The transactivator of transcription (Tat) is a key HIV regulatory protein. We aimed to identify the frequency of key polymorphisms in HIV-1C compared with HIV-1B Tat protein, chiefly in the cysteine-, arginine-, and glutamine-rich domains and identify novel point mutations in HIV-1B and C sequences from Southern Brazil. This study was the first to investigate the genetic diversity and point mutations within HIV-1 Tat C in a Brazilian cohort. This was an observational, cross-sectional study, which included sequences of HIV-1B (n = 20) and HIV-1C (n = 21) from Southern Brazil. Additionally, 344 HIV-1C sequences were obtained from the Los Alamos database: 29 from Brazil and 315 from Africa, Asia, and Europe. The frequency of C31S substitution on HIV-1 Tat C in Brazil was 82% vs. 10% in the HIV-1B group (p < 0.0001). The frequency of the R57S substitution among the HIV-1C sequences from Brazil was 74% vs. 20% in HIV-1B (p = 0.004), and that of substitution Q63E in HIV-1C was 80% and 20% in HIV-1B (p < 0.0001). The mutation P60Q was more frequent in HIV-1B than in HIV-1C (55% and 6.12%, respectively, p < 0.0001)). Novel point mutations in the HIV-1C and B Tat functional domains were described. The frequency of C31S and other key point mutations in HIV-1 Tat C in Brazil were similar to those described in Africa, although lower than those in India. The Tat-B and C sequences found in Southern Brazil are consistent with biological differences and have potential implications for HIV-1 subtype pathogenesis.

转录反式激活蛋白 (Tat) 是一种关键的 HIV 调节蛋白。我们的目的是确定与 HIV-1B Tat 蛋白相比，HIV-1C 中关键多态性的频率，主要是富含半胱氨酸、精氨酸和谷氨酰胺的结构域，并确定来自巴西南部的 HIV-1B 和 C 序列中的新点突变。这项研究首次在巴西队列中调查了 HIV-1 Tat C 的遗传多样性和点突变。这是一项观察性横断面研究，其中包括来自巴西南部的 HIV-1B ( n = 20) 和 HIV-1C ( n = 21) 序列。此外，从洛斯阿拉莫斯数据库获得了 344 个 HIV-1C 序列：29 个来自巴西，315 个来自非洲、亚洲和欧洲。巴西 HIV-1 Tat C 的 C31S 取代频率为 82%，而 HIV-1B 组为 10% ( p < 0.0001)。巴西 HIV-1C 序列中 R57S 替换的频率为 74%，HIV-1B 中为 20% ( p = 0.004)，HIV-1C 中 Q63E 替换频率为 80%，HIV-1B 中为 20% （ p <0.0001）。 P60Q 突变在 HIV-1B 中比在 HIV-1C 中更常见（分别为 55% 和 6.12%， p < 0.0001））。描述了 HIV-1C 和 B Tat 功能域的新点突变。巴西 HIV-1 Tat C 中 C31S 和其他关键点突变的频率与非洲相似，但低于印度。在巴西南部发现的 Tat-B 和 C 序列与生物学差异一致，对 HIV-1 亚型发病机制具有潜在影响。