<div>Evidence of a novel cross-species transmission by ovine papillomaviruses</div><div>Short title: OaPV transmission in cattle</div><div>Francesca De Falco<sup>1</sup>, Anna
Cutarelli<sup>2</sup>, Bianca Cuccaro<sup>1</sup>, Cornel
Catoi<sup><b>3</b></sup> , Esterina De Carlo<sup>2</sup>,
Sante Roperto<sup>1*</sup></div><div><b>1</b> Dipartimento di Medicina Veterinaria e delle Produzioni
Animali, Università degli Studi di Napoli Federico II, Napoli, Italia;<b>2</b> Istituto Zooprofilattico Sperimentale del Mezzogiorno,
Portici (NA), Italia: <b>3</b> Pathology Department, Faculty of
Veterinary Medicine, University of Agricultural Sciences and Veterinary
Medicine, Cluj-Napoca, Romania</div><div>Corresponding author: Dr. Sante Roperto</div><div>email:<i>sante.roperto@unina.it</i></div><div><b>Summary</b></div><div>Ovine papillomavirus (OaPV) comprises four genotypes; OaPV1, OaPV2, and
OaPV4 are fibropapillomaviruses within the genus<i>Delta</i> -papillomavirus (<i>Delta-</i> PV<i>)</i> , whereas OaPV3 is
an epitheliotropic virus that belongs to the genus<i>Dyokappa</i> -papillomavirus (<i>Dyokappa-</i> PV<i>)</i> . To date, all
of them have been known to infect sheep only. OaPV1, OaPV2, and OaPV4
have been associated with ovine cutaneous and mucosal fibropapillomas,
while OaPV3 is a key factor in the squamous cell carcinoma (SCC) pathway
of the sheep skin. Peripheral blood mononuclear cell (PBMC) samples
obtained from 128 cattle at public slaughterhouses were investigated
using droplet digital polymerase chain reaction (ddPCR). ddPCR is a
new-generation PCR technique that enables accurate and absolute
quantification of target molecules with high sensitivity and
specificity. All OaPVs were detected by identification and
quantification of nucleic acids using specific fluorescent probes. Of
128 PBMC samples, 100 (~78%) showed OaPV infections.
Further, 42, 35, and 23 PBMC samples showed single, double, and triple
OaPV infections, respectively. OaPV1 was responsible for 22 single
infections, OaPV2 caused 16 single infections, and OaPV3 and OaPV4
caused two single infections each. OaPV1 and OaPV2 were the most
frequent ovine viruses in dual and triple infections. In many PBMC
samples, both ovine <i>Delta-</i> PV and <i>Dyokappa</i> -PV were found to
be transcriptionally active, as shown by the detection and
quantification of E5 oncogene transcripts for OaPV1, L1 transcripts for
OaPV2, E6 and E7 transcripts for OaPV3, and E6 for OaPV4. OaPVs were
found in the blood samples from cattle that shared grasslands rich in
bracken ferns known to contain immunosuppressant substances.
Furthermore, OaPVs were also found in cattle from intensive livestock
farming without any contact with sheep. Because OaPV DNA was detected in
both grass hay and corn silage, it is conceivable that these feed may be
the viral sources.</div><div><b>Keywords:</b> Cross-species transmission; Ovine papillomaviruses;
cattle; blood; grass hay; corn silage.</div>