Avian reticuloendotheliosis (RE) represents an important immunosuppressive disease of poultry. The occurrence of RE in both chickens and turkeys has an immunosuppressive effect and may lead to vaccination failures. Avian reticuloendotheliosis virus (REV) is widely distributed in different kinds of birds, causing subclinical infections. Another important issue adhering to this disease is contamination of vaccines against fowl pox (FP) and Marek’s disease (MD) with REV. The capability of REV to integrate into the genome of other larger DNA viruses complicates its diagnosis and prevention. There are no efficient vaccines against RE nor treatment, which also complicates how to limit its impact on poultry farming. This paper reviews the current state of knowledge of this important immunosuppressive agent of poultry emphasising the importance of this problem in terms of diagnosis of RE.

In an attempt to isolate reticuloendotheliosis virus (REV) from field cases, plasma of commercial broiler chickens-suspect to have virus infection-were examined. Samples were inoculated in chicken embryo fibroblasts and after proper incubation infected cultures were assayed for REV-antigen by ELISA, immuno-peroxidase (IP) plaque assay, and PCR.Specificity of ELISA and IP was evaluated by comparing their results with that obtained by PCR. REV could be isolated and virus antigen was detected in cell cultures by all three techniques. Results showed that PCR and ELISA are more specific than IP in detection of REV-antigen. However, the sensitivity of ELISA was affected by the criterion used for determination of the cut-off point. Further studies are needed for full characterization of the isolated virus by using reference antiserum or strain specific primers for PCR.