Paxton, W. A. | Search bioRxiv

bioRxiv2024

SARS-CoV-2 S, M and E Structural Proteins Down-modulate HIV-1 LTR Activity and Modulate Endoplasmic Reticulum Stress Responses

We have previously shown that the Hepatitis C Virus (HCV) E1E2 envelope glycoprotein can down-modulate HIV-1 long-terminal repeat (LTR) activity through disruption to NF-{kappa}B activation. This response is associated with up-regulation of the endoplasmic reticulum (ER) stress response pathway. Here we demonstrate that the SARS-CoV-2 S, M and E but not the N structural protein can perform similar down-modulation of HIV-1 LTR activation and in a dose-dependent manner in both HEK293 and lung BEAS-2B cell-lines and interpreted as a result of NF-{kappa}B down-modulation. The effect is highest with the SARS-CoV-2 Wuhan S strain and decreases over-time for the subsequent emerging variants of concern (VOC) with omicron providing the weakest effect. We developed pseudo-typed viral particle (PVP) molecular viral tools that allowed for the generation of cell-lines constitutively expressing separately the four SARS-CoV-2 structural proteins and utilising the VSV-g envelope protein to deliver the integrated gene construct. Differential gene expression analysis (DGEA) was performed on cells expressing S, E, M or N to determine cell activation status. It it was determined that gene expression differences were found in a number of interferon-stimulated genes (ISGs), including IF16, IFIT1, IFIT2 and ISG15 as well as for a number of heat shock protein (HSP) genes, including HSPH1, HSPA6 and HSPBP1 with all four SARS-CoV-2 structural proteins. There were also differences observed with expression patterns of transcription factors with both SP1 and MAVS upregulated in the presence of S, M and E but not the N protein. Collectively the results indicate that gene expression patterns associating with ER stress pathways can be identified with SARS-CoV-2 envelope glycoprotein expression. The results suggest the SARS-CoV-2 can modulate activation of an array of cell pathways resulting in disruption to NF-{kappa}B signalling hence providing alterations to multiple physiological responses of SARS-CoV-2 infected cells.

immunology↗

bioRxiv2019

Streptolysin production and activity is central to in vivo pathotype and disease outcome in GAS infections

Streptococcus pyogenes (GAS) is among the most diverse of all human pathogens, responsible for a range of clinical manifestations, from mild superficial infections such as pharyngitis to serious invasive infections such as necrotising fasciitis and sepsis. The drivers of these different disease phenotypes are not known. The GAS cholesterol-dependent cytolysin, streptolysin O (SLO), has well established cell and tissue destructive activity. We investigated the role of SLO in determining disease outcome in vivo, by using two different clinical lineages; the recently emerged hypervirulent outbreak emm type 32.2 strains, which result in sepsis, and the emm type 1.0 strains which cause septic arthritis. Using clinically relevant in vivo mouse models of sepsis and a novel septic arthritis model, we demonstrated that the amount and activity of SLO is vital in determining the pathotype of infection. The emm32.2 strain produced large quantities of highly haemolytic SLO that resulted in rapid development of sepsis. By contrast, the lower levels and haemolytic activity of emm1.0 SLO led to translocation of bacteria to joints. Importantly, sepsis associated strains that were attenuated by deletion or inhibition of SLO also translocated to the joint, confirming the key role of SLO in determining infection niche. Our findings demonstrate that SLO is key to in vivo pathotype and disease outcome. Careful consideration should be given to novel therapy or vaccination strategies that target SLO. Whilst neutralising SLO activity may reduce severe invasive disease, it has the potential to promote chronic inflammatory conditions such as septic arthritis.

microbiology↗