African swine fever (ASF) is a highly contagious and severe hemorrhagic viral disease of domestic pigs. The analysis of variable regions of African swine fever virus (ASFV) genome led to more genotypic and serotypic information about circulating strains. The present study aimed at investigating the genetic diversity of ASFV strains in symptomatic pigs in South Kivu province of the Democratic Republic of Congo (DRC). Blood samples collected from 391 ASF symptomatic domestic pigs in 6 of 8 districts in South Kivu were screened for the presence of ASFV, using a VP73 gene-specific polymerase chain reaction (PCR) with the universal primer set PPA1-PPA2. To genotype the strains, we sequenced and compared the nucleotide sequences of PPA-positive samples at three loci: the C-terminus of B646L gene encoding the p72 protein, the E183L gene encoding the p54 protein, and the central hypervariable region (CVR) of the B602L gene encoding the J9L protein. In addition, to serotype and discriminate between closely related strains, the EP402L (CD2v) gene and the intergenic region between the I73R and I329L genes were analyzed. ASFV was confirmed in 26 of 391 pigs tested. However, only 19 and 15 PPA-positive samples, respectively, were successfully sequenced and phylogenetically analyzed for p72 (B646L) and p54 (E183L). All the ASFV studied were of genotype X. The CVR tetrameric repeat clustered the ASFV strains in two subgroups: the Uvira subgroup (10 TRS repeats, AAAABNAABA) and another subgroup from all other strains (8 TRS repeats, AABNAABA). The phylogenetic analysis of the EP402L gene clustered all the strains into CD2v serogroup 7. Analyzing the intergenic region between I73R and I329L genes revealed that the strains were identical but contained a deletion of a 33-nucleotide internal repeat sequence compared to ASFV strain Kenya 1950. ASFV genotype X and serogroup 7 was identified in the ASF disease outbreaks in South Kivu province of DRC in 2018–2019. This represents the first report of ASFV genotype X in DRC. CVR tetrameric repeat sequences clustered the ASFV strains studied in two subgroups. Our finding emphasizes the need for improved coordination of the control of ASF.

中文翻译：

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首次在刚果民主共和国出现症状的猪中检测到非洲猪瘟 (ASF) 病毒基因型 X 和血清群 7。


非洲猪瘟（ASF）是家猪的一种高度传染性、严重的出血性病毒性疾病。对非洲猪瘟病毒（ASFV）基因组可变区域的分析获得了有关流行毒株的更多基因型和血清型信息。本研究旨在调查刚果民主共和国 (DRC) 南基伍省有症状猪的 ASFV 毒株的遗传多样性。使用 VP73 基因特异性聚合酶链反应 (PCR) 和通用引物组 PPA1-PPA2，从南基伍省 8 个地区中的 6 个地区采集的 391 头有 ASF 症状的家猪的血液样本中筛查 ASFV 的存在。为了对菌株进行基因分型，我们对 PPA 阳性样品的三个位点的核苷酸序列进行了测序和比较：编码 p72 蛋白的 B646L 基因的 C 端、编码 p54 蛋白的 E183L 基因以及编码 p54 蛋白的中央高变区 (CVR)。编码J9L蛋白的B602L基因。此外，为了对密切相关的菌株进行血清分型和区分，还分析了 EP402L (CD2v) 基因以及 I73R 和 I329L 基因之间的基因间区域。在 391 头测试的猪中，有 26 头被确诊为 ASFV。然而，只有 19 和 15 个 PPA 阳性样本分别成功完成了 p72 (B646L) 和 p54 (E183L) 的测序和系统发育分析。研究的所有 ASFV 均为 X 基因型。CVR 四聚体重复将 ASFV 毒株分为两个亚组：Uvira 亚组（10 个 TRS 重复，AAAABNAABA）和来自所有其他毒株的另一个亚组（8 个 TRS 重复，AABNAABA）。 EP402L 基因的系统发育分析将所有菌株聚类为 CD2v 血清群 7。 分析 I73R 和 I329L 基因之间的基因间区域显示，与肯尼亚 1950 年 ASFV 毒株相比，这些毒株相同，但包含 33 核苷酸内部重复序列的删除。在南基伍省 ASF 疾病暴发中鉴定出 ASFV 基因型 X 和血清群 7 2018-2019 年刚果民主共和国省。这是刚果民主共和国首次报告 X 基因型 ASFV。 CVR 四聚体重复序列将所研究的 ASFV 毒株分为两个亚组。我们的发现强调需要改进非洲猪瘟控制的协调。