The role and diagnostic value of deregulated miRNAs in cervical cancer

Cervical cancer (CC) remains a significant global health concern, particularly affecting women in low-income countries. Despite advancements in screening programs, CC continues to pose a substantial mortality risk, highlighting the need to explore diagnostic and treatment modalities. This review focuses on the role of deregulated microRNAs (miRNAs) in CC development, emphasizing their potential as biomarkers for early detection and prognosis in body fluids. miRNAs have emerged as critical regulators of key cellular processes, including proliferation, migration, invasion, and apoptosis, and their dysregulation is closely linked to CC progression. Upregulated miRNAs such as miR-146b-3p, miR-1908, and miR-21 promote CC progression by targeting tumor suppressor genes, while downregulated miRNAs like miR-23-3p and miR-4262 are associated with reduced tumor aggressiveness. miRNAs also hold significant promise as non-invasive prognostic biomarkers. Their expression levels correlate with clinical outcomes, including tumor stage, metastasis, and overall survival, making them valuable tools for risk stratification and personalized treatment strategies. Liquid biopsies, which detect circulating miRNAs in bodily fluids, offer a minimally invasive approach to monitor tumor dynamics and predict patient outcomes. Furthermore, exosomal miRNAs are emerging as promising diagnostic and prognostic tools for CC. Advanced diagnostic technologies and bioinformatics tools are anticipated to enhance the identification of evident miRNA biomarkers in the clinical settings. Standardized protocols for sample collection and analysis will improve the reproducibility of miRNA studies, while a deeper understanding of miRNA biology may unlock their potential as therapeutic targets. In conclusion, this review consolidates current research on deregulated miRNAs in CC, highlighting their diagnostic and prognostic significance. The findings underscore the potential of miRNAs to revolutionize CC management through innovative diagnostic and therapeutic strategies.

Molecular typing of bovine papillomaviruses in Costa Rica

Bovine papillomaviruses are related to cause fibroepithelial proliferations in the skin and mucosae and are associated with economic loss mainly related to poor body condition and reduced milk production. This study aimed to investigate the presence and types of bovine papillomaviruses (BPVs) in cattle sampled in different areas of Costa Rica using molecular techniques. A descriptive study with a non-probability convenience sampling was carried out. A total of 99 papillomatous lesions were collected from 63 animals in 32 farms, and analyzed by polymerase chain reaction, rolling circle amplification (RCA), sequencing, and restriction enzymes digestion. Seven bovine papillomavirus types (BPV1, BPV2, BPV4, BPV6, BPV7, BPV10, BPV11) and two putative novel viral variants (BPV-CR1 and BPV-CR2) were identified for the first time in Costa Rica. BPV6 was the most frequently detected virus in lesions (31.2%), followed by BPV2 (25%) and BPV1 (25%). BPV1 and BPV2 were the most widely distributed in the Country. Coinfections were recorded in two animals (BPV1 / BPV2 and BPV4 / BPV6). Restriction analyses allowed differentiating BPV1 from BPV2, BPV4, and BPV7, but failed to identify BPV6, BPV10, and BPV11. Results suggest that a great PVs diversity is harbored by bovines in Costa Rica and indicate the need for further investigations aimed to uncover PV diversity at the full genomic level.

Detection of Human Papillomavirus DNA in Paired Peripheral Blood and Cervix Samples in Patients with Cervical Lesions and Healthy Individuals

This study evaluated the presence of Human Papillomavirus (HPV) DNA in the cervix and peripheral blood of women with cervical intraepithelial neoplasia (CIN I, II, and III) and healthy individuals. Overall, 139 paired peripheral blood and cervix samples of healthy women and women with CIN I, II, and III (n = 68) were tested for HPV DNA by using standard procedures. Polymerase chain reaction (PCR) sequencing determined HPV types. Quantification of HPV16 E6 and E2 genes was performed to determine viral load and physical state. HPV DNA was detected in the cervix (21.1% in healthy individuals; 48.8–55.5% in CIN patients), blood (46.4% in healthy individuals; 44.1–77.7% in CIN patients) and paired peripheral blood and cervix samples (24% in healthy individuals; 32.5–44.4% in CIN patients). The most frequent types found in the cervix were HPV16, 18, 31, 33, 58, and 70, while HPV16, 18, 33, 58, and 66 were the most frequent types found in the blood. HPV DNA in the cervix was associated with previous sexually transmitted infections (STIs) (p = 0.023; OR: 2.978; CI:1.34–7.821), HPV DNA in the blood (p = 0.000; OR: 8.283; CI:3.700–18.540), and cervical lesions (CIN I/II or III) (p = 0.007). Binomial logistic regression showed that HPV DNA in the blood (p = 0.000; OR: 9.324; CI:3.612–24.072) and cervical lesions (p = 0.011; OR: 3.622; CI:1.338–9.806) were associated with HPV DNA in the cervix. However, we did not find an association between HPV DNA in the blood and cervical lesions (p = 0.385). Our results showed that only HPV DNA found in the cervix was associated with cervical lesions.

The contribution of bovines to human health against viral infections

In the last 40 years, novel viruses have evolved at a much faster pace than other pathogens. Viral diseases pose a significant threat to public health around the world. Bovines have a longstanding history of significant contributions to human nutrition, agricultural, industrial purposes, medical research, drug and vaccine development, and livelihood. The life cycle, genomic structures, viral proteins, and pathophysiology of bovine viruses studied in vitro paved the way for understanding the human counterparts. Calf model has been used for testing vaccines against RSV, papillomavirus vaccines and anti-HCV agents were principally developed after using the BPV and BVDV model, respectively. Some bovine viruses-based vaccines (BPIV-3 and bovine rotaviruses) were successfully developed, clinically tried, and commercially produced. Cows, immunized with HIV envelope glycoprotein, produced effective broadly neutralizing antibodies in their serum and colostrum against HIV. Here, we have summarized a few examples of human viral infections for which the use of bovines has contributed to the acquisition of new knowledge to improve human health against viral infections covering the convergence between some human and bovine viruses and using bovines as disease models. Additionally, the production of vaccines and drugs, bovine-based products were covered, and the precautions in dealing with bovines and bovine-based materials.

Association Between BoLA-DRB3.2 Polymorphism and Bovine Papillomavirus Infection for Bladder Tumor Risk in Podolica Cattle

Blood samples from 260 unrelated cattle (132 animals affected by papillomavirus-associated bladder tumors and 128 healthy) were genotyped using the classic polymerase chain reaction/restriction fragment length polymorphism method to screen MHC class II bovine leukocyte antigen-DRB3. 2 polymorphism. The DRB3^*22 allele was significantly (p ≤ 0.01) detected in healthy cattle, thus appearing to have a negative association (protective effect) with virus infection of the urinary bladder known to represent a bladder tumor risk for cattle living free at pasture. Considering the two sequence alleles identified in animals carrying DRB3^*22, DRB3^*011:01 allele from samples of animals harboring the unexpressed bovine papillomaviruses (BPV)-2 E5 gene was characterized by amino acid residues believed to have a protective effect against BPV infection such as arginine at position 71 (R⁷¹) in pocket 4, histidine at position 11 (H¹¹) in pocket 6, and both glutamine at position 9 (Q⁹) and serine at position 57 (S⁵⁷) in pocket 9 of the antigen-binding groove. The DRB3^*011:02v allele from affected animals was characterized by amino acids believed to be susceptibility residues such as lysine (K⁷¹), tyrosine (Y¹¹), glutamic acid (E⁹), and aspartic acid (D⁵⁷) in these pockets. These results suggest that animals harboring the DRB3^*011:01 allele may have a lower risk of BPV infection and, consequently, a reduced risk of bladder tumors.

Digital droplet PCR for the detection and quantification of circulating bovine Deltapapillomavirus

In this study, the digital droplet polymerase chain reaction (ddPCR) was used to quantify circulating bovine papillomavirus (BPV; genus: Deltapapillomavirus) DNA levels in blood samples from 25 clinically normal cows and 15 cows with chronic enzootic haematuria due to papillomavirus-associated bladder tumours. ddPCR detected BPV DNA in 95% of all the samples (i.e. in 24 of the clinically normal cows and 14 of the diseased animals), whereas quantitative real-time PCR (qPCR) detected it in only 57.5% of the same blood samples, with percentage differences between ddPCR and qPCR being statistically significant (p-value ≤ .05), according to chi-squared test. Furthermore, ddPCR detected BPV infections by a single genotype and by multiple genotypes in 37% and 63% of the cows, whereas qPCR detected these in 16% and 16%. Of the two assays, ddPCR was the more sensitive and accurate clinical diagnostic tool, allowing the detection of otherwise undetectable BPV genotypes, and consequently, a higher number of BPV co-infections. qPCR failed to detect many BPV co-infections by multiple genotypes. Therefore, ddPCR may be an essential tool for improving diagnostic procedures, allowing the identification of the genotypic distribution of BPV and a better understanding about the territorial divergence, if any, of the BPV prevalence in different areas. No significant differences in the blood viral load estimations were observed between the two animal groups, suggesting that the bloodstream could be a site of primary infection. Finally, as BPV DNA was detected in cows affected by non-invasive urothelial tumours, including papilloma and papillary urothelial neoplasms of low malignant potential, the circulating BPVs appeared to be independent of the status of urothelial neoplasms. Therefore, unlike in humans, circulating BPVs cannot be an actual prognostic marker of urothelial tumours in cows.

Prevalence of Equus caballus Papillomavirus Type-2 Infection and Seropositivity in Asymptomatic Western Canadian Horses

Equus caballus papillomavirus type 2 (EcPV-2) has been recognized as a potential cause of a subset of genital squamous cell carcinomas (SCCs) in horses. In the current study, we measured EcPV-2 seropositivity in 50 healthy horses from Western Canada, and these were compared to a herd of horses with known EcPV-2 exposure. Second, the presence of EcPV-2 DNA was measured using EcPV-2-specific PCR (polymerase chain reaction), performed on a variety of tissues collected at necropsy from 70 horses that lacked any history, gross, or histologic evidence of neoplasia or papillomavirus-associated disease. EcPV-2-specific RNA in situ hybridization (R-ISH) was performed on PCR-positive samples to identify the specific tissues infected. The prevalence of asymptomatic infection with EcPV-2 in Western Canadian horses was 20/70 (29%). Exposure to EcPV-2 as measured by seropositivity was 18/50 (36%). EcPV-2 positivity by anatomic location, as measured by R-ISH, was as follows: penis 10/29 (35%), vulva 5/34 (15%), eyelid 8/68 (12%), oral mucosa 7/65 (11%), skin from muzzle 7/68 (10%), and retropharyngeal lymph node 2/64 (3%). The youngest horses with EcPV-2 infection, based on PCR, were fetuses, suggesting for the first time that vertical transmission of EcPV-2 occurs in horses. The current study observed an increased prevalence of EcPV-2 as compared to previous studies. We suggest that this difference is due to our use of biopsies in place of superficial swabs. We propose that EcPV-2 infection in asymptomatic horses is more common than previously reported and that the virus' role in equine genital SCCs may be more complex than originally thought.

Papillomavirus DNA is not Amplifiable from Bladder, Lung, or Mammary Gland Cancers in Dogs or Cats

Simple Summary

Papillomaviruses (PVs) are well established to cause genital and oral cancer in humans. Additionally, some evidence suggests that these viruses may also have a role in the development of human lung, breast, and bladder cancer. Recent studies have revealed that PVs can influence the development of some cancers in cats and, less frequently, in dogs. In the present study, 47 lung, mammary gland, and bladder cancers in dogs and 25 cancers in cats were evaluated for evidence of any role PVs may have in cancer development. Histology did not reveal any lesions suggestive of PV infection, and no PV DNA was amplified from any cancer. Therefore, these findings suggest that PVs do not frequently infect these tissues and are therefore unlikely to be significant factors in the development of lung, mammary gland, or bladder cancer in either dogs or cats.

Abstract

Papillomaviruses (PVs) cause around 5% of all human cancers, including most cervical cancers and around a quarter of all oral cancers. Additionally, some studies have suggested that PVs could cause a proportion of human lung, breast, and bladder cancers. As PVs have been associated with skin cancer in cats and, more rarely, dogs, it was hypothesized that these viruses could also contribute to epithelial cancers of the lung, mammary gland, and bladder of dogs and cats. Formalin-fixed paraffin-embedded samples of 47 canine and 25 feline cancers were examined histologically for evidence of PV infection. Additionally, three sets of consensus PCR primers were used to amplify PV DNA from the samples. No histological evidence of PV infection was visible in any of the cancers. DNA from a bovine PV type was amplified from one sample, while two different samples were found to contain human PV DNA. However, these were considered to be contaminants, and no canine or feline PV types were amplified from any of the cancers. These results suggest that PVs do not frequently infect the lung, mammary gland, or bladder of dogs and cats and therefore are unlikely to be significant factors in the development of cancers in these tissues.

Detection and quantitation of human papillomavirus DNA in peripheral blood mononuclear cells from blood donors

Human papillomavirus (HPV) is the etiological agent of cervical cancer. Also, HPV has been associated with anogenital cancer, oropharyngeal cancer, genital warts, and other dermatological diseases. HPV infects epithelial cells and their replication is closely linked to epithelial differentiation. The presence of HPV DNA in peripheral blood mononuclear cells (PBMC) has been reported in some patients with head and neck cancer, cervical cancer, and other genital diseases. However, the presence of HPV DNA in blood in asymptomatic subjects is still unresolved. The objective of this study was to evaluate the presence of HPV DNA in PBMC from asymptomatic blood donors. Blood samples were collected from 207 healthy Chilean blood donors. Genomic DNA was extracted from PBMC and HPV DNA detection was performed by real-time quantitative polymerase chain reaction assays with GP5+/6+ primers. HPV typing was carried out by genetic sequencing of a 140 to 150 bp fragment of the L1 gene. HPV DNA was detected in 6.8% (14/207) of blood donors. Single HPV infections were detected in seven blood donors. High-risk HPV was found in 6.3% (13/207) of cases: nine blood donors were infected with HPV-16, five with HPV-18, two with HPV-51, and one case was infected with either 32, 33, 45, 59, 66, 70, or 82. The median viral load value was 21.3 copies/mL blood or 13.4 HPV (+) cells per 10 ⁴ PBMC. These results show that HPV DNA is present in PBMC from healthy blood donors and it suggests that blood could be a new route of HPV dissemination.

Comparative transcriptomic analysis of bovine papillomatosis

BACKGROUND

Bovine papillomavirus (BPV) belongs to the Papillomaviridae family and infects epithelial cells of bovines and closely related animals, causing hyperproliferative lesions known as warts or papillomas, which may regress or progress to form benign or malignant tumors. The virus enters the host cell and interacts with it by altering the regulation of genes that are responsible for controlling the cell cycle, thus triggering lesion formation. It is not yet known which host genes are regulated by viral infection. Therefore, the objective of this study was to make use of next-generation RNA sequencing methods to identify differentially expressed genes associated with BPV infection, which might elucidate possible marker genes that could be used to control the disease.

RESULTS

Transcriptome analysis revealed that 1343 genes were differentially regulated (FDR < 0.05). A comparison of gene expression in infected and noninfected cows indicated that 655 genes were significantly upregulated, and 688 genes were significantly downregulated. Most differentially expressed genes were associated with BPV infection pathways, which supports the hypothesis that viral infection was the mechanism associated with this regulation.

CONCLUSIONS

This is the first study that focused on a large-scale evaluation of gene expression associated with BPV infection, which is important to identify possible metabolic pathways regulated by host genes for lesion development. In addition, novel targets could be identified in order to find ligands that interact with BPV, with the aim of interrupting the infection cycle.

Bovine papillomavirus 24: a novel member of the genus Xipapillomavirus detected in the Amazon region

Bovine papillomaviruses (BPVs) have been described as etiologic agents of cutaneous and mucosal papillomas in cattle. In the present study, we describe a new BPV that was detected in a cutaneous papilloma from a cow. Phylogenetic analysis suggests that this virus belong to the genus Xipapillomavirus, and we refer to it here as BPV type 24 (BPV24). Coinfection with members of the genera Epsilonpapillomavirus and Deltapapillomavirus in a cutaneous papilloma from a different animal was also detected, and the full genomes of these viruses were sequenced. Both papillomas were from cattle within Acre State in the Amazon region of Brazil. The data presented here demonstrate the utility of using high-throughput methods to indentify coinfections and allow the characterization of new genomes.

Chaperone-assisted selective autophagy in healthy and papillomavirus-associated neoplastic urothelium of cattle

Chaperone-assisted selective autophagy (CASA) is a newly-described selective tension-induced macroautophagy pathway mediated by Bag3 that is believed to be essential for mechanotransduction in skeletal muscle and to be an important regulator of the immune system. We investigated CASA machinery both in healthy and in fifteen papillomavirus-associated neoplastic bovine urothelium. The components of CASA complex, that comprises the molecular chaperones HspA8/Hsc70 and Hsp8B/Hsp22 and the cochaperones Bag3 and STUB1/CHIP, were studied by molecular, microscopic and submicroscopic investigations. CASA complex was found to be constitutively expressed in healthy bovine urothelium; its expression increased in urothelial cancers of cattle, namely thirteen papillary carcinomas and two papillary urothelial neoplasm of low malignant potential (PUNLMPs). We suggest that basal levels of CASA are important in the healthy urothelium which interfaces with the community of urinary microbiota thus representing an important epithelial cell-autonomous mechanism of antibacterial defense. Co-immunoprecipitation studies using an antibody against bovine papillomavirus E5 protein revealed that the oncoprotein co-localized with CASA complex in urothelial cancer cells. This suggests that infection by BPV E5 could influence cell behaviour by interfering with basal autophagy processes although this study did not conclusively show that this interaction increased the expression of CASA proteins. In neoplastic urothelium, CASA could be involved in regulating fundamental cellular processes such adhesion, migration, and proliferation and so might influence the biological behaviour of urothelial tumors in cattle.

Detection of bovine Deltapapillomavirus DNA in peripheral blood of healthy sheep (Ovis aries)

Blood samples from 65 sheep were tested for the presence of bovine Deltapapillomavirus (δPVs) DNA. The sheep were divided into three groups. Sheep in groups 1 and 2 were from Sardinia and Campania, respectively, and were in contact with cattle and grazed on lands contaminated with bracken fern. Sheep in Group 3 lived in closed pens and had no contact with cattle. These sheep were fed hay that did not contain bracken fern. Bovine δPV E5 DNA was detected in blood from 24 of 27 (89%) sheep in Group 1. A single bovine δPV type was detected in the blood from nine (33%) sheep, including the detection of bovine δPV-1 DNA in four sheep, bovine δPV-2 in four and δPV-13 in one sheep. Two δPV types were detected in 33% of the sheep, and three bovine δPV types were detected in 22% of the sheep. Bovine δPVs were detected in 17 of 20 (85%) sheep from Group 2. The detection rate by a single δPV type was 40% with just δPV-1 DNA amplified from two, just δPV-2 DNA from four, and just δPV-13 DNA from two sheep. Two and three δPVs were detected in 30% and 15%, respectively. All sequenced amplicons showed a 100% identity with papillomaviral E5 DNA deposited in GenBank. Bovine δPV-14 DNA sequences were not detected from any sheep. No bovine δPV DNA was revealed in blood samples from sheep in Group 3. The detection of bovine δPV DNA in the blood of sheep means that sheep may be able to be infected by these PVs. This suggests that bovine δPVs could potentially be a previously unrecognized cause of disease in sheep. Furthermore, it is possible that sheep could act as a reservoir for these viruses.

Felis catus papillomavirus type-2 but not type-1 is detectable and transcriptionally active in the blood of healthy cats

Papillomaviruses (PVs) are small DNA viruses that induce benign and/or malignant epithelial tumours in different species, including the domestic cat (Felis catus). To date, five F. catus papillomavirus genotypes have been identified (FcaPV-1 to FcaPV-5). FcaPV-1 is associated with skin and oral benign lesions, while FcaPV-2 infection is widely associated with feline squamous cell carcinomas. Several human and animal PVs have been found in body fluids such as peripheral blood; however, the presence of FcaPVs in non-epithelial tissues has not previously been investigated. The aim of this study was to assess the presence and gene expression of FcaPV-1 and FcaPV-2 in the blood of healthy cats. We detected FcaPV-2 DNA in 26 of 103 (25%) blood samples. Importantly, FcaPV-2 L1, E2, E6 and E7 genes were found to be expressed in 3 (25%), 11 (92%), 6 (50%) and 5 (42%) of the samples available for mRNA analysis, respectively. FcaPV-1 was not detected in any of the blood samples analysed here. The data obtained in this work suggest active and eventually productive infection of FcaPV-2 in the blood of healthy cats, implying a possible role in intra-individual spreading as well as in vertical and horizontal transmission.

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.

Molecular and Phylogenetic Analysis of Bovine Papillomavirus Type 1: First Report in Iraqi Cattle

This study aimed to provide the first molecular characterization of bovine papillomavirus type 1 (BPV-1) in Iraq. BPV is a widely spread oncogenic virus in Iraqi cattle and is associated with the formation of both benign and malignant lesions, resulting in notable economic losses in dairy and beef cattle. In the current study, 140 cutaneous papilloma specimens were collected from cattle in central Iraq. These samples were submitted to histopathological examination, PCR, and sequencing analysis. The histopathology revealed that the main lesion type among the specimens was fibropapilloma. BPV-1 DNA was detected in 121 of the samples (86.42%) in Iraqi cattle as the main causative agent for the disease. A partial sequence for the E2, L2 genes, and complete sequence for the E5 gene were deposited in GenBank. Phylogenetic analysis confirmed the presence of BPV-1 and showed that the origin of infection may be imported European cattle. Obtaining a complete E5 gene sequence enabled us to perform structural predictions. This study presents the first report of BPV-1 infection in the Iraqi cattle and contributes to extending the knowledge of the origin of the spread of this disease. The results of this study will aid in the development of appropriate control measures and therapeutic strategies.

Detection and quantification of bovine papillomavirus type 2 in urinary bladders and lymph nodes in cases of Bovine Enzootic Hematuria from the endemic region of Azores

Bovine Enzootic Hematuria (BEH) is a disease with a severe impact on production indexes and characterized by the development of bovine urinary bladder tumors, particularly in the Azores archipelago. The purpose of this study was to investigate and quantify BPV2 tissue distribution in bovine urinary bladder tumors, normal bladders, and iliac lymph nodes of cattle from the Azores. A real-time PCR system targeting the L1 gene was developed and allowed for the specific detection of the virus. BPV2 DNA was detected in a large proportion of the samples tested, both from neoplastic and healthy tissues, indicating that this virus is very prevalent in the bovine population of the Azores. Moreover, all types of tissues tested were positive, confirming a wide viral distribution within the infected animal. Bovine cutaneous papillomas sampled from Portuguese mainland dairy cattle were used as controls. Viral load ranged between 2.2×10(4) copies/cell in the skin papillomas, and 0.0002 copies/cell in the urinary bladders tumors from the Azores. This is the first report presenting quantitative data on BPV2 infection in bovine urinary bladder lesions from the Azores. This approach will provide a useful tool to evaluate the role of BPV2 not only in the pathogenesis BEH but also in cell transformation mechanisms.

Bovine Papillomavirus Type 13 Expression in the Urothelial Bladder Tumours of Cattle

Bovine papillomavirus type 13 (BPV-13), a novel Deltapapillomavirus, has been found associated with urothelial tumours of the urinary bladder of cattle grazing on lands infested with bracken fern. BPV-13 was detected in 28 of 39 urothelial tumours. Diagnosis was based on sequencing of L1 and E5 amplicons from tumour samples. The nucleotide sequences generated from these amplicons showed a 100% homology with the sequences of BPV-13 L1 and E5 DNA found in Brazil from a fibropapilloma of the ear in a cow and from equine sarcoids in two horses. GenBank accession number of our representative BPV-13 sequences is JQ798171.1. Furthermore, mRNA encoding BPV-13 E5 oncoprotein was also documented, and its expression was also shown by immunohistochemistry and immunofluorescence in the basal and suprabasal urothelial tumour cells. In twenty-three tumours, BPV-13 was simultaneously found with BPV-2, a Deltapapillomavirus genus, species 4. The latter virus was detected by amplifying and sequencing a 154-bp-sized DNA fragment of BPV-2 E5. In addition, BPV-13 by itself was seen to be expressed in five BPV-2-negative urothelial tumours. This study shows that BPV-13 is present in urothelial tumour cells thus sharing biological properties with BPV-1 and BPV-2. Although further studies are needed, BPV-13 appears to be another worldwide infectious agent responsible for a distressing disease causing severe economic losses in cattle industry.

Bovine papillomavirus isolation by ultracentrifugation

The bovine papillomavirus (BPV) is the etiological agent of bovine papillomatosis, which causes significant economic losses to livestock, characterized by the presence of papillomas that regress spontaneously or persist and progress to malignancy. Currently, there are 13 types of BPVs described in the literature as well as 32 putative new types. This study aimed to isolate viral particles of BPV from skin papillomas, using a novel viral isolation method. The virus types were previously identified with new primers designed. 77 cutaneous papilloma samples of 27 animals, Simmental breed, were surgically removed. The DNA was extracted and subjected to PCR using Delta-Epsilon and Xi primers. The bands were purified and sequenced. The sequences were analyzed using software and compared to the GenBank database, by BLAST tool. The viral typing showed a prevalence of BPV-2 in 81.81% of samples. It was also detected the presence of the putative new virus type BR/UEL2 in one sample. Virus isolation was performed by ultracentrifugation in a single density of cesium chloride. The method of virus isolation is less laborious than those previously described, allowing the isolation of complete virus particles of BPV-2.

Bovine and Human Papillomaviruses

Fifty years ago, inoculation with bovine papillomavirus (BPV) was found to cause mesenchymal tumors of the skin in cattle and horses, as well as tumors of the bladder in cattle. Subsequent to these studies of BPVs, human papillomaviruses (HPVs) were found to cause cervical cancer resulting in intense research into papillomaviruses. During the past 50 years, the ways that HPVs and BPVs cause disease have been investigated, and both HPVs and BPVs have been associated with an increasingly diverse range of diseases. Herein, the biology, oncogenic mechanisms, and diseases associated with BPVs are compared with those of HPVs. As reviewed, there are currently significant differences between BPVs and HPVs. However, research 50 years ago into BPVs formed a prologue for the recognition that papillomaviruses have a significant role in human disease, and it is possible that future research may similarly reveal that BPVs are less different from HPVs than is currently recognized.

Detection of Different Bovine Papillomavirus Types and Co-infection in Bloodstream of Cattle

Bovine papillomavirus (BPV) is a diverse group of double-stranded DNA oncogenic viruses. BPVs are classically described as epitheliotropic, however, they have been detected in body fluids, such as blood and semen. The presence of BPV in these sites can have implications for the dissemination of BPV. The aim of this study was to verify the prevalence of BPV types in cattle blood. A total of 57 blood samples were analyzed by PCR using BPV type-specific primers to BPVs 1-6 and 8-10, and subsequent sequencing. Sequencing quality was determined using Staden package with Phred 20. Similarity analysis was performed with BioEdit and BLAST programs to assess the identity with known BPV types. Statistical analysis was performed by Fisher's exact test. The results showed seven different types of BPVs in the blood, with the exception of BPV 5 and 9. This is the first study that demonstrates BPVs 3, 6, 8 and 10 DNA in cattle blood. BPVs 1 and 2 were the viral types most frequent in blood, while BPVs 4 and 10 were the least frequent types. All the samples showed co-infection by at least two BPV types. These data suggest that several BPV types may infect blood cells at the same time and demonstrate the possibility that the BPV infection in non-epithelial tissue can occur without restriction to one or two viral types. These results can contribute to future studies aimed at the control and prevention of papillomaviruses.

Bovine Papillomavirus: New Insights into an Old Disease

Bovine papillomaviruses (BPVs) are small DNA tumoral viruses able to induce benign cutaneous and/or mucosal epithelial lesions. Generally, the benign tumours affecting the skin or mucosa spontaneously regress, but under special circumstances, the defence system may be overwhelmed, thus leading to cancer, especially in the presence of immunosuppressant and mutagen agents from bracken fern. To date, thirteen different BPV genotypes have been associated with skin and mucosal tumours in cattle, and out of these, only four types (BPV-1, -2, -5 and -13) cross-infect other species. Recent investigations in vivo have revealed new insights into the epidemiology and pathogenesis of this viral infection. This review briefly discusses viral epidemiology, will give data on BPV genome structure and viral genes and will describe the cellular events and new aspects of both cutaneous and mucosal tumours in large ruminants. Finally, some aspects of active immunization will be described.

Bovine papillomavirus type 2 (BPV-2) E5 oncoprotein binds to the subunit D of the V₁-ATPase proton pump in naturally occurring urothelial tumors of the urinary bladder of cattle

Background

Active infection by bovine papillomavirus type 2 (BPV-2) was documented for fifteen urinary bladder tumors in cattle. Two were diagnosed as papillary urothelial neoplasm of low malignant potential (PUNLMP), nine as papillary and four as invasive urothelial cancers.

Methods and Findings

In all cancer samples, PCR analysis revealed a BPV-2-specific 503 bp DNA fragment. E5 protein, the major oncoprotein of the virus, was shown both by immunoprecipitation and immunohistochemical analysis. E5 was found to bind to the activated (phosphorylated) form of the platelet derived growth factor β receptor. PDGFβR immunoprecipitation from bladder tumor samples and from normal bladder tissue used as control revealed a protein band which was present in the pull-down from bladder cancer samples only. The protein was identified with mass spectrometry as “V₁-ATPase subunit D”, a component of the central stalk of the V₁-ATPase vacuolar pump. The subunit D was confirmed in this complex by coimmunoprecipitation investigations and it was found to colocalize with the receptor. The subunit D was also shown to be overexpressed by Western blot, RT-PCR and immunofluorescence analyses. Immunoprecipitation and immunofluorescence also revealed that E5 oncoprotein was bound to the subunit D.

Conclusion

For the first time, a tri-component complex composed of E5/PDGFβR/subunit D has been documented in vivo. Previous in vitro studies have shown that the BPV-2 E5 oncoprotein binds to the proteolipid c ring of the V₀-ATPase sector. We suggest that the E5/PDGFβR/subunit D complex may perturb proteostasis, organelle and cytosol homeostasis, which can result in altered protein degradation and in autophagic responses.

Bovine papillomavirus E2 and E5 gene expression in sperm cells of healthy bulls

Papillomaviruses are found in epithelial lesions and are linked to different carcinogenic processes in humans and other animals. Although BPV has been characterized as epitheliotropic, the presence of viral DNA has been detected in other tissues and fluids, such as fresh semen. The aim of this study was to evaluate the presence and expression of BPV in sperm cells of bulls (Bos taurus) asymptomatic for papillomatosis. A PCR assay was carried out with specific primers to test BPV2 in 26 semen samples. The presence of BPV transcripts was assessed by RT-PCR to E2 and E5 genes. BPV2 DNA was detected in nine out of 26 samples and the expression of E2 and E5 were detected in five out of nine BPV positive samples. This is the first record of BPV2 expression in bull sperm cells.

Chromosome aberrations in cells infected with bovine papillomavirus: comparing cutaneous papilloma, esophagus papilloma, and urinary bladder lesion cells

The majority of malignant cells present genetic instability with chromosome number changes plus segmental defects: these changes involve intact chromosomes and breakage-induced alterations. Some pathways of chromosomal instability have been proposed as random breakage, telomere fusion, and centromere fission. Chromosome alterations in tumor cells have been described in animal models and in vitro experiments. One important question is about possible discrepancies between animal models, in vitro studies, and the real events in cancer cells in vivo. Papillomaviruses are relevant agents in oncogenic processes related to action on host genome. Recently, many reports have discussed the presence of virus DNA in peripheral blood, in humans and in animals infected by papillomaviruses. The meaning of this event is of controversy: possible product of apoptosis occurring in cancer cells, metastasized cancer cells, or active DNA sequences circulating in bloodstream. This study compares chromosome aberrations detected in bovine cells, in peripheral blood cells, and in BPV lesion cells: the literature is poor in this type of study. Comparing chromosome aberrations described in the different cells, a common mechanism in their origin, can be suggested. Furthermore blood cells can be evaluated as an effective way of virus transmission.

Bovine papillomavirus clastogenic effect analyzed in comet assay

Bovine papillomavirus (BPV) is an oncogenic virus related to serious livestock diseases. Oncoproteins encoded by BPV are involved in several steps of cellular transformation and have been reported as presenting clastogenic effects in peripheral lymphocytes and primary culture cells. The aim of this study was to evaluate the clastogenic potential of BPV types 1, 2, and 4 by comet assay. Peripheral blood was collected from 37 bovines, 32 infected with different levels of papillomatosis (12 animals have no affection) and five calves, virus free (negative control). The viral identification showed presence of more than one virus type in 59.375% of the infected animals. Comet assay was performed according to alkaline technique. The Kruskal-Wallis test showed statistical difference between the negative control group and infected animals (P = 0.0015). The Dunn post hoc test showed difference comparing the infected animals with calves. Mann-Whitney U test verified no difference between animals infected with only one viral type and animals presenting more than one viral type. The comet assay is considered an efficient tool for assessment of damage in the host chromatin due to viral action, specifically highlighting viral activity in blood cells.

Expression and in Silico analysis of the recombinant bovine papillomavirus E6 protein as a model for viral oncoproteins studies

Bovine papillomaviruses (BPVs) are recognized as the causal agents of economical relevant diseases in cattle, associated with the development of tumors in skin and mucosa. The oncogenesis process is mainly associated with different viral oncoprotein expressions, which are involved in cell transformation. The expression and characterization of recombinant viral oncoproteins represent an attractive strategy to obtain biotechnological products as antibodies and potential vaccines, Thus, the aim of this work was to clone and express the BPV-1 and BPV-2 E6 recombinant proteins and perform in silico analysis in order to develop a strategy for the systematic study of other papillomaviruses oncoproteins. The results demonstrated that BPV-1 and BPV-2 E6 recombinant proteins were expressed and purified from bacterial system as well as its in silico analysis was performed in order to explore and predict biological characteristics of these proteins.

Bovine papillomavirus type 2 infection and microscopic patterns of urothelial tumors of the urinary bladder in water buffaloes

Microscopic patterns of thirty-four urothelial tumors of the urinary bladder of water buffaloes from the Marmara and Black Sea Regions of Turkey are here described. All the animals grazed on lands rich in bracken fern. Histological diagnosis was assessed using morphological parameters recently suggested for the urinary bladder tumors of cattle. Papillary carcinoma was the most common neoplastic lesion (22/34) observed in this study, and low-grade carcinoma was more common (seventeen cases) than high-grade carcinoma (five cases). Papilloma, papillary urothelial neoplasm of low malignant potential (PUNLMP), and invasive carcinomas were less frequently seen. Carcinoma in situ (CIS) was often detected associated with some papillary and invasive carcinomas. De novo (primary) CIS was rare representing 3% of tumors of this series. A peculiar feature of the most urothelial tumors was the presence in the tumor stroma of immune cells anatomically organized in tertiary lymphoid organs (TLOs). Bovine papillomavirus type-2 (PV-2) E5 oncoprotein was detected by molecular and immunohistochemistry procedures. Early protein, E2, and late protein, L1, were also detected by immunohistochemical studies. Morphological and molecular findings show that BPV-2 infection contributes to the development of urothelial bladder carcinogenesis also in water buffaloes.

Comparison of two PCR strategies for the detection of bovine papillomavirus

Bovine papillomavirus (BPV) is a diverse group of double-stranded DNA oncogenic viruses, which have been detected in epithelial lesions and body fluids. Most studies of BPV infection rely on a single method for DNA detection; however the use of any single method or technique may underestimate the true prevalence of this virus. The purpose of this study was to compare two PCR strategies for the detection of BPV in skin lesions and fluids: these involve the use of BPV type-specific and consensus primers. Seventy-two cutaneous lesions, 57 blood samples and 59 semen samples were collected. PCR was used with the FAP consensus primers and BPV type-specific primers (for BPVs 2, 3, 4, 5, 8, 9 and 10), along with sequencing assays, to detect the BPV types. Phylogenetic analysis was carried out by means of the maximum likelihood method. It was found that both FAP and BPV type-specific primer sets could amplify BPV types of DNA in skin lesions, blood and semen samples. However, the BPV type-specific primers were more sensitive than the consensus primers and were able to detect co-infection of BPV in the samples. The consensus primers amplified five BPV types and were more suitable for detecting new putative BPV types. Thus, account should be taken of both PCR primer systems to identify co-infection, the presence of novel viruses, and avoid false-negative results.

Productive infection of bovine papillomavirus type 2 in the urothelial cells of naturally occurring urinary bladder tumors in cattle and water buffaloes

Background

Papillomaviruses (PVs) are highly epitheliotropic as they usually establish productive infections within squamous epithelia of the skin, the anogenital tract and the oral cavity. In this study, early (E) and late (L) protein expression of bovine papillomavirus type 2 (BPV-2) in the urothelium of the urinary bladder is described in cows and water buffaloes suffering from naturally occurring papillomavirus-associated urothelial bladder tumors.

Methods and Findings

E5 protein, the major oncoprotein of the BPV-2, was detected in all tumors. L1 DNA was amplified by PCR, cloned and sequenced and confirmed to be L1 DNA. The major capsid protein, L1, believed to be only expressed in productive papillomavirus infection was detected by Western blot analysis. Immunohistochemical investigations confirmed the presence of L1 protein both in the cytoplasm and nuclei of cells of the neoplastic urothelium. Finally, the early protein E2, required for viral DNA replication and known to be a pivotal factor for both productive and persistent infection, was detected by Western blot and immunohistochemically. Electron microscopic investigations detected electron dense particles, the shape and size of which are consistent with submicroscopic features of viral particles, in nuclei of neoplastic urothelium.

Conclusion

This study shows that both active and productive infections by BPV-2 in the urothelium of the bovine and bubaline urinary bladder can occur in vivo.

Bovine papillomavirus E5 and E7 oncoproteins in naturally occurring tumors: are two better than one?

Bovine papillomaviruses (BPVs) are oncogenic DNA viruses, which mainly induce benign lesions of cutaneous and/or mucosal epithelia in cattle. Thirteen (BPV 1-13) different viral genotypes have been characterized so far. BPVs are usually species-specific but BPV 1/2 may also infect equids as well as buffaloes and bison and cause tumors in these species. BPV-induced benign lesions usually regress, however occasionally they develop into cancer particularly in the presence of environmental carcinogenic co-factors. The major transforming protein of BPV is E5, a very short hydrophobic, transmembrane protein with many oncogenic activities. E5 contributes to cell transformation through the activation of the cellular β receptor for the platelet-derived growth factor (PDGFβ-r), it also decreases cell surface expression of major histocompatibility complex class I (MHCI) causing viral escape from immunosurveillance, and plays a role in the inhibition of the intracellular communication by means of aberrant connexin expression. E7 is considered as a weak transforming gene, it synergies with E5 in cell transformation during cancer development. E7 expression correlates in vivo with the over-expression of β1-integrin, which plays a role in the regulation of keratinocytes proliferation and differentiation. Additionally, E7 is involved in cell-mediated immune responses leading to tumour rejection, in anoikis process by direct binding to p600, and in invasion process by upregulation of Matrix metalloproteinase1 (MMP-1) expression. Studies on the role of BPV E5 and E7 oncoproteins in naturally occurring tumours are of scientific value, as they may shed new light on the biological role of these two oncogenes in cell transformation.

The environmental and human effects of ptaquiloside-induced enzootic bovine hematuria: a tumorous disease of cattle

In this review, we address the major aspects of enzootic bovine hematuria and have placed special emphasis on describing the etiology, human health implications, and advanced molecular diagnosis of the disease.Enzootic bovine hematuria (EBH) is a bovine disease characterized by the intermittent presence of blood in the urine and is caused by malignant lesions in the urinary bladder. This incurable disease is a serious malady in several countries across many continents. Accurate early-stage diagnosis of the disease is possible by applying advanced molecular techniques, e.g., detection of genetic mutations in the urine of cows from endemic areas. Use of such diagnostic approaches may help create an effective therapy against the disease.There is a consensus that EBH is caused primarily by animals consuming bracken fern (P. aquilinum) as they graze. The putative carcinogen in bracken is ptaquiloside(PT), a glycoside. However, other bracken constituents like quercetin, isoquercetin,ptesculentoside, caudatoside, astragalin, and tannins may also be carcinogenic.Studies are needed to identify the role of other metabolites in inducing urinary bladder carcinogenesis.The bovine papilloma virus is also thought to be an associated etiology in causing EBH in cattle. There is growing alarm that these fern toxins and their metabolites reach and contaminate the soil and water environment and that the carcinogen (PT)is transmitted via cow's milk to the human food chain, where it may now pose a threat to human health. An increased incidence of gastric and esophageal cancer has been recorded in humans consuming bracken ferns, and among those living for long periods in areas infested with bracken ferns.Although preliminary therapeutic vaccine trials with inactivated BPV-2 against EBH have been performed, further work is needed to standardize and validate vaccine doses for animals.

The presence and gene expression of bovine papillomavirus in the peripheral blood and semen of healthy horses

Papillomavirus (PV) are double-stranded DNA viruses that can cause both benignant and malignant tumours in mammals. Twelve genotypes of bovine papillomavirus (BPV1-12) have been identified so far. The presence of BPV1 and 2 has been found in the body fluids of cattle and horses. The aim of this study is to investigate the presence of BPV DNA and the expression of viral genes in the blood and sperm cells of healthy horses using PCR and RT-PCR. BPV-1 or 2 was detected in 14 of 70 blood samples (20%) and in 11 of 31 semen samples (35%). In five of fourteen blood samples, the E5 expression tested positive, while no blood sample was positive for L1 expression. Four of 11 (36%) semen cell samples proved to be positive for E5 expression, while no gene expression in L1 could be detected. This is the first study that shows BPV1 gene expression in the blood and semen of healthy horses. Our data illustrate the need for a better understanding of the presence of BPV in non-epithelial tissues of horses and their role in the vertical and horizontal transmission of these viruses.

Expression of heat shock proteins in premalignant and malignant urothelial lesions of bovine urinary bladder

Abnormal heat shock protein (HSP) levels have been observed in a number of human tumours, where they are involved in all hallmarks of cancer. Since bovine urothelial tumours share striking morphological and biochemical features with their human counterparts, the aim of this study was to evaluate the immunohistochemical levels of Hsp27, Hsp60, Hsp72, Hsp73 and Hsp90 in 28 normal bovine urinary bladders and 30 bovine papillomavirus-positive urothelial tumours (9 in situ carcinomas, 9 low-grade and 12 high-grade carcinomas) and adjacent premalignant lesions obtained from cows suffering from chronic enzootic haematuria, in order to investigate the role of these proteins in the process of urothelial carcinogenesis. A semi-quantitative method was used for the analysis of the results. Western blot analysis was also used to confirm HSP expression in normal controls. All investigated HSPs were expressed in normal bovine urothelium, showing characteristic patterns of immunolabelling throughout urothelial cell layers, which usually appeared to be conserved in urothelial hyperplasia and dysplasia. On the other hand, gradual loss of Hsp27 immunostaining resulted to be significantly associated with increasing histological grade of malignancy (P < 0.01). As well, a significantly reduced immunosignal of Hsp73 and Hsp90 was observed in high-grade and low-/high-grade carcinomas, respectively (P < 0.01). In contrast, Hsp60 (P < 0.01) and Hsp72 (P < 0.05) immunoreactivity appeared to be significantly increased both in premalignant and malignant lesions when compared to that observed in normal urothelium, thus suggesting an early involvement of these proteins in neoplastic transformation of urinary bladder mucosa.

Bovine papillomavirus type 2 infects the urinary bladder of water buffalo (Bubalus bubalis) and plays a crucial role in bubaline urothelial carcinogenesis

Bovine papillomavirus type 2 (BPV-2) has been shown to infect and play a role in urinary bladder carcinogenesis of buffaloes grazed on pastures with ferns from the Marmara and Black Sea Regions of Turkey. BPV-2 DNA has been found in both neoplastic and non-neoplastic lesions of the urinary bladder. Furthermore, this virus may be a normal inhabitant of the urinary bladder since BPV-2 DNA has also been detected in clinically normal buffaloes. The viral activation by fern immunosuppressant or carcinogen may trigger the urothelial cell transformation. The E5 oncoprotein was solely detected in urothelial tumours and appeared to be co-localized with the overexpressed and phosphorylated platelet derived growth factor (PDGF) β receptor in a double-colour immunofluorescence assay. Our results indicate that the E5-PDGF β receptor interaction also occurs in spontaneous tumours of the bubaline urinary bladder, revealing an additional role of BPV-2 in bladder carcinogenesis of buffaloes.

Expression of connexin 26 and bovine papillomavirus E5 in cutaneous fibropapillomas of cattle

Bovine papillomaviruses (BPVs) can infect epithelial cells and fibroblasts, inducing fibropapillomas in cattle. Gap junctions are communication channels between cells composed of connexins (Cxs). This study evaluated expression of Cx26 and the major BPV oncoprotein E5 in bovine cutaneous fibropapillomas. BPV DNA was amplified from 20/20 fibropapillomas and 3/3 samples of normal skin. All fibropapillomas (20/20) were positive by immunostaining for E5, whereas the three normal skin samples were negative. Cx26 was expressed faintly in the normal skin epithelium. Positive cytoplasmic and juxtanuclear immunoreactivity for Cx26 was evident in 18/20 (90%) fibropapillomas. Western blot analysis demonstrated higher expression of Cx26 in 6/6 fibropapillomas compared to normal skin samples.

Bacterial isolates from the urine of cattle affected by urothelial tumors of the urinary bladder

Microbiological investigations were performed on urine samples from 108 cows affected by urothelial tumors of the urinary bladder. Bacteria, frequently of mixed population, were isolated from 100 animals. Gram-positive bacteria prevailed, with Staphylococcus spp. and Bacillus spp. being the most common. Escherichia coli and Acinetobacter spp. were the most frequently recovered Gram-negative bacteria. E5 oncoprotein was detected in 86 of the 108 urothelial tumors under study. In the majority of cases, bacterial agents and BPV-2 E5 were simultaneously detected. A marked down-regulation of Tamm-Horsfall protein was also observed in the examined cases. In addition, the p65 subunit of the nuclear factor-κB (NF-κB) transcription factor appeared to be overexpressed. In all cases, a mild to severe chronic inflammation was evident in the stroma of urinary bladder tumors. Bacterial components may play a role in the activation of the NF-κB and might cause chronic inflammation resulting in an impaired ability to clear BPV-2 infection, thus cooperating with the virus in cancer development. As in man, therefore, bacteria could play both a direct and an indirect role in bovine bladder carcinogenesis.

Productive infection of bovine papillomavirus type 2 in the placenta of pregnant cows affected with urinary bladder tumors

Papillomaviruses (PVs) are believed to be highly epitheliotropic as they usually establish productive infections within stratified epithelia. In vitro, various PVs appear to complete their entire life-cycle in different trophoblastic cell lines. In this study, infection by and protein expression of bovine papillomavirus type 2 (BPV-2) in the uterine and chorionic epithelium of the placenta has been described in four cows suffering from naturally occurring papillomavirus-associated urothelial bladder tumors. E5 oncoprotein was detected both by Western blot analysis and immunohistochemically. It appears to be complexed and perfectly co-localized with the activated platelet-derived growth factor ß receptor (PDGFßR) by laser scanning confocal microscopy. The activated PDGFßR might be involved in organogenesis and neo-angiogenesis rather than in cell transformation during pregnancy. The major capsid protein, L1, believed to be only expressed in productive papillomavirus infection has been detected by Western blot analysis. Immunohistochemical investigations confirmed the presence of L1 protein both in the cytoplasm and nuclei of cells of the uterine and chorionic epithelium. Trophoblastic cells appear to be the major target for L1 protein expression. Finally, the early protein E2, required for viral DNA replication and known to be expressed during a productive infection, has been detected by Western blot and immunohistochemically. Electron microscopic investigations detected viral particles in nuclei of uterine and chorionic epithelium. This study shows that both active and productive infections by BPV-2 in the placenta of pregnant cows can occur in vivo.

The RBP-Jκ binding sites within the RTA promoter regulate KSHV latent infection and cell proliferation

Kaposi's sarcoma-associated herpesvirus (KSHV) is tightly linked to at least two lymphoproliferative disorders, primary effusion lymphoma (PEL) and multicentric Castleman's disease (MCD). However, the development of KSHV-mediated lymphoproliferative disease is not fully understood. Here, we generated two recombinant KSHV viruses deleted for the first RBP-Jκ binding site (RTA_1st) and all three RBP-Jκ binding sites (RTA_all) within the RTA promoter. Our results showed that RTA_1st and RTA_all recombinant viruses possess increased viral latency and a decreased capability for lytic replication in HEK 293 cells, enhancing colony formation and proliferation of infected cells. Furthermore, recombinant RTA_1st and RTA_all viruses showed greater infectivity in human peripheral blood mononuclear cells (PBMCs) relative to wt KSHV. Interestingly, KSHV BAC36 wt, RTA_1st and RTA_all recombinant viruses infected both T and B cells and all three viruses efficiently infected T and B cells in a time-dependent manner early after infection. Also, the capability of both RTA_1st and RTA_all recombinant viruses to infect CD19+ B cells was significantly enhanced. Surprisingly, RTA_1st and RTA_all recombinant viruses showed greater infectivity for CD3+ T cells up to 7 days. Furthermore, studies in Telomerase-immortalized human umbilical vein endothelial (TIVE) cells infected with KSHV corroborated our data that RTA_1st and RTA_all recombinant viruses have enhanced ability to persist in latently infected cells with increased proliferation. These recombinant viruses now provide a model to explore early stages of primary infection in human PBMCs and development of KSHV-associated lymphoproliferative diseases.

Kaposi's sarcoma-associated herpesvirus (KSHV) is tightly linked to at least two lymphoproliferative disorders, primary effusion lymphoma (PEL) and multicentric Castleman's disease (MCD). The life cycle of KSHV consists of latent and lytic phase. RTA is the master switch for viral lytic replication. In this study, we first show that recombinant viruses deleted for the RBP-Jκ sites within the RTA promoter have a decreased capability for lytic replication, and thus enhanced colony formation and proliferation of infected cells. Interestingly, the recombinant viruses show greater infectivity in human peripheral blood mononuclear cells (PBMCs). The recombinant viruses also infected CD19+ B cells and CD3+ T cells with increased efficiency in a time-dependent manner and now provide a model which can be used to explore the early stages of primary infection in human PBMCs, as well as the development of KSHV-associated lymphoproliferative diseases.

Inoculation of young horses with bovine papillomavirus type 1 virions leads to early infection of PBMCs prior to pseudo-sarcoid formation

Bovine papillomavirus types 1 and 2 (BPV-1 and BPV-2) are known to induce common equine skin tumours, termed sarcoids. Recently, it was demonstrated that vaccination with BPV-1 virus-like particles (VLPs) is safe and highly immunogenic in horses. To establish a BPV-1 challenge model for evaluation of the protective potential of BPV-1 VLPs, four foals were injected intradermally with infectious BPV-1 virions and with viral genome-based and control inocula, and monitored daily for tumour development. Blood was taken before inoculation and at weekly intervals. BPV-1-specific serum antibodies were detected by a pseudo-virion neutralization assay. Total nucleic acids extracted from tumours, intact skin and PBMCs were tested for the presence of BPV-1 DNA and mRNA using PCR and RT-PCR, respectively. Intralesional E5 oncoprotein expression was determined by immunofluorescence. Pseudo-sarcoids developed exclusively at sites inoculated with virions. Tumours became palpable 11-32 days after virion challenge, reached a size of ≤20 mm in diameter and then resolved in ≤6 months. No neutralizing anti-BPV-1 serum antibodies were detectable pre- or post-challenge. BPV-1 DNA was present in lesions but not in intact skin. In PBMCs, viral DNA was already detectable before lesions were first palpable, in concentrations correlating directly with tumour growth kinetics. PBMCs from two of two foals also harboured E5 mRNA. Immunofluorescence revealed the presence of the E5 protein in tumour fibroblasts, but not in the apparently normal epidermis overlying the lesions. Together with previous findings obtained in horses and cows, these data suggest that papillomavirus infection may include a viraemic phase.

PBMCs are additional sites of productive infection of bovine papillomavirus type 2

Bovine papillomavirus type 2 (BPV-2) is an oncogenic virus infecting both epithelial and mesenchymal cells. Its life cycle, similar to other papillomaviruses (PVs), appears to be linked to epithelial differentiation. Human and bovine PVs have been known to reside in a latent, episomal form in PBMCs; therefore, it is believed that blood cells, like all mesenchymal cells, function as non-permissive carriers. Here, for the first time in veterinary and comparative medicine, the BPV-2 E5 oncoprotein and the major structural L1 capsid protein, known to be expressed only in productive infections, were shown to occur in defined subsets of PBMCs. E5 oncoprotein was detected in sorted T- and B-cells as well as in monocytes by flow cytometry and Western blot analysis. However, CD4(+) and CD8(+) lymphocytes appeared to be the main circulating targets of the virus, thus possibly representing the most important reservoir of active BPV-2 in blood. L1 protein was identified by flow cytometry in a population of blood cells recognized as lymphocytes by morphological scatter properties. Western blot analysis was performed on lysates obtained from the sorted subpopulations of PBMCs and detected L1 protein in CD4(+) and CD8(+) cells only. Thus, this study showed that CD4(+) and CD8(+) lymphocytes are permissive for BPV-2 and are new, hitherto unknown sites of productive PV infection. In light of these observations, the life cycle of PVs needs to be revisited to gain novel insights into the epidemiology of BPV infection and the pathogenesis of related diseases.