Anti-parasitic activity of a chimeric peptide Cecropin A (2-8)-Melittin (6-9) (CM11) against tachyzoites of Toxoplasma gondii and the BALB/c mouse model of acute toxoplasmosis

Antibacterial mechanism and structure-activity relationships of Bombyx mori cecropin A

Bombyx mori cecropin A (Bmcecropin A) has antibacterial, antiviral, anti-filamentous fungal and tumour cell inhibition activities and is considered a potential succedaneum for antibiotics. We clarified the antibacterial mechanism and structure-activity relationships and then directed the structure-activity optimization of Bmcecropin A. Firstly, we found Bmcecropin A shows a strong binding force and permeability to cell membranes like a detergent; Bmcecropin A could competitively bind to the cell membrane with the cell membrane-specific dye DiI, then damaged the membrane for the access of DiI into the cytoplasm and leading to the leakage of electrolyte and proteins. Secondly, we found Bmcopropin A could also bind to and degrade DNA; furthermore, DNA library polymerase chain reaction (PCR) results indicated that Bmcecropin A inhibited DNA replication by non-specific binding. In addition, we have identified C-terminus amidation and serine-lysine- glycine (SLG) amino acids of Bmcecropin A played critical roles in the membrane damage and DNA degradation. Based on the above results, we designed a mutant of Bmcecropin A (E9 to H, D17 to K, K33 to A), which showed higher antibacterial activity, thermostability and pH stability than ampicillin but no haemolytic activity. Finally, we speculated that Bmcecropin A damaged the cell membrane through a carpet model and drew the schematic diagram of its antibacterial mechanism, based on the antibacterial mechanism and the three-dimensional configuration. These findings yield insights into the mechanism of antimicrobial peptide-pathogen interaction and beneficial for the development of new antibiotics.

Global prevalence of Toxoplasma gondii in birds: A systematic review and meta-analysis

Among the potential animal reservoirs of the zoonotic parasite T. gondii, birds have received relatively little attention. This systematic review and meta-analysis aimed to assess the global status and to provide an overview of the epidemiology of T. gondii infection in birds. The standard protocol of preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines were followed. Scopus, PubMed, Web of Science, Science Direct, ProQuest, and Google Scholar were searched for relevant publications from January 1990, to March 2024. All peer-reviewed original research articles describing the prevalence of T. gondii in birds were included. Inclusion and exclusion criteria were applied, and both direct and indirect detection were considered. The point estimates and 95% confidence intervals were calculated using the meta-package in R (version 3.6.1). The variance between studies (heterogeneity) was quantified by the I2 index. Finally, 258 articles (including 380 datasets) were eligible for inclusion in the systematic review and meta-analysis. The global pooled prevalence was 24% (21 - 26%). The highest prevalence of T. gondii was observed in buzzards (52%, 34 - 70%), turkeys (31%, 17 - 46%), and chickens (30%, 26 - 34%). The present study provides a comprehensive view of the global prevalence of T. gondii in birds.

Optimization of plasmid electrotransformation into Bacillus subtilis using an antibacterial peptide

Bacillus subtilis can potentially serve as an efficient expression host for biotechnology due to its ability to secrete extracellular proteins and enzymes directly into the culture medium. One of the important challenges in the biotechnology industry is to optimize the transformation conditions of B. subtilis bacteria. This study aims to provide a new method to optimize the transformation conditions and improve the transformation efficiency of B. subtilis WB600. To increase the transformation efficiency in B. subtilis, two methods of adding CM11 antibacterial peptides to the bacterial medium along with electroporation and optimizing the variables including the growth medium composition, time to adding CM11 peptide, electroporation voltage, recovery medium, and cell recovery time are used. The results of this study showed that the addition of antimicrobial peptides (AMPs) with a concentration of 2 μg/ml increases the transformation efficiency by 4 times compared to the absence of AMP in the bacterial medium. Additionally, the findings from our study indicated that the most optimal rate of transformation for B. subtilis was observed at a voltage of 7.5 kV/cm, with a recovery period of 12 h. With the optimized method, the transformation efficiency came up to 1.69 × 104 CFU/µg DNA. This improvement in transformation efficiency will be attributed to the research of expression of exogenous genes in B. subtilis, gene library construction for transformation of wild-type B. subtilis strains.