Course of Veterinary Medicine, University of Cuiabá, Cuiabá, MT, Brazil.
Department of Pathology, University of Texas Medical Branch at Galveston, Galveston, USA.
Acta Trop. 2021 Jul;219:105931. doi: 10.1016/j.actatropica.2021.105931. Epub 2021 Apr 24.
Ehrlichia spp. are important tick-borne pathogens of animals in Brazil, and Ehrlichia canis is the most prevalent species infecting dogs. Moreover, Ehrlichia minasensis has also recently been identified as a novel ehrlichial agent that infects cattle in Brazil. The objective of this study was to determine whether dogs could be infected by E. minasensis. To investigate this possibility, sera (n = 429) collected from dogs in the Pantanal region were retrospectively analyzed for the presence of antibodies against E. canis and E. minasensis. Canine sera were screened by two isolates of E. canis in indirect immunofluorescence assay (IFA) and the majority (n = 298; 69.4%) had antibodies with endpoint titers ranging from 80 to 327,680. In order to further confirm E. canis-specific antibodies, IFA positive sera were analyzed by ELISA using E. canis-specific peptides (i.e. TRP19 and TRP36 US/BR/CR), which detected E. canis antibodies in 80.2% (239/298) of the dog sera. Fifty-nine (13.7%) samples had detectable antibodies to E. canis by IFA but were negative by E. canis peptide ELISA. These sera were then tested by E. minasensis IFA (Cuiaba strain) as antigen and 67.8% (40/59) were positive (titers ranging from 80 to 20,480). Eleven sera had antibody titers against E. minasensis at least two-fold higher than observed for E. canis and suggests that these dogs were previously infected with E. minasensis. The results of the present study suggest that multiple ehrlichial agents infect dogs in Brazil, which highlights the need to consider different Ehrlichia spp. in Brazilian dogs, particularly in areas where dogs are frequently exposed to multiple tick species. This investigation is the first to provide serologic evidence of E. minasensis infection in dogs from Brazil.
埃立克体属是巴西重要的蜱传动物病原体，其中犬埃立克体是感染犬最常见的物种。此外，最近还发现米纳斯埃立克体是一种新型的蜱传埃立克体病原体，可感染巴西的牛。本研究的目的是确定犬是否可能感染米纳斯埃立克体。为了研究这种可能性，回顾性分析了潘塔纳尔地区犬血清（n=429）中针对犬埃立克体和米纳斯埃立克体的抗体。采用间接免疫荧光试验（IFA）检测了 2 株犬埃立克体分离株，结果显示，大多数（n=298；69.4%）血清具有 80 至 327,680 的终点滴度的抗体。为了进一步确认犬埃立克体特异性抗体，使用犬埃立克体特异性肽（即 TRP19 和 TRP36 US/BR/CR）分析了 IFA 阳性血清，这些肽可检测到 80.2%（239/298）犬血清中的犬埃立克体抗体。59（13.7%）个样本通过 IFA 检测到犬埃立克体抗体，但通过犬埃立克体肽 ELISA 检测为阴性。然后，这些血清用米纳斯埃立克体 IFA（库亚巴株）作为抗原进行检测，结果 67.8%（40/59）为阳性（滴度为 80 至 20,480）。11 个血清的米纳斯埃立克体抗体滴度至少是犬埃立克体的两倍，提示这些犬之前曾感染过米纳斯埃立克体。本研究结果表明，巴西的犬可能感染多种埃立克体病原体，这突出表明，在巴西犬中，特别是在犬经常接触多种蜱的地区，需要考虑不同的埃立克体属。本研究首次提供了巴西犬感染米纳斯埃立克体的血清学证据。
