A Gammaherpesvirus Noncoding RNA Is Essential for Hematogenous Dissemination and Establishment of Peripheral Latency.
Recent intense investigations have uncovered important functions for a diverse array of novel noncoding RNA (ncRNA) species, including microRNAs (miRNAs) and long noncoding RNAs. Not surprisingly, viruses from multiple families have evolved to encode their own regulatory RNAs; however, the specificin vivofunctions of these ncRNAs are largely unknown. The human gammaherpesviruses Epstein-Barr virus (EBV) and Kaposi's sarcoma-associated herpesvirus (KSHV) are highly ubiquitous pathogens that are associated with the development of a wide range of malignancies, including Burkitt's lymphoma, Hodgkin's lymphoma, nasopharyngeal carcinoma, and Kaposi's sarcoma. Like EBV and KSHV, murine gammaherpesvirus 68 (MHV68) establishes lifelong latency in B cells and is associated with lymphoproliferative disease and lymphoma. Similar to the EBV-encoded small RNA (EBER)-1 and -2, MHV68 encodes eight 200- to 250-nucleotide polymerase III-transcribed ncRNAs called TMERs (tRNA-miRNA-encoded RNAs), which are highly expressed in latently infected cells and lymphoproliferative disease. To define thein vivocontribution of TMERs to MHV68 biology, we generated a panel of individual TMER mutant viruses. Through comprehensivein vivoanalyses, we identified TMER4 as a key mediator of virus dissemination. The TMER4 mutant virus replicated normally in lungs and spread with normal kinetics and distribution to lung-draining lymph nodes, but it was significantly attenuated for infection of circulating blood cells and for latency establishment at peripheral sites. Notably, TMER4 stem-loops but not miRNAs were essential for wild-type TMER4 activity. Thus, these findings revealed a crucial miRNA-independent function of the TMER4 ncRNA in MHV68 hematogenous dissemination and latency establishment.


OBJECTIVE
Noncoding RNAs (ncRNAs) represent an intriguing and diverse class of molecules that are now recognized for their participation in a wide array of cellular processes. Viruses from multiple families have evolved to encode their own such regulatory RNAs; however, the specificin vivofunctions of these ncRNAs are largely unknown. Epstein-Barr virus (EBV) and Kaposi's sarcoma-associated herpesvirus (KSHV) are ubiquitous human pathogens that are associated with the development of numerous malignancies. Like EBV and KSHV, murine gammaherpesvirus 68 (MHV68) establishes lifelong latency in B cells and is associated with lymphomagenesis. The work described here reveals that the MHV68 ncRNA TMER4 acts at a critical bottleneck in local lymph nodes to facilitate hematogenous dissemination of the virus and establishment of latency at peripheral sites.
Department of Molecular Genetics and Microbiology and UF Health Cancer Center, College of Medicine, University of Florida, Gainesville, Florida, USA.
Emily R
ER
Feldman
Department of Molecular Genetics and Microbiology and UF Health Cancer Center, College of Medicine, University of Florida, Gainesville, Florida, USA.
Mehmet
M
Kara
Department of Microbiology and Immunology, University of Colorado School of Medicine, Aurora, Colorado, USA.
Lauren M
LM
Oko
Department of Molecular Genetics and Microbiology and UF Health Cancer Center, College of Medicine, University of Florida, Gainesville, Florida, USA.
Katrina R
KR
Grau
Department of Molecular Genetics and Microbiology and UF Health Cancer Center, College of Medicine, University of Florida, Gainesville, Florida, USA.
Brian J
BJ
Krueger
Department of Molecular Microbiology and Immunology, Keck School of Medicine, University of Southern California, Los Angeles, California, USA.
Junjie
J
Zhang
Department of Molecular Microbiology and Immunology, Keck School of Medicine, University of Southern California, Los Angeles, California, USA.
Pinghui
P
Feng
Department of Microbiology and Immunology, University of Colorado School of Medicine, Aurora, Colorado, USA.
Linda F
LF
van Dyk
Department of Molecular Genetics and Microbiology and UF Health Cancer Center, College of Medicine, University of Florida, Gainesville, Florida, USA.
Rolf
R
Renne
Department of Molecular Genetics and Microbiology and UF Health Cancer Center, College of Medicine, University of Florida, Gainesville, Florida, USA.
Scott A
SA
Tibbetts
TMER; dissemination; herpesviruses; latency; miRNA; noncoding RNA; viral pathogenesis