A New Clade of Insect-Specific Flaviviruses from Australian <italic toggle="yes">Anopheles</italic> Mosquitoes Displays Species-Specific Host Restriction
Agathe M. G. Colmant,
Jody Hobson-Peters,
Helle Bielefeldt-Ohmann,
Andrew F. van den Hurk,
Sonja Hall-Mendelin,
Weng Kong Chow,
Cheryl A. Johansen,
Jelke Fros,
Peter Simmonds,
Daniel Watterson,
Chris Cazier,
Kayvan Etebari,
Sassan Asgari,
Benjamin L. Schulz,
Nigel Beebe,
Laura J. Vet,
Thisun B. H. Piyasena,
Hong-Duyen Nguyen,
Ross T. Barnard,
Roy A. Hall
Affiliations
Agathe M. G. Colmant
School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, Queensland, Australia
Jody Hobson-Peters
School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, Queensland, Australia
Helle Bielefeldt-Ohmann
School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, Queensland, Australia
Andrew F. van den Hurk
Public Health Virology, Forensic and Scientific Services, Department of Health, Coopers Plains, Queensland, Australia
Sonja Hall-Mendelin
Public Health Virology, Forensic and Scientific Services, Department of Health, Coopers Plains, Queensland, Australia
Weng Kong Chow
Australian Army Malaria Institute, Gallipoli Barracks, Enoggera, Queensland, Australia
Cheryl A. Johansen
School of Pathology and Laboratory Medicine, The University of Western Australia, Nedlands, Western Australia, Australia
Jelke Fros
Nuffield Department of Medicine, University of Oxford, Oxford, England, United Kingdom
Peter Simmonds
Nuffield Department of Medicine, University of Oxford, Oxford, England, United Kingdom
Daniel Watterson
School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, Queensland, Australia
Chris Cazier
Technical Services, Biosciences Division, Faculty of Health, Queensland University of Technology, Gardens Point Campus, Brisbane, Queensland, Australia
Kayvan Etebari
Australian Infectious Diseases Research Centre (AIDRC), The University of Queensland, St. Lucia, Queensland, Australia
Sassan Asgari
Australian Infectious Diseases Research Centre (AIDRC), The University of Queensland, St. Lucia, Queensland, Australia
Benjamin L. Schulz
School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, Queensland, Australia
Nigel Beebe
School of the Biological Sciences, The University of Queensland, St. Lucia, Queensland, Australia
Laura J. Vet
School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, Queensland, Australia
Thisun B. H. Piyasena
School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, Queensland, Australia
Hong-Duyen Nguyen
School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, Queensland, Australia
Ross T. Barnard
School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, Queensland, Australia
Roy A. Hall
School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, Queensland, Australia
ABSTRACT Flaviviruses are arthropod-borne viruses found worldwide and are responsible for significant human and veterinary diseases, including dengue, Zika, and West Nile fever. Some flaviviruses are insect specific and replicate only in mosquitoes. We report a genetically divergent group of insect-specific flaviviruses from Anopheles mosquitoes that do not replicate in arthropod cell lines or heterologous Anopheles species, exhibiting unprecedented specialization for their host species. Determination of the complete sequences of the RNA genomes of three of these viruses, Karumba virus (KRBV), Haslams Creek virus, and Mac Peak virus (McPV), that are found in high prevalence in some Anopheles mosquito populations and detection of virus-specific proteins, replicative double-stranded RNA, and small interfering RNA responses in the host mosquito species provided strong evidence of a functional replicating virus in the mosquito midgut. Analysis of nucleotide composition in the KRBV and McPV sequences also revealed a pattern consistent with the virus evolving to replicate only in insects. These findings represent a significant advance in our knowledge of mosquito-borne flavivirus ecology, host restriction, and evolution. IMPORTANCE Flaviviruses like dengue, Zika, or West Nile virus infect millions of people each year and are transmitted to humans via infected-mosquito bites. A subset of flaviviruses can only replicate in the mosquito host, and recent studies have shown that some can interfere with pathogenic flaviviruses in mosquitoes and limit the replication and transmission of the latter. The insect-specific flaviviruses (ISFs) reported here form a new Anopheles mosquito-associated clade separate from the Aedes- and Culex-associated ISF clades. The identification of distinct clades for each mosquito genus provides new insights into the evolution and ecology of flaviviruses. One of these viruses was shown to replicate in the midgut of the mosquito host and exhibit the most specialized host restriction reported to date for ISFs. Understanding this unprecedented host restriction in ISFs could help identify the mechanisms involved in the evolution of flaviviruses and their emergence as mosquito-borne pathogens.
