Salmonella enterica Serovar Enteritidis Antimicrobial Peptide Resistance Genes Aid in Defense against Chicken Innate Immunity, Fecal Shedding, and Egg Deposition

Abstract

c Salmonella enterica serovar Enteritidis (S. Enteritidis) is a major etiologic agent of nontyphoid salmonellosis in the United States. S. Enteritidis persistently and silently colonizes the intestinal and reproductive tract of laying hens, resulting in contaminated poultry products. The consumption of contaminated poultry products has been identified as a significant risk factor for human salmonellosis. To understand the mechanisms S. Enteritidis utilizes to colonize and persist in laying hens, we used selective capture of transcribed sequences to identify genes overexpressed in the HD11 chicken macrophage cell line and in primary chicken oviduct epithelial cells. From the 15 genes found to be overexpressed in both cell types, we characterized the antimicrobial peptide resistance (AMPR) genes, virK and ybjX, in vitro and in vivo. In vitro, AMPR genes were required for natural morphology, motility, secretion, defense against detergents such as EDTA and bile salts, and resistance to antimicrobial peptides polymyxin B and avian ␤-defensins. From this, we inferred the AMPR genes play a role in outer membrane stability and/or modulation. In the intestinal tract, AMPR genes were involved in early intestinal colonization and fecal shedding. In the reproductive tract, virK was required in early colonization whereas a deletion of ybjX caused prolonged ovary colonization and egg deposition. Data from the present study indicate that AMPR genes are differentially utilized in various host environments, which may ultimately assist S. Enteritidis in persistent and silent colonization of chickens.

Efficacy of Antibacterial Peptides Against Peptide-Resistant MRSA Is Restored by Permeabilization of Bacteria Membranes

“…The presence of Triton X-100 did not increase the bactericidal efficacy of melittin or mel12-26 against resistant bacteria. It is possible that outer surface modifications on resistant bacteria may reduce the cells’ sensitivity to other membrane permeabilizing agents, as shown in Salmonella enterica by McKelvey et al (2014).…”

Genetic Basis of Salmonella Enteritidis Pathogenesis in Chickens

“…In general, most studies have focused on the role of intrinsic bacterial structures such as type-1 fimbriae and LPS in avian RT infection. A few high-throughput screening studies have resulted in identification of genes that may play coordinated roles in RT infection in the hen and in egg microenvironments (Gantois et al, 2008a;McKelvey et al, 2014;Raspoet et al, 2014).…”

“…It was also reported that expression of specific stressresponse and cell membrane/wall genes might aid in survival and persistence of SE in oviduct and eggs, presumably by protecting bacteria against cell membrane and DNA damage (Raspoet et al, 2011(Raspoet et al, , 2014. A high-throughput screening strategy that involved microarray-based selective capture of transcribed sequences identified several genes that were overrepresented in both COECs and avian macrophages (HD-11) (McKelvey et al, 2014). Five SPI-2 genes (all belonging to the ssa operon) were overrepresented, suggesting a potential role for SPI-2 in survival within COEC and HD-11.…”

“…Five SPI-2 genes (all belonging to the ssa operon) were overrepresented, suggesting a potential role for SPI-2 in survival within COEC and HD-11. Overall, published reports suggest that efficient invasion of COEC and survival within HD-11 could, in part, be attributed to SPI-2 (Bohez et al, 2008;Li et al, 2009;McKelvey et al, 2014). Another high-throughput negative selection screening of a transposon-inserted mutant library identified 81 genes that impacted SE colonization of hen oviduct loops and cultured chicken oviduct tubular gland cells (Raspoet et al, 2014).…”

Antimicrobial Peptides: Potential Application in Liver Cancer

“…They are constitutively or inducibly expressed in various tissues and organs that are constantly exposed to microbial pathogens (Huttner and Bevins, 1999), such as epithelial cells of skin and the gastrointestinal and respiratory tracts. AMPs possess broad-spectrum antimicrobial activities against bacteria, fungi, protozoa, and viruses (Ganz, 2003), and their application for treating multiple-drug resistant (MDR) pathogens are well-studied (McKelvey et al, 2014; Zhao et al, 2014; Yang et al, 2015; Maitz et al, 2018).…”