Cell-selectivity of tryptophan and tyrosine in amphiphilic α-helical antimicrobial peptides against drug-resistant bacteria.

The increasing emergence of drug-resistant bacteria creates a requirement for new antibiotics and various types of antibiotic materials such as proteins, peptides, polymers, and chemical compounds. Among these, antimicrobial peptides (AMPs) are considered to be promising antibiotic candidates for clinical treatments. In this study, we have designed a novel series of peptides with repeated sequences of minimum membrane-active motif, 'XWZX' basic sequence (X: lysine or arginine, Z: leucine, tyrosine, valine, or glycine), and an α-helical secondary structure. Some peptides displayed a potent antibacterial activity via membranolytic action and high therapeutic index (toxic dose/minimum inhibitory concentration) in vitro. Furthermore, in vivo experiments using bacterial ear-skin infection models verified that these peptides have the potential to be powerful and safe antibiotics. The present study provides a lead sequence for designing peptide antibiotics against bacterial membranes and information for cell-selectivity of hydrophobic amino acids with aromatic side chains such as Trp and Tyr.

Effects of germanium biotite supplement on immune responses of vaccinated mini-pigs to foot-and-mouth disease virus challenge.

Since the outbreaks of foot-and-mouth disease (FMD) in South Korea in 2010-2011, a trivalent vaccine has been used as a routine vaccination. Despite the high efficacy of the trivalent vaccine, low antibody formation was reported in the pig industry and there is considerable concern about the ability of the vaccine to protect against the Andong strain responsible for recent outbreaks in South Korea. To overcome these problems, immunostimulators have been widely used to improve vaccine efficacy in South Korea, although without any scientific evidence. Based on the current situation, the aim of this study was to investigate the effects of germanium biotite, a feed supplement used to enhance the immune system, on the immune responses to FMD vaccination through the Andong strain challenge experiment in trivalent vaccinated pigs. Following the challenge, the germanium biotite-fed pigs showed high levels of IL-8 in serum, and increased cellular immune responses to stimulation with the Andong strain antigen compared to nonsupplemented pigs. In addition, higher FMD virus (FMDV) neutralizing antibody titers were detected in the germanium biotite-fed group than in the nonsupplemented group before the challenge. The findings of this study indicate that germanium biotite supplement might enhance immune responses to the FMD vaccine in pigs.

Supplementation of dietary germanium biotite enhances induction of the immune responses by foot-and-mouth disease vaccine in cattle.

BACKGROUND: After the recent outbreak of foot-and-mouth disease (FMD) in Korea, a vaccination policy has been applied to control the disease. In addition, several non-specific immune stimulators have been used without any scientific evidence that they would enhance the immune response after FMD vaccination and/or protect against FMD. Based on the current situation, the aim of this study was to evaluate the effect of the non-specific immune stimulator germanium biotite on FMD vaccination and immune responses in cattle. To achieve our goal, immune responses to FMD vaccination, such as levels of IgG and IgA, antibody duration, and virus-neutralizing titers were investigated after germanium biotite feeding. The PBMC typing and proliferative response after stimulation with mitogens, the cytokines expression level of PBMC, and the lysozyme activity in the serum were measured to evaluate the immune enhancing effects of germanium biotite following its administration. RESULTS: Following the first vaccination, high level of IgG (at 4 weeks) and IgA (at 2 and 31 weeks) titers in serum and saliva were observed in the germanium biotite-feeding group (p < 0.05). The germanium biotite group also showed high and longstanding inhibition percentage value in ELISA assay at 31 weeks (p < 0.05). Generally, higher virus-neutralizing antibody titers were observed in the feeding group at 20 and 31 weeks after vaccination. Following the feeding germanium biotite, the germanium biotite group showed increased subpopulation of CD4+ lymphocytes and MHC I+II+ cells in PBMCs at 23 week, responding to stimulation of ConA. The levels of IFN-γ (at 3 and 8 weeks), IL-1α (at 3, 11, and 23 weeks), IL-1ß (at 3, 8, and 11 weeks), and IL-4 (at 8 and 11 weeks) gene expression were also significantly increased in the feeding group (p < 0.01 and p < 0.05). Feeding with germanium biotite increased the lymphocytes' proliferative response to the stimulation of ConA and LPS at 23 weeks and lysozyme activity at 9 weeks after feeding. CONCLUSIONS: These results suggest that germanium biotite feeding could increase the protection against FMD virus infection via the induction of higher humoral and cellular immune responses in cattle.

Dietary germanium biotite supplementation enhances the induction of antibody responses to foot-and-mouth disease virus vaccine in pigs.

We evaluated the potential ability of germanium biotite (GB) to stimulate the production of antibodies specific for foot-and-mouth disease virus (FMDV). To this aim, we measured the total FMDV-specific antibody responses and IgM production after vaccination against FMD both experimentally and in the field. GB supplementation with FMDV vaccination stimulated the production of anti-FMDV antibodies, and effectively increased IFN-γ and TNF-α levels. These results suggest that GB may be a novel alternative feed supplement that can serve as a boosting agent and an immunostimulator for increasing the efficacy of FMDV vaccination in pigs.

Efficacy of thiolated eudragit microspheres as an oral vaccine delivery system to induce mucosal immunity against enterotoxigenic Escherichia coli in mice.

A vaccine delivery system based on thiolated eudragit microsphere (TEMS) was studied in vivo for its ability to elicit mucosal immunity against enterotoxigenic Escherichia coli (ETEC). Groups of mice were orally immunized with F4 or F18 fimbriae of ETEC and F4 or F18 loaded in TEMS. Mice that were orally administered with F4 or F18 loaded TEMS showed higher antigen-specific IgG antibody responses in serum and antigen-specific IgA in saliva and feces than mice that were immunized with antigens only. In addition, oral vaccination of F4 or F18 loaded TEMS resulted in higher numbers of IgG and IgA antigen-specific antibody secreting cells in the spleen, lamina propria, and Peyer's patches of immunized mice than other groups. Moreover, TEMS administration loaded with F4 or F18 induced mixed Th1 and Th2 type responses based on similarly increased levels of IgG1 and IgG2a. These results suggest that F4 or F18 loaded TEMS may be a promising candidate for an oral vaccine delivery system to elicit systemic and mucosal immunity against ETEC.