar for infection with both small and large Babesia spp. and include pyrexia, anemia, jaundice, hemoglobinuria, splenomegaly and weakness [3, 10,11,12,13]. The severity of canine babesiosis varies from mild to serious illness, largely depending on the specific species of infecting parasite, and conditions of the affected dog, such as age, nutritional and immune status [10,11,12]. B. rossi, a highly virulent species, is associated with higher mortality in infected dogs compared to other Babesia species due to various complications of infection, such as disseminated intravascular coagulation and multi-organ dysfunction [14]

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