Latest COVID-19 Research Provides Insight on Antibodies, ACE2 and How the Disease Enters the Body

A little more than six months have passed since the novel coronavirus that has swept across the globe and infected more than 6 million people first reared its head in China. Since that time, researchers have been learning as much about the disease as possible in order to accurately diagnose it and develop effective treatments.

In its ongoing examination of COVID-19 related research, the journal Nature has provided updates on several scientific papers assessing diagnostics related to the detection of the virus as well as questions surrounding antibody testing and the likely way the virus enters the body.

Regarding viral entry into the body, researchers at the University of North Carolina at Chapel Hill speculate that nasal passages are the most likely entryway for the virus to get into a body. They examined different cells in the respiratory tract as part of their study and discovered that the most easily infected cells are in the nasal cavity, and the least easily infected are deep in the lungs. The gradient of infectivity “mapped neatly onto the distribution of cells that express ACE2, a protein that SARS-CoV-2 uses to enter cells,” Nature reported. Last week, BioSpace reported on the possible link of ACE2 and COVID-19. As BioSpace noted, ACE2 interfaces with the RAAS system, with the ACE2 enzyme countering RAAS (renin-angiotensin-aldosterone system) activation but also acting as a receptor for both SARS-CoV-2, the virus that causes COVID-19. The Chapel Hill researchers posit that SARS-CoV-2 gains a foothold in the nose then moves down the respiratory tract. They say the results support the use of masks and preventative measures such as nasal cleansing.

When it comes to the spread of the virus from one person to another, Nature pointed to some information that could be key to containing infection rates. According to research from the University of Manitoba in Winnipeg, Canada, the virus is not likely to be spread from symptomatic patients eight days after the start of those symptoms. The research was based on experiments conducted with primate cells. The team of scientists found that RNA-positive samples that were collected eight days after symptoms began did not infect other cells. This suggests that the window of infectious time is smaller than initially thought and could cut down on times of self-quarantine following the onset of COVID-19 related symptoms.

Much hope has been placed in antibody tests as a way to determine if a person has been infected and recovered from COVID-19, particularly as governments begin to re-open economies that had stagnated for the past few months. However, a new report from the University of California at San Francisco suggests there could be a bias in antibody testing. The potential bias relates to how severe a case an infected person may have had. According to the Nature report, antibody levels may be significantly higher in people who were hospitalized with the disease than those who could have been exposed but were asymptomatic or only had mild symptoms. The research team said more detailed studies will need to be conducted in order to assess how well antibody tests detect the previous infection in people who had mild disease, Nature reported.