Evaluation of RT-LAMP for SARS-CoV-2 Detection in Animal Feces

The wide host range, potential lethality, and zoonotic potential of SARS-CoV-2 infection in animals highlights the need for additional surveillance strategies. We validated a commercial, pH-based, colorimetric RT-LAMP assay for the detection of SARS-CoV-2 RNA in animal feces. The comparator assay was rRT-PCR. The limit of detection of the RT-LAMP assay was 72 genome copies per reaction. RT-LAMP was highly specific for SARS-CoV-2 and did not detect other human or animal coronaviruses. RT-LAMP was robust, with valid results generated for incubation lengths of 30 to 45 min, incubation temperatures of 60 to 70 °C, and reaction volumes of 10 to 25 µL. The diagnostic sensitivity was 100% for clinical fecal samples with high viral loads (Ct ≤ 25), 97.4% for samples with moderate to high viral loads (Ct ≤ 33), and 62% overall (Ct ≤ 40). The diagnostic specificity was 97.9%. Blinded method testing organized by an independent laboratory confirmed the satisfactory reproducibility of the assay. To our knowledge, this study represents the first validation of RT-LAMP for SARS-CoV-2 detection in animals. RT-LAMP testing could detect SARS-CoV-2 infection more rapidly and at the point of care in animals with moderate to high viral loads, allowing for earlier implementation of control measures.