ABSTRACT
Even after two years of the pandemic, a completely effective treatment against SARS-CoV-2 has not yet been established. Considering this fact and the emergence of successive new viral variants, the development of therapies based on natural polyclonal antibodies recovered from convalescent plasma remains relevant. This study presents a comparison between different methods of screening antibodies in samples of 41 individuals previously diagnosed with COVID-19. We found a significant correlation between Abbot Architect anti-SARS-CoV-2 IgG and Abbott Allinity SARS-CoV-2 IgG II Quantitative assay intensity of reactivity and neutralizing antibody (nAb) titers. Thus, we propose an initial antibody screening with IgG anti-N Abbott Architect test, with an index of, for example, > 3.25 or SARS-CoV-2 IgG II Quantitative Abbott Allinity assay > 137.65 AU/mL as good predictors of Nab ≥ 1:80. For the quantitative method, this threshold demonstrated a 100 % sensitivity and 80 % specificity, with 97.3 % accuracy. An interesting observation was the increase in the neutralizing activity of the anti-SARS-CoV-2 antibodies with the longest interval between the end of the symptoms and the collection, demonstrating that the delay in plasma collection does not affect the achievement of adequate nAbs levels. These results demonstrate the possibility of using faster and more widely available commercial serological tests with a good correlation with viral neutralization tests in culture, allowing for optimized large-scale donor selection, which will be of utmost importance for the development of therapies such as hyperimmune immunoglobulin.
Subject(s)
COVID-19 , SARS-CoV-2 , Humans , COVID-19/therapy , Antibodies, Neutralizing , Antibodies, Viral , Immunoglobulin G , COVID-19 SerotherapyABSTRACT
Despite being initially considered at higher risk for severe COVID-19, sickle cell disease (SCD) patients have mostly presented clinical severity similar to the general population. As their vulnerability to become infected remains uncertain, we assessed the seroreactivity for SARS-CoV-2 to estimate the prevalence of infection and possible phenotypic and socioeconomic determinants for their contagion. Serologic evaluation was performed on 135 patients with an overall prevalence of 11%; positivity was associated with older age and use of public transportation. We speculate that social distancing instructions recommended by our clinic may have contributed to lower levels of infection, but potential protection factors need further investigation.