Virologica Sinica最新文献

Protein nanotubes (PNTs) can be regarded as two-dimensional (2D) lattices with p1 or p2 symmetry rolled into tubes. However, attempts to re-assemble their building blocks into stable 2D nanomaterials often fail. Here, starting from two baculoviral capsid proteins, we screened protein variants for the in vitro assembly of various nanotubes and nanosheets. These high-order assemblies were structurally characterized by cryo-electron microscopy techniques. Interfacial analysis of three groups of PNTs revealed that helical heterogeneity is largely the result of the redundancy of p2 symmetry-related contacting interfaces. The assembled nanosheets showed similar interfacial networks to their nanotubular counterparts. In addition, foreign macromolecules could be efficiently displayed on the size-controllable double-layered nanosheets. This study sheds light on the rational design of flexible nanosheets, and it also provides novel 2D protein scaffolds for developing biocompatible materials.

Emerging tick-borne viruses are posing an increasing health concern. However, there is limited knowledge about the distribution characteristics of tick virome in Yunnan Province, southwestern China, where it is distinguished by its diverse eco-climatic zones and rich biodiversity, making it a hotspot for studying tick-borne pathogens. The present study aimed to explore the diversity and ecological characteristics of tick virome in Yunnan Province, especially to identify novel potentially pathogenic viruses threatening human and vertebrate animals, and to investigate host-specific viral tropisms and their transmission characteristics. Using a meta-transcriptomic approach, the study analyzed the viromes of 448 individual ticks and approximately 10,000 eggs collected from nine counties with different hosts, altitudes and landscapes. The ticks encompassed eight species across four genera. The study focused on delineating virome diversity profiles, evaluating host-specific viral tropisms, and investigating potential transovarial transmission through viral contigs identification and Sanger sequencing. The study identified 53 viral families, revealing significant virome diversity and geographic and environmental specificity. Haemaphysalis and Ixodes ticks exhibited greater viral richness and abundance, with host taxonomy being a primary influencing factor. We determined 102 viral genomes encompassing 35 species, comprising 15 novel viruses identified when their RNA-dependent RNA polymerase/DNA polymerase sequences exhibited <90% amino acid identity to known viruses. The novel vectors for vertebrate-related or potentially pathogenic viruses were also detected, thus providing new insights into transmission cycles. The evidence for transovarial transmission was reinforced by the absence of significant differences in Chuviridae and Nairoviridae families between female ticks and their eggs. These findings underscore the necessity of continuous surveillance to avert the spillover of emerging pathogens.

With recent advances in synthetic biology methods, the genomes of several large DNA viruses have been de novo synthesized and assembled, leading to the functional rescue of the respective viruses. Pseudorabies virus (PRV), a large DNA virus belonging to the family Herpesviridae, causes severe diseases in swine, resulting in significant economic losses to the global pig farming industry. Genome editing is crucial for attenuating virulence and developing safer vaccines for PRV. However, its complex repetitive sequences and extremely high GC-rich genome pose significant challenges for genetic manipulation. In this study, we developed a PRV genome assembly platform using yeast-based transformation-associated recombination (TAR) technology. The genome of a prevalent genotype II variant strain, PRV-GX-2011 (GenBank number PV405324.1), was divided into nine A-level fragments and cloned into vectors via TAR. Subsequently, three B-level fragments were generated by recombining three A-level fragments each. In vitro CRISPR/Cas9-mediated editing was introduced to insert an egfp gene into the non-coding intergenic region between UL23 and UL22 genes. Infectious viruses were rescued by co-transfection of linearized B-level fragments in Vero cells, and an isolated virus, PRV-GX-Syn1, was purified via plaque assay. While PRV-GX-Syn1 exhibited reduced viral titer and smaller plaque size compared to the parental strain, its morphological characteristics remained indistinguishable from the parental virus. In BALB/c mice, PRV-GX-Syn1 caused lethal infection, producing lung pathology comparable to the parental strain. This TAR-based platform offers faster and more flexible genomic modification of PRV, facilitating both basic research and PRV-based vaccine vectors.