Function Of Human Cytomegalovirus UL49 Gene During Virus Replication

Objective:UL49 gene is essential for HCMV growth and encodes a protein which is positioned within the tegument of the virus particle, a protein structure that resides between the capsid and envelope. In these studies, we have investigated the function of pUL49 during HCMV growth cycle and viral gene expression.Methods:(1) HCMV infected Human foreskin fibroblasts(HFFs) were harvested at different hours postinfection. RT-PCR and Western Blot analyses were carried out to determine UL49 gene expression kinetics. (2) External guide sequences (EGS) molecules that target the mRNA coding for the UL49 gene and negative control were chemically synthesized. HFF cells that treated with liposome complexes in the absence and presence of EGSs were infected with HCMV. Quantitative real-time PCR and Western Blot analyses were carried out to determine the expression levels of UL49 gene. Based on down-regulation of UL49 gene, we detected the expression lever change of protein IE2-86, gB and pp28. (3) Based on the results above, HFF Cells that were first treated with liposome complexes in the absence and presence of EGSs were infected with HCMV, At 24,48 and 72 hours postinfection, we detected the change of total virus DNA content in EGS treated HFF cells using quantitative real-time PCR. By these experiment, we determined whether pUL49 protein participate in virus DNA replication events.Results:(1) We comfirmed that UL49 gene was E-β2 gene, pUL49 protein expressed within 24 hr postinfection in HFF cells. (2) Reduction of pUL49 expression lever did not affect the protein IE2-86 and protein gB expression, but down-regulated pp28 protein synthesis. (3) We found no significant difference in the level of total intracellular viral DNA in the functional EGS-treated cells.Conclusion:pUL49 protein did not participate in viral DNA replication but affect the expression of protein pp28. pUL49 may functioned related pp28 protein which required for the final envelopment of the human cytomegalovirus virion in the cytoplasm and virus egress.