RT Journal Article SR Electronic(1) A1 Roperto, Sante A1 Comazzi, Stefano A1 Ciusani, Emilio A1 Paolini, Francesca A1 Borzacchiello, Giuseppe A1 Esposito, Iolanda A1 LucĂ , Roberta A1 Russo, Valeria A1 Urraro, Chiara A1 Venuti, Aldo A1 Roperto, FrancoYR 2011 T1 PBMCs are additional sites of productive infection of bovine papillomavirus type 2 JF Journal of General Virology, VO 92 IS 8 SP 1787 OP 1794 DO https://doi.org/10.1099/vir.0.031740-0 PB Microbiology Society, SN 1465-2099, AB Bovine papillomavirus type 2 (BPV-2) is an oncogenic virus infecting both epithelial and mesenchymal cells. Its life cycle, similar to other papillomaviruses (PVs), appears to be linked to epithelial differentiation. Human and bovine PVs have been known to reside in a latent, episomal form in PBMCs; therefore, it is believed that blood cells, like all mesenchymal cells, function as non-permissive carriers. Here, for the first time in veterinary and comparative medicine, the BPV-2 E5 oncoprotein and the major structural L1 capsid protein, known to be expressed only in productive infections, were shown to occur in defined subsets of PBMCs. E5 oncoprotein was detected in sorted T- and B-cells as well as in monocytes by flow cytometry and Western blot analysis. However, CD4+ and CD8+ lymphocytes appeared to be the main circulating targets of the virus, thus possibly representing the most important reservoir of active BPV-2 in blood. L1 protein was identified by flow cytometry in a population of blood cells recognized as lymphocytes by morphological scatter properties. Western blot analysis was performed on lysates obtained from the sorted subpopulations of PBMCs and detected L1 protein in CD4+ and CD8+ cells only. Thus, this study showed that CD4+ and CD8+ lymphocytes are permissive for BPV-2 and are new, hitherto unknown sites of productive PV infection. In light of these observations, the life cycle of PVs needs to be revisited to gain novel insights into the epidemiology of BPV infection and the pathogenesis of related diseases., UL https://www.microbiologyresearch.org/content/journal/jgv/10.1099/vir.0.031740-0