Yao, Yongxiu Zhao, Yuguang Xu, Hongtao Smith, Lorraine P. Lawrie, Charles H. Sewer, Alain Zavolan, Mihaela Nair, Venugopal <jats:title>ABSTRACT</jats:title> <jats:p>MicroRNAs (miRNAs) are increasingly being recognized as major regulators of gene expression in many organisms, including viruses. Among viruses, members of the family <jats:italic>Herpesviridae</jats:italic> account for the majority of the currently known virus-encoded miRNAs. The highly oncogenic Marek's disease virus type 1 (MDV-1), an avian herpesvirus, has recently been shown to encode eight miRNAs clustered in the MEQ and LAT regions of the viral genome. The genus <jats:italic>Mardivirus</jats:italic>, to which MDV-1 belongs, also includes the nononcogenic but antigenically related MDV-2. As MDV-1 and MDV-2 are evolutionarily very close, we sought to determine if MDV-2 also encodes miRNAs. For this, we cloned, sequenced, and analyzed a library of small RNAs from the lymphoblastoid cell line MSB-1, previously shown to be coinfected with both MDV-1 and MDV-2. Among the 5,099 small RNA sequences determined from the library, we identified 17 novel MDV-2-specific miRNAs. Out of these, 16 were clustered in a 4.2-kb long repeat region that encodes R-LORF2 to R-LORF5. The single miRNA outside the cluster was located in the short repeat region, within the C-terminal region of the ICP4 homolog. The expression of these miRNAs in MSB-1 cells and infected chicken embryo fibroblasts was further confirmed by Northern blotting analysis. The identification of miRNA clusters within the repeat regions of MDV-2 demonstrates conservation of the relative genomic positions of miRNA clusters in MDV-1 and MDV-2, despite the lack of sequence homology among the miRNAs of the two viruses. The identification of these novel miRNAs adds to the growing list of virus-encoded miRNAs.</jats:p> application/pdf https://sonar.ch/global/documents/64383 eng info:eu-repo/semantics/altIdentifier/doi/10.1128/jvi.00112-07 info:eu-repo/semantics/altIdentifier/issn/0022-538X info:eu-repo/semantics/openAccess Journal of Virology. - American Society for Microbiology. - 2007, vol. 81, no. 13, p. 7164-7170 Immunology Insect Science Microbiology Virology Marek's Disease Virus Type 2 (MDV-2)-Encoded MicroRNAs Show No Sequence Conservation with Those Encoded by MDV-1 http://purl.org/coar/resource_type/c_6501