Design and application of a multi-epitope ACE2 antigen for detection of autoantibodies in post-COVID-19 diagnosed...

Type 1 diabetes mellitus (T1DM) is an autoimmune condition involving pancreatic β-cell destruction. Recent publications associate SARS-CoV-2 infection with autoimmune activation and the development of de novo Type 1 Diabetes Mellitus (T1DM), possibly via molecular mimicry, inflammation, and direct β-cell damage. The angiotensin-converting enzyme 2 (ACE2) receptor, exploited by SARS-CoV-2 for cellular entry, is present in pancreatic islets and may be susceptible to autoantibody attack. This study was done to assess anti-ACE2 autoantibody titers in newly diagnosed patients with T1DM post-COVID-19 infection.

Blood samples were collected from thirty-five patients with new-onset T1DM post-COVID-19 and thirty healthy controls who recovered from COVID-19. Bioinformatic epitope prediction software was used to construct an eleven-epitope multi-epitope antigen of ACE2. The recombinant was cloned into BL21 E. coli via pET-32a+ vector, expressed, purified by affinity chromatography, and verified by Western blotting. Indirect ELISA was established to measure anti-ACE2 antibodies, and the Mann-Whitney test was applied for statistical comparison.

The designed multi-epitope vaccine had significant structural stability and effective expression. ELISA results demonstrated significantly higher anti-ACE2 autoantibody levels in T1DM patients compared with the control group (p = 0.01).

The results are consistent with a potential association between SARS-CoV-2 infection and the onset of T1DM by autoimmune responses against ACE2. Very high levels of anti-ACE2 antibodies may cause β-cell dysfunction and insulin deficiency. More longitudinal studies are required to establish causality and investigate anti-ACE2 as a prospective biomarker for post-COVID autoimmune diabetes.