Abstract

Backgroundβ-defensins have attracted considerable research interest because of their roles in protecting hosts from various pathogens. This study was conducted to investigate the expression profiles of the porcine β-defensin 114 (PBD114) in different breeds and in response to infections. Moreover, the function of PBD114 protein was partially investigated.MethodsSix Tibetan pigs (TP) and six DLY (Duroc×Landrace×Yorkshire) pigs were slaughtered to explore the expression profiles of PBD114 in different breeds and tissues. For infection models, sixteen DLY pigs were divided into two groups and challenged either with sterile saline or E. coli K88. The recombinant protein PBD114 (rPBD114) was obtained by using a heterologous expression system in E. coli.ResultsPBD114 gene was highly expressed in tissues such as the intestine, liver, spleen, and thymus. Interestingly, the expression level of PBD114 gene was higher in the TP pigs than in the DLY pigs (P < 0.05), and was significantly elevated upon E. coli K88 challenge (P < 0.05). The nucleotide sequences of PBD114 from Tibetan and DLY pigs was identical, and both showed a 210-bp open reading frame encoding a 69-amino acid mature peptide. To explaore the function of PBD114 protein, PBD114 gene was successfully expressed in E. coli Origami B (DE3) and the molecular weight of the rPBD114 was estimated by SDS-PAGE to be 25 kDa. The rPBD114 was purified and mass spectrometry verified the protein as PBD114. Importantly, rPBD114 showed antimicrobial activities against E. coli DH5α and E. coli K88, and the minimal inhibitory concentrations (MICs) were 64 and 128 μg/mL, respectively. Hemolytic and cytotoxicity assays showed that rPBD114 did not affect cell viability under physiological concentrations.ConclusionsPBD114 is an infection response gene that is differentially-expressed between different porcine breeds and tissues. The antimicrobial activity of PBD114 protein, against pathogens such as the E. coli K88, suggested that it may serve as a candidate for the substitution of conventionally used antibiotics.

Highlights

  • The availability of antibiotics for treating bacterial infections has significantly improved the health of animals and humans

  • The results showed that the expression levels of Porcine beta defensin 114 (PBD114) of Tibetan pigs (TP) pigs in jejunum, colon and lung were higher than DLY pigs (P < 0.05)

  • Diarrhea scores of K88 group were higher than CON group over 24 h except at 20 h (P < 0.05), and the results indicated that E. coli K88 challenged model was successful

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Summary

Introduction

The availability of antibiotics for treating bacterial infections has significantly improved the health of animals and humans. Liberal antibiotic use Innate immunity is the first line of host defense against invading pathogens such as bacteria, virus, and fungus. Previous studies have indicated that one of the primary innate immune responses are the secretion of antimicrobial peptides (AMPs) [3, 4]. HDPs are a family of low molecular weight peptides secreted by organisms, and can protect hosts from a broad range of pathogens including bacteria, virus and fungus [3,4,5]. The administration of HDPs is a potentially novel therapeutic strategy for inflammatory and infectious diseases of the gastrointestinal tract [7, 9], and may present a promising alternative to the traditional antibiotic feed additives used in the livestock industry

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