'Why Antibodies May Not Be The Key To Beating Coronavirus'
'Why Antibodies May Not Be The Key To Beating Coronavirus,' By Carrie Arnold, National Geographic, Aug. 7, 2020.
Winter break had arrived in Stockholm in late February, and Soo Aleman watched as her fellow Swedes departed the capital city for ski vacations across Europe. Aleman’s colleagues at the Karolinska University Hospital, where she works as a researcher and physician, returned relaxed and invigorated, with stories to tell about their days on the slopes. But a few of the city’s residents also brought back a most unwelcome souvenir: the SARS-CoV-2 coronavirus.
Like much of the rest of the world, Sweden soon found itself in the grips of an outbreak. As Aleman pivoted from her work on the hepatitis B and C viruses to study COVID-19, she began screening patients for the novel infection and for signs of the body’s immune response. And that’s when things got weird. The body should produce both protective antibodies, which keep the virus from invading, and killer T cells, which tell virus-infected human cells to destroy themselves to keep the virus from spreading. Normally, these immune responses appear in tandem. But in a subset of those who tested positive for COVID-19, Aleman found T cells but no antibodies.
Other scientists around the world also had similar findings. Much of this work is still preliminary, and scientists don’t know what it means in terms of assessing how well a vaccine will work or how well people are protected from severe forms of the disease. But one thing is becoming clear: antibodies might not be telling the whole story when it comes to COVID-19 immunity. “We shouldn’t just look blindly at antibody tests,” Aleman says. “I don’t know another virus like this,” adds Rory de Vries, a virologist at the Erasmus Medical Center in the Netherlands. “We are living in special times with a special virus.”
The Bs and Ts of immune cells: Wellness gurus may exhort us to treat our bodies like temples, but when it comes to fighting off pathogens, the body is more like a castle under siege. Like any fortress, the body has several lines of defenses to protect it from infectious microbes. The innate immune system is the first line, and it sets out to discourage any potential intruder by making the body as inhospitable for them as possible by raising the body’s temperature with a fever and assaulting pathogens with toxic chemicals. It acts like an overzealous security guard and reacts against any sign that a cell or protein is not the body’s own.
Even these security forces can be overwhelmed and outmaneuvered by pathogens that have evolved stealth to evade the immune system and counter inflammatory responses dedicated to stopping germs...
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https://www.msn.com/en-us/health/medical/why-antibodies-may-not-be-the-key-to-beating-coronavirus/ar-BB17Gn8w?ocid=msedgdhp
- A cell infected with particles of SARS-CoV-2. Credit: Cynthia S. Goldsmith and Azaibi Tamin/CDC/SPL
- 'Coronavirus research updates: For fast and low-cost COVID-19 testing, just spit.' Nature wades through the literature on the new coronavirus — and summarizes key papers as they appear, Aug. 7, 2020.
https://www.nature.com/articles/d41586-020-00502-w
.. 7 August — For fast and low-cost COVID-19 testing, just spit. A quick, cheap and painless test that detects SARS-CoV-2 RNA in spit could be used for mass testing.. Compared with the gold-standard nose and throat swab, the saliva test is less invasive, does not need to be conducted by a trained professional and avoids the use of scarce chemicals that are needed to store and extract viral RNA.. The researchers estimate a cost-per-spit of US$1.29–$4.37, and have requested that the United States Food and Drug Administration authorize the test for emergency use.
.. 6 August — Immune reaction to some common colds might provide protection. Some immune cells that recognize coronaviruses that cause the common cold also respond to SARS-CoV-2, the coronavirus responsible for the COVID-19 pandemic.
Previous studies have found that some people who have never been exposed to SARS-CoV-2 nevertheless have immune cells called memory T cells that can recognize the virus. Daniela Weiskopf and Alessandro Sette at the La Jolla Institute for Immunology in California analysed such T cells, and found that they recognize particular sequences of several SARS-CoV-2 proteins (J. Mateus et al. Science http://doi.org/d5v5; 2020).
The team then identified similar sequences in common-cold coronaviruses, and showed these sequences could activate some T cells that also respond to SARS-CoV-2. The findings add weight to the hypothesis that existing immunity to cold coronaviruses could contribute to differences in COVID-19 severity, but further studies are required to support that conclusion....
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