College of Veterinary Medicine, Hunan Agricultural University, Changsha, Hunan Province, PR China.
Children's Medical Center, Hunan Provincial People's Hospital, Changsha, PR China.
J Gen Virol. 2024 May;105(5). doi: 10.1099/jgv.0.001991.
Tick-borne orthoflaviviruses (TBFs) are classified into three conventional groups based on genetics and ecology: mammalian, seabird and probable-TBF group. Recently, a fourth basal group has been identified in ticks from Africa: Mpulungu flavivirus (MPFV) in Zambia and Ngoye virus (NGOV) in Senegal. Despite attempts, isolating these viruses in vertebrate and invertebrate cell lines or intracerebral injection of newborn mice with virus-containing homogenates has remained unsuccessful. In this study, we report the discovery of Xinyang flavivirus (XiFV) in ticks from Xìnyáng, Henan Province, China. Phylogenetic analysis shows that XiFV was most closely related to MPFV and NGOV, marking the first identification of this tick orthoflavivirus group in Asia. We developed a reverse transcriptase quantitative PCR assay to screen wild-collected ticks and egg clutches, with absolute infection rates of 20.75 % in adult females and 15.19 % in egg clutches, suggesting that XiFV could be potentially spread through transovarial transmission. To examine potential host range, dinucleotide composition analyses revealed that XiFV, MPFV and NGOV share a closer composition to classical insect-specific orthoflaviviruses than to vertebrate-infecting TBFs, suggesting that XiFV could be a tick-only orthoflavivirus. Additionally, both XiFV and MPFV lack a furin cleavage site in the prM protein, unlike other TBFs, suggesting these viruses might exist towards a biased immature particle state. To examine this, chimeric Binjari virus with XIFV-prME (bXiFV) was generated, purified and analysed by SDS-PAGE and negative-stain transmission electron microscopy, suggesting prototypical orthoflavivirus size (~50 nm) and bias towards uncleaved prM. structural analyses of the 3'-untranslated regions show that XiFV forms up to five pseudo-knot-containing stem-loops and a prototypical orthoflavivirus dumbbell element, suggesting the potential for multiple exoribonuclease-resistant RNA structures.
蜱传黄病毒（TBFs）根据遗传学和生态学分为三个常规组：哺乳动物、海鸟和可能的 TBF 组。最近，在非洲的蜱中发现了第四个基础组：赞比亚的姆普伦古黄病毒（MPFV）和塞内加尔的恩戈耶病毒（NGOV）。尽管进行了尝试，但在脊椎动物和无脊椎动物细胞系中分离这些病毒或用含有病毒的匀浆脑内注射新生小鼠仍然不成功。在这项研究中，我们报告了在中国河南省信阳市的蜱中发现的信阳黄病毒（XiFV）。系统发育分析表明，XiFV 与 MPFV 和 NGOV 最为密切相关，标志着该蜱传黄病毒组在亚洲的首次鉴定。我们开发了一种逆转录定量 PCR 检测法来筛选野外采集的蜱和卵囊，在成年雌性中的绝对感染率为 20.75%，在卵囊中为 15.19%，表明 XiFV 可能通过经卵传递传播。为了检查潜在的宿主范围，二核苷酸组成分析表明，XiFV、MPFV 和 NGOV 与经典昆虫特异性黄病毒的组成更为接近，而与感染脊椎动物的 TBFs 相比，这表明 XiFV 可能是一种仅感染蜱的黄病毒。此外，与其他 TBFs 不同，XiFV 和 MPFV 在 prM 蛋白中缺乏弗林裂解位点，这表明这些病毒可能存在偏向不成熟颗粒状态的倾向。为了检查这一点，生成了具有 XIFV-prME（bXiFV）的嵌合 Binjari 病毒，通过 SDS-PAGE 和负染透射电子显微镜进行了纯化和分析，表明具有典型的黄病毒大小（~50nm）和偏向未裂解的 prM。3'非翻译区的结构分析表明，XiFV 形成多达五个含有假结的茎环和典型的黄病毒哑铃元件，表明存在多个外切核酸酶抗性 RNA 结构的潜力。
