Sensitive and rapid detection of Salmonella enterica serovar Indiana by cross-priming amplification.

Salmonella enterica serovar Indiana (S. Indiana) was the most frequently reported foodborne pathogen, which has a broad host range including poultry, swine, and humans. Traditional methods used for the detection of S. Indiana from contaminated food products are time-consuming and labor-intensive. Therefore, rapid detection methods with high sensitivity and specificity are vitally important to prevent the spread of S. Indiana. In this study, we developed a nearly instrument-free, simple molecular method which incorporates cross-priming amplification (CPA) combined with a nucleic acid detection strip (NADS) for sensitive detection of S. Indiana. A set of CPA primers was designed based on S. Indiana specific nucleotide sequences and the specificity of CPA-NADS was tested against 42 bacterial strains. The results showed that this method was highly specific for detection of S. Indiana. The sensitivity of CPA-NADS was evaluated and compared with that of the serovar-specific PCR method and the real-time PCR method. The limit of detection of the CPA method was 8.997 fg/µL for genomic DNA and 6.2 × 101 CFU/mL for bacteria in pure culture. An application of the CPA assay was conducted with 90 inoculated specimens by S. Indiana. The accuracy of CPA-NADS was consistent with the results of the traditional culture-based methods in inoculated specimens. This method showed a higher sensitivity than the serovar-specific PCR method did and was more convenient to perform. In conclusion, we demonstrated that the CPA-NADS system offers high specificity, sensitivity, rapidity, and a simple detection tool for screening S. Indiana.

miR-146a-5p promotes replication of infectious bronchitis virus by targeting IRAK2 and TNFRSF18.

Avian infectious bronchitis virus (IBV) is a coronavirus which infects chickens (Gallus gallus) of all ages and causes significant economic losses to the poultry industry worldwide. The present study aims to analyze the miRNAs related to pathogenicity of nephropathogenic IBVs. It was found that four miRNAs (miR-1454, miR-3538, miR-146a-5p and miR-215-5p) were related to the infection of virulent nephropathogenic IBV with transcript per million (TPM) > 500 and more than a 2-fold alteration. In vitro study results showed that the alterations of these four miRNAs were consistent with in vivo data. In vitro, we found that high levels of miR-146a-5p could enhance the replication of IBV at the early stage of infection, and its down regulated level could slow down the replication of IBV. Finally, high levels of exogenous miR-146a-5p in HD11 cells led to down regulation of IL-1 receptor associated kinase-2 (IRAK2) and Tumor necrosis factor receptor superfamily member 18 (TNFRSF18) genes. Luciferase reporter assays revealed that miR-146a-5p could bind to the 3'-UTRs of IRAK2 and TNFRSF18. This is the first study demonstrating that IBV induced miR-146a-5p is related to virus pathogenesis by down regulating IRAK2 and TNFRSF18, which may serve as a therapeutic strategy for the prevention of IBV infections.