Tuyển tập các báo cáo nghiên cứu về bệnh học thý y được đăng trên tạp chí Acta Veterinaria Scandinavica cung cấp cho các bạn kiến thức về bệnh thú yđề tài: Molecular characteristics of Polish field strains of Marek’s disease herpesvirus isolated from vaccinated chickens. | Wozniakowski et al. Acta Veterinaria Scandinavica 2011 53 10 http content 53 1 10 AVS ACTAVETERINARIA SCANDINAVICA RESEARCH Open Access Molecular characteristics of Polish field strains of Marek s disease herpesvirus isolated from vaccinated chickens Grzegorz Wozniakowski Elzbieta Samorek-Salamonowicz Wojciech Kozdrun Abstract Background Twenty-nine Marek s disease virus MDV strains were isolated during a 3 year period 2007-2010 from vaccinated and infected chicken flocks in Poland. These strains had caused severe clinical symptoms and lesions. In spite of proper vaccination with mono- or bivalent vaccines against Marek s disease MD the chickens developed symptoms of MD with paralysis. Because of this we decided to investigate possible changes and mutations in the field strains that could potentially increase their virulence. We supposed that such mutations may have been caused by recombination with retroviruses of poultry - especially reticuloendotheliosis virus REV . Methods In order to detect the possible reasons of recent changes in virulence of MDV strains polymerase chain reaction PCR analyses for meq oncogene and for long-terminal repeat LTR region of REV were conducted. The obtained PCR products were sequenced and compared with other MDV and REV strains isolated worldwide and accessible in the GeneBank database. Results Sequencing of the meq oncogene showed a 68 basepair insertion and frame shift within 12 of 24 field strains. Interestingly the analyses also showed kb and other random LTR-REV insertions into the MDV genome in 28 of 29 of strains. These genetic inserts were present after passage in chicken embryo kidney cells suggesting LTR integration into a non-functional region of the MDV genome. Conclusion The results indicate the presence of a recombination between MDV and REV under field conditions in Polish chicken farms. The genetic changes within the MDV genome may influence the virus replication and its .
