Abstract: In order to select the candidate strain of live attenuated vaccine with gene deletion for equine rhinopneumonitis(ER).The primers were designd according to the target gene sequence in GenBank of EHV-1 (accession No.:KF644579.1),using the DNA of the popular strain XJ2015 in this region as a template,the left and right homology arms gEH1,gEH1 of gE gene were amplified by PCR,EGFP expression cassette (CMV+EGFP+polyA) as the marker gene,after enzyme digestion,the genes were ligated to the vector pUC-19 in turn,and the plasmid pUC-gEH1H2-EGFP was successfully constructed.Co-transfection of XJ2015 genome and plasmid pUC-gEH1H2-EGFP into RK-13 cells for homologous recombination,screening for gE-deletion strains with a markered gene EGFP,and then determining the titer of recombinant strain after purification.The results showed that,a recombinant strain XJ2015-△gE-EGFP with EGFP gene was successfully obtained after 5 rounds of fluorescent plaque purification,PCR and sequencing identification,and the titer of the recombinant strain (10^7.1TCID₅₀/0.1 mL) decreased by about 10^1.7TCID₅₀/0.1 mL compared with the original strain (10^8.8TCID₅₀/0.1 mL).A gE gene deletion mutant of equine herpesvirus type 1 strain was successfully constructed with homologous recombination technology which provided a foundation for future screening of weak virus vaccine with gene deletion in equine rhinopneumonitis.

Key words: equine rhinopneumonitis (ER); equine herpesvirus type 1 (EHV-1); gE gene deletion