Identification of Single Nucleotide Polymorphisms Associated with Hyperproduction of Alpha-Toxin in Staphylococcus aureus

The virulence factor α-toxin (hla) is needed by Staphylococcus aureus in order to cause infections in both animals and humans. Although the complicated regulation of hla expression has been well studied in human S. aureus isolates, the mechanisms of of hla regulation in bovine S. aureus isolates remain undefined. In this study, we found that many bovine S. aureus isolates, including the RF122 strain, generate dramatic amounts of α-toxin in vitro compared with human clinical S. aureus isolates, including MRSA WCUH29 and MRSA USA300. To elucidate potential regulatory mechanisms, we analyzed the hla promoter regions and identified predominant single nucleotide polymorphisms (SNPs) at positions −376, −483, and −484 from the start codon in α-toxin hyper-producing isolates. Using site-directed mutagenesis and hla promoter-gfp-luxABCDE dual reporter approaches, we demonstrated that the SNPs contribute to the differential control of hla expression among bovine and human S. aureus isolates. Using a DNA affinity assay, gel-shift assays and a null mutant, we identified and revealed that an hla positive regulator, SarZ, contributes to the involvement of the SNPs in mediating hla expression. In addition, we found that the bovine S. aureus isolate RF122 exhibits higher transcription levels of hla positive regulators, including agrA, saeR, arlR and sarZ, but a lower expression level of hla repressor rot compared to the human S. aureus isolate WCUH29. Our results indicate α-toxin hyperproduction in bovine S. aureus is a multifactorial process, influenced at both the genomic and transcriptional levels. Moreover, the identification of predominant SNPs in the hla promoter region may provide a novel method for genotyping the S. aureus isolates

Transparency Too Little, Too Late? Why and How Health Canada Should Make Clinical Data and Regulatory Decision-Making Open to Scrutiny in the Face of COVID-19

Hard-won gains in the transparency of therapeutic product data in recent years1 have occurred alongside growing reliance by regulators upon expedited review processes.2 The concurrence of these two trends raises fundamental questions for the future of pharmaceutical regulation about whether the institutionalization of transparency will foster improved oversight of drugs, biologics, vaccines, and other interventions, or else, provide cover for a relaxing of regulatory standards of safety, effectiveness, and quality.3 The urgency of the COVID-19 pandemic, however, has brought this tension into immediate and sharp relief. During the course of the global health crisis, regulatory bodies have markedly expanded the number and use of expedited review processes for COVID-19 therapies, and at the same time, the proliferation of misinformation about any potential SARS-CoV-2 intervention4 reveals the limitations of recently implemented transparency measures

Transparency Too Little, Too Late? Why and How Health Canada Should Make Clinical Data and Regulatory Decision-Making Open to Scrutiny in the Face of COVID-19

Hard-won gains in the transparency of therapeutic product data in recent years1 have occurred alongside growing reliance by regulators upon expedited review processes.2 The concurrence of these two trends raises fundamental questions for the future of pharmaceutical regulation about whether the institutionalization of transparency will foster improved oversight of drugs, biologics, vaccines, and other interventions, or else, provide cover for a relaxing of regulatory standards of safety, effectiveness, and quality.3 The urgency of the COVID-19 pandemic, however, has brought this tension into immediate and sharp relief. During the course of the global health crisis, regulatory bodies have markedly expanded the number and use of expedited review processes for COVID-19 therapies, and at the same time, the proliferation of misinformation about any potential SARS-CoV-2 intervention4 reveals the limitations of recently implemented transparency measures

Building Responsive Collections with the Getting It System Toolkit

Keywords: GIST, Resource Sharing, Interlibrary LoanKeywords: GIST, Resource Sharing, Interlibrary Loa