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PubMed1992

Reticuloendotheliosis in a wild turkey (Meleagris gallopavo) from coastal Georgia.

An emaciated wild turkey (Meleagris gallopavo) exhibiting neurologic signs was found on Ossabaw Island, Chatham County, Georgia (USA) on 11 April 1989. The neurologic abnormalities observed included ataxia, drooping wings, head tremors, torticollis, and circling. At necropsy, discrete yellowish-white nodules, varying in size from 2 to 5 mm, were present in the spleen. White nodular lesions approximately 2 mm in diameter were observed beneath the mucosal surface of the distal esophagus. Histopathologic examination of the splenic nodules disclosed large numbers of primitive lymphoreticular cells with leptochromatic nuclei and abundant, slightly basophilic cytoplasms. The mitotic index in these cells was moderate to high. Similar neoplastic cells composed the masses observed in the esophagus. Multifocal, mild perivascular cuffing with mononuclear cells was found in the lumbar spinal cord, brain, and brain stem. Reticuloendotheliosis virus, subtype 3, was isolated from samples of the spleen and liver.

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PubMedDate not supplied

Mechanisms of the Eimeria tenella growth inhibitory activity induced by concanavalin A and reticuloendotheliosis virus supernatants with interferon gamma activity in chicken macrophages and fibroblasts.

Pretreatment of chicken bone marrow macrophages and embryo fibroblasts with supernatants containing chicken interferon gamma (IFN-gamma) for 24 hr prior to inoculation inhibited intracellular Eimeria tenella replication, measured by [3H] uracil incorporation. The supernatants (Sns) were obtained from culture of lymphoblastoid cells transformed by a reticuloendotheliosis virus (REV) and chicken splenocytes stimulated with concanavalin A (Con A). The mechanisms of the E. tenella growth inhibitory activity induced by Sn REV and Sn Con A in chicken macrophages and fibroblasts were studied. Addition of oxygen scavengers (superoxide dismutase, D-mannitol, DABCO, benzoic acid, L-histidine hydrochloride) was able to overcome the inhibition of E. tenella replication after pretreatment with Sn REV or Sn Con A in macrophage cultures but not in fibroblast cultures. Nitric oxide (NO) synthesis was induced in macrophage culture treated with Sn REV or Sn Con A but not in fibroblast culture. Addition of NG monomethyl-L-arginine, an NO synthase inhibitor together with the supernatants was also able to overcome inhibition of E. tenella replication in macrophage culture. On the other hand, addition of L-tryptophan to Sn REV- or Sn Con A-treated fibroblasts was able to reverse the inhibitory effect on E. tenella replication. In conclusion, production of inorganic NO or toxic oxygen intermediates may be involved in the E. tenella growth inhibitory activity of chicken macrophages pretreated with supernatants containing an IFN-gamma activity, and cellular tryptophan depletion may be involved for chicken fibroblasts, thus matching the mechanisms of the IFN-gamma-induced growth inhibitory activity for protozoans in mammals.

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PubMedDate not supplied

Reticuloendotheliosis virus (REV) long terminal repeats incorporated in the genomes of commercial fowl poxvirus vaccines and pigeon poxviruses without indication of the presence of infectious REV.

Because of reticuloendotheliosis virus (REV) contamination in commercial poultry vaccines, polymerase chain reaction (PCR) assays have been described to increase the sensitivity of biological assays used to detect REV in vaccines. The PCR assay designed to amplify the long terminal repeat (LTR) region of REV identified REV LTRs in many of the commercial fowl poxvirus (FPV) vaccines evaluated. These commercial vaccines were not thought to be contaminated with replicating REV because of the lack of REV outbreaks, the lack of in vitro amplification, and lack of a serologic response to REV. As previously described, the FPV S vaccine strain is known to carry infectious integrated proviral REV, whereas FPV M vaccine strain and its derivatives carry integrated LTRs or remnants of REV proviral DNA inserted into the FPV genome. Another PCR assay designed to amplify the envelope gene of REV was used to verify that the envelope proviral gene was not present in REV LTR PCR-positive samples. Southern blot analysis with REV LTR probes hybridized to the 9-kb EcoRI genomic fragment of all FPV and pigeon poxviruses evaluated, whereas the envelope probe did not hybridize to any poxvirus genome. Sequence analysis of the 9-kb EcoRI fragment indicated that an integrated REV LTR exists in the 9-kb EcoRI of some poxvirus genomes. A new PCR assay designed to amplify integrated REV LTRs in the 9-kb EcoRI fragment identified complete and incomplete integrated REV LTRs in all FPV and pigeon poxvirus genomes evaluated.

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PubMedDate not supplied

Reticuloendotheliosis virus integration in the fowl poxvirus genome: not a recent event.

Integration of reticuloendotheliosis virus (REV) into the genome of fowl poxvirus (FPV) has been reported recently. With a view to determine whether this event had occurred in the past, we screened by polymerase chain reaction (PCR) for the presence of REV provirus in the DNAs of nine avian poxviruses, some of which had been lyophilized 50 yr ago. For REV, 5' long terminal repeat (LTR) and REV envelope sequences were amplified, whereas for FPV, the major envelope antigen gene and the region flanking REV sequences were amplified. In six of seven FPV strains examined, the specific PCR amplicons were obtained for both REV provirus and FPV sequences. One isolate in which presence of REV 5' LTR and envelope was not detected by PCR, a LTR remnant was detected by Southern hybridization. Interestingly, no REV sequence was detected in either canary poxvirus or pigeon poxvirus genome. These observations indicate that REV integration in the FPV genome is not a recent phenomenon but probably occurred prior to 1949.

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PubMedDate not supplied

Stable transfection of reticuloendotheliosis virus-transformed lymphoblastoid cell lines.

Lymphoblastoid T cell lines were established by infection of chicken splenocytes with reticuloendotheliosis virus (REV). The target cells first were cultured in interleukin-containing conditioned medium or were stimulated by concanavalin A, or both. Most cell lines were T cells expressing CD3 and one of the T cell receptors, and all cell lines were positive for major histocompatibility complex (MHC) class II antigens. Several REV-transformed cell lines were stably transfected using electroporation with a selectable plasmid, pNL1, containing the neor gene. Transfected cell lines were selected using G418 and were maintained for periods up to 137 days. Transfected cell lines were susceptible to MHC class-I restricted lysis by cytotoxic T lymphocytes from REV-infected chickens.

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PubMed1977

Characteristics of two new reticuloendotheliosis virus isolates of turkeys.

Reticuloendotheliosis (RE) virus strains MN81 and MN67 isolated from epiornithics of RE in turkeys were partially characterized. Strains MN81 and MN67 replicated in chicken embryo fibroblast,duck embryo fibroblast and turkey embryo-fibroblast cultures and produced syncytial cytopathic effects in duck embryo fibroblast and turkey embryo fibroblast cultures. The virions of MN81 and MN67 measured approximately 100 nm in diameter, resembled RE virus strain T, and could be distinguished from avian leukosis viruses morphologically. The buoyant density of strain MN81 was found to be 1.15 g/cm3 in sucrose gradients. Strains MN81 and MN67 were inactivated by heat, acid pH, ether, and chloroform treatments. These strains were serologically unrelated to avian leukosis virus but were related to RE virus strains T, CS, DIA, and SN.

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PubMed2005

[Immunogenicity of envelope glycoprotein gene of reticuloendotheliosis virus expressed in insect cell].

A recombinant baculovirus expressing reticuloendotheliosis virus env gene was constructed with Bac-to-Bac Baculovirus Expression Systems. After transfecting the recombinant virus into Sf9 cells for 3 days, REV env can be detected by indirect immunofluorescence antibody assay (IFA) and Western blot with specific monoclonal antibodies of REV. The oil-water emulsion vaccine was then produced using this infected Sf9 cells lycates and inoculated SPF chickens to validate the immunogenicity for REV. The results show that special anti-REV antibody can maintain more than 45 days and resist the infection of REV viruses. This is the first success to induce anti-REV antibody in chickens by none-live viruses.

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PubMed2006

[Sequence analysis of integration sites of reticuloendotheliosis virus LTR in fowlpox vaccine virus genomes].

By use of genomic DNA prepared from 5 fowlpox virus (FPV) vaccines made in China (from Shandong, Beijing, Liaoning, Zhejing and Shanghai respectively) as the templates, reticuloendotheliosis virus (REV) LTR was amplified in PCR with a pair of primers synthesized according to the sequences flanking the integrated REV-5'LTR in FPV genomes published in US and Australia. Sequence analysis indicated that the REV-5'LTR integration sites in genomes of all 5 Chinese PFV vaccine products were identical to American and Australian FPV vaccines with integrated REV-5' LTR. Among the 5 FPV vaccine products made in China, 3 productes Vac-B-Ch, Vac-D-Ch and Vac-E-Ch had the integrated REV-5' LTR sequences of 223bp with 100% homology to that in American vaccine Vac-3-Am and Australian vaccine Vac-M3-Au. The integrated 505bp REV-LTR sequences in another Chinese products Vac-A-Ch and Vac-C-Ch had 99.6% homology to the integrated REV-LTR of American vaccine Vac-1-Am and Australian vaccine Vac-S-Au. However, REV-5'LTR integrated in all 5 FPV vaccines made in China gave only 75.4%-91.5% homology to LTR of a Chinese field strain HA9901 of REV. Based on the above results, it is reasonable to speculate that the virus stocks for the 5 Chinese FPV vaccine products were rather originally imported with their integrated REV LTR than recombinated with LTR of REV local field strains in China.

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PubMed2006

Detection of reticuloendotheliosis virus in live virus vaccines of poultry.

In vitro and in vivo assays have been used for the detection of reticuloendotheliosis virus (REV) in live virus vaccines of poultry. The presence of REV is confirmed by the demonstration of viral antigen or provirus in chicken embryo fibroblasts (CEFs) or in specific-pathogen-free chickens inoculated with vaccine. Using REV polyclonal or monoclonal antibodies, CEFs inoculated with vaccines can be examined for REV by immunofluorescence or immunoperoxidase staining methods. Cell lysates from such inoculated CEFs can also be used for detection of REV major group-specific antigen (p30) by an enzyme-linked immunoassay. Detection of proviral DNA by polymerase chain reaction (PCR) assays that amplifies the 291 base pairs product of REV LTR has been shown to be a sensitive and specific method for detection of various strains of REV in infected CEFs and in the blood of SPF chickens inoculated with contaminated fowlpox virus (FPV) vaccines. Recently, using PCR tests that amplify REV envelope and REV 3' LTR sequences provided a more accurate assessment of the insertion of REV provirus in FPV than PCR assays that amplify the REV 5' LTR. This paper reviews the most common methods used for testing live virus vaccines of poultry for contamination with REV.

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PubMedDate not supplied

Studies on the etiology of lymphomas in turkeys: isolation of reticuloendotheliosis in virus.

Studies of tissues from 25 normal turkey flocks and of 15 selected turkey lymphoid tumors revealed no Marek's disease or lymphoid leukosis viruses, although reticuloendotheliosis viruses (REV) were isolated from 3 flocks (2 with a history of neoplastic disease). The REV isolates were culturally and antigenically similar to the prototype REV strain T but were of low pathogenicity. Attempts failed to transmit 6 lymphoid tumors of diverse origin by inoculation into 2 strains of recipient turkeys. These data support an etiological role for REV in some though not all forms of turkey neoplastic disease.

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PubMed1977

Pathological changes in chickens inoculated with reticuloendotheliosis-virus-contaminated Marek's disease vaccine.

A disease characterized by delayed growth, anemia, abnormal feathers, and leg paralysis occurred among chickens inoculated with Marek's disease vaccine over a period from spring to fall in 1974. These chickens were recognized among flocks inoculated with the vaccine produced by two vaccine makers. The affected ones were examined pathologically. Gross examination revealed a slight enlargement of peripheral nerves and atrophy of the spleen, thymus, and bursa of Fabricius. Histopathologically, the peripheral nerves had a mild cell infiltration of lymphoid and plasma cells, edema, degeneration of nerve fibers with Schwann's cell proliferation. Perivascular cuffings consisting mainly of lymphoid cells were seen in the brain and spinal cord. Atrophic changes displayed by prominent reduction of lymphocytes were recognized in the spleen, thymus, and bursa of Fabricius. Etiological examination suggested that most of the chickens examined might have been infected with reticuloendotheliosis virus and not with Marek's disease virus. The pathological changes observed in the peripheral nerves and central nervous system, however, were not distinguishable from those of Marek's disease.

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PubMed1979

Suspected reticuloendotheliosis in turkeys with cutaneous lesions reminiscent of fowl pox.

Twelve turkeys from a flock of 2,500 had cutaneous lesions somewhat resembling fowl pox. Lymphoid-like tumors were evident in livers and spleens. Closer examination of cutaneous lesions, and histopathological examinations indicated skin lesions were also infiltrative and not unlike reticuloendotheliosis. Electron micrographs revealed the presence of C-type virus particles.

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PubMed1986

Monoclonal antibodies against avian reticuloendotheliosis virus: identification of strain-specific and strain-common epitopes.

We report the generation and partial characterization of a panel of 11 monoclonal antibodies (MCA) made against the nondefective strain T reticuloendotheliosis virus (REV). In an enzyme-linked immunosorbent assay (ELISA), nine MCA cross-reacted with both homologous strain T and heterologous strain chick syncytial virus (CS), whereas two MCA were strain specific and reacted with strain T but not with CS. Competitive antibody inhibitory ELISA tests demonstrated that the nine MCA recognized at least two distinct type-common epitopes. By using MCA-mediated immunoprecipitation and polyacrylamide gel electrophoresis analysis, we identified a 62,000 dalton glycoprotein that may contain both type-common epitopes and a 21,000 dalton glycoprotein that contains one of these epitopes. The competitive antibody inhibitory ELISA tests confirmed that the remaining two MCA recognize a strain T-specific epitope. We identified a 54,000 to 72,000 dalton glycoprotein that contains the type-specific epitope. All of the MCA reacted in an ELISA assay with cell-free virus preparations, suggesting that the polypeptides we identified are virion envelope glycoproteins. To identify the nonglycosylated precursor proteins, we treated infected cells with tunicamycin. We found a 48,000 polypeptide that was the nonglycosylated precursor to the 54,000 to 72,000 glycoprotein, and 48,000 and 20,000 dalton proteins that were the nonglycosylated precursors to the 62,000 and 21,000 dalton glycoproteins, respectively. These MCA may be of value in the field. They were able to distinguish in preliminary tests in ELISA between strains T and CS, which were otherwise undistinguishable in assays that made use of conventional polyvalent serum.

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PubMedDate not supplied

Vertical transmission of reticuloendotheliosis virus in breeder turkeys.

Epizootiological studies were conducted on a commercial turkey breeder flock naturally infected with nondefective reticuloendotheliosis (RE) virus. Although RE virus was isolated from 27 (46%) of the 59 hens studied, only 4 of the 45 hens tested transmitted RE virus to progeny during a 6-week observation period and the overall transmission rate was 1.8%. The transmitter hens were of two types: three hens were consistently viremic and antigenemic and lacked antibody; one hen was viremic but lacked detectable viral antigen and possessed antibody. Toms appeared to play no role in vertical transmission of the infection. Of several tests evaluated for detection of transmitter hens, the direct enzyme-linked immunosorbent assay on albumen was probably best, since it detected three of four transmitter hens, detected relatively few nontransmitter hens, and had the best consistency of any test. No significant differences in hatchability were found between eggs from viremic and non-viremic hens. These findings can be utilized in the development of programs for eradication of RE virus from turkey breeding flocks.

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PubMedDate not supplied

Monoclonal-antibody-mediated enzyme-linked immunosorbent assay for detection of reticuloendotheliosis viruses.

An enzyme-linked immunosorbent assay (ELISA) is described for the detection of reticuloendotheliosis viruses (REVs). The assay uses a mixture of monoclonal antibodies (MCAs) prepared against a 62-kilodalton REV envelope glycoprotein (gp62) to capture antigen, rabbit anti-REV serum as detection antibody, and peroxidase-conjugated anti-rabbit IgG as indicator antibody. The MCAs were reactive with REV strain T, chick syncytial virus, and duck infectious anemia virus but unreactive against Marek's disease and avian leukosis viruses. The ELISA was compared with complement fixation test and REV immunofluorescent assay of infected fibroblasts, plasmas, and egg albumen from infected chickens. The lower limit of gp62 detection was about 120 ng of REV protein. Limit dilution of infectious REV was detected after 7-8 days of cultivation of infected fibroblasts.

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PubMedDate not supplied

Some evidence of mechanical transmission of reticuloendotheliosis virus by mosquitoes.

The possible role of mosquitoes in the mechanical transmission of reticuloendotheliosis virus (REV) in chickens was examined. A carbon-dioxide-baited trap was used to capture mosquitoes in poultry pens for one year to determine the seasonal occurrence and the species of mosquitoes prevalent in the area. Homogenates of captured mosquitoes were used for REV isolation in chicken embryo fibroblast cultures. Sera from sentinel chickens were also examined for REV antibodies. Population peaks of mosquitoes were seen in February, March, and April, and the dominant species, Culex quinqufasciatus, was present throughout the year. Of the 39 batches of mosquitoes examined, REV was isolated on seven occasions: once in summer and six times in autumn. Isolation of REV twice from unengorged mosquitoes from a pen with persistently viremic chickens and once from engorged mosquitoes in a pen with sentinel chickens implied that feeding on the viremic birds had been interrupted. Mechanical transmission of REV could have occurred when unengorged mosquitoes contaminated with REV completed their feeding on sentinel chickens. The birds developed REV antibodies following REV isolation from sentinel pens. REV was experimentally transmitted from persistently viremic donor chickens to a recipient chicken using Culex annulirostris.

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PubMedDate not supplied

Serologic evidence in commercial chicken and turkey flocks of infection with reticuloendotheliosis virus.

A serologic survey has documented probable infection with reticuloendotheliosis (RE) virus in 21.0% of 101 layer flocks, 23.5% of 85 broiler and broiler-breeder flocks, 2.3% of 43 backyard chicken flocks, and 4.8% of 125 turkey production and breeder flocks. However, no infection was detected in 72 grandparent lines of chicken breeding stocks representing meat-type and layer strains. The existence of natural infection was further supported by isolation of RE virus from one experimental chicken flock and two commercial turkey flocks. This study supports earlier but subsequently discounted data by Aulisio and Shelokov that exposure to RE virus occurs commonly among commercial chickens in the United States, as has also been reported in other countries.

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PubMed1981

Modification of low virulent Newcastle disease virus infection in chickens infected with reticuloendotheliosis virus.

One-day-old SPF chicks were inoculated with reticuloendotheliosis virus (REV) which had been isolated from contaminated Marek's disease vaccine. Then they were subjected to super infection with the B1 or TCND strain of Newcastle disease virus (NDV) and examined for virus recovery, antibody response and the appearance of symptoms. Regardless of the time, from 0 to 8 weeks, of inoculation with the NDV-B1 strain after the REV infection, the antibody response was suppressed and the duration of the NDV recovery prolonged. Specific death preceded by severe respiratory or neural signs occurred more frequently to chicks inoculated with REV than to uninoculated controls after inoculation with the NDV-B1 strain in the neonatal stage or with the NDV-TCND strain at 5 weeks of age.

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