False positive serology of prepandemic chagasic samples with SARS-CoV-2 antigen.

ABSTRACT

OBJECTIVE: To determine whether prepandemic sera from patients with Chagas disease recognise SARS-CoV-2 antigens. MATERIALS AND METHODS: Forty sera from patients with Chagas disease were tested for the presence of IgG cross-reactivity against the nucleocapsid protein (NP) and spike (S) SARS-CoV-2 proteins by ELISA. Positive samples were tested again using a different ELISA and CLIA, both against NP. RESULTS: None of the sera from patients with Chagas disease, previously confirmed as positive for the presence of anti-Trypanosoma cruzi antibodies reacted against the SARS-CoV-2 S protein, and six samples tested positive for the NP antigen (15%). The six positive samples were re-tested, five remained positive by ELISA and all were negative by CLIA. CONCLUSION: According to our data, false-positive results might be a concern in the detection of SARS-CoV-2 antibodies in patients with Chagas disease.