Persistence of SARS-CoV-2-antibodies against N, S and RBD after natural infection

Mitra Jafari; Samira Asli; Fateme Moghbeli; Mohammad Gholami Fesharaki; Nazila Hajiahmadi; Faezeh Mojtahedzadeh; Saeid Amel Jamehdar; Taravat Bamdad

doi:10.18502/ijm.v15i6.14161

Mitra Jafari Department of Virology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
Samira Asli Clinical Research Development, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
Fateme Moghbeli Department of Health Information Technology, Varastegan Institute for Medical Sciences, Mashhad, Iran
Mohammad Gholami Fesharaki Department of Statistics, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
Nazila Hajiahmadi Department of Virology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
Faezeh Mojtahedzadeh Department of Virology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
Saeid Amel Jamehdar Clinical Research Development, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
Taravat Bamdad Department of Virology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran

DOI: https://doi.org/10.18502/ijm.v15i6.14161

Keywords: SARS-CoV-2; Antibody persistence; COVID-19; Humoral immunity; Long-term immunity

Abstract

Background and Objectives: Coronavirus disease 2019 (COVID-19) pandemic has affected most countries in the world. Monitoring the humoral immune responses during the natural course of Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) infection and the duration of them provide useful information for the development of vaccination strategies against this virus and its emerging variants. The importance of the antibody response especially neutralizing antibodies in long-term immunity to SARS-CoV-2 is significant.

Materials and Methods: The present study is a cross-sectional study of sero-epidemiological type that has been proposed to compare the persistence of Immunoglobulin G (IgG) against N (nucleocapsid), S (spike) and RBD (receptor-binding domain) proteins in the community after the time of primary disease. A total of 652 serum samples were collected from hospital staff working in COVID wards, as well as a number of community members with different occupations, among those with positive antibody titers, 86 participated in the resampling test before vaccination.

Results: There was no association between antibody titer and disease severity (p>0.05). A significant decrease in Ab levels was observed in the paired second samples. The highest rate of decrease was related to anti-N, then anti-RBD and anti-S IgG levels, respectively. There is a significant relationship between the initial antibody titer and its reduction over time (p-value<0.05).

Conclusion: Our data revealed that humoral immunity following natural infection of SARS-CoV-2 is detectable for at least 4 months, regardless of disease severity. The most decrease in antibody titer over time was related to anti-N IgG levels.