Track 3: SARS-CoV-2 Infection in Macrophages

Virologists have discovered a receptor known as CD169 (also known as Siglec1) that is only expressed in macrophages and is responsible for the hyper-inflammatory reaction of macrophages following SARS-CoV-2 infection. These results could explain why SARS-CoV-2 infection of macrophages in COVID-19 patients' lungs causes inflammatory reactions. It has been proposed that the severity of COVID-19 illness is influenced by the dysregulation of macrophages during SARS-CoV-2 infection and the excessive production of pro-inflammatory cytokines by these macrophages. However, it is still unknown what causes macrophages to react in a hyper-inflammatory manner. The SARS-CoV-2 receptor ACE2 is not expressed by these macrophages. Rather, a lectin called CD169 that detects the SARS-CoV-2 spike protein helped SARS-CoV-2 enter macrophages.

The virologists propose that the abnormal inflammation linked to severe COVID-19 illness may be influenced by the ongoing activation of viral sensing systems that identify these viral replication intermediates in macrophages. Future study is required, according to the virologists, to examine the molecular specifics of this distinct virus entrance mechanism, the limited virus replication in macrophages, and how this entry mechanism varies from the traditional ACE2-mediated entry pathway. Importantly, it is necessary to take into account treatments that aim to block this alternative viral entry pathway as they may help to lessen the negative consequences of SARS-CoV-2 infection in macrophages.


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