Development of a Rapid Live SARS-CoV-2 Neutralization Assay Based on a qPCR Readout.

Measuring SARS-CoV-2 neutralizing antibodies after vaccination or natural infection remains a priority in the ongoing COVID-19 pandemic to determine immunity, especially against newly emerging variants. The gold standard for assessing antibody-mediated immunity against SARS-CoV-2 are cell-based live virus neutralization assays. These assays usually take several days, thereby limiting test capacities and the availability of rapid results. In this study, therefore, we developed a faster live virus assay, which detects neutralizing antibodies through the early measurement of antibody-mediated intracellular virus reduction by SARS-CoV-2 qRT-PCR. In our assay, Vero E6 cells are infected with virus isolates preincubated with patient sera and controls. After 24 h, the intracellular viral load is determined by qRT-PCR using a standard curve to calculate percent neutralization. Utilizing COVID-19 convalescent-phase sera, we show that our novel assay generates results with high sensitivity and specificity as we detected antiviral activity for all tested convalescent-phase sera, but no antiviral activity in prepandemic sera. The assay showed a strong correlation with a conventional virus neutralization assay (rS = 0.8910), a receptor-binding domain ELISA (rS = 0.8485), and a surrogate neutralization assay (rS = 0.8373), proving that quantifying intracellular viral RNA can be used to measure seroneutralization. Our assay can be adapted easily to new variants, as demonstrated by our cross-neutralization experiments. This characteristic is key for rapidly determining immunity against newly emerging variants. Taken together, the novel assay presented here reduces turnaround time significantly while making use of a highly standardized and sensitive SARS-CoV-2 qRT-PCR method as a readout.

Augmented exercise in the treatment of deconditioning from major burn injury.

OBJECTIVE: To investigate the efficacy of a 12-week exercise program in producing greater improvement in aerobic capacity in adult burn survivors, relative to usual care. DESIGN: Randomized, controlled, double-blinded trial. SETTING: Burn center. PARTICIPANTS: A population-based sample of 35 adult patients admitted to a burn center for treatment of a serious burn injury. INTERVENTION: A 12-week, 36-session, aerobic treadmill exercise program where work to quota (WTQ) participants intensified their exercise according to preset quotas and work to tolerance (WTT) participants continued to their tolerance. Participants completed a maximal stress test at baseline and 12 weeks to measure physical fitness. MAIN OUTCOME MEASURE: Maximal aerobic capacity. RESULTS: The WTT and the WTQ exercise groups both made significant improvements in aerobic capacity from baseline to 12 weeks (t=-3.60, P< or =.01; t=-3.17, P< or =.01, respectively). The control group did not (t=-1.39, P=.19). WTT and WTQ participants demonstrated significantly greater improvements in aerobic capacity in comparison to the control group members (F=4.6, P< or =.05). The WTT and WTQ groups did not differ significantly from each other with regard to their respective improvements in aerobic capacity (F=.014, P=.907). CONCLUSIONS: The aerobic capacity of adult burn survivors can be improved with participation in a structured, 12-week exercise program after injury.