Molecular and genomic characterization of a novel equine molluscum contagiosum-like virus

Abstract

Cases of pox-like lesions in horses and donkeys have been associated with poxviruses belonging to different genera of the family Poxviridae. These include the orthopoxviruses vaccinia virus (VACV), horsepoxvirus (HPXV) and cowpoxvirus (CPXV), as well as a potentially novel parapoxvirus and molluscum contagiosum virus (MOCV). However, with the exception of VACV, HPXV and CPXV, the genomic characterization of the causative agents remains largely elusive with only single short genome fragments available. Here we present the first full-length genome sequence of an equine molluscum contagiosum-like virus (EMCLV) directly determined from skin biopsies of a horse with generalized papular dermatitis. Histopathological analysis of the lesions revealed severe epidermal hyperplasia with numerous eosinophilic inclusion bodies within keratinocytes. Virions were detected in the lesions in embedded tissue by transmission electron microscopy. The genome sequence determined by next- and third-generation sequencing comprises 166 843 nt with inverted terminal repeats (ITRs) of 3473 nt. Overall, 20 of the predicted 159 ORFs have no equivalents in other poxviruses. Intriguingly, two of these ORFs were identified to encode homologues of mammalian proteins involved in immune signalling pathways, namely secreted and transmembrane protein 1 (SECTM1) and insulin growth factor-like family receptor 1 (IGFLR1), that were not described in any virus family so far. Phylogenetic analysis with all relevant representatives of the Poxviridae suggests that EMCLV should be nominated as a new species within the genus Molluscipoxvirus.

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

“…WGS will also facilitate the classification of new virus genomes suspected to belong to PPV species, especially when derived from wildlife ( Dalton et al, 2023 ; Ehmann et al, 2020 ; McInnes et al, 2006 ; Pfaff F, 2023 ; Wibbelt et al, 2017 ) . For example, the muskox-derived virus MxOV is clearly attributed by WGS as well as by eight viral genes to the ORFV species ( Fig.…”

Downregulation of HLA-I by the molluscum contagiosum virus mc080 impacts NK-cell recognition and promotes CD8+ T-cell evasion

“…The fact that MC080 and MC033 do not align closely with a human MHC-I implies there has been an evolutionarily complex route from host capture to the MCV genome. The ancient nature of their gene capture is further supported by the identification of homologues to both mc033 and mc080 in the recently characterized equine molluscum contagiosum-like virus (Ehmann et al ., in press) [38]. While the function of MC033 has still to be defined, the modulation of endogenous HLA-I expression by MC080 is associated both with the evasion of MHC-I restricted cytotoxic T cells and modulating NK-cell activation.…”

Partial genome characterization of a novel potentially zoonotic parapoxvirus in a horse, Finland

“…PPV genomes are usually 130-140 kb ( 2, 3 ). Recently, poxviruses have emerged in humans and horses ( 4, 5 ).…”