The genome sequence of Pavonine herpesvirus 1, a novel Mardivirus infecting peafowl

Avian alphaherpesviruses of the genus Mardivirus include several economically important pathogens, such as the tumour-causing Mareks disease virus (MDV-1) of chickens. However, the diversity of related viruses in wild and non-model avian hosts remains poorly characterised. Here, we describe the genome of Pavonine herpesvirus 1 (PaHv1), a novel Mardivirus infecting peafowl (Pavo spp.). Through de novo assembly of reads generated from whole-genome sequencing of 370 captive peafowl, we generated a single viral genomic scaffold of 134,149 bp in length and an estimated total genome size of [~]146 kbp following reconstruction of terminal repeat regions. PaHv1 exhibits canonical Mardivirus UL-IRL-IRS-US genomic architecture and encodes 169 open reading frames, of which 82 have clear orthologs in other Mardivirus species. Comparative genomic analyses revealed strong syntenic concordance between PaHv1, MDV-1, MDV-2 and Meleagrid alphaherpesvirus 1 (HVT), but with notable absences of the Meq oncogene, viral interleukin-8 (vIL8), and a truncated pp38 gene - genes known to underpin oncogenicity and virulence in MDV-1. Phylogenetic analysis places PaHv1 firmly within the Mardivirus genus as a sister to the poultry-associated MDV-1 and MDV-2 viruses, but distinct from a previously described Phasianid herpesvirus with a partial DNA terminase sequence. PaHv1 was detected predominantly in feather-derived samples, consistent with replication or persistence in the feather follicle epithelium. Taken together, these findings identify PaHv1 as a novel, likely non-oncogenic Mardivirus, expanding our understanding of herpesvirus diversity, evolution and host association in galliform birds. ImportanceHerpesviruses cause several economically important diseases in domesticated birds, including Mareks disease, duck plague and infectious laryngotracheitis. Despite this, our understanding of herpesviruses infecting wild and semi-wild birds remains limited. Here, we present the genome of Pavonine herpesvirus 1 (PaHv1), a virus in the Mardivirus genus which infects peafowl. Based on comparative genomics with other Mardivirus species, we note the absence of several genes important for the high virulence of Mareks Disease Virus, such as the Meq oncogene, viral interleukin-8 and a truncated pp38. This, taken together with absence of clinical disease in preliminary observations, suggests that PaHv1 causes either a subclinical infection or one with mild symptoms. Our work expands the known evolutionary breadth of avian herpesviruses in the Mardivirus genus. In addition, PaHv1 may provide a useful starting point for the development of novel vaccine vectors for pathogenic herpesvirus infections.