• Skip to main content
  • Skip to primary sidebar
virology blog

virology blog

About viruses and viral disease

interferon

TWiV 902: Autoantibodies drive severe COVID-19

22 May 2022 by Vincent Racaniello

TWiV reviews recent cases of monkeypox, presence of SARS-CoV-2 RNA but not infectious virus in feces, and the association of autoantibodies to interferons with severe COVID-19.

Hosts: Vincent Racaniello, Dickson Despommier, Rich Condit, Kathy Spindler, and Brianne Barker

Click arrow to play
Download TWiV 902 (76 MB .mp3, 127 min)
Subscribe (free): Apple Podcasts, Google Podcasts, RSS, email

Become a patron of TWiV!

Show notes at microbe.tv/twiv

Filed Under: This Week in Virology Tagged With: autoantibodies, coronavirus, COVID-19, feces, interferon, monkeypox, pandemic, SARS-CoV-2, smallpox, viral, virology, virus, viruses

Cigarette smoke increases infection severity of SAR-CoV-2 in airway cells in culture

19 November 2020 by Vincent Racaniello

CoV2-cigarette

Cigarette smoking appears to be associated with more severe COVID-19, but the underlying mechanisms have not been deciphered. The results of infection of airway cells in culture with SARS-CoV-2 provide some insight.

Smoking is the most important cause of chronic lung disease, which in turn is a risk factor for severe COVID-19. Some studies have identified cigarette smoking as a risk factor for severe COVID-19, and chronic smoke exposure appears to trigger the expansion of cell types in the respiratory tract that produce ACE2, the receptor for SARS-CoV-2. But there have been no direct studies to determine how cigarette smoke affects SARS-CoV-2 infection of the airway epithelium.

To address this question, air-liquid interface cultures of respiratory epithelium from non-smokers were studied. Such cultures are initiated by plating cells taken from the human respiratory tract on a permeable membrane. When medium is removed from the top of the cell layer, it develops into a mucociliary pseudostratified epithelium, similar to the respiratory epithelium. When treated with cigarette smoke and then infected with SARS-CoV-2, these cells in culture produced 2-3 times more viral RNA compared with unexposed cells. Furthermore, the number of infected cells increased in cigarette smoke-treated cultures.

To understand the mechanism by which treatment with cigarette smoke leads to increased viral replication, single-cell RNA sequencing was done to determine the alterations of mRNAs caused by virus infection. This analysis identified a set of genes whose transcription was induced by virus infection of untreated cells, but down-regulated in cigarette smoke-treated cells. These genes encode interferon induced proteins, suggesting that exposure to cigarette smoke impairs an effective innate immune response to infection. In support of this hypothesis, addition of interferon to cultures after treatment with cigarette smoke, but before infection, blocked the production of infectious virus.

These observations do provide some insight into the effect of cigarette smoke on infection of airway epithelial cells with SARS-CoV-2. The finding that viral RNA increased in smoke-treated cells should be extended to determine if the amounts of infectious virus also increases. Blocking virus production with interferon does not illuminate the effect of smoke treatment because this cytokine also blocks infection in untreated cells. It would be more informative to specifically restore the expression of the interferon-induced genes that are reduced by smoke treatment.

Would a 2-3 fold increase in virus production, and a similar increase in the number of infected cells after smoke treatment of these airway cultures, explain why smokers might be a risk for serious COVID-19? A reduced innate immune response might allow substantial viral reproduction in the tract, which could in turn stimulate the over-exuberant immune responses that drive serious COVID-19. However an increase in viral yields alone seems too simplistic to explain the association of serious disease with smoking. An intriguing hint is the effect of cigarette smoke airway basal stem cells, which are important for the repair of damaged airways. Smoke not only increases the number of these cells but also leads to their death. Such an effect could worsen tissue damage in the infected respiratory tract, leading to more severe disease.

Filed Under: Basic virology, Information Tagged With: cigarette smoke, coronavirus, COVID-19, interferon, pandemic, respiratory epithelium, SARS-CoV-2, viral, virology, virus, viruses

TWiV 671: Prizes, polio, and a pandemic puzzle

12 October 2020 by Vincent Racaniello

Daniel Griffin provides a clinical report on COVID-19, then Amy joins us to discuss the 2020 Chemistry Nobel Prize for gene editing using CRISPR/Cas9, continuing circulation of poliovirus in Afghanistan, inborn errors of interferon in patients with severe COVID-19, and listener questions.

Click arrow to play
Download TWiV 671 (102 MB .mp3, 170 min)
Subscribe (free): iTunes, Google Podcasts, RSS, email

Become a patron of TWiV!

Show notes at microbe.tv/twiv

Filed Under: This Week in Virology Tagged With: coronavirus, COVID-19, diagnostic test, inborn errors, interferon, lateral flow assay, pandemic, polio eradication, poliomyelitis, SARS-CoV-2, SNIP, vaccine, viral, virology, virus, viruses

TWiV 633: Singapore viral

30 June 2020 by Vincent Racaniello

From DukeNUS Medical School, Vincent speaks with Ashley, Sheemei, Eng Eong and Dahai about their careers and their research on flaviviruses and sensing of viral RNA.

Click arrow to play
Download TWiV 633 (56 MB .mp3, 93 min)
Subscribe (free): iTunes, Google Podcasts, RSS, email

Become a patron of TWiV!

Show notes at microbe.tv/twiv

Filed Under: This Week in Virology Tagged With: dengue virus, DukeNUS, flavivirus, interferon, RIG-I, RNA sensor, viral, virology, virus, viruses, yellow fever virus

TWiV 597: A lot of immunology and some COVID-19 with Jon Yewdell

3 April 2020 by Vincent Racaniello

Immunologist Jon Yewdell joins Vincent and Rich to discuss immune responses in the context of infection with SARS-CoV-2.

Click arrow to play
Download TWiV 597 (69 MB .mp3, 115 min)
Subscribe (free): iTunes, Google Podcasts, RSS, email

Become a patron of TWiV!

Show notes at microbe.tv/twiv

Filed Under: This Week in Virology Tagged With: antibody, B cell, coronavirus, COVID-19, immunology, interferon, SARS-CoV-2, T cell, viral, virology, virus, viruses

A cell RNA that regulates innate immunity

18 October 2018 by Vincent Racaniello

RIG-I activationAll immune responses, from intrinsic to adaptive, need to be regulated – if left on indefinitely they will damage the host. The innate immune response is no exception, and a cellular RNA has been identified that binds to a sensor of viral RNA and regulates the production of interferon (IFN).

[Read more…] about A cell RNA that regulates innate immunity

Filed Under: Basic virology, Information Tagged With: dsRNA, IFN, innate immunity, interferon, lncRNA, long non-coding RNA, RIG-I, viral, virology, virus, viruses

  • Go to page 1
  • Go to page 2
  • Go to page 3
  • Interim pages omitted …
  • Go to page 6
  • Go to Next Page »

Primary Sidebar

by Vincent Racaniello

Earth’s virology Professor
Questions? virology@virology.ws

With David Tuller and
Gertrud U. Rey

Follow

Facebook, Twitter, YouTube, Instagram
Get updates by RSS or Email

Contents

Table of Contents
ME/CFS
Inside a BSL-4
The Wall of Polio
Microbe Art
Interviews With Virologists

Earth’s Virology Course

Virology Live
Columbia U
Virologia en Español
Virology 101
Influenza 101

Podcasts

This Week in Virology
This Week in Microbiology
This Week in Parasitism
This Week in Evolution
Immune
This Week in Neuroscience
All at MicrobeTV

Useful Resources

Lecturio Online Courses
HealthMap
Polio eradication
Promed-Mail
Small Things Considered
ViralZone
Virus Particle Explorer
The Living River
Parasites Without Borders

Creative Commons License
This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.