Complete genome sequence of a novel sea otterpox virus

Parapoxvirus species revisited by whole genome sequencing: A retrospective analysis of bovine virus isolates

Parapoxviruses (PPV) of animals are spread worldwide. While the Orf virus (ORFV) species is a molecularly well-characterized prototype pathogen of small ruminants, the genomes of virus species affecting large ruminants, namely Bovine papular stomatitis virus (BPSV) and Pseudocowpox virus (PCPV), are less well known. Using Nanopore sequencing we retrospectively show the whole genome sequences (WGS) of six BPSV, three PCPV isolates and an attenuated ORFV strain, originating from different geographic locations. A phylogenetic tree shows that the de novo assembled genomes belong to PPV species including WGS of reference PPV. Remarkably, Nanopore sequencing allowed the molecular resolution of inverted terminal repeats (ITR) and the hairpin loop within the de novo assembled WGS. Additionally, peculiarities regarding map location of two genes and the heterogeneity of a genomic region were noted. Details for the molecular variability of an interferon response modulatory gene (ORF116) and the PCPV specificity of gene 073.5 are reported. In summary, WGS gained by Nanopore sequencing allowed analysis of complete PPV genomes and confident virus species attribution within a phylogenetic tree avoiding uncertainty of limited gene-based diagnostics. Nanopore-based WGS provides robust comparison of PPV genomes and reliable identity determination of new Poxviruses.

Detection of Cetacean Poxvirus in Peruvian Common Bottlenose Dolphins (Tursiops truncatus) Using a Pan-Poxvirus PCR

Cetacean poxviruses (CePVs) cause ‘tattoo’ skin lesions in small and large cetaceans worldwide. Although the disease has been known for decades, genomic data for these poxviruses are very limited, with the exception of CePV-Tursiops aduncus, which was completely sequenced in 2020. Using a newly developed pan-pox real-time PCR system targeting a conserved nucleotide sequence located within the Monkeypox virus D6R gene, we rapidly detected the CePV genome in typical skin lesions collected from two Peruvian common bottlenose dolphins (Tursiops truncatus) by-caught off Peru in 1993. Phylogenetic analyses based on the sequencing of the DNA polymerase and DNA topoisomerase genes showed that the two viruses are very closely related to each other, although the dolphins they infected pertained to different ecotypes. The poxviruses described in this study belong to CePV-1, a heterogeneous clade that infects many species of dolphins (Delphinidae) and porpoises (Phocoenidae). Among this clade, the T. truncatus CePVs from Peru were more related to the viruses infecting Delphinidae than to those detected in Phocoenidae. This is the first time that CePVs were identified in free-ranging odontocetes from the Eastern Pacific, surprisingly in 30-year-old samples. These data further suggest a close and long-standing pathogen–host co-evolution, resulting in different lineages of CePVs.

Taxonomic Changes for Human and Animal Viruses, 2018 to 2020

The classification of viruses is relevant to a number of scientific and clinical disciplines, including the practice of diagnostic virology. Here, we provide an update to our previous review of taxonomic changes for disease-causing viruses in humans and vertebrate animals, covering changes between 2018 and 2020. Recent advances in virus taxonomy structure by the International Committee on Taxonomy of Viruses inform this update.

A novel poxvirus isolated from an Egyptian fruit bat in Israel

An Egyptian fruit bat (Rousettus aegyptiacus) from the Zoological Gardens, at Tel Aviv, Israel, showed pox‐like clinical signs including vesicular and nodular skin lesions on the wings. Cell culture isolation, histopathology, electron microscopy and molecular analysis, revealed the presence of a novel bat poxvirus. Future research is needed to determine whether this virus can affect human health.

Genome characterization of cetaceanpox virus from a managed Indo-Pacific bottlenose dolphin (Tursiops aduncus)

Cetaceanpox viruses (CePVs) are associated with a cutaneous disease in cetaceans often referred to as "tattoo" lesions. To date, only partial genomic data are available for CePVs, and thus, they remain unclassified members of the subfamily Chordopoxvirinae within the family Poxviridae. Herein, we describe the first complete CePV genome sequenced from the tattoo lesion of a managed Indo-Pacific bottlenose dolphin (Tursiops aduncus), using next-generation sequencing. The T. aduncus CePV genome (CePV-TA) was determined to encode 120 proteins, including eight genes unique to the CePV-TA and five genes predicted to function as immune-evasion genes. The results of CePV-TA genetic analyses supported the creation of a new chordopoxvirus genus for CePVs. The complete sequencing of a CePV represents an important first step in unraveling the evolutionary relationship and taxonomy of CePVs, and significantly increases our understanding of the genomic characteristics of these chordopoxviruses.

Viral and metazoan poxins are cGAMP-specific nucleases that restrict cGAS-STING signalling

Cytosolic DNA triggers innate immune responses through activation of cyclic GMP–AMP synthase (cGAS) and production of the cyclic dinucleotide second messenger 2′3′ cGAMP^1–4. 2′3′ cGAMP is a potent inducer of immune signaling, but no intracellular nucleases are known to cleave 2′3′ cGAMP and prevent activation of the receptor stimulator of interferon genes (STING)^5–7. Through a biochemical screen analyzing 24 mammalian viruses, here we identify poxvirus immune nucleases (poxins) as a family of 2′3′ cGAMP-specific degrading enzymes. Poxins cleave 2′3′ cGAMP to restrict STING-dependent signaling, and deletion of the poxin gene (B2R) attenuates vaccinia virus replication in vivo. Crystal structures of vaccinia virus poxin in pre- and post-reactive states define the mechanism of selective 2′3′ cGAMP degradation through metal-independent cleavage of the 3′–5′ bond, converting 2′3′ cGAMP into linear Gp[2′–5′]Ap[3′]. Poxins are conserved in mammalian poxviruses, and remarkably, we further identify functional poxin homologues in the genomes of moths and butterflies and the baculoviruses which infect them. Baculovirus and insect host poxin homologues retain selective 2′3′ cGAMP degradation activity, suggesting an ancient role for poxins in cGAS-STING regulation. Our results define poxins as a family of 2′3′ cGAMP-specific nucleases and demonstrate a mechanism for how viruses evade innate immunity.