Dados do Trabalho

Título

Development of a urine-based ELISA using recombinant non-glycosylated SARS-CoV-2 spike protein for the detection of anti-SARS-CoV-2 spike antibodies

Introdução

Serological assays have been used to detect antibodies against SARS-CoV-2, which are produced following prior exposure to the virus or vaccination. Recently, the presence of anti-SARS-CoV-2 Nucleocapsid antibodies was identified in patients' urine using an in-house urine-based ELISA platform, providing a non-invasive method for sample collection and evaluation of immune conversion.

Objetivo (s)

Evaluate and validate an in-house urine-based ELISA to detect anti-SARS-CoV-2 Spike antibodies, by using two recombinant SARS-CoV-2 S (Prok1-S1 and Prok2-S1 subunits) proteins.

Material e Métodos

Three recombinant SARS-CoV-2 Spike proteins that encompass the Receptor Binding Domain and were expressed in either eukaryotic or prokaryotic systems were tested in an ELISA platform against a panel of over 140 urine and matched serum samples obtained from 106 patients who were confirmed positive for SARS-CoV-2 by qRT-PCR. Unpaired samples from thirty-one pre-pandemic or healthy individuals (negative qPCR followed up) were used as negative controls.

Resultados e Conclusão

Our main findings were that anti-SARS-CoV-2 Spike antibodies could be detected in urine samples and that the prokaryotic expression of the rSARS-CoV-2 Spike protein did not hinder the attainment of a relatively high serology efficiency for the urine-based assay. Sensitivity of 63% and 40% and specificity of 95% and 97% were found when serum samples were used against rSARS-CoV-2 proteins expressed in the prokaryotic system (Prok1-S1 and Prok2-S1, respectively). However, we found significantly higher sensitivity (81% and 90%) and specificity (94% and 97%) using the SARS-CoV-2 proteins expressed in the prokaryote system (Prok1-S1 and Prok2-S1, respectively) when applied our in-house urine-based ELISA. For the SARS-CoV-2 protein expressed in eukaryote system (Euk1-S1) sensitivity and specificity values of 67% and 97%, respectively, were calculated for urine samples, as well as 81% and 98%, respectively, for serum samples. Therefore, the use of a urine-based ELISA assay with rSARS-CoV-2 Spike proteins expressed in a prokaryotic system could be regarded as a practical tool for screening the presence of anti-SARS-CoV-2 Spike antibodies and circumventing challenges associated with sample collection and the need for recombinant proteins produced via eukaryotic expression systems.

Palavras-chave

SARS-CoV-2; COVID-19; immunodiagnostic; urine; antibody; Spike protein.

Agradecimentos

CAPES; Fapemig; CNPq; MCTI – Iniciativa Rede Vírus; SESU/MEC