Molecular Xenomonitoring (MX) allows real-time surveillance of West Nile and Usutu virus in mosquito populations.

West Nile Virus (WNV) and Usutu virus (USUV) circulate through complex cryptic transmission cycles involving mosquitoes as vectors, birds as amplifying hosts and several mammal species as dead-end hosts. Both viruses can be transmitted to humans through mosquito bites, which can lead to neuroinvasive and potentially fatal disease. Notably, WNV can also be transmitted through blood donations and organ transplants.

Transcriptome Analysis Reveals a Diverse Range of Novel Viruses in Australian Sugarcane Soldier Fly () Larvae.

In Australia, Soldier flies ( spp.) are economically significant pests of sugarcane that currently lack a viable management strategy. Despite various research efforts, the mechanisms underlying the damage caused by soldier fly larvae remain poorly understood.

A chimeric vaccine protects farmed saltwater crocodiles from West Nile virus-induced skin lesions.

West Nile virus (WNV) causes skin lesions in farmed crocodiles leading to the depreciation of the value of their hides and significant economic losses. However, there is no commercially available vaccine designed for use in crocodilians against WNV. We tested chimeric virus vaccines composed of the non-structural genes of the insect-specific flavivirus Binjari virus (BinJV) and genes encoding the structural proteins of WNV.

Structure-guided optimization of adenosine mimetics as selective and potent inhibitors of coronavirus nsp14 N7-methyltransferases.

The COVID-19 pandemic reveals the urgent need to develop new therapeutics targeting the SARS-CoV-2 replication machinery. The first antiviral drugs were nucleoside analogues targeting RdRp and protease inhibitors active on nsp5 Mpro. In addition to these common antiviral targets, SARS-CoV-2 codes for the highly conserved protein nsp14 harbouring N7-methyltransferase (MTase) activity.

Jingmenviruses: Ubiquitous, understudied, segmented flavi-like viruses.

Jingmenviruses are a group of viruses identified recently, in 2014, and currently classified by the International Committee on Taxonomy of Viruses as unclassified . These viruses closely related to flaviviruses are unique due to the segmented nature of their genome. The prototype jingmenvirus, Jingmen tick virus (JMTV), was discovered in ticks collected from China in 2010.

Arthropod-Borne Virus Surveillance as a Tool to Study the Australian Mosquito Virome.

Mosquitoes ( = 4381 in 198 pools) were collected in March and April 2018 to survey the presence of West Nile virus Kunjin strain in mosquito populations around crocodile farms in the Darwin region of the Northern Territory (NT) of Australia. While no Kunjin virus was detected in these mosquitoes, we applied our viral replicative intermediates screening system termed monoclonal antibodies to viral RNA intermediates in cells or MAVRIC to this set of samples. This resulted in the detection of 28 pools with virus replicating in C6/36 mosquito cells and the identification of three insect viruses from three distinct virus classes.

The giant mimivirus 1.2 Mb genome is elegantly organized into a 30-nm diameter helical protein shield.

Mimivirus is the prototype of the family of giant dsDNA viruses. Little is known about the organization of the 1.2 Mb genome inside the membrane-limited nucleoid filling the ~0.

Nucleic Acid Preservation Card Surveillance Is Effective for Monitoring Arbovirus Transmission on Crocodile Farms and Provides a One Health Benefit to Northern Australia.

The Kunjin strain of West Nile virus (WNV) is a mosquito-transmitted flavivirus that can infect farmed saltwater crocodiles in Australia and cause skin lesions that devalue the hides of harvested animals. We implemented a surveillance system using honey-baited nucleic acid preservation cards to monitor WNV and another endemic flavivirus pathogen, Murray Valley encephalitis virus (MVEV), on crocodile farms in northern Australia. The traps were set between February 2018 and July 2020 on three crocodile farms in Darwin (Northern Territory) and one in Cairns (North Queensland) at fortnightly intervals with reduced trapping during the winter months.

Discovery of a Novel Jingmenvirus in Australian Sugarcane Soldier Fly () Larvae.

In Australia, soldier flies are major pests of sugarcane, and they can cause significant yield losses in some areas, possibly due to the virus' transmission to the plants. We sequenced fly larvae salivary glands and identified a novel jingmenvirus, putatively named Inopus flavus jingmenvirus 1 (IFJV1). Phylogenetic trees confirmed that IFJV1 groups with insect-associated jingmenviruses, newly identified flavivirus-like viruses with a segmented genome.

Potent Inhibition of SARS-CoV-2 nsp14 7-Methyltransferase by Sulfonamide-Based Bisubstrate Analogues.

Enzymes involved in RNA capping of SARS-CoV-2 are essential for the stability of viral RNA, translation of mRNAs, and virus evasion from innate immunity, making them attractive targets for antiviral agents. In this work, we focused on the design and synthesis of nucleoside-derived inhibitors against the SARS-CoV-2 nsp14 (7-guanine)-methyltransferase (7-MTase) that catalyzes the transfer of the methyl group from the -adenosyl-l-methionine (SAM) cofactor to the 7-guanosine cap. Seven compounds out of 39 SAM analogues showed remarkable double-digit nanomolar inhibitory activity against the 7-MTase nsp14.

Structural analysis of 3'UTRs in insect flaviviruses reveals novel determinants of sfRNA biogenesis and provides new insights into flavivirus evolution.

Subgenomic flaviviral RNAs (sfRNAs) are virus-derived noncoding RNAs produced by pathogenic mosquito-borne flaviviruses (MBF) to counteract the host antiviral response. To date, the ability of non-pathogenic flaviviruses to produce and utilise sfRNAs remains largely unexplored, and it is unclear what role XRN1 resistance plays in flavivirus evolution and host adaptation. Herein the production of sfRNAs by several insect-specific flaviviruses (ISFs) that replicate exclusively in mosquitoes is shown, and the secondary structures of their complete 3'UTRs are determined.

Improved detection of flaviviruses in Australian mosquito populations via replicative intermediates.

Mosquito-borne flaviviruses are significant contributors to the arboviral disease burdens both in Australia and globally. While routine arbovirus surveillance remains a vital exercise to identify known flaviviruses in mosquito populations, novel or divergent and emerging species can be missed by these traditional methods. The MAVRIC (monoclonal antibodies to viral RNA intermediates in cells) system is an ELISA-based method for broad-spectrum isolation of positive-sense and double-stranded RNA (dsRNA) viruses based on detection of dsRNA in infected cells.

Insect-Specific Flavivirus Replication in Mammalian Cells Is Inhibited by Physiological Temperature and the Zinc-Finger Antiviral Protein.

The genus contains pathogenic vertebrate-infecting flaviviruses (VIFs) and insect-specific flaviviruses (ISF). ISF transmission to vertebrates is inhibited at multiple stages of the cellular infection cycle, via yet to be elucidated specific antiviral responses. The zinc-finger antiviral protein (ZAP) in vertebrate cells can bind CpG dinucleotides in viral RNA, limiting virus replication.

Genetic, Morphological and Antigenic Relationships between Mesonivirus Isolates from Australian Mosquitoes and Evidence for Their Horizontal Transmission.

The are a newly assigned family of viruses in the order . Unlike other nidoviruses, which include the , mesoniviruses are restricted to mosquito hosts and do not infect vertebrate cells. To date there is little information on the morphological and antigenic characteristics of this new group of viruses and a dearth of mesonivirus-specific research tools.

A Unique Relative of Rotifer Birnavirus Isolated from Australian Mosquitoes.

The family are a group of non-enveloped double-stranded RNA viruses which infect poultry, aquatic animals and insects. This family includes agriculturally important pathogens of poultry and fish. Recently, next-generation sequencing technologies have identified closely related birnaviruses in and mosquitoes.

Metagenomic Analysis of the Virome of Mosquito Excreta.

Traditional screening for arboviruses in mosquitoes requires knowledge and the utilization of appropriate assays for their detection. Mosquitoes can also provide other valuable information, including unexpected or novel arboviruses, nonarboviral pathogens ingested from hosts they feed on, and their own genetic material. Metagenomic analysis using next-generation sequencing (NGS) is a rapidly advancing technology that allows us to potentially obtain all this information from a mosquito sample without any prior knowledge of virus, host, or vector.

Inactivation of Japanese encephalitis virus in plasma by methylene blue combined with visible light and in platelet concentrates by ultraviolet C light.

Unlabelled: Japanese encephalitis virus (JEV) is endemic to tropical areas in Asia and the Western Pacific. It can cause fatal encephalitis, although most infected individuals are asymptomatic. JEV is mainly transmitted to humans through the bite of an infected mosquito, but can also be transmitted through blood transfusion.

Antigenic Characterization of New Lineage II Insect-Specific Flaviviruses in Australian Mosquitoes and Identification of Host Restriction Factors.

We describe two new insect-specific flaviviruses (ISFs) isolated from mosquitoes in Australia, Binjari virus (BinJV) and Hidden Valley virus (HVV), that grow efficiently in mosquito cells but fail to replicate in a range of vertebrate cell lines. Phylogenetic analysis revealed that BinJV and HVV were closely related (90% amino acid sequence identity) and clustered with lineage II (dual-host affiliated) ISFs, including the Lammi and Nounané viruses. Using a panel of monoclonal antibodies prepared to BinJV viral proteins, we confirmed a close relationship between HVV and BinJV and revealed that they were antigenically quite divergent from other lineage II ISFs.

Tenth Scientific Biennial Meeting of the Australasian Virology Society-AVS10 2019.

The Australasian Virology Society (AVS) aims to promote, support and advocate for the discipline of virology in the Australasian region. The society was incorporated in 2011 after 10 years operating as the Australian Virology Group (AVG) founded in 2001, coinciding with the inaugural biennial scientific meeting. AVS conferences aim to provide a forum for the dissemination of all aspects of virology, foster collaboration, and encourage participation by students and post-doctoral researchers.

Targeting bedaquiline mycobacterial efflux pump to potentially enhance therapy in abscessus.

Background: Mycobacterium abscessus is notorious for being intrinsically resistant to most antibiotics. Antibiotic efflux is one of the mechanisms used by M. abscessus to pump out antibiotics from their cells.

NS4/5 mutations enhance flavivirus Bamaga virus infectivity and pathogenicity in vitro and in vivo.

Flaviviruses such as yellow fever, dengue or Zika viruses are responsible for significant human and veterinary diseases worldwide. These viruses contain an RNA genome, prone to mutations, which enhances their potential to emerge as pathogens. Bamaga virus (BgV) is a mosquito-borne flavivirus in the yellow fever virus group that we have previously shown to be host-restricted in vertebrates and horizontally transmissible by Culex mosquitoes.

Mosquito-Independent Transmission of West Nile virus in Farmed Saltwater Crocodiles ().

West Nile virus, Kunjin strain (WNV) is endemic in Northern Australia, but rarely causes clinical disease in humans and horses. Recently, WNV genomic material was detected in cutaneous lesions of farmed saltwater crocodiles (), but live virus could not be isolated, begging the question of the pathogenesis of these lesions. Crocodile hatchlings were experimentally infected with either 10 ( = 10) or 10 ( = 11) TCID-doses of WNV and each group co-housed with six uninfected hatchlings in a mosquito-free facility.

Novel monoclonal antibodies against Australian strains of negeviruses and insights into virus structure, replication and host -restriction.

We report the isolation of Australian strains of Bustos virus and Ngewotan virus, two insect-specific viruses in the newly identified taxon , originally isolated from Southeast Asian mosquitoes. Consistent with the expected insect-specific tropism of negeviruses, these isolates of Ngewotan and Bustos viruses, alongside the Australian negevirus Castlerea virus, replicated exclusively in mosquito cells but not in vertebrate cells, even when their temperature was reduced to 34 °C. Our data confirmed the existence of two structural proteins, putatively one membrane protein forming the majority of the virus particle, and one glycoprotein forming a projection on the apex of the virions.

A recombinant platform for flavivirus vaccines and diagnostics using chimeras of a new insect-specific virus.

Flaviviruses such as dengue, yellow fever, Zika, West Nile, and Japanese encephalitis virus present substantial global health burdens. New vaccines are being sought to address safety and manufacturing issues associated with current live attenuated vaccines. Here, we describe a new insect-specific flavivirus, Binjari virus, which was found to be remarkably tolerant for exchange of its structural protein genes (prME) with those of the aforementioned pathogenic vertebrate-infecting flaviviruses (VIFs).