(Natural News) A precedent-setting study on natural immunity was published in Cell on July 14, 2021. The study finds that natural immunity to SARS-CoV-2, the virus responsible for COVID-19, is comprehensive and durable, with persisting antibody responses, robust memory B cell recognition and T cell immunity. The study followed 254 covid patients for eight months and measured immune markers in their blood samples. The recovered patients included men and women who experienced a range of outcomes, from mild, moderate, and severe disease.
The researchers used cross-sectional and longitudinal studies and found that SARS-CoV-2 infection causes the immune system to generate poly-clonal, humoral and cellular immune responses that target multiple viral proteins while establishing long-term immunity to SARS-CoV-2 and a host of other coronaviruses.
T cell memory is comprehensive and promises future protection to coronavirus variants
After eight months, the CD4 and CD8 T cells were able to recognize distinct viral epitope regions and displayed durable, poly-functional immunity to SARS-CoV-2 and a host of other coronaviruses, namely HKU1 and OC43. The natural infection also boosts antibody titers to SARS-CoV-1. The CD4 T cells target the SARS-CoV-2 proteins equally, promising a comprehensive immune response. The CD8 T cells specifically target the nucleoprotein of SARS-CoV-2, promising precision immune responses to future coronaviruses.
The neutralizing and binding antibodies that were detected post-infection exhibit a bi-phasic decay, with an extended half-life greater than 200 days. This indicates the development of longstanding plasma cells that can recognize and neutralize future SARS-CoV-2 viral proteins.
The researchers used the Mesoscale multiplex assay to measure IgG, IgA, and IgM antibody responses to SARS-CoV-2 proteins. The researchers measured binding antibodies to the full-length spike protein, to the receptor-binding domain (RBD), and to the N-terminal domain (NTD) of the spike protein. These results were compared to control blood samples, which were obtained from pre-pandemic individuals vaccinated with either yellow fever or influenza vaccines. The antibodies that bind to the spike RBD and NTD epitopes are able to block the SARS-Co-2 infection of the respiratory epithelial cells. These natural antibodies inhibit interactions between the viral spike and the ACE2 receptor. The IgG antibodies spiked by 92 percent in covid-19 convalescent recipients, when compared to the controls. The IgG response was robust after infection and predictably declined before stabilizing again, indicating long-living plasma cells that can convey immunity long into the future.