Effect of bacille Calmette-Guerin immunotherapy on feline sarcoma virus-induced neoplasms in the cat

Kittens infected experimentally with feline sarcoma virus (FeSV) were inoculated with emulsions of bacille Calmette-Guerin (BCG) cell wall preparations to determine the effect of BCG immunotherapy on FeSV-induced sarcoma-genesis. The BCG preparations or emulsificant control preparations were administered (i) subcutaneously at the same time and site as was the FeSV inoculation, (ii) at the same site but 1 week after FeSV inoculation, or (iii) with a mixture of viable autochthonous neoplastic cells approximately 35 days after FeSV inoculation. There was no difference in the percentage of kittens that developed neoplasms, the prepatent period for neoplastic development, the percentage of kittens with neoplastic regression, or the survival rate among groups given BCG, emulsificant control, or FeSV alone. Significantly (P less than 0.05) greater dissemination of neoplasms was seen in groups given BCG or emulsificant control preparations, compared with dissemination in groups given FeSV alone.

In vitro and in vivo investigations on reticuloendotheliosis virus infection

Experimental transmission of reticuloendotheliosis (RE) in 1-day-old SPF chickens was achieved by intraperitoneal inoculation of cell-associated and cell-free RE virus (REV). REV-inoculated chickens exhibited an immune response throughout the entire observation period. Viremia persisted for 5--6 months in chickens hatched from REV-inoculated SPF embryonated eggs. The natural occurrence of RE was detected in turkey flocks of farms Bc.

A generalized inclusion body disease in the budgerigar (Melopsittacus undulatus) caused by a papovavirus-like agent

High mortality rates have been reported in budgerigars between one and 15 days of age in 19 aviaries in the Province of Quebec. The most consistent signs of disease were abdominal distention, lack of down feathers on the back and abdomen, lack of filoplumes on the head and neck, and retarded growth of the tail and contour feathers in birds that either survived or died later. Internal gross lesions were hydropericardium, enlarged heart and liver with multiple pinpoint white spots or large, yellow foci, pale or congested kidneys, congested lungs, and ascites. Histologic examination revealed large, slightly basophilic inclusion bodies in the enlarged nuclei of many different cells. These inclusion bodies were composed of viral particles. Multiple foci of coagulation necrosis were scattered in the myocardium and liver parenchyma, and granulovacuolar degeneration was common in renal tubular epithelial cells. Ballooning degeneration was multifocal in the epidermis and very extensive in the epithelial cells of developing feather follicles, and this led to their partial or complete destruction. Viral particles 50 to 55 nm in diameter were observed in negatively stained preparations from different organs of affected birds. These particles had the size and morphology of a papovavirus. In experimentally infected 25-day-old budgerigars, histologic examinations revealed the presence of intranuclear inclusions in hepatocytes, epithelial cells of the kidney tubules, and reticular cells of the spleen, despite the absence of clinical signs. We feel that this disease is caused by a papovavirus-like agent that can replicate in many tissues of the body, causing widespread lesions responsible for the high mortality rate of very young budgerigars and for the absence and/or incomplete development of feathers.

Investigation of the possible role of the tuberculin intradermal test in the spread of enzootic bovine leukosis

The single intradermal comparative test was used with both avian and bovine tuberculin. Three cattle infected with bovine leukosis virus (BLV) were used as a source of infection. BLV-positive and susceptible animals were tuberculin tested alternately. Fifteen susceptible calves and 15 susceptible sheep were tested. A further three valves and three sheep were used as controls; the needles of the tuberculin syringes were deliberately contaminated with blood from the BLV-infected cattle, before being used in the test. Whereas all three calves and the three sheep inoculated intradermally with contaminated needles developed BLV infections, all of the other 30 animals have remained serologically negative to BLV for 10 months. Transmission of BLV with needles contaminated with BLV-infected blood was prevented by wiping the needles with absorbent cotton wool.

Tolerance, viral shedding, and neoplasia in chickens infected with non-defective reticuloendotheliosis viruses

Chickens inoculated as embryos with non-defective reticuloendotheliosis viruses (ndREVs) generally developed a "tolerant" infection characterized by lack of immunofluorescent antibody and by a viremia that persisted through 93 weeks. Chickens inoculated at hatching generally developed a "non-tolerant" infection characterized by antibody development that gradually waned as the chickens aged and by a transient or intermittent viremia. Although chickens tolerantly infected with ndREV strain T were immunodepressed, tolerance to ndREVs did not depend on immunodepression, because 17-to-20-week-old chickens tolerantly infected with ndREV strain CS were normal in antibody response to sheep red blood cells and Brucella abortus and in mitogen-stimulated blastogenesis of blood lymphocytes. Tolerantly infected dams shed low levels of gs antigen and virus into eggs at high frequencies; however, in two trials, congenital transmission of virus by strain-CS-infected dams was documented in only 2 of 42 and 1 of 132 progeny chicks. Eggs and progeny chicks from non-tolerantly infected dams were always negative for virus and gs antigen. After long latent period (17 to 93 weeks), ndREV-infected chickens developed lymphomas involving the bursa of Fabricius and other visceral organs at high frequency and developed sarcomas, carcinomas, and inflammatory nerve lesions at a lower frequency. The ability of ndREVs to induce tolerant and non-tolerant infection, virus- and antigen-shedding into eggs, and chronic neoplastic disease resembled that of lymphoid leukosis virus, another common avian retrovirus. Certain differences in epidemiological properties of these 2 viruses are discussed.

Demyelination and wasting associated with polyomavirus infection in nude (nu/nu) mice

Nude (nu/nu) mice bearing human tumour heterografts were affected with posterior paralysis and wasting. There was demyelination and infection of the oligodendrocytes of the spinal cord with a papovavirus. Similar virus particles and inclusion bodies were found in the bronchial epithelium, which showed histopathological changes. Similar changes were shown by the epithelia of the renal pelvis, ureter and choroid plexus. The virus was found in a transplantable human tumour, and evidence of spread by contact was also obtained. Intracerebral injection of spinal cord suspension from infected mice resulted in virus infected cutaneous carcinomata, demyelination with virus particles in the oligodendrocytes and posterior paralysis with wasting in adult nude mice. The suspension injected intraperitoneally into newborn Syrian hamsters produced tumours similar to those produced by murine polyoma. No evidence of infection was found in mice from the colony of origin. The virus was identified as murine polyoma Wild Type A2.

Visna-maedi-like disease associated with an ovine retrovirus infection in a Corriedale sheep

A visna-maedi-like disease was found in a Corriedale sheep from which a retrovirus sharing the group antigen of visna-progressive pneumonia virus was isolated from lung, brain, and spleen. Clinically, the sheep had acute neurologic signs and dyspnea. Pathologic examination showed lesions similar to both visna and maedi. In the lung, there was a patchy interstitial pneumonia with marked lymphoid hyperplasia. Changes in the central nervous system were necrotizing nonsuppurative encephalitis of the brain stem, poliomyelitis of the cervical cord, and ependymitis and subependymal gliosis of the ventricles. Histologically, the central nervous system lesions seemed to have arisen sequentially, perhaps in response to bursts of virus replication as the agent underwent possible antigenic mutation. The severe lesions in both the central nervous system and lungs suggested a virus strain with dual tropism.

Equine connective tissue tumors contain unintegrated bovine papilloma virus DNA

Bovine papilloma virus (BPV) appears to be the etiological agent of common equine connective tissue tumors. We investigated the physical state of the viral DNA within such tumors and found no indication for integration into the host genome. The BPV genomes were present as free circular episomes. Two equine sarcoids were shown to contain multiple copies of free circular BPV type 1 (BPV-1) DNA. When the tumors were digested with several single-cut restriction enzymes, there were only form III BPV-1 DNA sequences could be revealed. One of the sarcoids contained, apart from wild-type BPV-1 DNA, a class of smaller BPV-1 circular DNA molecules bearing a deletion of approximately 9% of the BPV-1 genome. This deletion is located in the physical map between the relative units 0 and 0.32.

Natural feline leukemia virus infection and the immune response of cats of different ages

Forty-two kittens and 28 adult cats were placed as tracers in leukemia cluster environments in contact with resident cats, 30% of which were persistently infected with feline leukemia virus (FeLV). After 7 months exposure, FeLV viremia had been detected in 71% of the tracer kittens, although only 55% of these remained persistently infected; in the same period, 11% of tracer adults became infected, but by 2 years the figure reached 43%. Mean latent periods before detection of viremia were 3.4 +/- 1.8 (S.D.) and 13.0 +/- 5.9 months for kittens and adults, respectively. First detection of FeLV infection was accompanied by a sharp although transient drop in peripheral white blood cell numbers, and infection onset triggered the humoral immune response which was comprised of separate antibodies with virus-neutralizing and tumor lysis activities. High titers of virus-neutralizing antibody appeared in transiently viremic cats immediately following elimination of viremia; this antibody was rarely detected in cats that remained persistently viremic. Lytic complement-dependent antibody to feline oncornavirus-associated cell membrane antigen appeared in most cats 1 to 2 weeks after FeLV infection was first detected, and subsequently high titers of this antibody remained in both transiently and persistently infected cats. If the rate of FeLV infection was summarized by using viremia and/or antibody appearance, then 95% of the kittens became infected within 1 year and 61% of the adults within 2 years. Adult cats are, therefore, susceptible to FeLV infection following long-term natural exposure, and their apparent resistance cannot be attributed to a protective humoral immune response that developed immediately after exposure commenced.

A transmissible chicken tumour associated with reticuloendotheliosis virus infection

Histiocytic lymphosarcomas of the intestine, liver, spleen and sciatic nerve were found at necropsy in a 36-week-old laying hen that was culled from a flock of 1800 birds because of emaciation. Type C particles were observed in ultrathin sections of liver and spleen. The serum of the hen contained reticuloendotheliosis virus (REV) antigen, and antibody against REV, but lacked antibodies reactive with Marek's disease virus or subgroups A and B of Rous sarcoma virus. The tumour was transmitted to chickens using a suspension of the initial tumours. These experimental tumours were then transmitted to further chickens, using cultured spleen cells, viable spleen cells that had been stored frozen, and disrupted spleen cells. The tumours, which developed after incubation periods as short as 2 weeks, were histologically similar to those in the original hen. A few chickens also developed feather abnormalities. The chickens with experimentally transmitted tumours developed antibody against REV and REV antigen was demonstrated in cultured cells from these chickens. The chickens failed to develop antibody against Rous sarcoma virus and only 1 of 29 developed antibody against Marek's disease virus.

Reduced prevalence of the Lucké renal adenocarcinoma in populations of Rana pipiens in Minnesota

Northern leopard frogs (Rana pipiens) afflicted with the Lucké renal adenocarcinoma virtually disappeared from Minnesota in the autumn of 1977. Frogs from four sites in Minnesota counties (Polk, Otter Tail, Kandiyohi, and Scott) with a previously high prevalence of Lucké renal tumor were studied. In the past decade, prevalence averaged 4.2% in 29 collections (total, 1,870 frogs). No tumors were detected in 685 frogs autopsied in the autumn of 1977 by the method of previous studies. Frog collections, each comprised of 20 or more individuals, were compared for the presence or absence of tumor-bearing frogs. Significantly fewer collections contained tumor-bearing frogs in the autumn of 1977 than did collections of previous years.

[Papovavirus papillomatosis in beagles]

Canine papillomatosis was diagnosed in 5 out of 12 dogs of the beagle race, aged three to four months, two weeks after arrival from a breeding station. The histological as well as electronmicroscopical findings were typical of the disease.

Lymphoid neoplasms in chicken flocks free of infection with exogenous avian tumor viruses

More than 4,500 breeding female chickens of nine inbred lines maintained under specific-pathogen-free conditions to approximately 500 days of age were studied. Routine monitoring and special assays indicated that they were free of infection by exogenous viruses of the leukosis-sarcoma and the reticuloendotheliosis groups. Some birds were maintained free of Marek's disease (MD) virus infection in plastic isolators, and others were maintained in conventional chicken houses and vaccinated with the herpesvirus of turkeys to prevent the lesions of MD. Ten birds bearing lymphoid tumors were observed in two sublines of one line of chickens known to produce embryos that spontaneously produce Rous-associated virus, type 0 (RAV-O), an endogenous virus of the chicken. Four tumors were found in chickens of one subline maintained free of MD virus infection in isolators. These tumors did not involve the bursa and had some histologic features different from those typical of lymphoid leukosis. Six tumors were found in chickens of the other subline that were vaccinated to prevent MD; these tumors involved the bursa and were typical of lymphoid leukosis but not MD. These results suggest that two types of tumors may have been observed. The fact that DNA extracted from both types of tumors did not contain exogenous lymphoid leukosis virus sequences confirms the virologic evidence that exogenous viruses were not involved. The fact that endogenous viral sequences were not increased in copy number suggests that the endogenous virus RAV-O did not directly induce the tumors. Two birds with tumors not involving the bursa were found alive, and transplantable lymphoid tumors were developed. These tumors were of T-cell origin rather than of bursa cell origin as would be expected of lymphoid leukosis. These are the first reported lymphoid tumors that have been observed in the absence of known exogenous tumor virus infection in chickens. Our evidence suggests that the endogenous virus RAV-O did not play a primary role in the induction of these tumors.

Infectivity tests of secretions and excretions from cattle infected with bovine leukemia virus

Secretions and excretions from cattle with persistent bovine leukemia virus (BLV) infections were tested for BLV by inoculation into sheep. Development of antibody to the BLV glycoprotein antigen and reisolation of virus from peripheral blood leukocytes were the two criteria used to confirm infection in test sheep. The virus was detected in milk from 4 of 6 cows examined and in colostrum from 1 of 4 cows examined. The virus was not detected in semen from 8 bulls or in nasal secretions, saliva, and urine from 2 cows.

Leukemia and lymphoma: infrequent manifestations of common viral infections? A review

Horizontally transmitted viruses have been etiologically linked to leukemia and lymphoma in several higher mammals (gibbons, cows, and cats). In the best-studied example, the cat, feline leukemia virus is a common community-acquired virus that infrequently produces cancer. However, the infection and its complications (cancer) are not typical of infectious diseases. Epidemilogically, serologically, and virologically, infections with this type of virus can contradict classic infectious disease dogma. Therefore, previous studies that failed to link characteristics of infectious diseases (epidemiologic, serologic, or virologic) to human cancer must be cautiously interpreted. A link between retroviruses and/or DNA viruses and human lympho-reticular malignancies is hypothesized, and it is suggested that systematized nation-wide studies of selected cancer patients and their contacts be executed with the most sensitive and specific laboratory probes available.

Common membrane neoantigens on bovine papilloma virus-induced fibroma cells from cattle and horses

Cultured cells from bovine papilloma virus (BPV)-induced fibroblastic tumors and normal dermis of cattle, horses, and hamsters were examined for cell membrane or internal neoantigens, using the indirect immunofluorescence technique. Sera from cattle and horses bearing BPV-induced fibromas cross reacted with cell membranes of tumor, but not with normal dermal cells of both species. The reaction could be blocked with homologous, but not heterologous, serum of these 2 species. Immunofluorescence was not detected with sera from hamsters bearing BPV-induced sarcomas if incubated with bovine, equine, or hamster cells. Internal neoantigens were not found in any of the acetone-fixed tumor cells, using sera from the 3 species. Both tumor and normal cells were all found free of BPV antigen, using direct immunofluorescence.

Natural transmission of gibbon leukemia virus

Gibbon leukemia virus can infect prenatal gibbons through in utero infection or postnatal gibbons through contact transmission. The transmission of infectious virus was from viremic gibbons and not from uninfected or antibody-positive animals. The two modes of transmission could be distinguished by the amount of proviral DNA integrated into the muscle tissue of viremic gibbons. Muscle of gibbons infected postnatally had little or no proviral DNA, whereas gibbons infected prenatally had a large quantity of proviral DNA.

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.

Identification and behavior of the precipitating BLV antibodies in sera of leukotic cattle

Precipitating bovine leukemia virus antibodies isolated from bovine leukemic sera by ion-exchange chromatography, gel filtration and affinity chromatography were identified as immunoglobulins of the IgG1 subclass and IgA class. They proved to be different with regard to molecular size and electrical charge. Immunoglobulins IgG2 and IgM as well as low-molecular components ranging in the microglobulin regions (less than 4S) failed to precipitate BLV antigens. Individual bovine leukemic sera showed differing precipitating activities against p24 and gp69 antigens. Precipitating monospecific gp69 antibodies represented exclusively the IgG1 subclass. Some unidentified antigens in disrupted BLV preparations showed serological relationship to p24 and gp69, respectively.

The epidemiology of the feline leukemia virus (FeLV)

Clustering of cases of feline lymphosarcoma (LSA) has been observed by veterinarians for many years. In 1964 it was discovered that feline LSA was caused by an oncornavirus, the feline leukemia virus (FeLV). In 1970, a simple, indirect immunoflourescent antibody (IFA) test for FeLV was developed which enabled large numbers of cats, living in their natural (household) environments, to be tested for the virus. In one study, over 2,000 cats were tested and the results showed conclusively that FeLV is a contagious agent for cats. This finding was independently confirmed by several other investigators using different testing procedures. After discovering the contagious nature of FeLV a test and removal program was devised which successfully prevents the spread of FeLV and the development of FeLV diseases in the pet cat population. There is, at present, no evidence that FeLV infects humans living with FeLV infected cats.

Naturally occurring infants fibroma in the domestic rabbit

Infectious fibromas developed in eight domestic rabbits that were all kept in outside cages. Each rabbit had a single cutaneous tumor. Six of these tumors, which were studied by light microscopy, consisted of tumor cells resembling fibroblasts and large areas of inflammation. The overlying epidermis was hyperplastic and contained easily recognizable intracytoplasmic inclusion bodies. Inclusion bodies were also in subepithelial fibroma cells. Electron microscopy of three of these tumors revealed typical pox-virus inclusions, sites of viral replication, maturation, and mature particles in epithelial cells of the epidermis and in subepithelial tumor cells. Virus was not seen in inflammatory cells or leukocytes within vascular channels.