Host Jump in BPVs: is Species- Specificity Still Appropriate for Papillomaviruses?

Into the family Papillomaviridae, four different genera Delta Epsilon Xi and Dyoxi include the fifteen Bovine Papillomaviruses (BPVs) that have been characterized so far in cattle, even though it has been estimated that type number may exceed 20. Current classification system assumes that the host species in which a PV was firstly detected, is the original host, and the identified types are therefore named after it. Papillomaviruses (PVs) are indeed generally considered to be highly specific for their hosts; however, within the Delta-PVs, BPV types 1, 2 and 13 are well recognized to infect multiple species. Our results deepen the knowledge on circulation of BPV types in Italy and further contribute to a better understanding on their intra-genus variability. Besides observing that BPVs can contribute to the spread of other epitheliotropic viruses, we confirmed the host-jumping ability of the Delta PVs. The presence of co-infections between BPVs belonging to Delta and Xi genera in the healthy skin and mucosa of chamois and deer strongly suggest the reservoir role of wild ruminants belonging to the Bovidae and Cervidae families for domestic ruminant PVs. Furthermore, we identified the Eqsarc1 variant in healthy subjects and in non-equid species, suggesting an “equine adaptation” of the virus variant.