Inhibition of Rab1B Impairs Trafficking and Maturation of SARS-CoV-2 Spike Protein

Longitudinal Assessment of Nasopharyngeal Biomarkers Post-COVID-19: Unveiling Persistent Markers and Severity Correlations

SARS-CoV-19 infection provokes a variety of symptoms; most patients present mild/moderate symptoms, whereas a small proportion of patients progress to severe illness with multiorgan failure accompanied by metabolic disturbances requiring ICU-level care. Given the importance of the disease, researchers focused on identifying severity-associated biomarkers in infected patients as well as markers associated with patients suffering long-COVID. However, little is known about the presence of biomarkers that remain a few years after SARS-CoV-2 infection once the patients fully recover of the symptoms. In this study, we evaluated the presence of persistent biomarkers in the nasopharyngeal tract two years after SARS-Cov-2 infection in fully asymptomatic patients, taking into account the severity of their infection (mild/moderate and severe infections). In addition to the direct identification of several components of the Coronavirus Infection Pathway in those individuals that suffered severe infections, we describe herein 371 proteins and their associated canonical pathways that define the different adverse effects of SARS-CoV-2 infections. The persistence of these biomarkers for up to two years after infection, along with their ability to distinguish the severity of the infection endured, highlights the surprising presence of persistent nasopharyngeal exudate changes in fully recovered patients.

The cellular protein phosphatase 2A is a crucial host factor for Marburg virus transcription

Little is known regarding the molecular mechanisms that highly pathogenic Marburg virus (MARV) utilizes to transcribe and replicate its genome. Previous studies assumed that dephosphorylation of the filoviral transcription factor VP30 supports transcription, while phosphorylated VP30 reduces transcription. Here, we focused on the role of the host protein phosphatase 2A (PP2A) for VP30 dephosphorylation and promotion of viral transcription. We could show that MARV NP interacts with the subunit B56 of PP2A, as previously shown for the Ebola virus, and that this interaction is important for MARV transcription activity. Inhibition of the interaction between PP2A and NP either by mutating the B56 binding motif encoded on NP, or the use of a PP2A inhibitor, induced VP30 hyperphosphorylation, and as a consequence a decrease of MARV transcription as well as viral growth. These results suggest that NP plays a key role in the dephosphorylation of VP30 by recruiting PP2A. Generation of recombinant (rec) MARV lacking the PP2A-B56 interaction motif on NP was not possible suggesting an essential role of PP2A-mediated VP30 dephosphorylation for the MARV replication cycle. Likewise, we were not able to generate recMARV containing VP30 phosphomimetic mutants indicating that dynamic cycles of VP30 de- and rephosphorylation are a prerequisite for an efficient viral life cycle. As the specific binding motifs of PP2A-B56 and VP30 within NP are highly conserved among the filoviral family, our data suggest a conserved mechanism for filovirus VP30 dephosphorylation by PP2A, revealing the host factor PP2A as a promising target for pan-filoviral therapies.

IMPORTANCE

Our study elucidates the crucial role of host protein phosphatase 2A (PP2A) in Marburg virus (MARV) transcription. The regulatory subunit B56 of PP2A facilitates VP30 dephosphorylation, and hence transcription activation, via binding to NP. Our results, together with previous data, reveal a conserved mechanism of filovirus VP30 dephosphorylation by host factor PP2A at the NP interface and provide novel insights into potential pan-filovirus therapies.

Integrated analysis of RNA-seq datasets reveals novel targets and regulators of COVID-19 severity

During the COVID-19 pandemic, RNA-seq datasets were produced to investigate the virus-host relationship. However, much of these data remains underexplored. To improve the search for molecular targets and biomarkers, we performed an integrated analysis of multiple RNA-seq datasets, expanding the cohort and including patients from different countries, encompassing severe and mild COVID-19 patients. Our analysis revealed that severe COVID-19 patients exhibit overexpression of genes coding for proteins of extracellular exosomes, endomembrane system, and neutrophil granules (e.g., S100A9, LY96, and RAB1B), which may play an essential role in the cellular response to infection. Concurrently, these patients exhibit down-regulation of genes encoding components of the T cell receptor complex and nucleolus, including TP53, IL2RB, and NCL Finally, SPI1 may emerge as a central transcriptional factor associated with the up-regulated genes, whereas TP53, MYC, and MAX were associated with the down-regulated genes during COVID-19. This study identified targets and transcriptional factors, lighting on the molecular pathophysiology of syndrome coronavirus 2 infection.