Abstract: According to the env and LTR gene of avian leukosis virus subgroup J, 4 and 5 short hairpin RNAs (shRNAs) targeting their conserved sequences were designed systhessised and cloned into pSilencer 4.1 vector respectively. The recombinant plasmids were transfected into DF-1 cell and infected with 10³ TCID₅₀ ALV-J at 6 hours post-transfection, the efficiency of RNA interfering was assayed by Real-time RT-PCR .The results revealed that the recombinant plasmids of pSi4.1-env inhibited virus growth by 18.15% to 63.43% and pSi4.1-LTR by 19.37% to 45.41% compared to negative control.

Key words: avian leukosis virus subgroup J virus; env gene; LTR gene; siRNA