Antiviral proteins AID/APOBECs play crucial roles in the body's resistance against SARS-CoV-2 virus.

A research team at MedUni Vienna has published a groundbreaking study in the journal Frontiers in Immunology, shedding light on the pathobiology of COVID-19. The study, funded by the "Medical and Scientific fund of the Mayor of the Federal Capital Vienna" and the "Foundation Fund to Promote the Fight against Tuberculosis and other Lung Diseases", was conducted in collaboration with international partners through integrative data mining and gene expression analyses.

The study focuses on two important factors in the body's immune response against DNA and RNA viruses: AID (Activation-induced cytidine deaminase) and APOBEC (Apolipoprotein B mRNA editing enzyme catalytic subunit). AID strengthens the human immune response, while APOBECs block viruses.

The research revealed an extremely high level of expression of both APOBEC family members and ACE2, the entry receptor for SARS-CoV-2, in the gastrointestinal tract, heart, and testis. APOBEC4, in particular, is highly expressed in cells and tissues that are points of attack for SARS-CoV-2, such as epithelial cells in the bronchi, lungs, trachea, and nose.

The role of complex lymphoid structures and AID is of great importance for our further understanding of the pathobiology of COVID-19. AID co-determines the strength of an adaptive immune response, leading to the production of high-affinity antibodies by plasma cells or memory B cells.

The specific APOBEC repertoire in cells and tissues susceptible to SARS-CoV-2 varies among patients or patient groups, influencing viral RNA editing and immune response. However, detailed patient-dependent APOBEC expression patterns in COVID-19 are still under investigation.

The clinical challenge in the future is to characterise the antiviral cell status attributed to AID/APOBECs specific to patients and correlate it with the organs affected by SARS-CoV-2 infection and the severity of COVID-19. Understanding these interrelations could lead to the development of new therapeutic approaches for the disease.

For more details, you can access the published study using the following DOI: 10.3389/fimmu.2021.690416. This research is a significant step forward in our understanding of COVID-19, and its findings could pave the way for more effective treatments in the future.