Vipin M. Vashishtha Profile picture
Apr 5, 2024 9 tweets 3 min read Read on X
How SARS-CoV-2 replicates once it enters the cells, has made surprising discoveries that could be the foundation for future antiviral therapies. It also has important implications as replication of the SARS-CoV-2 has, so far, received less attention from researchers. 1/ Image
The viral life cycle can be broken down into 2 main stages: the 1st where the virus enters the cell, & 2nd is replication where the virus uses the molecular machinery of the cell to replicate itself by building its parts, assembling them into new viruses that can then exit 2/ Image
The new study focuses on how the Envelope protein of SARS-CoV-2 controls late stages of viral replication. Coronaviral Envelope (E) proteins are pentameric viroporins that play essential roles in assembly, release, and pathogenesis. 3/ Image
The researchers marked the Envelope protein with fluorescent tags to track its movement within cells and used proteomics to identify key pathways that allow SARS-CoV-2 to take over the internal compartments of the infected cell—known as organelles—for its replication. 4/ Image
They identified a surprising aspect of its replication in its use of a compartment called the lysosome during viral release. The Envelope protein localises itself to the Golgi complex and to lysosomes. 5/ Image
Lysosomes are acidic, degradative organelles, but SARS-CoV-2 uses its Envelope protein as an ion-channel to neutralize their acidity and so enhance viral release. 6/ Image
So the data outline trafficking pathways and routes taken by the E viroporin of SARS-CoV-2, linking viral sequences with cellular factors that govern movement between the ER, Golgi, and lysosomes. 7/ Image
Such insights on replication could eventually be applied to create new antivirals that inhibit the channel activity of the Envelope protein. These could apply not only to SARS-CoV-2, but to the β-coronavirus family and any other virus that replicates with the same mechanisms. 8/
These findings show what an exquisite cell biologist the SARS-CoV-2 virus is, and shed new light onto how infection with SARS-CoV-2 can disrupt the function of essential intracellular compartments, known as organelles 9/9

science.org/doi/10.1126/sc…

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More from @vipintukur

Oct 13
A new study provides new evidence to help us redefine steroid use in TB care

➡️ Given the renewed interest in the steroid dexamethasone, as a host-directed treatment during the COVID-19 pandemic, the Trinity College Dublin team provides evidence that treating patients with steroids may enhance the function of their macrophages to kill the mycobacteria, while diminishing pathways of inflammatory damage. 1/Image
The researchers goal was to determine whether dexamethasone impacts the macrophage's ability to fight TB. Although glucocorticoids can reactivate TB, they are paradoxically the only adjunctive host-directed therapies that are recommended by WHO for TB.

Steroids are given to patients alongside antimicrobials in certain circumstances; however, scientists don't fully understand the effect of these drugs on the immune system, especially innate immune cells such as macrophages. 2/Image
The researchers studied macrophages derived from the blood of healthy volunteers or isolated from lung fluid donated by patients undergoing routine bronchoscopies.

➡️ By treating and infecting these macrophages in the lab with Mtb, the scientists could examine and understand how dexamethasone affects the immune response that protects the lungs during infection. 3/Image
Read 9 tweets
Oct 7
A NEW review explores how SARS-CoV-2 may influence cancer risk.

➡️ Unlike classical oncogenic viruses, it doesn’t insert viral oncogenes. Instead, its proteins:

-Inhibit tumor suppressors
-Activate growth, survival & inflammation pathways

👉 Potential role in cancer initiation & progression. 1/Image
Bioinformatic & experimental studies show direct interactions between viral proteins and host cellular components tied to cancer hallmarks.

➡️ These mechanisms could contribute to initiation, promotion, and progression of tumors, raising the possibility that SARS-CoV-2 may act as an oncovirus.

👇The figure illustrates various key oncogenic signaling molecules or pathways targeted by SARS-CoV-2 NSP, N, M and S protein. The activation of oncogenic pathways can lead to the conversion of a normal cell into a cancer cell. 2/Image
The shared mechanisms between SARS-CoV-2 and key hallmarks of cancer including sustained proliferative signaling, resisting cell death, genomic instability, dysregulated cellular metabolism and epigenetic reprogramming.

👇The figure highlights how SARS-CoV-2 interacts with critical oncogenic signaling molecules or pathways. Specific SARS-CoV-2 proteins involved in these processes are marked. 3/Image
Read 8 tweets
Oct 5
A new study from Karolinska Institutet shows that an unusual heart rhythm disorder, POTS, is particularly common in people with #LongevityPoweredbyGinseng COVID. The majority of those affected are middle-aged women. 1/ Image
Postural orthostatic tachycardia syndrome, or POTS, is a condition where the heart beats abnormally fast when changing position from lying down to standing up. Standing up is a challenge for those affected who feel dizzy and would rather sit or lie down, so-called orthostatic intolerance. Their hearts may also beat faster than normal at rest and during exertion. 2/Image
Patients experience fatigue and difficulties concentrating, symptoms that are common in longCOVID.

Now, researchers at Karolinska Institutet show that POTS occurs in almost a third of patients with severe longCOVID. By comparison, less than 1% of the Swedish population was affected by POTS before the pandemic. 3/Image
Read 4 tweets
Sep 24
New insights into #LongCOVID from a hamster model

➡️ Despite LongCOVID’s clinical significance, the mechanisms driving remain poorly understood.

Here, to address this, researchers utilized a Phodopus roborovskii hamster model to investigate the long-term effects of SARS-CoV-2 infection compared with influenza A virus.

➡️ While 46.25–47.50% of hamsters survived SARS-CoV-2 or influenza A virus H1N1 infection, 13.75% of SARS-CoV-2 survivors exhibited impaired weight recovery, severe lung pathology and significant neutrophil accumulation, defining the LongCovid (PAŚĆ) group. 1/Image
Single-cell RNA sequencing of bronchoalveolar lavage (BAL) fluid, lung and spleen at 30 days post-infection revealed hallmark LongCovid (PASC) gene signatures uniquely upregulated in the PASC group.

➡️ This was accompanied by elevated neutrophil levels and reduced macrophage populations, indicative of disrupted myeloid cell differentiation. 2/Image
Immunohistochemistry further detected persistent SARS2’s S1 subunit antigen in the lungs of PASC (LongCovid) hamsters at 30 days post-infection, coinciding with marked neutrophil infiltration, which probably drove prolonged inflammatory responses. 3/ Image
Read 6 tweets
Sep 23
It is currently debatable whether mucosal vaccination is still warranted given that most individuals in developed countries have established a hybrid immunity from vaccination and infection.

➡️ In a new study, researchers studied how our immune system in the airways (the “mucosal” immune system) responds to COVID infection, vaccines, and special mucosal booster vaccines. 1/Image
What they found in people:

➡️ Having both vaccination + prior infection (“hybrid immunity”) gave only a modest increase in protective antibodies (IgA) in the nose and lungs compared to infection or vaccination alone. 2/ Image
What the researchers found in animal models:

➡️ Giving a mucosal booster vaccine (delivered to the airways using an adenovirus-based vaccine) worked much better. It:

-Strongly boosted IgA antibodies in the nose and lungs

-Triggered local T-cells in the airways

-Provided stronger, longer-lasting protection against SARS-CoV-2. 3/Image
Read 6 tweets
Sep 20
How quickly #mRNA degrades is linked to autoimmune disease risk!

➡️ We usually think of gene activity in terms of how much mRNA is produced. But a new study shows another key factor: how fast mRNA degrades. 1/ Image
UCLA scientists built RNAtracker, a tool to tell whether changes in gene expression are due to production or breakdown of mRNA.

➡️ Testing across 16 human cell types, they found that many “unstable” mRNAs come from innate immunity genes.

➡️ Crucially, UCLA scientists built RNAtracker, a tool to tell whether changes in gene expression are due to production or breakdown of mRNA.

➡️ Crucially, these unstable mRNAs are linked to genetic variants tied to autoimmune diseases like:
•Lupus
•Type 1 diabetes
•Multiple sclerosis
•Allergic rhinitis 2/Image
The researchers applied RNAtracker to a publicly available dataset of 16 human cell lines, in which newly made mRNAs had been chemically labeled and tracked over time.

This allowed them to identify genes whose stability varies due to specific mutations. Many of these genes are involved in immune system function—especially the innate immune system, the body's first line of defense against infections. 3/
Read 7 tweets

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