Embrapa Pecuária Sudeste, Rodovia Washington Luiz, Km 234, Fazenda Canchim, zip code: 13560-970, São Carlos, SP, Brazil.
Departamento de Zootecnia - Universidade Estadual Paulista "Júlio de Mesquita Filho", Via de Acesso Prof. Paulo Donato Castellane s/n, zip code: 14884-900, Jaboticabal, SP, Brazil.
Vet Immunol Immunopathol. 2020 Dec;230:110132. doi: 10.1016/j.vetimm.2020.110132. Epub 2020 Oct 15.
Different allelic forms of bovine CD4 were previously described in cattle and were also observed in Canchim calves examined in the present experiment. However, the functional relevance of these different CD4 phenotypes has not yet been investigated. CD4 + T helper cells are known to play a central role in immune control against Babesia bovis infection. Thus, our study aimed to compare the profiles of immune cells, specific antibody titers and blood infection levels measured by qPCR (quantitative polymerase chain reaction) in calves naturally infected with B. bovis, phenotyped as CD4- (absence of anti-CD4 staining), CD4 + (intermediate staining) or CD4 ++ (high staining). The CD4 mRNA precursor was also measured in these animals. Calves with the CD4- phenotype showed higher amounts of B. bovis DNA in blood samples, compared to the other CD4 phenotypes. It was also observed that these calves with higher levels of infection had lower amounts of natural killer cells and higher expression of the CD4 gene, which can be interpreted as a compensation for the failure of the altered CD4 receptor to recognize relevant B. bovis epitopes.
先前在牛中描述了不同的牛 CD4 等位基因形式，在本实验中检查的 Canchim 小牛中也观察到了这些等位基因形式。然而，这些不同 CD4 表型的功能相关性尚未得到研究。已知 CD4+辅助性 T 细胞在控制对牛巴贝斯虫感染的免疫中发挥核心作用。因此，我们的研究旨在比较自然感染牛巴贝斯虫的小牛的免疫细胞谱、特异性抗体滴度和通过 qPCR（定量聚合酶链反应）测量的血液感染水平，这些小牛表型为 CD4-（缺乏抗 CD4 染色）、CD4+（中等染色）或 CD4++（高染色）。还测量了这些动物的 CD4 mRNA 前体。与其他 CD4 表型相比，CD4-表型的小牛血液样本中含有更多的牛巴贝斯虫 DNA。还观察到，这些感染水平较高的小牛自然杀伤细胞数量较少，CD4 基因表达较高，这可以解释为对改变的 CD4 受体无法识别相关牛巴贝斯虫表位的补偿。
