Detection and quantification of bovine papillomavirus DNA by digital droplet PCR in sheep blood

Molecular detection of transcriptionally active ovine papillomaviruses in commercial equine semen

Virological evaluation was performed on equine semen to detect the presence of papillomaviruses (PVs) using droplet digital polymerase chain reaction (ddPCR) as the aim of this study was to investigate whether the sperm from asymptomatic stallions harbors ovine papillomaviruses (OaPVs). Twenty-seven semen samples were analyzed, 18 of which were commercially acquired. The remaining nine samples comprising semen and peripheral blood, were collected from nine stallions with no apparent signs of PV-related diseases during clinical examination at the Didactic Veterinary University Hospital (DVUH) of Naples. OaPV was detected in 26 semen samples. OaPV1 was the most prevalent virus infecting equine semen. OaPV1 infected 21 semen samples (~80.8%) and showed a high number of DNA and RNA copies per microliter. qPCR was used to detect OaPV1 DNA in the 18 semen samples. ddPCR was used to detect and quantify the expression of OaPV2, OaPV3, and OaPV4. qPCR failed to detect DNA for these genotypes. Additionally, ddPCR was used to detect the transcriptionally active OaPV1 in six blood and semen samples from the same stallion. ddPCR failed to detect any nucleic acids in OaPVs in peripheral blood samples from the three stallions. In one semen sample, ddPCR detected OaPV1 DNA but failed to detect any nucleic acid in the remaining two semen samples, and peripheral blood from the same animals of the remaining 18 semen samples was not available, OaPV1 and OaPV4 were responsible for nine and five single infections, respectively. No single infections with either OaPV3 or OaPV4 were seen.

Clinico-histopathological and molecular detection of small ruminants' papillomaviruses in Iran

BACKGROUND

Papilloma DNA viruses are one of the viruses that cause skin lesions in ruminants.

OBJECTIVES

The clinical, histopathological and molecular characteristics of cutaneous papilloma in ruminants in Iran are to be investigated in this study.

METHODS

Samples were collected from 19 small ruminants (5 sheep and 14 goats) with various papillomatosis lesions. The samples taken were studied with histopathological and molecular techniques.

RESULTS

In clinical terms, the lesions appeared in different sizes, ranging from 0.5 to 11 cm, and the cauliflower exophytic masses appeared in other parts of the animal's body. In the limbs, most papilloma lesions have been seen (42.1%). In histopathological examination, perinuclear vacuolation epidermal granule layer with various degrees of hypergranulosis, hyperkeratosis, acanthosis, orthokeratosis and parakeratosis were seen. Moreover, all the suspected samples were positive for papillomavirus using the polymerase chain reaction technique.

CONCLUSIONS

Although the prevalence of papillomaviruses in Iranian sheep and goats is low, it seems necessary to distinguish them from other viral skin diseases, such as cutaneous contagious ecthyma, using molecular techniques and histopathology.

Development of a touchdown droplet digital PCR assay for the detection and quantitation of human papillomavirus 16 and 18 from self-collected anal samples

IMPORTANCE

The quantity of the human papillomavirus (HPV) is associated with disease outcome. We designed an accurate and precise digital PCR assay for quantitating HPV in anal samples, a sample type that is typically problematic due to the presence of PCR inhibitors.

Detection and Quantification of Nocardia crassostreae, an Emerging Pathogen, in Mytilus galloprovincialis in the Mediterranean Sea Using Droplet Digital PCR

Nocardia crassostreae is a novel pathogen responsible for infections in oysters (Crassostrea gigas) and mussels (Mytilus galloprovincialis). N. crassostreae is also responsible for nocardiosis both in immunocompetent and immunocompromised patients. We investigated N. crassostreae DNA in mussels grown in marine sites of the Mediterranean Sea in the Campania Region. We examined 185 mussel pooled samples by droplet digital PCR (ddPCR) and real-time quantitative PCR (qPCR), each pool composed of 10 mussels and 149 individual mussels. ddPCR detected N. crassostreae DNA in 48 mussel pooled samples and in 23 individual mussel samples. qPCR detected N. crassostreae DNA in six pooled samples and six individual mussel samples. The two molecular assays for the detection of N. crassostreae DNA showed significant differences both in the pooled and in individual samples. Our study demonstrated that ddPCR outperformed real-time qPCR for N. crassostreae DNA detection, thus confirming that ddPCR technology can identify the pathogens in many infectious diseases with high sensitivity and specificity. Furthermore, in individual mussels showing histological lesions due to N. crassostreae, the lowest copy number/microliter detected by ddPCR of this pathogen was 0.3, which suggests that this dose could be enough to cause infections of N. crassostreae in mussels.

Prevalence and genotype distribution of caprine papillomavirus in peripheral blood of healthy goats in farms from three European countries

Caprine papillomaviruses (ChPVs, Capra hircus papillomaviruses) were detected and quantified for the first time using droplet digital polymerase chain reaction (ddPCR) in blood samples of 374 clinically healthy goats from farms located in Italy, Romania, and Serbia. Overall, ddPCR revealed ChPV DNA in 78 of the 374 examined samples, indicating that ~21% of the goats harbored circulating papillomavirus DNA. In particular, in Italian goat farms, ChPV genotypes were detected and quantified in 58 of 157 blood samples (~37%), 11 of 117 samples from Serbian farms (~9.4%), and 9 of 100 from Romanian blood samples (9%). Blood samples from Italian goat farms showed a high prevalence of ChPV1, which was detected in 45 samples (28.6%). The ChPV2 genotype was detected in 13 samples (~8.3%). Therefore, significant differences in prevalence and genotype distributions were observed. On Serbian and Romanian farms, no significant differences were observed in the genotype prevalence of ChPVs. Molecular findings are consistent with ChPV prevalence, characterized by a territorial distribution similar to that of papillomaviruses in other mammalian species. Furthermore, this study showed that ddPCR is a very sensitive and accurate assay for ChPV detection and quantification. The ddPCR may be the molecular diagnostic tool of choice, ultimately providing useful insights into the molecular epidemiology and field surveillance of ChPV.

Possible etiological association of ovine papillomaviruses with bladder tumors in cattle

INTRODUCTION

Bladder tumors of cattle are very uncommon accounting from 0.1% to 0.01% of all bovine malignancies. Bladder tumors are common in cattle grazing on bracken fern-infested pasturelands. Bovine papillomaviruses have a crucial role in tumors of bovine urinary bladder.

AIM OF THE STUDY

To investigate the potential association of ovine papillomavirus (OaPV) infection with bladder carcinogenesis of cattle.

METHODS

Droplet digital PCR was used to detect and quantify the nucleic acids of OaPVs in bladder tumors of cattle that were collected at public and private slaughterhouses.

RESULTS

OaPV DNA and RNA were detected and quantified in 10 bladder tumors of cattle that were tested negative for bovine papillomaviruses. The most prevalent genotypes were OaPV1 and OaPV2. OaPV4 was rarely observed. Furthermore, we detected a significant overexpression and hyperphosphorylation of pRb and a significant overexpression and activation of the calpain-1 as well as a significant overexpression of E2F3 and of phosphorylated (activated) PDGFβR in neoplastic bladders in comparison with healthy bladders, which suggests that E2F3 and PDGFβR may play an important role in OaPV-mediated molecular pathways that lead to bladder carcinogenesis.

CONCLUSION

In all tumors, OaPV RNA could explain the causality of the disease of the urinary bladder. Therefore, persistent infections by OaPVs could be involved in bladder carcinogenesis. Our data showed that there is a possible etiologic association of OaPVs with bladder tumors of cattle.

Co-infection of distinct papillomavirus types in a captive North American porcupine

BACKGROUND

Only two cases of papillomavirus infections in North American porcupines (Erethizon dorsatum) have been described thus far, and molecular investigation linked these cases to two distinct papillomavirus species.

METHODS

In this report, we present the clinical, histological and molecular investigation of a third case of a porcupine papillomavirus infection. Papillomatous lesions occurred on the upper and lower lip of an otherwise healthy three-year old female that was kept in captivity. Within one month, the lesions progressed into exophytic black nodules, followed by a temporary stabilization and ultimately spontaneous regression within seven months of their initial observation. PCR-based screening using specific primers for Erethizon dorsatum papillomavirus 1 and 2 revealed the presence of both these virus types, after which nanopore sequencing was used to determine the complete sequences of the two virus genomes.

RESULTS

One of the genomes shares 99.9% similarity with the only known sequence for Erethizon dorsatum papillomavirus 1, while the second represents a distinct lineage of Erethizon dorsatum papillomavirus 2, sharing only 93.3% similarity with the previously discovered strain.

CONCLUSIONS

This report marks the first observation of a papillomavirus co-infection in a North American porcupine, although the individual contribution of the two virus types to the clinical presentation was not assessed.

Bovine delta papillomavirus E5 oncoprotein negatively regulates the cGAS-STING signaling pathway in cattle in a spontaneous model of viral disease

Persistent infection and tumorigenesis by papillomaviruses (PVs) require viral manipulation of various cellular processes, including those involved in innate immune responses. The cyclic guanosine monophosphate-adenosine monophosphate synthase-stimulator of interferon genes (cGAS-STING) pathway has emerged as an essential innate immune sensing system, that recognizes DNA and trigger potent antiviral effector responses. In this study, we found that bovine PV (BPV) E5 protein, the major oncoprotein of bovine delta PVs, interacts with STING but not with cGAS in a spontaneous BPV infection of neoplastic urothelial cells of cattle. Real-time RT-PCR revealed a significant reduction in both cGAS and STING transcripts in E5-expressing cells. Furthermore, western blot (WB) analysis failed to detect any variation in the expression of interferon-inducible protein 16 (IFI16), an upstream effector of the STING pathway. A ternary complex composed of E5/STING/IFI16 was also observed. Co-immunoprecipitation studies showed that STING interacts with a protein network composed of total and phosphorylated TANK-binding kinase 1 (TBK1), total and phosphorylated interferon regulatory factor 3 (IRF3), IRF7, IKKα, IKKβ, IKKϵ, ELKS, MEKK3, and TAK1. RT-qPCR revealed a significant reduction in TBK1 mRNA levels in BPV-infected cells. WB analysis revealed significantly reduced expression levels of pTBK1, which is essential for the activation and phosphorylation of IRF3, a prerequisite for the latter to enter the nucleus to activate type 1 IFN genes. WB also revealed significantly down-expression of IKKα, IKKβ, IKKϵ, and overexpression of IRF7, ELKS, MEKK3, and TAK1in BPV-positive urothelial cells compared with that in uninfected healthy cells. Phosphorylated p65 (p-p65) was significantly reduced in both the nuclear and cytosolic compartments of BPV-infected cells compared with that in uninfected urothelial cells. Our results suggest that the innate immune signaling pathway mediated by cGAS-STING is impaired in cells infected with BPV. Therefore, effective immune responses are not elicited against these viruses, which facilitates persistent viral infection and subsequent tumorigenesis.

Molecular Epidemiology of Ovine Papillomavirus Infections Among Sheep in Southern Italy

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 blood samples 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.