Insertion of microRNA targets into the flavivirus genome alters its highly neurovirulent phenotype.
Flaviviruses such as West Nile, Japanese encephalitis, and tick-borne encephalitis (TBEV) viruses are important neurotropic human pathogens, causing a devastating and often fatal neuroinfection. Here, we demonstrate that incorporation into the viral genome of a target sequence for cellular microRNAs expressed in the central nervous system (CNS) enables alteration of the neurovirulence of the virus and control of the neuropathogenesis of flavivirus infection. As a model virus for this type of modification, we used a neurovirulent chimeric tick-borne encephalitis/dengue virus (TBEV/DEN4) that contained the structural protein genes of a highly pathogenic TBEV. The inclusion of just a single target copy for a brain tissue-expressed mir-9, mir-124a, mir-128a, mir-218, or let-7c microRNA into the TBEV/DEN4 genome was sufficient to prevent the development of otherwise lethal encephalitis in mice infected intracerebrally with a large dose of virus. Viruses bearing a complementary target for mir-9 or mir-124a were highly restricted in replication in primary neuronal cells, had limited access into the CNS of immunodeficient mice, and retained the ability to induce a strong humoral immune response in monkeys. This work suggests that microRNA targeting to control flavivirus tissue tropism and pathogenesis might represent a rational approach for virus attenuation and vaccine development.
Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA.
Brian L
BL
Heiss
Olga A
OA
Maximova
Alexander G
AG
Pletnev
D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D001921:Brain / Q000166:cytology / Q000378:metabolism / Q000821:virology; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D009033:Culicidae / Q000821:virology; D003715:Dengue / Q000235:genetics / Q000276:immunology / Q000517:prevention & control / Q000821:virology; D003716:Dengue Virus / Q000235:genetics / Q000254:growth & development / Q000276:immunology / Q000472:pathogenicity*; D004669:Encephalitis Viruses, Tick-Borne / Q000235:genetics / Q000254:growth & development / Q000276:immunology / Q000472:pathogenicity*; D004675:Encephalitis, Tick-Borne / Q000235:genetics / Q000276:immunology / Q000517:prevention & control / Q000821:virology; D016679:Genome, Viral; D006801:Humans; D008253:Macaca mulatta; D051379:Mice; D035683:MicroRNAs / Q000235:genetics*; D016254:Mutagenesis, Insertional; D009474:Neurons / Q000821:virology; D051381:Rats; D011916:Rats, Inbred F344; D011993:Recombinant Fusion Proteins / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D014613:Vaccines, Attenuated / Q000235:genetics; D014709:Vero Cells; D014759:Viral Envelope Proteins / Q000235:genetics / Q000276:immunology; D014765:Viral Vaccines / Q000235:genetics; D014779:Virus Replication
D000914:Antibodies, Viral; C551804:MIRN9 microRNA, mouse; D035683:MicroRNAs; C550324:Mirn128 microRNA, mouse; D011993:Recombinant Fusion Proteins; D014613:Vaccines, Attenuated; D014759:Viral Envelope Proteins; D014765:Viral Vaccines; C074932:prM protein, Flavivirus