Development of a novel PCR-RFLP assay for improved detection and typing of bovine papillomaviruses

The possible role of haematophagous flies in the incidence of bovine teat papillomatosis

The relationship between the incidence of bovine teat papillomatosis and the activity of haematophagous flies was investigated in Japan. A total of 15,737 flies consisting of 33 species were collected by dry ice-baited mosquito net (DMN) trap and a sweep net from udders of cattle. Simulium aokii (Takahasi) of Simuliidae (black flies) was the predominant species, followed by S. tobetsuense Ono and S. iwatense (Shiraki). Simulium aokii had the highest peak in October, followed by September. Numbers of blood spots from the bites per teat in nulliparous cattle were significantly correlated with numbers of S. aokii collected by DMN trap. Numbers of teats with warts and spots of blood from the bites per teat were significantly more abundant in anterior teats than posterior teats. The average incidence of teat papillomatosis in nulliparous cattle was significantly higher than that in parous cattle, and the highest incidence by month was in May, followed by April. Although bovine papillomavirus (BPV) DNA was not detected in flies examined, the presence of black flies and blood spots from their bites were associated with subsequent high incidence of growing warts. In particular, it would pay to give attention to species such as S. aokii that severely attack udders in the present locality. Further investigations for the detection of BPV DNA from flies parasitizing on teats are needed.

Characterization of Episomal Replication of Bovine Papillomavirus Type 1 DNA in Long-Term Virion-Infected Saccharomyces Cerevisiae Culture

We have previously reported that bovine papillomavirus type 1 (BPV-1) DNA can replicate its genome and produce infectious virus-like particles in short term virion-infected S. cerevisiae (budding yeast) cultures (Zhao and Frazer 2002, Journal of Virology, 76:3359–64 and 76:12265–73). Here, we report the episomal replications of BPV-1 DNA in long term virion-infected S. cerevisiae culture up to 108 days. Episomal replications of the BPV-1 DNA could be divided into three patterns at three stages, early active replication (day 3–16), middle weak replication (day 23–34/45) and late stable replication (day 45–82). Two-dimensional gel electrophoresis analysis and Southern blot hybridization have revealed further that multiple replication intermediates of BPV-1 DNA including linear form, stranded DNA, monomers and higher oligomers were detected in the virion-infected yeast cells over the time course. Higher oligomers shown as covalently closed circular DNAs (cccDNAs) are the most important replication intermediates that serve as the main nuclear transcription template for producing all viral RNAs in the viral life cycle. In this study, the cccDNAs were generated at the early active replication stage with the highest frequencies and then at late stable replication, but they appeared to be suppressed at the middle weak replication. Our data provided a novel insight that BPV-1 genomic DNA could replicate episomally for the long period and produce the key replication intermediates cccDNAs in S. cerevisiae system.

Genomic characterisation of bovine papillomavirus types 1 and 2 identified in equine sarcoids in Japan

BACKGROUND

Bovine papillomavirus types 1 and 2 (BPV1/2) infection in horses has been associated with the development of equine sarcoids. Previous findings revealed the presence of sarcoid-associated BPV sequence variants that have been proposed as a key factor of cross-species infection in horses. To verify this hypothesis, sarcoid-associated BPV variants should be identified regardless of geographic location.

OBJECTIVES

Sequence analyses of BPV1/2 derived from both horses and cattle were conducted to clarify the sarcoid-associated sequence variants. The aim of this study was to clarify the correlation between BPV phylogeny and the geographic origin/host species.

STUDY DESIGN

Cross-sectional study.

METHODS

Conventional PCR to detect BPV1/2 was performed with genomic DNA extracted from equine sarcoid (n = 10) and bovine papilloma (n = 10) samples collected in Japan. Direct sequencing results were compared between equine and bovine (equine/bovine)-derived BPV to identify sarcoid-associated variants of two early regions (E2, E5), one late region (L1) and the long control region (LCR). Phylogenetic and phylogeny-trait correlation were analysed using Bayesian Markov chain Monte Carlo (MCMC) method and Bayesian tip-association significance testing (BaTS).

RESULTS

Seven BPV1 and three BPV2 were identified from equine sarcoids using PCR and direct sequencing. Sequence analysis of equine/bovine-derived samples showed no sarcoid-associated variants in four regions (E2, E5, L1 and LCR) of either BPV1 or BPV2. The phylogenetic tree of BPV1 E2, L1 and LCR tended to cluster within its geographic origins. BaTS analysis demonstrated that BPV1 sequence variability may be due to the geographic origin rather than host species difference.

MAIN LIMITATIONS

There was a limitation in sample numbers.

CONCLUSIONS

This study supports the geographic-specific hypothesis of sequence variability, suggesting that BPV1 is shared between local equids and bovids. However, more extensively collected sequences worldwide and functional evaluations are needed to verify the geographic-specific sequence variability of BPV1/2 between equine- and bovine-derived sequence.

Anogenital-Associated Papillomaviruses in Animals: Focusing on Bos taurus Papillomaviruses

In contrast to the diverse studies on human papillomaviruses (HPVs), information on animal PVs associated with anogenital lesions is limited. In the animal kingdom, papillomas occur more commonly in cattle than in any other animals, and diverse types of Bos taurus papillomaviruses (BPVs) exist, including the very recently discovered BPV type 29 (BPV29). From this perspective, we will review previous studies describing PV types associated with anogenitals in animals, with a focus on BPVs. To date, two classical BPV types, classified into Deltapapillomavirus (BPV1 and BPV2) and Dyokappapapillomavirus (BPV22), and two novel Xipapillomaviruses (BPV28 and BPV29) have been identified from anogenital lesions and tissues of the domestic cow. Due to the limited reports describing anogenital-associated PVs in animals, the relationships between their phylogenetic and pathogenetic properties are still undiscovered. Animal studies are valuable not only for the veterinary field but also for human medicine, as animal diseases have been shown to mimic human diseases. Studies of anogenital-associated PVs in animals have a positive impact on various research fields.

Characterization of Bovine papillomavirus 28 (BPV28) and a novel genotype BPV29 associated with vulval papillomas in cattle

Papillomavirus (PV) infections are associated with the development of cutaneous and mucosal tumors in humans and various animal species. In humans, infection of high-risk human PVs (HPVs) causes anogenital cancers, while in animals, anogenital-associated PVs are not well understood. Among animal PVs, Bos taurus PVs (BPVs) have the most diverse genotypes, up to 28 of them. The present study will report two unique BPVs identified in vulval papilloma lesions from two Holstein Friesian cattle by conventional PCR and sequencing. In the first case, BPV28 harboring two L1 open reading frames (ORFs) due to a five-nucleotide deletion was identified. In the second case, histologically diagnosed as papilloma, an unclassified BPV genotype was detected. However, in both cases, the immunohistochemistry against PV antigen was negative. The full genome of the unclassified BPV was amplified by inverse PCR and analyzed by genome-walking sequencing. The L1 nucleotide sequence was most identical to BPV genotype 6 (BPV6), showing 78 % identity, indicating that this novel BPV should be classified as species Xipapillomavirus 1, genotype BPV29. The mRNA expression of three early genes (E1, E2, E10), but not L1, was confirmed in both BPV28- and BPV29-detected papilloma lesions. The present study suggests the involvement of novel types of BPV in vulval papilloma. The alteration of BPV28 pathogenicity due to the frameshift mutation of L1 needs to be elucidated in the future.

Genomic characterization of a novel bovine papillomavirus type 28

Infection of bovine papillomavirus (BPV) has been associated with mucosal and/or cutaneous tumor development in bovids. To date, up to 27 genotypes of BPVs have been identified and classified based on the nucleotide sequence identity of L1 open reading frame. In the present study, the complete sequence of a novel BPV concurrently identified with BPV1 and BPV2 in the facial cutaneous papilloma lesion of a domestic cattle was characterized. The whole genome of the unclassified BPV was 7263 base pairs in full length with GC ratio of 42.9%. In comparison with published BPV sequences, L1 nucleotide sequence of the novel BPV shared 75% identity with BPV15, and was suggested to be classified in the genus, Xipapillomavirus. According to the criteria established by the International Committee on the Taxonomy of Viruses, the novel BPV was designated as BPV type 28.

Identification of bovine papillomavirus type 1 and 2 from bovine anogenital fibropapillomas

Papillomavirus (PV) is a well-known pathogen associated with epithelial and mucosal neoplastic diseases. In contrast to human PVs, characterization of animal PVs from the aspect of anogenital neoplasm is still on a learning curve. In the present study, two vulval and one anal warts, histologically diagnosed as fibropapillomas, excised from dairy cattle were analyzed. PCR and sequencing revealed that bovine papillomavirus type 1 (BPV-1) and BPV-2 were detected from anal and vulval fibropapillomas, respectively. Immunohistochemistry detected PV antigen in a few differentiated keratinocytes of one vulval case. Reverse-transcriptase PCR detected the early region, but not the late region of BPV mRNA in all three cases. The present study will provide new insight into the relationship between BPV and anogenital papilloma in cattle.

Detection of bovine papillomavirus type 2 DNA in calf conjunctival myofibroblastoma

An 8-month-old male Japanese Black calf was referred for the evaluation of a slow-growing conjunctival mass in the right eye. A superficial keratectomy was performed followed by recurrence on two occasions. No metastases were found in surrounding tissues. Histological, immunohistochemical, and ultrastructural investigation revealed that both the primary and the recurrent lesions were benign, conjunctival, myofibroblastomas. Interestingly, bovine papillomavirus type 2 (BPV-2) DNA was detected in both myofibroblastoma lesions. Archival bovine myofibroblastomas from the vulva and neck were also analyzed for papillomaviral genomes. BPV-2 DNA was also amplified from these lesions. To the best of our knowledge, this is the first report describing a potential causal relationship between BPV-2 infection and conjunctival myofibroblastoma.

Full genome analysis of bovine papillomavirus type 1 derived from a calf with severe cutaneous multiple papillomatosis

Severe papillomatosis occasionally causes astasia leading to euthanizing cattle. There are currently a limited number of reports on virologic approach in severe bovine papillomatosis. Here we report a full genome characterization of bovine papillomavirus type 1 (BPV-1) from the case of severe papillomatosis. A calf developed numerous papillomas on the skin and some nodules in the upper gastrointestinal tract at seven months old. The skin lesion was diagnosed as the epithelial papilloma with BPV antigen expression, while the gastrointestinal lesions were diagnosed as the fibropapilloma without BPV antigen. Full genome analysis revealed that BPV-1s detected in all the lesions were exactly the same. Compared with the reference BPV-1 sequence, there was a single nucleotide insertion in the upstream regulatory region.

Detection of morbillivirus infection by RT-PCR RFLP analysis in cetaceans and carnivores

Morbillivirus genus comprises several members related to specific hosts, such as canine distemper virus (CDV) and cetacean morbillivirus (CeMV) in which the dolphin morbillivirus (DMV) is included. Both CDV and DMV are able to cause serious outbreak associated with high morbidity and mortality representing an important conservation threat for terrestrial and aquatic mammalian species. This paper describes a new RT-PCR RFLP technique based on a RT-PCR with degenerate primers targeting a 287 bp fragment located on the conserved N terminus of the morbillivirus NP gene, followed by MseI RFLP, in order both to confirm the detection of the virus and to distinguish DMV from CDV. Both carnivores and cetaceans tissues (brain, lung and lymph node) presenting evidence of morbillivirus infection (MI) were analyzed. RT-PCR positive samples were typed by RFLP analysis and then sequenced to confirm the RFLP results. This method was applied during the last morbillivirus cetacean die-off occurred in the Mediterranean basin in 2013, when there was the urgent need of a rapid and economic method to investigate among causes of death on stranded cetaceans. This new technique has proved to be a valuable, reliable, simple and relatively inexpensive diagnostic tool easily applicable also in limited-resource laboratories.

Papillomaviruses: a systematic review

In the last decades, a group of viruses has received great attention due to its relationship with cancer development and its wide distribution throughout the vertebrates: the papillomaviruses. In this article, we aim to review some of the most relevant reports concerning the use of bovines as an experimental model for studies related to papillomaviruses. Moreover, the obtained data contributes to the development of strategies against the clinical consequences of bovine papillomaviruses (BPV) that have led to drastic hazards to the herds. To overcome the problem, the vaccines that we have been developing involve recombinant DNA technology, aiming at prophylactic and therapeutic procedures. It is important to point out that these strategies can be used as models for innovative procedures against HPV, as this virus is the main causal agent of cervical cancer, the second most fatal cancer in women.