sante.roperto@unina.it
(SR)
Abstract – Ovine papillomaviruses (OaPVs) were detected and
quantified, for the first time, using droplet digital polymerase chain
reaction (ddPCR) and real-time quantitative PCR (qPCR) via liquid biopsy
of 165 clinically healthy sheep. OaPV DNA was detected in 126 blood
samples (~76.4%). DdPCR detected OaPV DNA in 124
samples; in only two additional samples positive for real-time qPCR,
ddPCR failed to detect the presence of any OaPVs. In 70 of the positive
samples (~55.6%), a single OaPV infection was observed,
12 of which were caused by OaPV1 (~17.1%) and 14 by
OaPV2 (20%). OaPV3 was responsible for 19 single infections
(~27.1%), and OaPV4 for 25 single infections
(~35.7%). Multiple OaPV coinfections were observed in
56 (~44.4%) positive samples. OaPV coinfections caused
by two genotypes were observed in 31 positive samples
(~55.4%), with dual OaPV3/OaPV4 infection being the
most prevalent as seen in 11 blood samples. In addition, five
OaPV1/OaPV4, four OaPV1/OaPV2, four OaPV2/OaPV3, four OaPV1/OaPV3, and
three OaPV2/OaPV4 dual coinfections were also detected. OaPV
coinfections by triple and quadruple genotypes were detected in 24
(~42.8%) and only one (~1.8%) of
coinfected blood samples, respectively. Multiple infections caused by
OaPV1/OaPV3/OaPV4 genotypes were the most prevalent, as observed in 12
(50%) blood samples harboring triple OaPV infections. This study showed
that ddPCR is the most sensitive and accurate assay for OaPV detection
and quantification thus outperforming real-time qPCR in terms of
sensitivity and specificity. Therefore, ddPCR may represent the
molecular diagnostic tool of choice, ultimately providing useful
insights into OaPV molecular epidemiology and field surveillance.
Keywords: droplet digital polymerase chain reaction; liquid
biopsy; molecular epidemiology; ovine papillomavirus; real-time
quantitative PCR.