Use of the polymerase chain reaction for the diagnosis of natural infection of chickens and turkeys with Marek's disease virus and reticuloendotheliosis virus

Abstract

Marek's disease (MD) is a highly contagious lymphoproliferative disease of chickens caused by a herpesvirus, while reticuloendotheliosis (REV) virus is an avian C-type retrovirus that causes bursal and nonbursal lymphomas which often closely resemble MDV lymphomas. To provide a rapid and sensitive means of diagnosing and differentiating between these two neoplastic conditions, we have applied the PCR. The primers chosen to detect MDV sequences flank the 132 bp tandem repeat of the BamHI-H fragment, whose PCR product is specific for serotype 1 MDVs. The primers selected for REV are based on proviral spleen necrosis virus-long terminal repeat (SNV-LTR) sequences, and can identify both defective and non-defective REVs. The PCR for field isolates of both viruses was standardized with DNA extracted from chick embryo fibroblasts (CEF) infected with various Israeli isolates of MDV and REV. All chickens were examined for REV antibodies by ELISA, REV isolation was performed in CEF and the tumours were examined histopathologically. In some instances, MDV- and REV-PCRs were performed on whole blood DNA and tumour DNA from the same bird. Normal and tumour-bearing birds from a total of 16 chicken and turkey flocks were studied by PCR. These included three laying flocks with MD, two pullet flocks with neurolymphomatosis, four laying flocks that were the progeny of a REV antibody positive flock, four other REV antibody positive flocks, one turkey flock and two chicken flocks with an immunodeficiency syndrome. Some flocks were bled two or three times at 1- to 3-month intervals. We also analysed 30 normal grandparent light breeding birds. Compared to virus isolation, PCR was more sensitive in detecting MDV and REV sequences. It appears, therefore, that PCR is an efficacious and sensitive method for differential diagnosis of tumour-bearing and immunodeficient birds.

Characterization of T-cell lymphomas associated with an outbreak of reticuloendotheliosis in turkeys

“…In this study, virus isolation and indirect immunofluorescent antibody were more sensitive in detecting tissues infected with REV than PCR. These results contradict previous studies (Davidson et al, 1995), where PCR was reported to be more sensitive for diagnosis of REV than virus isolation. Two possible reasons for PCR being less sensitive than virus isolation are that the quality of DNA might not have been good and, theoretically, one virus particle could be detected by virus isolation but not by PCR.…”

Insertion of reticuloendotheliosis virus long terminal repeat into a bacterial artificial chromosome clone of a very virulent Marek's disease virus alters its pathogenicity

“…The resultant virus, RM1, was highly attenuated; however, it induced severe BTA and immunosuppression similar to very virulent MDVs . Natural recombination is highly prevalent in commercial chicken and turkey flocks in Israel (Davidson et al, 1995(Davidson et al, , 2002Davidson & Borenshtain, 2001) and in China , further providing evidence that recombination between DNA and RNA viruses occurs readily in vivo in avian species. Understanding the mechanism of recombination events in vivo is important.…”

“…Integration of a REV long terminal repeat (LTR) into fowlpoxvirus in avian species demonstrated that natural recombination occurs in nature and can lead to unexpected changes in the retroviral spread pattern and pathogenicity of the resultant recombinant virus (Hertig et al, 1997). Furthermore, beginning in 1993, an extensive survey of Israeli commercial flocks evaluated the incidence and the prevalence of flocks and birds with multiple viral infections (Davidson et al, 1995;Davidson & Borenshtain, 2001). A total of 2926 DNA samples were analysed by Hot-Spot combined polymerase chain reaction (PCR) analysis (Borenshtain & Davidson, 1999), including 2428 chicken and 498 turkey DNA samples (Davidson & Borenshtain, 2001).…”

The Knowledge that Human Tumor Virology can Gain from Studies on Avian Tumor Viruses

“…[12][13][14] The survey of natural co-infections with MDV and each of the three avian retroviruses (REV, ALV and ALV-J) included a total of 306 chicken and 59 turkey commercial flocks, of which, about a quarter of the tumor-bearing commercial flocks carried a mixed MDV and retrovirus-infection. 22 A total 2926 DNA samples were analysed, including 2428 chicken and 498 turkey DNA samples.…”