Figure 2. Representative comparison of qRT-LAMP vs qRT-PCR amplification plots in 10 samples from COVID-19 patients (S1 to S10) using either (A) qRT-LAMP with the SARS-N primers set or (B) commercial qRT-PCR. N1 corresponds to isolated viral RNA from hCoV-229E as a negative control.

Validation of qRT-LAMP assays for aMPV detection

Compared to SARS-CoV-2 assays, a panel of only 50 RNA different samples from both turkeys and chickens was analyzed. The panel consisted of various positive/negative samples and included a reference sample of a commercial live-attenuated vaccine for aMPV (Figure 3). Our findings indicate that qRT-LAMP amplification of aMPV exhibited a high level of sensitivity (87.9%, n=29/33) and specificity (100%, n=17/17) after 30 minutes. Remarkably, we found a 100% coincidence of results by qRT-PCR or qRT-LAMP for turkey samples detection. However, coincidence values for chicken samples were lower than expected (80%). In fact, only 16 out of 20 chicken positive samples by qRT-PCR, were detected positive by qRT-LAMP (8/12 tracheal tissue and 8/8 in upper respiratory tract swabs). Of note, the four chicken samples (M8, M9, M39 and M41) negative by qRT-LAMP were viral RNA from tracheal tissue (Table S1), probably due to repeated freezing and thawing of the extracts.