Virus Has Multiple Pathways Into Cells, Hydroxychloroquine Blocks 'Trained Immunity'

The following is a brief roundup of some of the latest scientific studies on the novel coronavirus and efforts to find treatments and vaccines for COVID-19, the illness caused by the virus.

Coronavirus has more than one gateway into cells

Two teams of European researchers, working independently, have identified a new entryway by which the coronavirus infects cells, suggesting another approach to stopping it. One key route—via a protein on cell surfaces called ACE2—is well known. The newly identified gateway is a cell-surface protein called neuropilin-1, or NRP1. A "spike" on the surface of the coronavirus binds to NRP1, allowing the virus to break into the cell, similar to how the virus spike attaches itself to ACE2. Other viruses also employ NRP1 as an entry into cells, including the one that causes mononucleosis. In laboratory experiments with human cells, one of the teams found that an antibody that binds to NRP1 can block the coronavirus spike from attaching and prevent infection. Neither of the studies has been peer-reviewed. One was posted on the preprint server bioRxiv on Wednesday and the other late last week. The research groups say their findings suggest that NRP1 could be another target for drugs and vaccines against the new virus. (https://bit.ly/2C1nKk4; https://bit.ly/2UE2pDJ)

Hydroxychloroquine effect on immune system not helpful against virus

Researchers studying how hydroxychloroquine modifies the body's immune response have found it is unlikely to be helpful in fighting the coronavirus, in the latest evidence against use of the decades-old malaria drug promoted by US President Donald Trump. The medicine, which is also used treat inflammatory conditions like lupus and rheumatoid arthritis, was shown to prevent the new coronavirus from replicating in test tube experiments. While it does reduce severe inflammation, the researchers say, it simultaneously suppresses the immune responses needed to fight off the virus and does not allow the body to develop so-called trained immunity, which facilities the defense against infections. "The fact that hydroxychloroquine averts trained immunity argues against the usefulness of this drug in clearing SARS-CoV-2 infection," the researchers write in a preprint posted on Tuesday on the medRxiv server. (https://bit.ly/30CRQoe)

COVID-19 is a neurological disease too

Add problems with the brain and nervous system to the list of complications in patients with COVID-19, say doctors, providing further evidence that it is far more than a respiratory illness. For a report on Thursday in the Journal of Neurology, researchers pooled data from 41 previously published studies of the neurological effects of the coronavirus. The most common nonspecific neurological symptoms were fatigue (seen in 33.2% of patients), loss of appetite (30.0%), shortness of breath (26.9%), and general malaise (26.7%). The most common specific neurological symptoms—which occurred less often—included disorders of smell and taste, Guillain-Barré syndrome, and inflammation of the brain, spinal cord, and meninges. These tallies did not include strokes that result from blood clotting disorders caused by the coronavirus. In a report published on Sunday in Annals of Neurology, a separate team of doctors called COVID-19 "a global threat to the nervous system" and said, "the number of recognized neurologic manifestations of SARS-CoV-2 infection is rapidly accumulating." (https://bit.ly/2YnRuz6; https://bit.ly/3hgFCYp)

Mask-wearing significantly reduces infection risk

Of all the lifestyle changes imposed to prevent the spread of the new coronavirus, mask-wearing may be the most important, a new study suggests. Researchers say infection trends shifted dramatically when mask-wearing rules were implemented on April 6 in northern Italy and April 17 in New York City—two epicenters of the pandemic. "This protective measure alone significantly reduced the number of infections, that is, by over 78,000 in Italy from April 6 to May 9 and over 66,000 in New York City from April 17 to May 9," they calculated in a study published on Thursday in PNAS: The Proceedings of the National Academy of Sciences of the US. When mask-wearing went into effect in New York, the daily new infection rate fell by about 3% per day, researchers said. In the rest of the country, daily new infections continued to increase. Direct contact precautions—social distancing, quarantine and isolation, and hand sanitizing—were all in place before mask-wearing rules went into effect in Italy and New York City. But they only help minimize virus transmission by direct contact, while face covering helps prevent airborne transmission, the researchers say. "The unique function of face covering to block atomization and inhalation of virus-bearing aerosols accounts for the significantly reduced infections," they said. That would indicate "that airborne transmission of COVID-19 represents the dominant route for infection," they conclude. (https://bit.ly/3fvbabp)

—Nancy Lapid

Source