Uterine virobiota of healthy mares encompasses distinct papillomavirus genotypes in a no strict host specificity manner

A molecular study to assess the presence of some papillomaviruses was performed on 105 uterine flushings of healthy mares using real time quantitative polymerase chain reaction (qPCR) and digital PCR (dPCR). Bovine, equine, and ovine papillomavirus DNA was detected in 27 uterine flushing samples through dPCR (~ 25.71%); qPCR was able to detect 18 positive samples (~ 17.14%). Differences between the two molecular protocols were significant as shown by McNemar’s test (p˂ 0.005). EcPV DNA was detected in 10 samples by dPCR (~ 9.52%) of uterine samples. Conventional qPCR detected EcPV DNA in 7 samples (~ 6.66). dPCR revealed OaPV1 DNA in 13 samples (12.38%). qPCR revealed OaPV1 DNA in 9 samples (8.57%). BPV DNA was found by dPCR in 4 samples (~ 3.80%); conventional PCR revealed BPV DNA in two uterine flushings, that is ~ 1.90% of healthy uterine matrices. Overall, OaPV1 was the most detected papillomavirus from mare uterus. Similar molecular findings were found in the virobiota of mare vagina. EcPV9 was the most prevalent equine PV genotype. EcPV8, BPV13, ChPV1, ChPV2, OaPV2, OaPV3, and OaPV4 were not detected. This study argues against strict host specificity of BPVs and OaPVs.