Comparison of IFA and ELISA for Detection of Avain Leukosis Virus Subgroup J in DF1 Cell Cultures

To evaluate three ELISA kits for avain leukosis virus(ALV),an infectious clone rNX0101 of ALV subgroup J(ALV-J)was inoculated into DF1 cells with three different doses(9×103,9×102,90 TCID50respectively)and the supernatants of DF1 cell cultures were obtained at 1 to 6 days post inoculation and tested with A,B,C kits. The infected cells were detected by indirect immunofluorescence assay(IFA)at 3 and 6 days post inoculation respectively.The results showed that infected cells at 3 days and 6 days post inoculation all could be identified by IFA after inoculated with different dose,while only ELISA kit A could detect p27 antigen at 3 days post inoculation with the high dose and none of inoculated cells was detected positively with B and C ELISA kits at the same time. All samples infected by different doses showed positive to ALV-J with both ELISA kits and IFA 6 days post inoculation. The results indicated that sensitivity among A,B and C ELISA kits was different in the detection of ALV-J with three doses of inoculation and IFA was more sensitive than commercial ELISA kits.