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-kappaB 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-kappaB 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-kappaB signalling hence providing alterations to multiple physiological responses of SARS-CoV-2 infected cells.