The impact of sample processing on the rapid antigen detection test for SARS-CoV-2: Virus inactivation, VTM selection, and sample preservation

Many factors have been identified as having the ability to affect the sensitivity of rapid antigen detection(RAD)tests for severe acute respiratory syndrome coronavirus 2(SARS-CoV-2).This study aimed to identify the impact of sample processing on the sensitivity of the RAD tests.We explored the effect of different inactivation methods,viral transport media(VTM)solutions,and sample preservation on the sensitivity of four RAD kits based on two SARS-CoV-2 strains.Compared with non-inactivation,heat inactivation significantly impacted the sensitivity of most RAD kits;however,β-propiolactone inactivation only had a minor effect.Some of the VTM solutions(VTM2,MANTACC)had a significant influence on the sensitivity of the RAD kits,especially for low viral-loads samples.The detection value of RAD kits was slightly decreased,while most of them were still in the detection range with the extension of preservation time and the increase of freeze–thaw cycles.Our results showed that selecting the appropriate inactivation methods and VTM solutions is necessary during reagent development,performance evaluation,and clinical application。

Evaluation of a Rapid Immunochromatographic Middle East Respiratory Syndrome Coronavirus Antigen Detection Assay

Middle East respiratory syndrome coronavirus(MERS-CoV)infection in humans has a high mortality of>30%.Dromedaries are the reservoir of MERS-CoV and the main source of human infections.However,MERS-CoV infections in dromedaries are usually subclinical.Rapid diagnosis of MERS-CoV infection in these animals is important in preventing camel-to-human transmission of the virus.The possible cross-reactivity of a previously reported rapid nucleocapsid protein-based antigen detection assay for MERS-CoV was examined with different CoVs,including Tylonycteris bat CoV HKU4,dromedary camel CoV UAE-HKU23,human CoV-229E,human CoV-OC43,severe acute respiratory syndrome CoV-2 and rabbit CoV HKU14,where none of them showed false-positive results.The assay was further validated using quantitative real-time reverse transcription-polymerase chain reaction-confirmed MERS-CoV-positive and MERS-CoV-negative dromedary nasal samples collected in Dubai,the United Arab Emirates,which showed that the rapid antigen detection assay has a specificity of 100%and sensitivity of 91.7%.