Human cytomegalovirus expresses novel microRNAs during productive viral infection.
MicroRNAs (miRNAs) are a large class of approximately 22-nucleotide non-coding RNAs that facilitate mRNA cleavage and translation repression through the RNA interference pathway. Until recently, miRNAs have been exclusively found in eukaryotic organisms. A non-immunogenic molecule requiring minimal genomic investment, these RNAs may offer an efficient means for viruses to modulate both their own and the host's gene expression during a productive viral infection. In this study we report that human cytomegalovirus (HCMV) expresses miRNAs during its productive lytic infection of four clinically relevant human cell types: fibroblast, endothelial, epithelial and astrocyte cells. The sequences of the miRNAs, expressed from the UL23 and US24 loci of the viral genome, were conserved among all HCMV strains examined and in chimpanzee cytomegalovirus. Furthermore, their expression was detected from both a laboratory-adapted strain and a clinical isolate of HCMV. The conservation of these miRNAs and their expression in different cell types suggests that they represent an evolutionarily primitive feature in the viral genome, and that virus-encoded miRNAs may be more common than previously believed.
Dunn
Walter
W
Program in Infectious Diseases and Immunity, Program in Comparative Biochemistry, School of Public Health, University of California, Berkeley, CA 94720, USA.
Trang
Phong
P
Zhong
Qiu
Q
Yang
Edward
E
van Belle
Christopher
C
Liu
Fenyong
F
D001483:Base Sequence; D002460:Cell Line; D003001:Cloning, Molecular; D019295:Computational Biology / Q000379:methods; D003587:Cytomegalovirus / Q000235:genetics / Q000472:pathogenicity*; D016679:Genome, Viral; D006801:Humans; D035683:MicroRNAs / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data
D035683:MicroRNAs