Programmed ribosomal frameshift alters expression of west nile virus genes and facilitates virus replication in birds and mosquitoes.
West Nile virus (WNV) is a human pathogen of significant medical importance with close to 40,000 cases of encephalitis and more than 1,600 deaths reported in the US alone since its first emergence in New York in 1999. Previous studies identified a motif in the beginning of non-structural gene NS2A of encephalitic flaviviruses including WNV which induces programmed -1 ribosomal frameshift (PRF) resulting in production of an additional NS protein NS1'. We have previously demonstrated that mutant WNV with abolished PRF was attenuated in mice. Here we have extended our previous observations by showing that PRF does not appear to have a significant role in virus replication, virion formation, and viral spread in several cell lines in vitro. However, we have also shown that PRF induces an over production of structural proteins over non-structural proteins in virus-infected cells and that mutation abolishing PRF is present in ∼11% of the wild type virus population. In vivo experiments in house sparrows using wild type and PRF mutant of New York 99 strain of WNV viruses showed some attenuation for the PRF mutant virus. Moreover, PRF mutant of Kunjin strain of WNV showed significant decrease compared to wild type virus infection in dissemination of the virus from the midgut through the haemocoel, and ultimately the capacity of infected mosquitoes to transmit virus. Thus our results demonstrate an important role for PRF in regulating expression of viral genes and consequently virus replication in avian and mosquito hosts.
Australian Infectious Disease Research Centre, School of Chemistry and Molecular Biosciences, University of Queensland, St. Lucia, Queensland, Australia.
Ezequiel Balmori
EB
Melian
Virology, Public and Environmental Health, Forensic and Scientific Services, Department of Health, Queensland Government, Coopers Plains, Queensland, Australia.
Sonja
S
Hall-Mendelin
Australian Infectious Disease Research Centre, School of Chemistry and Molecular Biosciences, University of Queensland, St. Lucia, Queensland, Australia.
Fangyao
F
Du
Australian Infectious Disease Research Centre, School of Chemistry and Molecular Biosciences, University of Queensland, St. Lucia, Queensland, Australia.
Nick
N
Owens
Division of Vector-Borne Diseases, Centers for Disease Prevention and Control, Fort Collins, Colorado, United States of America; Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America.
Angela M
AM
Bosco-Lauth
Australian Infectious Disease Research Centre, School of Chemistry and Molecular Biosciences, University of Queensland, St. Lucia, Queensland, Australia.
Tomoko
T
Nagasaki
Queensland Facility for Advanced Bioinformatics (QFAB), University of Queensland, Brisbane, Queensland, Australia.
Stephen
S
Rudd
Division of Vector-Borne Diseases, Centers for Disease Prevention and Control, Fort Collins, Colorado, United States of America.
Aaron C
AC
Brault
Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America.
Richard A
RA
Bowen
Australian Infectious Disease Research Centre, School of Chemistry and Molecular Biosciences, University of Queensland, St. Lucia, Queensland, Australia.
Roy A
RA
Hall
Virology, Public and Environmental Health, Forensic and Scientific Services, Department of Health, Queensland Government, Coopers Plains, Queensland, Australia.
Andrew F
AF
van den Hurk
Australian Infectious Disease Research Centre, School of Chemistry and Molecular Biosciences, University of Queensland, St. Lucia, Queensland, Australia.
Alexander A
AA
Khromykh
D000818:Animals; D001717:Birds / Q000821:virology; D002522:Chlorocebus aethiops; D006224:Cricetinae; D009033:Culicidae / Q000821:virology; D018965:Frameshifting, Ribosomal / Q000502:physiology*; D015967:Gene Expression Regulation, Viral / Q000502:physiology*; D006801:Humans; D051379:Mice; D018345:Mice, Knockout; D009518:New York; D014709:Vero Cells; D014779:Virus Replication / Q000502:physiology*; D014901:West Nile Fever / Q000453:epidemiology / Q000378:metabolism*; D014902:West Nile virus / Q000502:physiology*