Divergent poxvirus identified in a non-native black rat from Madagascar

Non-native rodents serve as bridges between anthropogenic and natural landscapes. They have expanded across the planet alongside humans while bringing competition, predation, and pathogens, such as poxviruses, to naïve ecosystems. Although rodents serve as reservoirs for multiple zoonotic poxviruses, limited research has focused on rodents for identification of unknown poxviruses. Here, we characterized a divergent metagenome-assembled poxvirus, madamurpox virus, from the oral swab of a black rat in southeastern Madagascar. While madamurpox virus shares a phylogenetic relationship with human-infecting molluscum contagiosum virus and bat-associated Rousettus poxvirus, madamurpox virus presents extensive genetic variation and represents a putative new species and genus in the Chordopoxvirinae subfamily. Further, although madamurpox virus has a similar genome organization to molluscum contagiosum virus and Rousettus poxvirus, madamurpox virus lacks key immune modulators seen in molluscum contagiosum virus. Our findings highlight that substantial unexplored poxvirus diversity likely exists in rodents, with globally distributed, non-native rodent populations of increased interest.