Alimentary fibropapilloma in cattle: a spontaneous tumor, nonpermissive for papillomavirus replication.

Fibropapillomatosis of the upper alimentary canal of cattle is described. The tumors, found in the esophagus, esophageal groove, and rumen, showed involvement of the subepithelial fibroblasts as well as of the squamous epithelial layer. Although the fibropapilloma cells harbored multiple episomal copies of the genome of bovine papillomavirus type 2 (BPV-2) easily detected by hybridization techniques, no mature virus could be isolated from these lesions or seen by electron microscopy, and no viral antigen could be detected by immunohistochemical methods. It would appear, therefore, that within the limitations of the techniques employed the alimentary canal epithelium and the underlying fibroblasts, while allowing BPV-2 DNA replication, are nonpermissive for the expression of the viral vegetative functions and that transformation of the epithelial cells, like transformation of fibroblasts, can take place in the absence of infectious viral progeny.

Association of bovine papillomavirus type 2 and bracken fern with bladder cancer in cattle.

The bladder cancer syndrome that often accompanies chronic enzootic hematuria in cattle grazing on pastures infested by bracken fern has been experimentally reproduced in animals fed a diet of bracken. The experimentally induced tumors were histologically and pathologically indistinguishable from the naturally occurring ones and comprised two main types: (a) carcinoma of the urothelium identical to that seen in humans; and (b) hemangioendotheliomas of the subjacent capillaries. Often the two types of tumor occurred together in the same bladder. In animals experimentally immunosuppressed with azathioprine "bracken type" hemangiomas developed in the bladder lining. DNA of bovine papillomavirus (BPV) type 2 was found in 46% (7 of 15) of the natural cancer cases and in 69% (9 of 13) of the experimentally induced lesions, independently of histological type and including the hemangiomas of the azathioprine-treated animals, suggesting a close association between BPV and bovine bladder neoplasia. Moreover, BPV-2 DNA was found in experimental animals that had not been inoculated with BPV at all or had been inoculated with a different BPV type and had been kept in isolation, suggesting that BPV can persist in a latent state and be activated when the animal is exposed to the bracken cocarcinogens and to immunosuppressants.

Association of the human type C retrovirus with a subset of adult T-cell cancers.

To determine whether the human T-cell lymphoma-leukemia virus (HTLV) is associated with particular cancers, patient sera were surveyed for HTLV-specific antibodies. An association was seen with aggressive cancers of mature T-cells, specifically Japanese adult T-cell leukemia (ATL) and T-cell lymphosarcoma cell leukemia (TLCL), a similar cancer of Caribbean blacks. Ninety to 100% of these patients possessed HTLV-specific antibody. Forty-seven and 20% of relatives of ATL and TLCL patients, respectively, and 12 and 4% of healthy donors from ATL and TLCL endemic areas were also antibody positive. Visceral organ involvement, hypercalcemia, and skin manifestation, features of ATL and TLCL, were often seen in other antibody-positive patients. Childhood cancers, most cutaneous T-cell and all non-T-cell leukemias and lymphomas, myeloid leukemias, Hodgkin's disease, and solid tumors were not associated with HTLV. Healthy United States donors and European patients with non-malignant diseases were antibody negative. HTLV is thus associated with a subtype of adult T-cell leukemia-lymphoma, clustered in viral endemic areas, with apparent racial and geographic predilection.

The Harvey ras 1 gene is activated in papillomavirus-associated carcinomas of the upper alimentary canal in cattle.

The possible activation of ras sequences in papillomavirus-associated carcinomas of the upper alimentary canal of cattle was investigated by restriction enzyme and hybridization analysis, and by DNA-mediated transformation of NIH3T3 cells. In three cancers, a squamous cell carcinoma of the palate, a squamous cell carcinoma of the rumen, and a transitional cell carcinoma of the urinary bladder, repetitive DNA sequences present in the Ha-ras 1 locus showed anomalous restriction patterns, indicating rearrangements and, in the case of the palate cancer, amplification. Genomic DNA from several cancers was capable of inducing focus formation in the NIH3T3 transformation test. DNA from primary, secondary and tertiary transformants was analysed by hybridization to bovine ras probes and by nucleotide sequencing of polymerase chain reaction products. Bovine Ha-ras 1 sequences were found in all transformants, but no nucleotide differences were detected in exon 1 or exon 2 between normal, cancer and transformed cells. It is concluded that the Ha-ras 1 gene is activated in alimentary canal carcinomas, although the activating mutation has not yet been mapped. The possible relationship between papillomavirus infection and activation of the ras gene is considered.

Latent papillomavirus infection in cattle.

During a long term experiment designed to identify the contribution of bovine papillomavirus type 4 (BPV-4), environmental mutagens and immunosuppressants to the development of carcinomas of the upper alimentary tract of cattle, there was evidence of latent papillomavirus infection. Papillomatosis-free animals, when immunosuppressed either by feeding bracken fern or by azathioprine treatment, developed skin warts containing either BPV-1 or BPV-2. Skin warts appeared also in an immunocompetent animal at sites of damaged skin. It was concluded that the animals harboured latent papillomavirus which was reactivated by immunosuppression and/or physical trauma, causing skin warts. Papillomavirus DNA was also detected in lymphocytes of both experimental and control animals, suggesting that one of the sites of latency may be the circulating lymphocyte.

Transformation of warts to malignancy in alimentary carcinoma in cattle.

There is a high incidence of alimentary carcinoma in beef cattle in the highland areas of Britain. Evidence is presented to shown that this is associated with the presence of bracken fern on high incidence farms and that many of the carcinomas arise in pre-existing virus-induced papillomas. Papillomas are much commoner and occur in greater numbers in animals of all ages on the cancer farms as compared to lowland cattle. Papillomas are found in all ages of cattle; carcinomas have only been seen in cows over 6 years of age. The virus has been isolated, visualized and purified; it produces papillomas when inoculated into the alimentary tract and skin.

A new transmissible agent causing acute hepatitis, chronic hepatitis and cirrhosis in dogs.

There is a hepatitis of dogs which occurs in acute, persistent and chronic forms. Histological studies of spontaneous cases suggested that several apparently diverse hepatic diseases might be stages of one process. This was also implied by follow up studies and case histories: acute non-lethal episodes were followed later by the development of chronic hepatitis, cirrhosis and liver failure. Serum was taken and homogenates of liver were made from three field cases representing different putative temporal stages of the complex. These were injected into experimental dogs and a hepatitis was induced in all. The cytopathological and histological changes were the same in all animals and were identical to field cases. Acute lethal disease and persistent infections were produced. Two second passages were carried out and an identical condition was induced, characterised by recurrent episodes of subclinical hepatitis and persistent infection. It is suggested that the disease might be named canine acidophil cell hepatitis in view of the pathognomonic cytopathology. Specific morphological criteria have been established for this hepatitis.

Detection, cloning and characterisation of papillomaviral DNA present in sarcoid tumours of Equus asinus.

Molecular investigations on 18 naturally occurring sarcoid tumors removed from donkeys identified papillomaviral DNA homologous to bovine papillomavirus (BPV)-2 DNA under stringent conditions, in all the samples. Restriction endonuclease analysis of 15 of the tumours demonstrated papillomaviral DNA similar to BPV-1 and BPV-2. The type of DNA was not specific to either the site or the type of lesion. The analysis of the nucleotide base sequence of a cloned papillomaviral element from a sarcoid showed that the isolate was 96 and 98 per cent homologous to BPV-1 in the L1 and E5 open reading frames, respectively. It was concluded that the disease in the donkey is similar to that in the horse and that the E5 open reading frame may be involved in oncogenesis in the sarcoid.

Control of parasitic bronchitis in calves: vaccination or treatment?

A 16-day infection of Dictyocaulus viviparus in two groups of calves was treated with levamisole and fenbendazole respectively. Five days afterwards the calves were reinfected with 4000 larvae and necropsied 21 days later. Although the lungworm burdens of the two groups of calves were reduced by about 70 per cent compared to a control group the clinical signs of dyspnoea, tachypnoea and coughing were indistinguishable from a primary infection. This was due to pulmonary emphysema, oedema and an acute epithelialising pneumonia apparently associated with the death and disintegration of lungworms in situ, the result of an incompletely developed immune response. The results are compared with those obtained with the lungworm vaccine. It was concluded that the outcome of any system of "control" which depends on drug therapy and reinfection is unpredictable and that vaccination offers the only effective method of prophylaxis.

Papillomas of the teats and udder of cattle and their causal viruses.

An abattoir survey was carried out on 1657 cattle to determine the incidence and parameters of teat and udder papillomas and their causal viruses. Recent research has characterised six different bovine papillomaviruses of which three have been found to be particularly associated with teat tumours. Of the population studied 37.3 per cent had teat warts and 86.2 per cent of these had multiple infections; 28.4 per cent had papillomas attributed to bovine papillomavirus 1, 88.5 per cent to bovine papillomavirus 5 and 92.3 per cent to bovine papillomavirus 6. There was no predilection site between teats. Herefords and their crosses dominated the breed incidence and showed the highest numbers of warts but it was not possible to make a realistic comparison with other breeds. Dairy cattle were poorly represented. Bovine papillomavirus 4 was never found and from this it was concluded that there is no association between alimentary and teat papillomas. The implications of these findings in terms of prophylaxis and control are discussed.

Studies on vaccination against papillomaviruses: the immunity after infection and vaccination with bovine papillomaviruses of different types.

Calves, free of antibodies to bovine papillomaviruses (BPV), were reared in isolation. One was infected with BPV-2, developed tumours and was resistant to homologous reinfection. Groups of calves were infected with BPV-2, BPV-5 or BPV-6; they all developed and subsequently rejected type-specific tumours. They were then infected with BPV-4; they were not immune and oral papillomas were induced. Groups of animals were vaccinated by intramuscular preparations of purified BPV-4 and BPV-6 and were challenged with homologous virus; all were immune to reinfection. An earlier experiment had shown this to be true for BPV-2. Two calves, immune to BPV-6, were not immune to BPV-1. These experiments, although they do not cover all the possibilities of reciprocal immunisation and challenge, indicate that prophylactic immunity to a range of papillomaviruses is type-specific. This is the first clear demonstration of this phenomenon in the papillomavirus group.

Studies on vaccination against papillomaviruses: a comparison of purified virus, tumour extract and transformed cells in prophylactic vaccination.

Calves were vaccinated with two preparations made from one cutaneous fibropapilloma induced by bovine papillomavirus type 2 (BPV-2). One vaccine consisted of homogenised tumour; the other contained purified virus only. Both produced resistance to a heavy challenge infection of BPV-2. One calf in the vaccinated group developed a small tumour and rejected it earlier than the control calves. It would appear likely that the prophylactic immune response was induced by viral structural proteins only and that tumour-specific antigens are unnecessary. Bovine fibroblasts were transformed in vitro by BPV-2 and administered as a vaccine; immunity was not induced.