Molecular detection and characterization of reticuloendotheliosis virus in broiler breeder chickens with visceral tumors in Egypt

In the present study, reticuloendotheliosis (REV) provirus DNA was detected by PCR using LTR (long terminal repeat)-specific primers to amplify 200 bp fragment of the REV viral genome in tumor samples collected from broiler breeder flocks with 30–40 weeks of age demonstrating neoplastic lesions. Histopathology examination of the liver tumor tissue showed reticular cells infiltration and proliferation replacing hepatic parenchyma. Sequence analysis of the amplified PCR products revealed genetic similarity to REV-LTR in MDV (Marek Disease Virus) JM-Hi3. SPF (specific-pathogen free) chicks (1-day old) were experimentally inoculated with liver homogenate of the REV-positive sample and the chicks were housed for 8 weeks. Visceral organs and sera were collected from inoculated chicks at 3 and 6 weeks post inoculation. REV was detected by PCR in the organs of the inoculated chicks at 6 weeks post inoculation.REV antibodies were detected in sera of the inoculated chicks at 3 (3 out of 10 samples) and 6 (one of 2 samples) weeks post inoculation. Histopathology examination of liver and spleen collected from inoculated chicks showed the characteristic reticular cells infiltration in both organs. The study reports the existence of REV associated with visceral tumors in broiler breeder flocks in Egypt. The sequence of the detected virus was submitted in NCBI GenBank with access number KC018475.