Construction of recombinant fowl pox virus with ChIL-2 and glycoprotein D of infectious laryngotracheitis virus and its immune efficacy

The fowl pox transfer vector(pSY681-gD-LacZ) includes the gene of ILTV glycoprotein D and the LacZ gene with promoters in frame of each gene at NotⅠsite.The gene of ChIL-2 was cloned into pSY538 vector at EcoRⅠsite,then the ChIL-2 gene was cloned into the transfer vector(pSY681-gD-LacZ) with its promoter at NotⅠsite. The recombined transfer vector was transfected into the FPV infected chicken embryo fibroblast(CEF) cells by using lipofection procedure.Recombinant virus was selected by blue plague purification and named rFPV-IL2-ILTVgD. The recombinant virus rFPV-IL2-ILTV-gD,expressing ILTV glycoprotein D was identified by indirect immunofluoscence assay(IFA) and expressing ChIL-2 was measured by ELISA.Three groups chickens were immunized with water,commercial ILTV vaccine and recombinant virus rFPV-IL2-ILTV-gD,respectively.Serum antibody of chickens to ILT was measured by ELISA.The chickens were challenged with a lethal dose of virulent ILTV at 28 day post inoculation.Results of immune protection test showed that there was no significant difference between the recombinant virus rFPV-IL2-ILTV-gD and the commercial vaccine and the protection rates of the chickens after the virus challenge were 96%and 92%,whereas that of the control group was 8%.It indicates the recombined virus can effectively protect chicken from ILTV challenge.