The subtype C accounts for >50% of HIV type 1 (HIV-1) infections worldwide and it is currently the predominant viral form in South Brazil. Subtype C has been reported in all Brazilian regions; however, the phylogenetic relationship among strains circulating in those regions still remains unclear. This study aimed to investigate the origin and dynamic dispersion of HIV-1 subtype C toward Northeast Brazil. Our phylogenetic analysis suggests that most subtype C strains circulating in Brazil (99%) are descendant from the main lineage whose entrance in the country was previously described in the 1970s. According to the literature, additional introductions of subtype C were reported in the country through the Southeast region and in this study we identified another entry event that occurred most likely through the North region. Furthermore, our analysis suggests that the spread of subtype C to Brazilian Northeastern states occurred through multiple independent introductions of the main lineage that originated in South Brazil between mid-1980s and late 1990s. Despite the observation of eventual new HIV-1 subtype C introductions, our results highlight the predominance of a single lineage of this subtype in Brazil and the importance of South region in its dissemination throughout the country.

中文翻译：

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HIV-1 C 亚型向巴西东北部地区的动态扩散

C 亚型占全球 HIV 1 型 (HIV-1) 感染的 50% 以上，目前是巴西南部的主要病毒形式。巴西所有地区均报告了 C 亚型；然而，在这些地区流行的菌株之间的系统发育关系仍不清楚。本研究旨在调查 HIV-1 C 亚型向巴西东北部的起源和动态扩散。我们的系统发育分析表明，在巴西流行的大多数 C 亚型菌株 (99%) 是 1970 年代进入该国的主要血统的后代。根据文献，该国通过东南地区报道了额外的 C 亚型引入，在本研究中，我们确定了另一个最有可能通过北部地区发生的进入事件。此外，我们的分析表明，C 亚型向巴西东北部各州的传播是通过多次独立引入 1980 年代中期至 1990 年代后期起源于巴西南部的主要血统而发生的。尽管观察到最终新的 HIV-1 C 亚型引入，我们的结果强调了这种亚型的单一谱系在巴西的优势以及南部地区在其在全国传播中的重要性。