Pre-pandemic cross-reactive antibody and cellular responses against SARS-CoV-2 among female sex workers in Dakar, Senegal

• Published in: Frontiers in public health Vol. 13; p. 1522733
• Main Authors: Herrera, Bobby Brooke, Chaplin, Beth, MBoup, Souleymane, Abdullahi, Adam, He, Michelle, Fisher, Sydney M., Akanmu, Sulaimon, Chang, Charlotte A., Hamel, Donald J., Gupta, Ravindra K., Kanki, Phyllis J.
• Format: Journal Article
• Language: English
• Published: Switzerland Frontiers Media S.A 2025
• Subjects: Adult; Antibodies, Viral - blood; Antibodies, Viral - immunology; antibody; cellular responses; COVID-19 - epidemiology; COVID-19 - immunology; Cross Reactions - immunology; cross-reactivity; Female; Humans; Immunity, Cellular; Middle Aged; Public Health; SARS-CoV-2; SARS-CoV-2 - immunology; Senegal; Senegal - epidemiology; Seroepidemiologic Studies; Sex Workers - statistics & numerical data; Young Adult; Senegal; SARS-CoV-2; cellular responses; cross-reactivity; antibody; Senegal
• ISSN: 2296-2565; 2296-2565
• DOI: 10.3389/fpubh.2025.1522733

The COVID-19 pandemic had a severe impact globally, yet African populations exhibited unexpectedly lower rates of severe disease and mortality. We investigated the potential role of pre-existing immunity in shaping the epidemiology of COVID-19 in Africa. Plasma collected from Senegalese female sex workers prior to the COVID-19 pandemic was screened for SARS-CoV-2 and human coronavirus (hCoV) antibodies by virion immunoblots. For antibody-reactive plasma, paired peripheral blood mononuclear cells were stimulated by fusion proteins and IFN- cellular responses were assessed via ELISPOT. We observed substantial levels of pre-existing cross-reactive immunity to SARS-CoV-2, stemming from prior exposure to seasonal hCoVs. Our antibody analysis revealed a 23.5% (47/200) seroprevalence rate against SARS-CoV-2 nucleocapsid (N). These samples were then probed for antibodies against hCoV spike (S) and/or N antigens; 85.1% (40/47), 70.2% (33/47), and 95.7% (45/47) were antibody reactive against hCoV-229E, hCoV-OC43, or hCoV-HKU1, respectively. Our analysis of cellular responses also demonstrated cross-reactivity to SARS-CoV-2 with 80.0% (36/45) and 82.2% (37/45) showing IFN- responses against S and N, respectively. A unique pre-pandemic subject had cross-reactive SARS-CoV-2 S antibodies with detectable neutralization and cross-reactive cellular responses. These findings suggest that prior hCoV exposure may induce cross-reactive adaptive immunity, potentially contributing to protection against COVID-19. Our study provides unique data on the dynamics of hCoV and SARS-CoV-2 immunity in Senegal and underscores the importance of understanding the role of pre-existing immunity in shaping COVID-19 outcomes globally.