Establishment and application of TD-PCR for detection of subgroup J avian leukosis virus

In order to establish touchdown polymerase chain reaction(TD-PCR) tests for detection of subgroup J avian leukosis virus(ALV-J),we optimized the PCR reaction with the DNA template extracted from ALV-J infected DF1 cells and special primers pair H5/H7.The results showed that the sensitivity of the TD-PCR test was as low as 0.105 ng DNA of sample.It had no cross-reactions with the DNA from reticuloendotheliosis virus,Marek's disease virus(CVI988),chicken anemia virus and subtype I avian adenovirus.The detection rates of TD-PCR for clinical samples were the same as that of ELISA(100%),and higher than that of viral isolation(75%).All these data suggest that the established TD-PCR test is a rapid,sensitive and special method for detection of ALV-J,which is good enough to be used in the field and lab research.