Immunological Profiling of Toll-Like Receptor 3, Interferon-Alpha, and Antimicrobial Peptide LL-37 in Response to COVID-19 Infection and Vaccination in Iraqi Patients

Introduction:The COVID-19 pandemic, caused by the novel coronavirus SARS-CoV-2, has prompted extensive research into the immune response mechanisms triggered by infection and vaccination.This study investigates the immunological profiling of Toll-like receptor 3 (TLR3), Interferon-alpha (IFN-), and antimicrobial peptide LL-37 in Iraqi patients, comparing responses among unvaccinated, Pfizer-vaccinated, Sinopharm-vaccinated, and COVID-19 infected groups. Materials and Method:A total of 120 participants were categorised into four subgroups: 30 unvaccinated and uninfected, 30 Pfizer-vaccinated, 30 Sinopharm-vaccinated after the second dose, and 30 COVID-19infected but unvaccinated individuals.The study monitored TLR3 gene expression, IFN-, and LL-37 levels over three months using real-time PCR and ELISA techniques, respectively. Results:The study revealed significant variations in TLR3 gene expression across groups.The Pfizer group showed dynamic fluctuations, peaking at three months, indicating an active immune response.The Sinopharm group exhibited a steady increase in TLR3 expression, suggesting sustained immune activation.The infected group had a high initial response, tapering to baseline, reflecting immune resolution.Serum IFN- levels were significantly higher in both the infected and vaccinated groups compared to controls.The Sinopharm group also showed elevated LL-37 levels, indicating robust mucosal immunity Conclusion: This study underscores the critical roles of TLR3, IFN- and LL-37 in the immune response to COVID-19 infection and vaccination.The differential expression of these markers provides insights into the dynamics of the immune response, highlighting the importance of sustained immune surveillance and the potential of these markers for diagnostic and prognostic purposes.Further research is needed to explore the long-term implications and optimise vaccination strategies for better immune protection.