Molecular detection and genetic diversity of bovine papillomavirus in dairy cows in Xinjiang, China

Molecular findings and virological assessment of bladder papillomavirus infection in cattle

Bovine and ovine papillomaviruses (BPVs - OaPVs) are infectious agents that have an important role in bladder carcinogenesis of cattle. In an attempt to better understand territorial prevalence of papillomavirus genotypes and gain insights into their molecular pathway(s), a virological assessment of papillomavirus infection was performed on 52 bladder tumors in cattle using droplet digital polymerase chain reaction (ddPCR), an improved version of conventional PCR. ddPCR detected and quantified BPV DNA and mRNAs in all tumor samples, showing that these viruses play a determinant role in bovine bladder carcinogenesis. OaPV DNA and mRNA were detected and quantified in 45 bladder tumors. BPV14, BPV13, BPV2, OaPV2, OaPV1, and OaPV3 were the genotypes most closely related to bladder tumors. ddPCR quantified BPV1 and OaPV4 DNA and their transcripts less frequently. Western blot analysis revealed a significant overexpression of the phosphorylated platelet derived growth factor β receptor (PDGFβR) as well as the transcription factor E2F3, which modulate cell cycle progression in urothelial neoplasia. Furthermore, significant overexpression of calpain1, a Cys protease, was observed in bladder tumors related to BPVs alone and in BPV and OaPV coinfection. Calpain1 has been shown to play a role in producing free transcription factors of the E2F family, and molecular findings suggest that calpain family members work cooperatively to mutually regulate their protease activities in cattle bladder tumors. Altogether, these results showed territorial prevalence of BPV and OaPV genotypes and suggested that PDGFβR and the calpain system appeared to be molecular partners of both BPVs and OaPVs.

Molecular genotyping, histopathological and immunohistochemical studies of bovine papillomatosis

Background

Bovine papillomatosis (BP) is considered the most common health problem in large cattle farms.

Aim

This study attempts to confirm clinically suspected BP in cattle by polymerase chain reaction (PCR) assay, histopathology, immunohistochemistry (IHC), and genotyping analysis of local isolates.

Methods

According to morphological appearance and lesion features, a cross sectional study of 54 clinically diagnosed BP cattle was assigned to this current investigation from May to August (2021) in Al-Kut district (Wasit Province, Iraq) private veterinary clinics using purposive sampling technique based on set criteria. The cattle were diagnosed clinically, and the tissues were collected and some fixed in 10% neutral buffered formalin and other stored frozen and examined by histopathological technique, IHC, and PCR assays.

Results

Using PCR assay, all cattle were positive for the BPV L1 gene. According to detect the L1 gene, analysis of the phylogenetic tree showed that local BPV cattle isolates were closely related to the NCBI-BLAST BPV type-1 and type-2 of the Polish equine isolate (KF284133.1) and BPV Brazilian Bostaurus isolate (MH187961.1), respectively. Histological detection showed there were acanthosis, hyperkeratosis, epidermal thickening, severe infiltration of mononuclear cells, massive hemorrhage, dermal fibroplasias, multifocal spongiosis, moderate neovascularization, moderate to severe elongation of the retention ridge towards the dermis, parakeratosis, rings of calcification, and necrosis with nuclear pyknosis of some spinosum cells. Immunohistochemical findings of tumor necrosis factor-alpha, epidermal growth factor receptor and Fascin showed a significant variation in values of immunoreaction in the dermis and epidermis. These results ranged from negative (0) to mild positive (+1) to moderate positive (+2) reactions.

Conclusion

The study provided essential molecular and genotyping data to improve our knowledge by emphasizing the crucial of IHC as an elegant diagnostic method to detect cellular alterations.

Evidence from a Series of 104 Equine Sarcoids Suggests That Most Sarcoids in New Zealand Are Caused by Bovine Papillomavirus Type 2, although Both BPV1 and BPV2 DNA Are Detectable in around 10% of Sarcoids

Simple Summary

Equine sarcoids are common cancers of horses that are caused by bovine papillomaviruses (BPVs). Previous studies have suggested that most sarcoids are caused by either BPV1 or BPV2, with the proportion caused by each BPV type dependent on the country in which the horse lived. Additionally, some studies also suggest that other papillomavirus (PV) types could cause equine sarcoids. The study was comprised of 104 sarcoids from New Zealand horses and used both specific and consensus PCR primer sets. Overall, PV DNA was amplified from 90% of the sarcoids. Of the ones that contained BPV DNA, 88% contained only BPV2 DNA, 10% BPV1 and BPV2 DNA, and 2% only BPV1 DNA. Only the primers specific for BPV1 or specific for BPV2 amplified DNA and no other PV types were detected. There was little variability in the rates of detection between different regions of New Zealand and rates were consistent when two distinct time periods were compared. These results suggest that sarcoids from New Zealand horses are consistently most often caused by BPV2 and thus if vaccination is used to prevent these cancers, it will be important to use a vaccine that provides good protection against this BPV type.

Abstract

Equine sarcoids are common mesenchymal neoplasms of horses that are caused by cross-species infection by deltapapillomaviruses. While bovine papillomavirus (BPV) 1 and 2 are the most common causes, there are differences between countries regarding which of these BPV types cause the majority of sarcoids. Additionally, no causative PV can be detected in a subset of sarcoids, suggesting that other PV types could be rarer causes of these neoplasms. In the present study, consensus PCR primers and PCR primers specific for the five deltapapillomavirus types currently known to cause mesenchymal neoplasia (BPV1, BPV2, BPV13, BPV14, and Ovis aries PV2 DNA) were used to investigate the presence of PV DNA in 104 sarcoids from three defined regions in New Zealand and from two distinct time periods separated by 15 years. PV DNA was detected in 94 (90.4%) sarcoids. Of the sarcoids containing PV DNA, 83 (88.3%) contained only BPV2 DNA, 9 (9.6%) BPV1 and BPV2 DNA, and 2 (2.1%) only BPV1 DNA. No other PV types were detected. The predominance of BPV2 is consistent with studies of sarcoids from North America but dissimilar to studies of sarcoids from Europe and Australia. Detection rates of BPV1 and BPV2 were similar in sarcoids from different regions of New Zealand and in sarcoids from different time periods. These results suggest that most equine sarcoids in New Zealand are caused by BPV2 and thus if vaccines are developed to prevent sarcoids, vaccines that provide good protection against BPV2 will be required in this country.

The Development of Novel Primer Sets to Specifically Amplify Each of the Five Different Deltapapillomaviruses That Cause Neoplasia after Cross-Species Infection

Bovine papillomavirus (BPV) types 1 and 2 are recognized as the main cause of equine sarcoids. However, some studies report that up to a quarter of these tumors do not contain detectible BPV1 or BPV2 DNA. The absence of detectible BPV1 or BPV2 in these sarcoids suggests the possible involvement of other papillomavirus types. Currently, five deltapapillomaviruses are recognized to cause mesenchymal neoplasia after cross-species infection. In addition to BPV1 and BPV2, BPV13 has been associated with equine sarcoids in Brazil, BPV14 has been associated with feline sarcoids, and Ovis aries papillomavirus 2 caused a sarcoid-like lesion in a pig. To investigate the cause of equine sarcoids, PCR primers were developed to specifically amplify each of the five different deltapapillomaviruses that have been associated with mesenchymal neoplasia. The specificity of these primers was confirmed using samples of formalin-fixed tissue known to contain each PV type. These primers allow rapid and sensitive detection of deltapapillomavirus DNA in equine sarcoids. As studies have revealed marked regional variability in the cause of equine sarcoids, these primers will be useful to determine the predominant PV type causing sarcoids in a region. Additionally, there is a single report describing mixed infections by BPV1 and BPV2 in equine sarcoids. The specific primer sets are expected to enable more sensitive detection of mixed infections in equine sarcoids. Determining the cause of equine sarcoids is important as vaccines are developed to prevent these common malignant neoplasms.