The entry of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) into human cells is an essential step for virus transmission and development of COVID 19. Although the lung epithelial cells are its initial target, SARS-CoV-2 also can infect endothelial cells. Endothelial cells are the major constituents of the vascular system and cardiovascular complication is a hallmark of severe COVID-19. Angiotensin-converting enzyme 2 (ACE2) is the entry receptor for SARS-CoV-2. However, the possible involvement of other cellular components in the viral entry is not fully understood.

A team of researchers from the Boston University School of Medicine (BUSM) has identified extracellular vimentin as an attachment factor that facilitates SARS-CoV-2 entry into human cells. Vimentin is a structural protein that is widely expressed in the cells of mesenchymal origin such as endothelial cells and a potential novel target against SARS-CoV-2, which could block the infection of the SARS-CoV-2.

“Severe endothelial injury, vascular thrombosis, and obstruction of alveolar capillaries (tiny air sacs scattered throughout the lungs) are common features of severe COVID-19. Identification of vimentin as a host attachment factor for SARS-CoV-2 can provide new insight into the mechanism of SARS-CoV-2 infection of the vascular system and can lead to the development of novel treatment strategies,” said corresponding author Nader Rahimi, PhD, associate professor of pathology & laboratory medicine at BUSM.

The researchers used liquid chromatography–tandem mass spectrometry (LC-MS/MS) and identified vimentin as a protein that binds to the SARS-CoV-2 spike (S) protein and facilitates SARS-CoV-2 infection. They also found that depletion of vimentin significantly reduces SARS-CoV-2 infection of human endothelial cells. In contrast, over-expression of vimentin with ACE2 significantly increased the infection rate. “More importantly, we saw that the CR3022 antibody inhibited the binding of vimentin with CoV-2-S-protein, and neutralized SARS-CoV-2 entry into human cells,” explained Rahimi.

Collaborators from BUSM included Elke Mühlberger, PhD, Vipul Chitalia, MD, PhD and Catherine E. Costello, PhD.

These findings appear online in the Proceedings of the National Academy of Sciences.