Efficient inhibition of human cytomegalovirus UL122 gene expression in cell by small interfering RNAs

In order to develop a gene therapy to human cytomegalovirus (HCMV), RNA interference (RNAi) was employed to inhibit the expression of HCMV UL122 gene in vitro. Recombinant vector pUL122-EGFP, which expressed UL122-EGFP fusion protein, and recombinant vectors psi122-1, psi122-2 and psi122-3, which expressed small interfering RNAs (siRNAs) targeted to UL122 were contransfected into AD293 cells. The fluorescence signal of pUL122-EGFP was greatly suppressed by psi122-1 and psi122-2, with an inhibitory rate of 82.0% +/- 1.0% and 79.5% +/- 2.5%, respectively. The mRNA of pUL122-EGFP of the cells transfected with psi122-1 and psi122-2 was decreased 97.3% +/- 0.6% and 98.0% +/- 0.1%, respectively. Vector psi122-3 showed a slightly low suppression rate. Therefore, it may be concluded that plasmids encoding siRNAs targeted to UL122 is able to in vitro reduce markedly the expression of UL122-EGFP. And it is very likely that the psi122-1 and psi122-2 are potentially efficacious siRNAs in the gene therapy of HCMV infection in vivo, in which further investigations are required. This study is expected to greatly facilitate the use of the RNAi technology for the anti-HCMV studies.