RESUMO
The Coronavirus Disease 2019 (COVID-19), caused by the novel SARS-CoV-2, continues to spread globally with significantly high morbidity and mortality rates. Immunological surrogate markers, in particular antigen-specific responses, are of unquestionable value for clinical management of patients with COVID-19. Here, we investigated the kinetics of IgM, IgG against the spike (S) and nucleoproteins (N) proteins and their neutralizing capabilities in hospitalized patients with RT-PCR confirmed COVID-19 infection. Our data show that SARS-CoV-2 specific IgG, IgM and neutralizing antibodies (nAbs) were readily detectable in almost all COVID-19 patients with various clinical presentations. Notably, anti-S and -N IgG, peaked 20-40 day after disease onset, and were still detectable for at least up to 70 days, with nAbs observed during the same time period. Moreover, nAbs titers were strongly correlated with IgG antibodies. Significantly higher levels of nAbs as well as anti-S1 and N IgG and IgM antibodies were found in patients with more severe clinical presentations, patients requiring admission to intensive care units (ICU) or those with fatal outcomes. Interestingly, lower levels of antibodies, particularly anti-N IgG and IgM in the first 15 days after symptoms onset, were found in survivors and those with mild clinical presentations. Collectively, these findings provide new insights into the characteristics and kinetics of antibody responses in COVID-19 patients with different disease severity.
RESUMO
Diagnosis and surveillance of emerging pathogens such as SARS-CoV-2 depend on nucleic acid isolation from clinical and environmental samples. Under normal circumstances, samples would be processed using commercial proprietary reagents in Biosafety 2 (BSL-2) or higher facilities. A pandemic at the scale of COVID-19 has caused a global shortage of proprietary reagents and BSL-2 laboratories to safely perform testing. Therefore, alternative solutions are urgently needed to address these challenges. We developed an open-source method called Magnetic-nanoparticle-Aided Viral RNA Isolation of Contagious Samples (MAVRICS) that is built upon reagents that are either readily available or can be synthesized in any molecular biology laboratory with basic equipment. Unlike conventional methods, MAVRICS works directly in samples inactivated in acid guanidinium thiocyanate-phenol-chloroform (e.g., TRIzol), thus allowing infectious samples to be handled safely without biocontainment facilities. Using 36 COVID-19 patient samples, 2 wastewater samples and 1 human pathogens control sample, we showed that MAVRICS rivals commercial kits in validated diagnostic tests of SARS-CoV-2, influenza viruses, and respiratory syncytial virus. MAVRICS is scalable and thus could become an enabling technology for widespread community testing and wastewater monitoring in the current and future pandemics.
