PDF(Pubmed)
Abstract：
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 Rhipicephalus 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 Haemaphysalis flava 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. In silico 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.
摘要：
蜱传的正黄病毒（TBF）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Rhipicephalus蜱中发现了第四个基础组：赞比亚的Mpulungu黄病毒（MPFV）和塞内加尔的Ngoye病毒（NGOV）。尽管尝试,在脊椎动物和无脊椎动物细胞系中分离这些病毒，或用含病毒的匀浆在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Xänyáng的黄条上发现的信阳黄病毒（XiFV），河南省,中国。系统发育分析表明,XiFV与MPFV和NGOV的关系最为密切,标志着这种蜱正黄病毒在亚洲的首次鉴定。我们开发了一种逆转录酶定量PCR检测方法来筛选野生收集的蜱和卵，成年女性的绝对感染率为20.75％，卵离合器的绝对感染率为15.19％，这表明XiFV可能通过经静脉曲张传播。要检查潜在的主机范围，二核苷酸组成分析表明，XiFV，与感染脊椎动物的TBF相比，MPFV和NGOV与经典的昆虫特异性正黄病毒具有更紧密的组成，这表明XiFV可能是一种只有蜱的正黄病毒。此外,XiFV和MPFV在prM蛋白中都缺乏弗林蛋白酶切割位点，与其他TBF不同，这表明这些病毒可能存在于有偏见的未成熟粒子状态。为了检查这一点，产生了具有XIFV-prME（bXiFV）的嵌合Binjari病毒，通过SDS-PAGE和负染色透射电子显微镜纯化和分析，表明原型正黄病毒大小（〜50nm）和偏向未切割的PRM。在3个非翻译区的计算机结构分析中，XiFV形成了多达五个含有假结的茎环和典型的正黄病毒哑铃元件，提示多种抗核糖核酸酶RNA结构的潜力。
