Human cytomegalovirus UL49 encodes an early, virion-associated protein essential for virus growth in human foreskin fibroblasts
Despite recent results of deletion experiments showing that open reading frame (ORF) UL49 of human cytomegalovirus (HCMV) is essential, the expression, function and functional location of its encoded protein remain unknown. We generated an antibody specific for pUL49 to investigate the protein product encoded by the UL49 ORF and identified its function in HCMV-infected host foreskin fibroblasts. A bacterial artificial chromosome (BAC) of HCMV strain Towne (pRV-Towne) and the UL49-deleted mutant pRV-delUL49Towne were used to observe virus growth by plaque assay. Using a UL49-protein-binding antibody, we located pUL49 in the fibroblast cytoplasm. pUL49 exhibited expression kinetics resembling those of the class β-2 proteins and was detected in the virion tegument. Following deletion of UL49 ORF, the virus failed to replicate, but it could be recovered by addition of pUL49 from pCDNA3.1 (+)-UL49. Our findings indicate that UL49 ORF is essential for HCMV replication in host foreskin fibroblasts.
KeywordsBacterial Artificial Chromosome Bacterial Artificial Chromosome Clone HCMV Infection Tegument Protein Laser Scanning Confocal Fluorescence Microscopy
Feng Zhu and Jian Yuan contributed equally to this work and should be considered co-first authors. This work was supported by 211 grants of MOE, National Key Basic Research Program of China (2011CB504800), Guangdong Provincial Medical Science Study of China (Grant No. A2014598) and Guangdong Provincial Department of Science and Technology of China (Grant No. 2014A020212028 and Grant No. 2013B021800087).
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