The Detection of Salmonella Enteritidis on German Layer Farms after Cleaning and Disinfection.

The presence of Salmonella Enteritidis in poultry houses after cleaning and disinfection can pose a potential risk to public health, as Salmonella remains one of the most important causes of foodborne diseases. This study focused on ten German layer farms (including floor-reared and free-range systems) with a recent history of Salmonella Enteritidis, and samples were collected from July 2018 to March 2021 after the cleaning and disinfection process. A total of 244 swab samples were tested for the presence of Salmonella using real-time PCR, followed by a culture of positive samples. Results revealed that 61 out of the 244 swab samples tested positive for Salmonella, indicating a prevalence of 25% in the samples examined. Among the Salmonella-positive swab samples identified with the PCR assay, 65.6% (40 out of 61) were confirmed by the culture. Of the 40 isolates obtained from the culture, 36 were identified as Salmonella Enteritidis, while 4 were categorized as rough Salmonella strains. This study emphasizes the importance of both the surrounding area of the poultry houses in terms of infection carry-over and the meticulous implementation of cleaning and disinfection procedures to eliminate any remaining infection within the houses. To mitigate the risk of further Salmonella spread on layer farms, additional investigations are recommended to focus on the existing transmission pathways of Salmonella and their genetic diversity.

Innate immune responses of calves during transient infection with a noncytopathic strain of bovine viral diarrhea virus.

In this study, six immunocompetent calves were experimentally infected with a noncytopathic strain of bovine viral diarrhea virus (BVDV), and the effects of the viral infection on parameters of the innate immune response of the host were analyzed. Clinical and virological data were compared with the temporal activation of the alpha/beta interferon-regulated Mx gene in white blood cells (WBC) and skin as well as the upregulation of the acute-phase serum proteins haptoglobin (Hp) and serum amyloid A (SAA). The viral strain used did provoke transient health impairment, namely, fever and leukopenia that were associated with viremia, viral shedding with nasal secretions, and antiviral seroconversion. Complete recovery was observed within 3 weeks. Elevated levels of SAA and Hp were apparent from days 4 to 13 and 8 to 11, respectively. In WBC, the levels of Mx mRNA and Mx protein were elevated from days 2 to 15. In the context of this study with BVDV, the level of Mx protein expression in WBC provided the most telling diagnostic window to monitor the host's ongoing innate immune response.

In vitro and in vivo detection of Mx gene products in bovine cells following stimulation with alpha/beta interferon and viruses.

This study focused on products of the bovine Mx1 gene as specific markers for acute viral infections. The rationale for this is the fact that viral infections are commonly paralleled by the synthesis, release, and remote action of alpha/beta interferons (IFN-alpha/beta). Released IFN-alpha/beta act through specific receptors present on nucleated cells to transduce signals for the transcription of numerous IFN-regulated genes, such as the ones for double-stranded-RNA-dependent protein kinase, 2'-5'-oligoadenylate synthetase, or the Mx proteins. In this study, cultured MDBK cells and bovine white blood cells (WBC) were treated with recombinant IFN-alpha or infected with either bovine herpesvirus 1 (BHV-1) or bovine rotavirus (BRV). Treatment of cultured cells with IFN-alpha was followed within 4 h by a time- and dose-dependent accumulation of intracytoplasmic Mx protein as revealed by immunostaining and Western blot immunoassay. This was preceded by a distinct rise of Mx mRNA in similarly treated cells, as revealed by a newly established quantitative TaqMan PCR technique. The two viruses displayed a cell-dependent in vitro ability to induce Mx proteins, which was limited to bovine WBC with BHV-1 and to MDBK cells with BRV. The established methods were successfully used to show that infection of calves with a noncytopathic strain of bovine viral diarrhea virus, a pestivirus, was followed within 2 days postinfection by strong expression of both Mx mRNA and Mx proteins in WBC.