Oral Presentation Australian Society for Microbiology Annual Scientific Meeting 2016

A novel flavivirus in the yellow fever group, isolated from mosquitoes collected in northern Western Australia (#95)

Cheryl A Johansen 1 2 , Simon H Williams 3 , Lorna F Melville 4 , Roy A Hall 5 , Helle Bielefeldt-Ohmann 6 , Jay Nicholson 2 , Glenys R Chidlow 1 , Shani Wong 1 2 , Natalie Prow 5 , Rohini Sinha 3 , W. Ian Lipkin 3 , David W Smith 1 2
  1. PathWest Laboratory Medicine WA, Perth, WA, Australia
  2. School of Pathology and Laboratory Medicine, The University of Western Australia, Nedlands, Western Australia, Australia
  3. Centre for Infection and Immunity, Mailman School of Public Health, Columbia University, New York, United States of America
  4. Berrimah Veterinary Laboratories, The Northern Territory Government, Darwin, Northern Territory, Australia
  5. Australian Infectious Diseases Research Centre, School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Queensland, Australia
  6. School of Veterinary Science, The University of Queensland, Gatton, Queensland, Australia

A novel arbovirus was detected in mosquitoes collected in the wet seasons of 2011 and 2012 in northern Western Australia during mosquito and arbovirus surveillance activities. Preliminary monoclonal antibody and partial nucleotide sequence analysis revealed the virus to be a flavivirus related to Sepik virus (SEPV) and Wesselsbron virus (WESSV) in the Yellow Fever group. Whole genome sequence phylogenetic analysis and comparisons of polyprotein cleavage sites and critical sequences in the 5’ and 3’ untranslated regions confirmed the new flavivirus, named Fitzroy River virus (FRV), is a new virus rather than a sub-type of SEPV or WESSV. Of 16 isolates, most (81%) were from the temporary floodwater breeding mosquito species Aedes normanensis, providing circumstantial evidence that this mosquito species is the likely vector. Fitzroy River virus replicated in mosquito (C6/36), mammalian (Vero, PSEK and BSR) and avian (DF-1) cells. It also infected weanling mice inoculated with FRV i.p. and caused mild clinical disease in three mice inoculated i.c. Specific neutralising antibodies were detected in sentinel horses (12.6%), cattle (6.6%) and occasional chickens (0.5%) in the Northern Territory (NT) of northern Australia, including three seroconversions. In addition, neutralising antibodies were observed in 0.8% of human serum samples submitted to PathWest Laboratory Medicine for flavivirus and alphavirus diagnostic testing in the wet seasons of 2014 and 2015. These results indicate FRV is widespread in northern WA and the NT. Like SEPV and WESSV, FRV can infect humans and domestic animals, although its role in disease requires further investigation. The origin of FRV is unknown, however it seems most likely FRV entered northern Australia from the neighbouring Indonesian Archipelago. The detection of FRV highlights the importance of maintaining good surveillance programs using appropriate techniques for detection of existing and new arboviruses of potential significance to humans and animals.