Cross-reactive immunity against SARS-CoV-2 N protein in Central and West Africa precedes the COVID-19 pandemic
Jannie Pedersen, Ismaël Hervé Koumakpayi, Giorgi Babuadze, Mariana Baz, Oumar Ndiaye, Oumar Faye, Cheikh Tidiane Diagne, Ndongo Dia, Maedeh Naghibosadat, Allison McGeer, Samira Muberaka, Irène P. Moukandja, Stella Ndidi, Carlos Bernardo Tauil, Jean-Bernard Lékana-Douki, Cheikh Loucoubar, Ousmane Faye, Amadou A. Sall, Kelly Grace Magalhães, Nina Weis, Robert Kozak, Gary Kobinger, Hugues Fausther‐Bovendo
Abstract
Early predictions forecasted large numbers of severe acute respiratory syndrome coronavirus (SARS-CoV-2) cases and associated deaths in Africa. To date, Africa has been relatively spared. Various hypotheses were postulated to explain the lower than anticipated impact on public health in Africa. However, the contribution of pre-existing immunity is yet to be investigated. In this study, the presence of antibodies against SARS-CoV-2 spike (S) and nucleocapsid (N) proteins in pre-pandemic samples from Africa, Europe, South and North America was examined by ELISA. The protective efficacy of N specific antibodies isolated from Central African donors was tested by in vitro neutralization and in a mouse model of SARS-CoV-2 infection. Antibodies against SARS-CoV-2 S and N proteins were rare in all populations except in Gabon and Senegal where N specific antibodies were prevalent. However, these antibodies failed to neutralize the virus either in vitro or in vivo. Overall, this study indicates that cross-reactive immunity against SARS-CoV-2 N protein was present in Africa prior to the pandemic. However, this pre-existing humoral immunity does not impact viral fitness in rodents suggesting that other human immune defense mechanisms could be involved. In Africa, seroprevalence studies using the N protein are over-estimating SARS-CoV-2 circulation.