New Insight into COVID-19 Progression at Cellular Level

Scientists at the University of Missouri discovered more about the mechanisms behind coronavirus’ spread between cells in the body, identifying a specific protein called occludin that plays a critical role in the process. Occludin serves as a mediator for cell-to-cell viral transmission, and when damaged by the coronavirus, the virus is able to quickly replicate and spread to neighboring cells, making the infection worse and symptoms potentially more severe. These findings provide insight into how COVID-19 progresses inside the body’s cells and could help in the development of new antiviral drugs. 

The study, published in the Proceedings of the National Academy of Sciences, was led by Wenjun Ma, an associate professor in the MU College of Veterinary Medicine and the MU School of Medicine, who examined how the coronavirus spreads throughout cells by analyzing cell samples at the MU Laboratory for Infectious Disease Research.

Ma and his team found that the occludin protein is a key internalization factor for SARS-CoV-2 infection, critical for subsequent cell-to-cell transmission and syncytium formation. The protein directly interacts with the SARS-CoV-2 spike, and the endosomal entry pathway is involved in occludin-mediated cell-to-cell fusion rather than in the cell surface entry pathway. All SARS-CoV-2 strains tested depend on occludin for cell-to-cell transmission, although the extent of syncytium formation differs between strains.

This knowledge could assist developers of antiviral drugs by examining the potential impact the medications may have in strengthening the occludin protein against infection. “Whether it is studying how the virus enters the cell in the first place or studying the virus replication process, this basic, scientific research helps us learn more about how the disease progresses,” says Ma.

Going forward, Ma plans to investigate if other viral infections impact occludin to better understand how viruses interact at the cellular level with their infected hosts. These findings could impact the development of new antiviral therapies for COVID-19 and other viral diseases.