Development of a highly sensitive point-of-care test for African swine fever that combines EZ-Fast DNA extraction with LAMP detection: Evaluation using naturally infected swine whole blood samples from Vietnam.

BACKGROUND: While early detection and early containment are key to controlling the African swine fever (ASF) pandemic, the lack of practical testing methods for use in the field are a major barrier to achieving this feat. OBJECTIVES: To describe the development of a rapid and sensitive point-of-care test (POCT) for ASF, and its evaluation using swine whole blood samples for field settings. METHODS: In total, 89 swine whole blood samples were collected from Vietnamese swine farms and were performed the POCT using a combination of crude DNA extraction and LAMP (loop-mediated isothermal amplification) amplification. RESULTS: The POCT enabled crude DNA to be extracted from swine whole blood samples within 10 min at extremely low cost and with relative ease. The entire POCT required a maximum of 50 min from the beginning of DNA extraction to final judgment. Compared to a conventional real-time PCR detection, the POCT showed a 1 log reduction in detection sensitivity, but comparable diagnostic sensitivity of 100% (56/56) and diagnostic specificity of 100% (33/33). The POCT was quicker and easier to perform and did not require special equipment. CONCLUSIONS: This POCT is expected to facilitate early diagnosis and containment of ASF invasion into both regions in which it is endemic and eradicated.

Duplex nested reverse transcriptase polymerase chain reaction for simultaneous detection of type 2 porcine reproductive and respiratory syndrome virus and porcine circovirus type 2 from tissue samples

There are high levels of co-incidence of porcine reproductive and respiratory syndrome virus (PRRSV) and porcine circovirus type 2 (PCV2) in porcine tissue. This study established a duplex nested reverse transcriptase polymerase chain reaction (RT-PCR) method that targets the genomic RNA of type 2 PRRSV and the mRNA of PCV2 in infected tissues. The method amplified discriminative bands of 347 bp and 265 bp specific for type 2 PRRSV and PCV2, respectively. The limits of detection of the duplex nested RT-PCR were 10(1.5) TCID₅₀/mL for type 2 PRRSV and 10² infected cells/mL for PCV2. The kappa statistic, which measures agreement between methods, was 0.867, indicating a good level of agreement. This RNA-based duplex RT-PCR approach can be another way to detect type 2 PRRSV and PCV2 simultaneously and with improved convenience.