The unpaired analysis was carried out using non-parametric Mann-Whitney-U test

The unpaired analysis was carried out using non-parametric Mann-Whitney-U test.p0.05 was considered significant. plasma therapy using RBD-specific IgG assays as surrogate measurement for neutralizing antibodies in India. Further, this study provides useful info needed for developing large-scale studies towards understanding of inter-individual variance in Nicorandil immune memory space to SARS CoV-2 natural infection for future vaccine Pcdhb5 evaluation and implementation attempts. Keywords:SARS-CoV-2, COVID-19, Receptor binding website, Neutralizing antibodies, Memory space B cells, India == 1. Intro == Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), the computer virus responsible for the coronavirus disease 2019 (COVID-19) pandemic, emerged like a grave general public health threat beginning in December 2019 (WHO, 2020), paralyzing daily lives and causing economic downturns in many parts of the world. Currently, India is one of the countries most affected with more than 10.6 million COVID-19 confirmed cases and 155,732 associated deaths as of February 16, 2021 (Ministry of Health and Family Welfare GoI, 2020). Intense attempts are underway to develop vaccines and antiviral therapeutics (Al-Kassmy et al., 2020;Amanat and Krammer, 2020;Dagotto et al., 2020;Hashemian et al., 2020;Li and Kang, 2020;Malik et al., 2020;Nabil et al., 2020;Parvathaneni and Gupta, 2020;Verma et al., 2020). All these efforts require a detailed understanding of immune correlates of safety, formation of immune memory, and toughness of these reactions. Additionally, infusion of plasma derived from COVID-19 recovered individuals is being explored like a management strategy (Bloch, Nicorandil 2020;Dhanasekaran et al., 2020;Duan et al., 2020;Focosi et al., 2020;Rabelo-da-Ponte et al., 2020;Salazar et al., 2020;Shen et al., 2020;Ye et al., 2020;Ju et al., 2020) and its rate of success will become augmented with a better understanding of humoral immunity, immunoglobulin isotype utilization and neutralizing activity following recovery from SARS-CoV-2 illness. Moreover, given that many of the SARS-CoV-2 neutralizing epitopes are located in the viral receptor binding website (RBD) of the spike (S) protein (Barnes et al., 2020;Cao et al., 2007;Lan et al., 2020;Liu et al., 2020a;Mittal et al., 2020;Peterhoff et al., 2020;Wang et al., 2020a;Zost et al., 2020a,2020b), it is important to evaluate the relationship between RBD-specific IgG titers and neutralizing antibody reactions in recovered individuals from India. In this study, we evaluated Nicorandil IgG, IgA, IgM, neutralizing antibodies and memory space B cell reactions in PCR-confirmed COVID-19 convalescent subjects. Our results display that while a vast majority (38/42, 90.47%) of COVID-19 recovered individuals developed SARS-CoV-2 RBD-specific IgG reactions, we were able to detect appreciable levels of neutralizing antibody reactions in only half of the convalescent subjects. Neutralizing reactions correlated closely with RBD-specific IgG titers, but weakly with IgG titers Nicorandil measured against whole computer virus concentrate using a commercial Enzyme Linked Immunosorbant Assay (ELISA) kit. Taken collectively, these findings suggest that despite significant inter-individual variance in the RBD-specific IgG titers and neutralizing antibodies, RBD-specific IgG titers continue to serve as a valuable and strong surrogate measurement for neutralizing antibody reactions. Our observations, that many individuals do not develop appreciable levels of neutralizing antibodies, not only provides a glimpse of humoral immune reactions in COVID-19 recovered individuals from India, but also has timely implications for identifying potential plasma therapy donors using on RBD-specific IgG ELISA’s in India where routine overall performance of neutralization assays remains challenging. == 2. Methods == == 2.1. Patient recruitment == COVID-19 recovered individuals were recruited at Shaheed Hasan Khan Mewati Authorities Medical College, Nuh, Haryana, India, Super Niche Pediatric Hospital and Post Graduate Teaching Institute, Noida and ICMR-National Institute of Malaria Study, New Delhi. The Institutional honest boards authorized the study. Informed consent was acquired prior to inclusion in the study. All subjects (mean age 39.4 years, range Nicorandil 1570 years) were SARS-CoV-2 PCR positive at the time of initial diagnosis, and were PCR negative when recruited for this study at 3.612 weeks post initial diagnosis (Table 1). Samples collected from healthy adult blood standard bank donors in the year 2018 are included as pre-pandemic settings. == Table 1. == COVID-19 recovered individuals characteristics (n = 42)a. COVID-19 recovered individuals were recruited at.