Antimicrobial peptide hybrid fluorescent protein based sensor array discriminate ten most frequent clinic isolates.

Antimicrobial peptides killed bacteria through intercalating into the bacterial membrane. Their antimicrobial efficiencies varied in bacterial species and were affected by ion strength in the culture medium. A recombinant IGP protein consisted of an antimicrobial peptide, Ib-AMP4 fused with the Green Fluorescent Protein was expressed from E. coli cells and was found to maintain the antimicrobial activity. We demonstrated the interaction between the lipid membranes with IGP by quartz crystal microbalance with dissipation and tried to elucidate the effect of calcium ions by lipopolysaccharide monolayer surface isotherm assays. Ten most frequent clinic isolates were subjected to IGP incubation in buffers containing different calcium ion concentrations. The yielded fluorescent intensities ranging from several thousand to several million, differed greatly between species allowing big coefficient of variances that rendered this method a superior reproducibility and resolution. The classification and data treatment were performed by pattern identification with linear discriminant analysis. Seventy-nine isolates of the 10 most frequent clinic species were classified in the blind test with accuracy >70% by a single measurement and with a 100% accuracy by combined measurements for each species. In conclusion, the concept is based on a solid fact that antimicrobial proteins inhibit bacterial growth at a constant minimal inhibitory concentration through intercalating into the biomembrane. The developed method has a good resolution and high-faulty tolerance rate in discriminating bacteria.

Effective inhibition of human cytomegalovirus UL148 gene expression by external guide sequences in vitro / 中华实验和临床病毒学杂志

Objective@#To investigate the UL148 gene function of human cytomegalovirus (HCMV) low passage clinic isolate and new strategies for anti-HCMV treatment, the DNA-based external guide sequences (EGSs) were designed to inhibit UL148 RNA expression.@*Methods@#UL148 RNA secondary structure was analyzed by RNA structure technique, an appropriate region was chosen for DNA-based EGS57 synthesis, targeted the UL148 RNA. The M1RNA and UL148 RNA were generated by PCR for transcription in vitro. The UL148 RNA and M1RNA were transcribed in vitro under the function of T7 RNA polymerase. The UL148 was labelled by 32P. The cleavage reactions were carried out by mixing up EGS, M1RNA with UL148 RNA for 1 h. The products were separated by urea denaturing polyacrylamide gel electrophoresis and detected with Typhoon Phosphor Imager.@*Results@#UL148 RNA ranged from 58 to 72 sites was the binding position, and 57 was a cleavage site. EGS57 was designed and synthesized. EGS57 was combined with UL148 RNA to form the natural substrate of M1RNA. UL148 RNA and M1RNA were synthesized through T7 RNA polymerase catalyzing, and the products were conformed. After cleaving reactions, DNA-based EGS57 was shown to be able to cleave UL148 RNA efficiently in vitro by a complex with M1RNA.@*Conclusions@#UL148 RNA was cleaved efficiently by EGS57, and the cleaving site was conformed as expectation. It will provide the gene silent tool effectively for further study the function of UL148 gene.