Biology subjects

Monit, C.

Publications and source records attributed to Monit, C..

3 recordsLinked to original sources

bioRxiv2022

Macrophage activation of cGAS and TRIM5 distinguish pandemic and non-pandemic HIV

Pandemic viruses remain a global threat to health and economics but how they adapt to become pandemic remains poorly understood. Here we compare pandemic HIV-1(M) and non-pandemic HIV-(O) and HIV-2 strains finding that non-pandemic HIV replicate poorly in myeloid cell models due to activation of cGAS and TRIM5, and ensuing antiviral responses. We use phylogenetics and viral capsid structural biology to define specific differences between pandemic and non-pandemic HIV capsids and demonstrate that their genetic reversal in HIV-1(M) mutants causes TRIM5, cGAS and innate immune activation. We propose a model in which the parental lineage of pandemic HIV-1(M) has uniquely evolved a dynamic capsid that avoids activation of cGAS and TRIM5 to establish cloaked replication in myeloid cells. The unique adaptations of the pandemic virus lineage suggests a role in effective human-to-human transmissibility and highlight the importance of avoiding innate immune activation during pandemic human-to-human viral transmission.

immunology↗

bioRxiv2021

HIV-2/SIV Vpx antagonises NF-B activation by targeting p65

The NF-{kappa}B family of transcription factors and associated signalling pathways are abundant and ubiquitous in human immune responses. Activation of NF-{kappa}B transcription factors by viral pathogen-associated molecular patterns, such as viral RNA and DNA, is fundamental to anti-viral innate immune defences and pro-inflammatory cytokine production that steers adaptive immune responses. Diverse non-viral stimuli, such as lipopolysaccharide and cytokines, also activate NF-{kappa}B and the same anti-pathogen gene networks. Viruses adapted to human cells often encode multiple proteins aimed at varied NF-{kappa}B pathway targeted to mitigate the anti-viral effects of NF-{kappa}B-dependent host immunity. In this study we have demonstrated using numerous assays, in a number of different cell types, that plasmid-encoded or virus-delivered Simian Immunodeficiency Virus (SIV) accessory protein Vpx is a broad antagonist of NF-{kappa}B signalling active against diverse innate NF-{kappa}B agonists. Using targeted Vpx mutagenesis, we showed that this novel Vpx phenotype is independent of known Vpx cofactor DCAF1 and other cellular binding partners, including SAMHD1, STING and the HUSH complex. We found that Vpx co-immunoprecipitated with canonical NF-{kappa}B transcription factor p65 and not NF-{kappa}B transcription factor proteins p50 or p100, preventing nuclear translocation of p65, a novel mechanism of NF-{kappa}B antagonism by lentiviruses. We found that broad antagonism of NF-{kappa}B activation by Vpx was conserved across distantly related lentiviruses as well as for Vpr from SIV Mona monkey (SIVmon), which has Vpx-like SAMHD1-degradation activity. ImportanceBroad antagonism of NF-{kappa}B activation has been described for HIV-1, but not for Vpx-encoding lentiviruses such as HIV-2. Here we extend our understanding of lentiviral antagonism by identifying an interaction between Vpx and transcription factor NF-{kappa}B p65, leading to inhibition of its nuclear translocation and broad NF-{kappa}B antagonism. This further evidences a requirement for lentiviruses to target universal regulators of immunity, including NF-{kappa}B, to avoid the anti-viral sequelae of pro-inflammatory gene expression stimulated by both viral and extra-viral agonists, such as lipopolysaccharide translocation, during disruption of the gut microbiome barrier during HIV-1 infection. Further structural studies of p65 targeting by Vpx may yield translational insights in the form of novel pan-NF-{kappa}B inhibitors for pathologies characterised by excessive NF-{kappa}B activity. Our findings are also relevant to the gene therapy field where virus-like particle associated Vpx is routinely used to enhance vector transduction through antagonism of SAMHD1, and perhaps also through manipulation of other pathways such as NF-{kappa}B.

molecular biology↗

bioRxiv2019

Preadaptation of pandemic GII.4 noroviruses in hidden virus reservoirs years before emergence

The control of pandemic pathogens depends on early prediction of pandemic variants and, more generally, understanding origins of such variants and factors that drive their global spread. This is especially important for GII.4 norovirus, where vaccines under development offer promise to prevent hundreds of millions of annual gastroenteritis cases. Previous studies have suggested that new GII.4 pandemic viruses evolve from previous pandemic variants through substitutions in the antigenic region of the VP1 protein that enable evasion of host population immunity, leading to global spread. In contrast, we show here that the acquisition of new genetic and antigenic characteristics is not the proximal driver of new pandemics. Instead, pandemic GII.4 viruses circulate undetected for years before causing a new pandemic, during which time they diversify and spread over wide geographical areas. Serological data demonstrate that by 2003, some nine years before it emerged as a new pandemic, the ancestral 2012 pandemic strain had already acquired the antigenic characteristics that allowed it to evade prevailing population immunity against the previous 2009 pandemic variant. These results provide strong evidence that viral genetic changes are necessary but not sufficient for GII.4 pandemic spread. Instead, we suggest that it is changes in host population immunity that enable pandemic spread of an antigenically-preadapted GII.4 variant. These results indicate that predicting future GII.4 pandemic variants will require surveillance of currently unsampled reservoir populations. Furthermore, a broadly acting GII.4 vaccine will be critical to prevent future pandemics.\n\nSignificanceNorovirus pandemics and their associated public health and economic costs could be prevented by effective vaccines. However, vaccine development and distribution will require identification of the sources and drivers of new pandemics. We here use phylogenetics and serological experiments to develop and test a new hypothesis of pandemic norovirus emergence. We find that pandemic noroviruses preadapt, diversify and spread worldwide years prior to emergence, strongly indicating that genetic changes are necessary but not sufficient to drive a new pandemic. We instead suggest that changes in population immunity enable pandemic emergence of a pre-adapted low-level variant. These findings indicate that prediction of new pandemics will require surveillance of under-sampled virus reservoirs and that norovirus vaccines will need to elicit broad immunity.

evolutionary biology↗