Swine leukocyte antigens play indispensable roles in immune responses by recognizing a large numberof foreign antigens and thus, their genetic diversity plays a critical role in their functions. in this study, we developed a new high-resolution typing method for pig SLA-1 and successfully typed 307 individuals from diverse genetic backgrounds including 11 pure breeds, 1 cross bred, and 12 cell lines. We identified a total of 52 alleles including 18 novel alleles and 9 SLA-1 duplication haplotypes, including 4 new haplotypes. We observed significant differences in the distribution of SLA-1 alleles among the different pig breeds, including the breed specific alleles. SLA-1 duplication was observed in 33% of the chromosomes and was especially high in the biomedical model breeds such as SNU (100%) and NIH (76%) miniature pigs. Our analysis showed that SLA-1 duplication is associated with the increased level of SLA-1 mRnA expression in porcine cells compared to that of the single copy haplotype. therefore, we provide here the results of the most extensive genetic analysis on pig SLA-1. open Scientific RepoRtS | (2020) 10:743 | https://doi.org/10.1038/s41598-020-57712-5www.nature.com/scientificreports www.nature.com/scientificreports/ SLA-1, SLA-2, and SLA-3 are constitutively expressed classical MHC class I genes, but their expression may vary depending on the genetic differences. For example, SLA-1 is duplicated in the haplotypes Hp-2.0, Hp-8.0, Hp-11.0, Hp-12.0, Hp-19.0, Hp-20.0, and Hp-27.0 14,24-26 . In addition, SLA-1, 3, and 6 were not expressed in the haplotypes Hp-3.0, Hp-2.0, and Hp-5.0, respectively 24 . Recently, a method was reported to estimate the copy number of SLA-1 and to facilitate our understanding on the functional aspect of SLA-1 duplication 27 . The frequency of SLA-1 duplication could be abundant, but the detailed functional analysis is not been available.Therefore, we developed a genomic DNA based high resolution SLA-1 typing method with high accuracy regardless of CNVs and present the extensive analysis results of SLA-1 diversity including new alleles and haplotypes, and allelic distribution among different breeds. We also analyzed the level of SLA-1 expression in pig cells according to their copy numbers which could affect MHC class I-specific immune responses. The information presented in this study should contribute to improving our understanding on the genetic polymorphisms of SLA-1 in diverse pig breeds. ResultsDetermination of the SLA-1 specific region. To develop a genomic DNA-based typing method of SLA-1, the determination of conserved locus specific region to design SLA-1 specific primers is required. We previously reported the locus specific nucleotide sequence variations at the downstream promoter region from six classical SLA class I-related genes including . Here, we extended the results by incorporating genomic sequences from additional cloning and sequence analysis. As a result, we identified a SLA-1 specific motif between the TATA box and the CAP site in the 5ʹ UTR and designe...

Porcine protegrin-1 (PG-1) is a broad-spectrum antimicrobial peptide (AMP) with potent antimicrobial activities. We produced recombinant PG-1 and evaluated its cytotoxicity toward various types of mammalian cell lines, including embryonic fibroblasts, retinal cells, embryonic kidney cells, neuroblastoma cells, alveolar macrophage cells, and neutrophils. The sensitivity of the different mammalian cells to cytotoxic damage induced by PG-1 differed significantly among the cell types, with retinal neuron cells and neutrophils being the most significantly affected. A circular dichroism analysis showed there was a precise correlation between conformational changes in PG-1 and the magnitude of cytotoxicity among the various cell type. Subsequently, a green fluorescent protein (GFP) penetration assay using positively charged GFPs indicated there was a close correlation between the degree of penetration of charged GFP into cells and the magnitude of PG-1 cytotoxicity. Furthermore, we also showed that inhibition of the synthesis of anionic sulphated proteoglycans on the cell surface decreases the cytotoxic damage induced by PG-1 treatment. Taken together, the observed cytotoxicity of PG-1 towards different membrane surfaces is highly driven by the membrane’s anionic properties. Our results reveal a possible mechanism underlying cell-type dependent differences in cytotoxicity of AMPs, such as PG-1, toward mammalian cells.

In this study, we sought to identify novel antimicrobial peptides (AMPs) in through bioinformatic analyses of publicly available genome information and experimental validation. In our analysis of the python genome, we identified 29 AMP-related candidate sequences. Of these, we selected five cathelicidin-like sequences and subjected them to further analyses. The results showed that these sequences likely have antimicrobial activity. The sequences were named Pb-CATH1 to Pb-CATH5 according to their sequence similarity to previously reported snake cathelicidins. We predicted their molecular structure and then chemically synthesized the mature peptide for three putative cathelicidins and subjected them to biological activity tests. Interestingly, all three peptides showed potent antimicrobial effects against Gram-negative bacteria but very weak activity against Gram-positive bacteria. Remarkably, ΔPb-CATH4 showed potent activity against antibiotic-resistant clinical isolates and also was observed to possess very low hemolytic activity and cytotoxicity. ΔPb-CATH4 also showed considerable serum stability. Electron microscopic analysis indicated that ΔPb-CATH4 exerts its effects via toroidal pore preformation. Structural comparison of the cathelicidins identified in this study to previously reported ones revealed that these Pb-CATHs are representatives of a new group of reptilian cathelicidins lacking the acidic connecting domain. Furthermore, Pb-CATH4 possesses a completely different mature peptide sequence from those of previously described reptilian cathelicidins. These new AMPs may be candidates for the development of alternatives to or complements of antibiotics to control multidrug-resistant pathogens.

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The availability of simple, robust, and cost-effective methods for the large-scale production of bacteriotoxic peptides such as antimicrobial peptides (AMPs) is essential for basic and pharmaceutical research. However, the production of bacteriotoxic proteins has been difficult due to a high degree of toxicity in bacteria and proteolytic degradation. In this study, we inserted AMPs into the Green fluorescent protein (GFP) in a loop region and expressed them as insoluble proteins in high yield, circumventing the inherent toxicity of AMP production in Escherichia coli. The AMPs inserted were released by cyanogen bromide and purified by chromatography. We showed that highly potent AMPs such as Protegrin-1, PMAP-36, Buforin-2, and Bactridin-1 are produced in high yields and produced AMPs showed similar activities compared to chemically synthesized AMPs. We increased the yield more than two-fold by inserting three copies of Protegrin-1 in the GFP scaffold. The immunogold electron micrographs showed that the expressed Protegrin-1 in the GFP scaffold forms large and small size aggregates in the core region of the inclusion body and become entirely nonfunctional, therefore not influencing the proliferation of E. coli. Our novel method will be applicable for diverse bacteriotoxic peptides which can be exploited in biomedical and pharmaceutical researches.