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.

Unique morphological alterations of the HTLV-I transformed C8166 cells by infection with HIV-1.

C8166 cells express T lymphocyte markers, a monocyte-specific esterase, taxpolypeptide of HTLV-I. In spite of this transactivator, their HIV-1 yield is low. Their culture conditions were modified, and infected cells were immobilized on a poly-L-lysine sheet under semisolid overlays to study their phenotypic alterations and HIV-1 production by microscopy and electron microscopy. Another lymphoid cultures (MT-4, CEM, CEM-ss, AdCEM) similarly treated were infected with either HIV-1/RF or IIIB. Specificity of HIV-1 was compared to the effects of vesicular stomatitis virus (VSV). Unlike other cultures, HIV-1/RF infected C8166 cells in Eagle s MEM exhibited surface projections resembling hairy leukemia cells, which was followed by balloon degeneration and apoptosis. Immobilized HIV-1 infected cultures formed flat syncytia with several interdigitating dendritic projections. Syncytia shrunk with condensed nuclear material and axon-like filaments characteristic for infected macrophages. VSV induced enlargement and necrotic lysis of all cell types. Early postinfection with HIV-1, electron microscopy revealed irreversible membrane fusion above cell nuclei, and transient fusion between filaments. Transient presence of coated vesicles containing intact HIV-1 particles, Birbeck granule-like structures of Langerhans cells, fibrillar-lamellar structures resembling hairy leukemia or Sézary cells were detected. Late postinfection, high proportion of HIV-1 bud from polarized cytoplasm was empty particle, while that bud and entrapped in cytoplasmic vacuoles contained two or multiple cores in a fused envelope. The effect of early gene products of HIV-1 on HTLV-I and C8166 cells might elicit their latent potentials for monocyte or interdigitating dendritic cells, while in the later phase HTLV-I products might alter HIV-1 virion assembly.

Production of diarrhoea and dysentery in pigs by feeding pure cultures of a spirochaete differing from Treponema hyodysenteriae.

A weakly beta-haemolytic spirochaete, isolate P43/6/78, was isolated from a pig with diarrhoea and found not to fluoresce with a specific fluorescent antiserum to Treponema hyodysenteriae. Pure cultures of this spirochaete were used to inoculate experimental pigs. Diarrhoea, containing clear mucus, and, in one case, blood occurred in four of the eight animals inoculated. Colitis was present in six of the eight inoculated pigs at necropsy. Excess clear mucus and punctate haemorrhages were seen on the colonic mucosa and spirochaetes resembling isolate P43/6/78 were reisolated from the affected mucosa. The feed conversion efficiency and growth rate of affected pigs was reduced when compared with controls. Isolate P43/6/78 differed from T hyodysenteriae in its cultural, ultrastructural, biochemical and antigenic characters. On these grounds, and because of the clinical and pathological syndrome produced, it was considered to belong to a species other than T hyodysenteriae.

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.

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.

Unintegrated viral DNA sequences in a hamster tumor induced by bovine papilloma virus.

A fibrosarcoma was induced in a hamster by bovine papilloma virus type 2 (BPV2). The content of BPV2 DNA sequences was measured by DNA-DNA and cRNA-DNA hybridizations. The tumor contained approximately 300 BPV2 genome equivalents per cell. Southern blot hybridization indicated that the viral DNA was in free form, the entire genome most likely being present. In situ hybridization with BPV2 cRNA showed that multiple genome copies were present in each cell. Neither virus particles nor virus coat antigens could be detected in the tumor. A cell line was established from the fibrosarcoma, and the cells contained multiple copies of the BPV2 genome. The latter was in free form, and all of the DNA sequences appeared to be present in multiple copies and in all cells. An extensive search failed to reveal the presence of virus or viral antigens.

Virus-induced papillomas of the alimentary tract of cattle.

An abattoir survey was carried out to determine the incidence and aetiology of squamous papillomas of the alimentary tract of cattle in Scotland and North England as they were suspected of being involved in the genesis of alimentary carcinoma in certain localized geographical areas. A total of 7,746 cattle of a wide age range was examined. Various subsets of this number were subjected to analyses of certain specific factors. The calculated overall incidence was 19% and the detailed site incidence and tumour multiplicity are given. The sites at which papillomas were found were identical with those at which carcinoma had been noted in animals from a high-cancer area. The number of sites affected by papilloma and the tumour multiplicity were much lower in the general population than in the high-cancer area. Inclusion bodies, identified by electronmicroscopy as virus, were found in tumour cell nuclei and a typical papilloma virus was purified from the tumours. The structure of the tumours is described and the possible plurality of bovine papilloma-viruses is discussed in the light of recent findings in the human viruses. The general interest of a naturally occurring and geographically localized oncogenic system, in which an environmental carcinogen and a virus might be involved, is extended.

The influence of cell culture and storage conditions on HIV-1 infectivity and fusogenic activity.

We have previously demonstrated that acidic medium inhibits the replication of HIV-1. The present study was designed to examine the effects of other growth conditions and infection of fibroblasts by coculture with HIV infected lymphoid cells. Several lymphoblastoid cell lines normally grown in RPMI-1640 were grown in Eagle's MEM. These cells supported virus replication to higher titres than did RPMI-1640. Peak viral titres were achieved within 24-48 h after newly infected or chronically infected cells were placed in fresh medium. When virus was stored in liquid medium either frozen or at higher temperatures, virus titres were retained for several months while frozen but decreased upon storage at 4 degrees C or higher. If cells were passaged after trypsinization in Ca(++)-depleted medium, then a decreased susceptibility of cells for HIV-1 by 2 log10 at 24 h post infection was observed. Infectivity of cell-free and cell-associated HIV-1 was measured using syncytium formation, reverse transcriptase activity and p24 antigen. No fusion between HIV-1 infected CD4+ lymphoblasts and CD4- fibroblasts was observed but HIV-1 infected lymphoid cells, even in the absence of syncytium formation, exerted a strong toxic effect on fibroblasts. This study extends previous findings that medium acidity was inhibitory to virus replication and survival. Thus, conditions for study of HIV must be well controlled in buffered medium so that misleading results are not obtained regarding virus multiplication and possibly regarding transmission to and pathogenesis in CD4- cells.

A novel bovine papillomavirus (BPV-6) causing true epithelial papillomas of the mammary gland skin: a member of a proposed new BPV subgroup.

A papillomavirus has been isolated from frond epithelial papillomas of the bovine udder. It is clearly distinguishable from all other bovine papillomaviruses (BPVs) based on DNA sequence homology and antigenic properties and is thus characterised as a new entity, designated BPV-6. BPV-6 does not possess the interspecific papillomavirus antigen, its genomic DNA (7.2 kb) is smaller than, and does not show any sequence homology to BPV-1, BPV-2, or BPV-5, whereas it is approximately the same length as BPV-3 or BPV-4, with which it shares some sequence homology. The bovine papillomaviruses have been classified into two subgroups: subgroup A, composed of BPV-1, BPV-2, and BPV-5, all of which induce fibropapillomas, and subgroup B, composed of BPV-3, BPV-4, and BPV-6, all of which cause true epithelial papillomas.