Comparison of RT-PCR, RT-LAMP, and Antigen Quantification Assays for the Detection of SARS-CoV-2

Abstract

A rapid and simple alternative test to real-time reverse transcription polymerase chain reaction (RT-PCR) for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is required to help curb the spread of this infection. In this study, we compared the RT-PCR method with the chemiluminescent enzyme immunoassay (CLEIA) and reverse transcription loop mediated isothermal amplification (RT-LAMP) methods. The results for the number of SARS-CoV-2 RNA copies and the CLEIA antigen quantification values were highly correlated. The detection limit for antigen quantification was 42.8 RNA copies for saliva samples and 23.4 copies for nasopharyngeal swab (NPS) samples.The number of RNA copies and RT-LAMP threshold time (Tt) values were inversely correlated for both purified RNA and purification-free crude RNA. RT-LAMP with purified RNA detected low copy numbers of RNA (5-50 copies) whereas fewer than 250 RNA copies could not be detected using crude RNA. CLEIA antigen quantification is potentially useful for large scale screening because it is compatible with high throughput testing. RT-LAMP with crude RNA samples is applicable to rapid point-of-care testing because it can directly use the patient specimen. It is important to select a diagnostic method that is simple and rapid compared to RT-PCR, depending on the situation.

Analytical performance evaluation of Lumipulse® SARS‐CoV‐2 antigen assay in 392 asymptomatic patients

“…So, we cannot exclude that the performance of this test might largely differ in another population with different clinical characteristics. [19][20][21][22][23] In addition, we compared a quantitative assay as Lumipulse SARS-CoV-2 Ag with a qualitative one (real-time RT-PCR), but our purpose was only to evaluate the performance of Lumipulse test as a screening test in an asymptomatic population, avoiding any evaluation on its quantitative performance, as previously described. 12,15,[19][20][21][22][23][24] In conclusion, it is evident that the relevance of this study is considered as a potential model for preventing SARS-CoV-2 infection in large asymptomatic populations.…”

“…[19][20][21][22][23] In addition, we compared a quantitative assay as Lumipulse SARS-CoV-2 Ag with a qualitative one (real-time RT-PCR), but our purpose was only to evaluate the performance of Lumipulse test as a screening test in an asymptomatic population, avoiding any evaluation on its quantitative performance, as previously described. 12,15,[19][20][21][22][23][24] In conclusion, it is evident that the relevance of this study is considered as a potential model for preventing SARS-CoV-2 infection in large asymptomatic populations. Indeed, it is now clear that asymptomatic COVID-19 adult outpatients play a crucial role as transmitters of SARS-CoV-2 infection in the hospital environment and therefore their early detection may certainly be an effective strategy to prevent the recrudescence of new pandemic waves.…”

“…Moreover, considering the more and more reduced resources destined for the public health facilities, the Lumipulse SARS-CoV-2 antigen test shows many advantages: easy to use (completely automatized), reduced analysis times (approximately 45 min), and lower operational costs. [17][18][19][20][21][22][23][24] In addition, its diagnostic performance not seems to be afflicted by the new SARS-CoV-2 variants, which recently appeared in the pandemic scenario, [25][26][27][28] although further studies will be necessary to confirm these data.…”

“…The rationale of this exclusion criteria is strictly related to the aim of the study: to assess the diagnostic performance of the Lumipulse antigen test as screening test in a large and not at‐risk population. So, we cannot exclude that the performance of this test might largely differ in another population with different clinical characteristics 19–23 . In addition, we compared a quantitative assay as Lumipulse SARS‐CoV‐2 Ag with a qualitative one (real‐time RT‐PCR), but our purpose was only to evaluate the performance of Lumipulse test as a screening test in an asymptomatic population, avoiding any evaluation on its quantitative performance, as previously described 12,15,19–24 …”

A Review of SARS-CoV-2 Disease (COVID-19): Pandemic in Our Time

“…However, we must bear in mind that the CRISPR technology has its own limitations too since it is pretty much new technology that is still being worked on to understand more of it. The advancement in the technological world has made almost all of these methods achievable within 24 h or even less [ 75 , 76 , 77 , 78 , 79 , 80 , 81 ].…”