Rapid on-site detection of Salmonella pullorum based on lateral flow nucleic acid assay combined with recombinase polymerase amplification reaction

Caused by Salmonella pullorum, pullorosis is a bacterial disease threatening the poultry industry and has been listed as the bacterial disease to be eliminated by the government. However, antibiotic treatment of pullorosis has become increasingly difficult, resulting in severe influences on the sustainable development of poultry. Abuse of antibiotics may cause global drug-resistant problems. Hence, early diagnosis of young chickens and accurate treatment of sick chickens are urgently needed. Traditional serotyping for Salmonella detection is costly and labor-intensive, whereas other commonly used plate agglutination test methods often cause physical injury of chickens. Therefore, a rapid and nondamaging detection method is of great significance for early diagnosis, which is the key step in accurate medication and elimination of pullorosis. In this study, we propose a novel lateral flow nucleic acid assay (LFNAA) system combining recombinase polymerase amplification (RPA) for the detection of S. pullorum. In this method, the DNA of S. pullorum strains was quickly amplified by RPA under 37°C, and then, the RPA products were added onto the LFNAA sample pad until the final results could be observed by naked eyes within 3 min. The proposed assay is fast and delivers visible results to naked eyes in field test. The limit of detection for genomic DNA was 5 × 10^{-3} ng/μL, indicating high sensitivity. In addition, the proposed LFNAA system is cost-effective, efficient, and nondamaging to chicks in the field test. This system provides technical support for early diagnosis of S. pullorum in the poultry and paves a way for future precision medicine to avoid the global drug-resistance issues.