Expanding the Landscape of Amino Acid-Rich Antimicrobial Peptides: Definition, Deployment in Nature, Implications for Peptide Design and Therapeutic Potential.

Unlike the α-helical and ß-sheet antimicrobial peptides (AMPs), our knowledge on amino acid-rich AMPs is limited. This article conducts a systematic study of rich AMPs (>25%) from different life kingdoms based on the Antimicrobial Peptide Database (APD) using the program R. Of 3425 peptides, 724 rich AMPs were identified. Rich AMPs are more common in animals and bacteria than in plants. In different animal classes, a unique set of rich AMPs is deployed. While histidine, proline, and arginine-rich AMPs are abundant in mammals, alanine, glycine, and leucine-rich AMPs are common in amphibians. Ten amino acids (Ala, Cys, Gly, His, Ile, Lys, Leu, Pro, Arg, and Val) are frequently observed in rich AMPs, seven (Asp, Glu, Phe, Ser, Thr, Trp, and Tyr) are occasionally observed, and three (Met, Asn, and Gln) were not yet found. Leucine is much more frequent in forming rich AMPs than either valine or isoleucine. To date, no natural AMPs are simultaneously rich in leucine and lysine, while proline, tryptophan, and cysteine-rich peptides can simultaneously be rich in arginine. These findings can be utilized to guide peptide design. Since multiple candidates are potent against antibiotic-resistant bacteria, rich AMPs stand out as promising future antibiotics.

Ginsenoside Rg3 reduces the adhesion, invasion, and intracellular survival of Salmonella enterica serovar Typhimurium.

BACKGROUND: Invasive infections due to foodborne pathogens, including Salmonella enterica serovar Typhimurium, are prevalent and life-threatening. This study aimed to evaluate the effects of ginsenoside Rg3 (Rg3) on the adhesion, invasion, and intracellular survival of S. Typhimurium. METHODS: The impacts of Rg3 on bacterial growth and host cell viability were determined using the time kill and the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide assays, respectively. Gentamicin assay and confocal microscopic examination were undertaken to determine the effects of Rg3 on the adhesive and invasive abilities of S. Typhimurium to Caco-2 and RAW 264.7 cells. Quantitative reverse transcription polymerase chain reaction was performed to assess the expression of genes correlated with the adhesion, invasion, and virulence of S. Typhimurium. RESULTS: Subinhibitory concentrations of Rg3 significantly reduced (p < 0.05) the adhesion, invasion, and intracellular survival of S. Typhimurium. Rg3 considerably reduced (p < 0.05) the bacterial motility as well as the release of nitrite from infected macrophages in a concentration-dependent manner. The expression of genes related to the adhesion, invasion, quorum sensing, and virulence of S. Typhimurium including cheY, hilA, OmpD, PrgK, rsgE, SdiA, and SipB was significantly reduced after Rg3 treatment. Besides, the compound downregulated rac-1 and Cdc-42 that are essential for actin remodeling and membrane ruffling, thereby facilitating Salmonella entry into host cells. This report is the first to describe the effects of Rg3 on "trigger" entry mechanism and intracellular survival S. Typhimurium. CONCLUSION: Rg3 could be considered as a supplement agent to prevent S. Typhimurium infection.

Knowledge, attitudes and practices towards rabies: questionnaire survey in rural household heads of Gondar Zuria District, Ethiopia.

BACKGROUND: Rabies is a fatal animal disease of significant public health importance. Domestic dogs are the main reservoir and transmitter of this disease particularly in developing countries. Even though rabies is a highly fatal disease, it is a preventable disease. Community awareness about rabies is one of the key components for prevention. This study describes the knowledge, attitudes and practices of a rural community in Gondar Zuria District, Ethiopia. METHODS: A cross sectional study was conducted from March to June, 2013. A structured questionnaire was used to collect the data through face to face interviews among 400 respondents. The data were then analyzed using SPSS statistical software version 20. RESULTS: The current study indicated that almost all (99.3%) of the surveyed individuals were aware of the disease rabies. Rabies is considered to be a fatal disease in humans by 67.8% of the respondents while 27.8% believe that it is a treatable disease. Dogs were indicated as source of infection for humans by all respondents followed by equines (27.2%) and cats (12.1%). Bite was known as mode of rabies transmission by majority of the respondents (94%) while other means were given less weight. Aggression was described as a major clinical sign of rabies in animals. Consumption of cooked or boiled meat from rabid animals was considered as safe by 67.0% of the respondents and about 19% replied even raw meat is safe for human consumption. The need for immediate treatment after exposure was mentioned by less than half (47.4%) of the respondents and only 38.8% of the respondents considered modern medicine as appropriate treatment after exposure to rabid animals. Nearly 42% of respondents had experienced a dog bite. Following the dog bites, only 30.7% practiced washing of the wounds with water as first aid. CONCLUSION: Rabies was found to be well known in the study area. However, knowledge and practices in prevention of rabies were limited. Education of rabies about possible sources of infection, mode of transmission and measures to be taken after exposure is very important in the study area.