Biology subjects

Parry, R. H.

Publications and source records attributed to Parry, R. H..

4 recordsLinked to original sources

bioRxiv2024

The PAZ domain of Aedes aegypti Dicer 2 is critical for accurate and high-fidelity size determination of virus-derived small interfering RNAs.

The exogenous siRNA (exo-siRNA) pathway is a critical RNA interference response involved in controlling arbovirus replication in mosquito cells. It is initiated by the detection of viral long double-stranded RNA (dsRNA) by the RNase III enzyme Dicer 2 (Dcr2), which is processed into predominantly 21 nucleotide (nt) virus-derived small interfering RNAs, or vsiRNAs that are taken up by the Argonaute 2 (Ago2) protein to target viral single-stranded RNAs. The detailed understanding of Dicer structure, function and domains owes much to studies outside the context of viral infection, and how Dcr2 domains contribute to detecting viral dsRNA to mount antiviral responses in infected mosquito cells remains much less understood. Here, we used a Dcr2 reconstitution system in Aedes aegypti derived Dcr2 KO cells to assess the contribution of the PAZ domain to induction of the exo-siRNA pathway following infection with Semliki Forest virus (SFV; Togaviridae, Alphavirus). Amino acids critical for PAZ activity were identified, and loss of PAZ function affected the production of 21 nt vsiRNAs -though not the overall ability of Dcr2 to process viral dsRNA- and silencing activity. This study establishes the importance of correct vsiRNA size in mosquito exo-siRNA antiviral responses, as well as the PAZ domains functional contribution to Dcr2 processing of viral dsRNA to 21 nt vsiRNAs.

microbiology↗

bioRxiv2024

A 39.8kb flavi-like virus uses a novel strategy for overcoming the RNA virus error threshold

It is commonly held that there is a fundamental relationship between genome size and error rate, manifest as a notional "error threshold" that sets an upper limit on genome sizes. The genome sizes of RNA viruses, which have intrinsically high mutation rates due to a lack of mechanisms for error correction, must therefore be small to avoid accumulating an excessive number of deleterious mutations that will ultimately lead to population extinction. The proposed exceptions to this evolutionary rule are RNA viruses from the order Nidovirales (such as coronaviruses) that encode an error correcting exonuclease, enabling them to reach genome lengths greater than 40kb. The recent discovery of large genome flavi-like viruses (Flaviviridae), which comprise genomes up to 27kb in length yet seemingly do not encode exonuclease domains, has led to the proposal that a proofreading mechanism is required to facilitate the expansion of RNA virus genomes above 30kb. Herein, we describe a 39.8kb flavi-like virus identified in a Haliclona sponge metatranscriptome that does not encode an exonuclease. Structural analysis revealed that this virus may have instead captured bacterial domains associated with nucleic acid metabolism that have not been previously found in RNA viruses. Phylogenetic analysis placed this virus as a divergent pesti-like lineage, such that we have provisionally termed it Maximus pesti-like virus. This virus represents the first instance of a flavi-like virus achieving a genome size comparable to that of the Nidovirales and demonstrates that RNA viruses have evolved multiple solutions to overcome the error threshold.

evolutionary biology↗

bioRxiv2023

Identification of a novel papillomavirus from a New Zealand fur seal (Arctocephalus forsteri) with oral papilloma-like lesions

Despite being the predominant seal species in the Australian-New Zealand region and serving as a key indicator of marine environmental health, little is known about infectious diseases in New Zealand fur seals (Long-nosed fur seal; Arctocephalus forsteri). Several papillomaviruses have been identified in earless seals and sea lions, with the latter linked to cutaneous plaques and invasive squamous cell carcinoma. To date, no papillomaviruses have been reported in fur seals. We used traditional veterinary diagnostic techniques and metatranscriptomic sequencing of tissue samples to investigate the virome of New Zealand fur seals. We identified a novel papillomavirus, provisionally termed Arctocephalus forsteri papillomavirus 1 (AfPV1) in an animal with clinically and histologically identified oral papilloma-like lesions. RT-PCR confirmed the presence of AfPV1 only in oral papilloma samples from the affected individual. Phylogenetic analysis of the complete 7,926 bp genome of AfPV1 revealed that it clustered with taupapillomaviruses found in related Carnivora species. In addition, we identified the partial genome of a novel Gammaherpesvirus, Arctocephalus forsteri gammaherpesvirus 1 (AfGHV1), in a different individual without pathological evidence of viral infection. These findings highlight the need for further research into the disease associations and impact of undiagnosed and novel viruses on New Zealand fur seals.

microbiology↗

bioRxiv2023

A novel tamanavirus (Flaviviridae) of the European common frog (Rana temporaria) encodes a divergent class 1b XRN1-resistant RNA element.

Flavivirids are small, enveloped, positive-sense RNA viruses from the Flaviviridae family with genomes between [~]9-13kb. Metatranscriptomic analyses of metazoan organisms have revealed a diversity of flavivirus-like or flavivirid viral sequences in fish and marine invertebrate groups. To date, however, no flavivirus-like or flavivirid has been identified in amphibians. To remedy this, we investigated the virome of the European common frog (Rana temporaria) in the United Kingdom, utilising high-throughput sequencing at six catch locations. De novo assembly revealed a coding-complete virus contig of a novel flavivirid [~]11.2kb in length. The virus encodes a single open reading frame of 3456 amino acids and 5 and 3 untranslated regions (UTRs) of 227 and 666nt, respectively. We named this virus Rana tamanavirus (RaTV), as BLASTp analysis of the polyprotein showed the closest relationships to Tamana bat virus (TABV) and Cyclopterus lumpus virus from Pteronotus parnellii and Cyclopterus lumpus, respectively. Phylogenetic analysis of the RaTV polyprotein compared to Flavivirus and Flavivirus-like members indicated that RaTV was sufficiently divergent and basal to the vertebrate Tamanavirus clade. In addition to the Mitcham strain, partial but divergent RaTV, 95.64-97.39% pairwise nucleotide identity, were also obtained from the Poole and Deal samples, indicating that RaTV is widespread in UK frog samples. Bioinformatic analyses of putative secondary structures in the 3'-UTR of RaTV indicated a potential exoribonuclease-resistant RNA (xrRNA) structure identified in flaviviruses and TABV. To examine this biochemically, we conducted an in vitro XRN1 digestion assay showing that RaTV likely forms a divergent but functionally homologous XRN1-resistant xrRNA.

microbiology↗