Biology subjects

Lefteri, D.

Publications and source records attributed to Lefteri, D..

3 recordsLinked to original sources

bioRxiv2021

Wolbachia strain wAu differs in cellular perturbation and virus inhibition profiles from previously characterised Wolbachia strains

Some strains of the inherited bacterium Wolbachia have been shown to be effective at reducing the transmission of dengue and other positive-sense RNA viruses by Aedes aegypti in both laboratory and field settings and are being deployed for dengue control. The degree of virus inhibition varies between Wolbachia strains; density and tissue tropism can contribute to these differences but there are also indications that this is not the only factor involved: for example, strains wAu and wAlbA are maintained at similar densities but only wAu produces strong dengue inhibition. We previously reported perturbations in lipid transport dynamics, including sequestration of cholesterol in lipid droplets, with strains wMel / wMelPop in Ae. aegypti. Here we show that strain wAu does not produce the same cholesterol sequestration phenotype despite displaying strong virus inhibition and moreover, in contrast to wMel, wAu antiviral activity was not rescued by cyclodextrin treatment. To further investigate the cellular basis underlying these differences, proteomic analysis of midguts was carried out on Ae. aegypti lines and revealed that wAu-carrying midguts showed a distinct proteome when compared to Wolbachia-free, wMel- or wAlbA-carrying midguts, in particular with respect to lipid transport and metabolism. The data suggest a possible role for perturbed RNA processing pathways in wAu virus inhibition. Together these results indicate that wAu shows unique features in its inhibition of arboviruses compared to previously characterized Wolbachia strains. Author SummaryWolbachia endosymbionts can block transmission of dengue virus by Aedes aegypti mosquitoes, and Wolbachia release programs for dengue control are now being undertaken in several countries. Understanding the mechanisms of Wolbachia-mediated antiviral activity is important for maximizing the efficacy of this control approach. Using functional and proteomic analyses, this study indicates that different strains of Wolbachia perturb cellular functions in diverse ways and display different antiviral profiles. These differences raise the possibility that Wolbachia strain switching could be used to counteract viral escape mutations, should they arise and threaten the efficacy of dengue control programmes.

microbiology↗

bioRxiv2021

Inhibitors of the Small Membrane (M) Protein Viroporin Prevent Zika Virus Infection

Flaviviruses, including Zika virus (ZIKV), are a significant global health concern, yet no licensed antivirals exist to treat disease. The small Membrane (M) protein plays well-defined roles during viral egress and remains within virion membranes following release and maturation. However, it is unclear whether M plays a functional role in this setting. Here, we show that M forms oligomeric membrane-permeabilising channels in vitro, with increased activity at acidic pH and sensitivity to the prototypic channel-blocker, rimantadine. Accordingly, rimantadine blocked an early stage of ZIKV cell culture infection. Structure-based channel models, comprising hexameric arrangements of two trans-membrane domain protomers were shown to comprise more stable assemblages than other oligomers using molecular dynamics (MD) simulations. Models contained a predicted lumenal rimantadine binding site, as well as a second druggable target region on the membrane-exposed periphery. In silico screening enriched for repurposed drugs/compounds predicted to bind to either one site or the other. Hits displayed superior potency in vitro and in cell culture compared with rimantadine, with efficacy demonstrably linked to virion-resident channels. Finally, rimantadine effectively blocked ZIKV viraemia in preclinical models, supporting that M constitutes a physiologically relevant target. This could be explored by repurposing rimantadine, or development of new M-targeted-therapies.

microbiology↗

bioRxiv2021

Mosquito saliva sialokinin-dependent enhancement of arbovirus infection through endothelial barrier leakage

Viruses transmitted by Aedes mosquitoes constitute an increasingly important global health burden. Defining common determinants of host susceptibility to this large group of heterogenous pathogens are key for informing the rational design of new pan-viral medicines. Infection of the vertebrate host with these viruses is enhanced by the presence of mosquito saliva, a complex mixture of salivary gland-derived factors and microbiota. We show that enhancement of infection by saliva was dependent on vascular function and was independent of most anti-saliva immune responses, including to salivary microbiota. Instead, the Aedes gene product sialokinin mediated enhancement of virus infection through a rapid reduction in endothelial barrier integrity. Sialokinin is unique within the insect world as having vertebrate-like tachykinin sequence and is absent from non-vector competent Anopheles mosquitoes, whose saliva was not pro-viral and did not induce similar vascular permeability. Therapeutic strategies targeting sialokinin have potential to limit disease severity following infection with Aedes mosquito-borne viruses.

microbiology↗