Penzes Judit J, Kaelber Jason T
Institute for Quantitative Biomedicine, Rutgers, The State University of New Jersey, Piscataway, NJ 08812, USA.
Department of Entomology, Texas A&M University, College Station, TX 77845, USA.
Viruses. 2025 May 6;17(5):679. doi: 10.3390/v17050679.
Chapparvoviruses (ChPVs) comprise a divergent lineage of the ssDNA virus family and evolved to infect vertebrate animals independently from the subfamily. Despite being pathogenic and widespread in environmental samples and metagenomic assemblies, their structural characterization has proven challenging. Here, we report the first structural analysis of a ChPV, represented by the fish pathogen, Syngnathus scovelli chapparvovirus (SsChPV). We show through the SsChPV structure that the lineage harbors a surface morphology, subunit structure, and multimer interactions that are unique among parvoviruses. The SsChPV capsid evolved a threefold-related depression of α-helices that is analogous to the β-annulus pore of denso- and hamaparvoviruses and may play a role in monomer oligomerization during assembly. As interacting β-strands are absent from the twofold symmetry axis, the viral particle lacks the typical stability and resilience of parvovirus capsids. Although all parvoviruses thus far rely on the threading of large, flexible N-terminal domains to the capsid surface for their intracellular trafficking, our results show that ChPVs completely lack any such N-terminal sequences. This led to the subsequent degradation of their fivefold channel, the site of N-terminus externalization. These findings suggest that ChPVs harbor an infectious pathway that significantly deviates from the rest of the .
细环病毒（ChPVs）是单链DNA病毒家族中一个不同的谱系，独立于该亚科进化而来以感染脊椎动物。尽管它们具有致病性且在环境样本和宏基因组组装中广泛存在，但其结构表征已被证明具有挑战性。在此，我们报告了细环病毒的首次结构分析，以鱼类病原体——海马细环病毒（SsChPV）为代表。通过SsChPV的结构，我们表明该谱系具有细小病毒中独特的表面形态、亚基结构和多聚体相互作用。SsChPV衣壳进化出一种与α-螺旋相关的三重凹陷，类似于致密细小病毒和仓鼠细小病毒的β-环孔，可能在组装过程中单体寡聚化中发挥作用。由于二重对称轴上不存在相互作用的β-链，病毒颗粒缺乏细小病毒衣壳典型的稳定性和弹性。尽管迄今为止所有细小病毒都依赖于将大的、灵活的N端结构域穿入衣壳表面以进行细胞内运输，但我们的结果表明细环病毒完全缺乏任何此类N端序列。这导致其五重通道随后降解，五重通道是N端外化的位点。这些发现表明细环病毒具有一条与该家族其他成员显著不同的感染途径。
