The invention provides an antibacterial peptide and application thereof. A sequence of the antibacterial peptide is Gly-Leu-Leu-Trp-Arg-Lys-Cys-Cys-Arg-Arg-Lys-Lys. The antibacterial peptide uses a nature-derived antibacterial peptide which does not cause drug resistance of a human body easily, and can prevent and control initial adherent bacteria formed by oral biomembranes and inhibit formationof biomembranes of pathogenic microorganisms in a window period of tissue recovery after a non-medicine therapy by interfering the basic condition of forming biomembranes to achieve the purposes of prevent and control infectious diseases.

Bovine viral diarrhea virus is divided into two genotypes:genotype 1 (BVDV-1) and genotype 2 (BVDV-2).Previous epidemiological survey showed BVDV-1 isolates distributed more widely.However,the mobidity rate of BVDV-2 is increasing in recent years.In general,BVDV-2 infection can cause more severe disease characterized by acute infection and haemorrhagic syndrome,causing enormous losses to the cattle industry.In this review,we dilate on the following aspects:the establishment of the specific detection and genotyping methods of BVDV-2,the isolation and identification of BVDV-2,complete genomic sequencing and phylogenetic analyzation of BVDV-2 isolates,and the establishment of detection platform to virus and antibody of BVDV-1 and BVDV-2.

In this study, we constructed for the first time a full-length cDNA clone of pig-original bovine viral diarrhea virus 2 (BVDV-2) strain SH-28, modified the cDNA clone (pASH28) for mutant pASHΔNpro and derived virus strain vASHΔNpro by deleting the genomic region encoding the Npro polypeptide, and examined significance of protein Npro for antiviral responses in vitro. Data showed that Npro-deletion mutant virus vASHΔNpro led to significant overexpression of oligo adenylate synthetase (OAS), myxovirus-resistant protein 1 (Mx1), and ubiquitin-like protein 15 (ISG15). Data also revealed that overexpression of Npro, but not NS2 and NS3 proteins, resulted in significant down-regulation of OAS, Mx1, and ISG15 production (p ≤ 0.05) in bovine cells as well as porcine cells transfected with Npro recombinant eukaryotic expression plasmids. Npro (but not NS2 and NS3) was also found to inhibit poly(IC) from inducing production of type I interferon (IFN-I). These results indicated that protein Npro may play multiple roles in regulating antiviral response in host cells interfered by pig BVDV-2 strain, and provided useful information to understand better the mechanism of BVDV-2 persistent infection in pigs.

The aim of this study was to elucidate the biological phenotypes of 16S rRNA methylase RmtB in Escherichia coli and the impact of RmtB acquisition on the fitness of the target bacterium. An rmtB in-frame deletion mutant in E. coli was constructed using a suicide vector (pDMS197)-based double crossover allelic exchange, and its corresponding complemented strain was established. Combined studies of microdilution susceptibility testing, conjugation experiments, growth kinetics assays, competitive experiments, biofilm formation tests and motility assays were performed to study the rmtB-mediated fitness among the prototype E. coli strain, its isogenic mutant and the corresponding complemented strain. The minimum inhibitory concentrations (MICs) of 4,6-disubstituted 2-deoxystreptamines for the rmtB wild-type strain, its isogenic mutant and the complemented strain were ≥1024, ≤2 and ≥1024 mg/L, respectively. Both the growth rates and the competitive abilities of the wild-type and complemented strains were relatively inferior to the ΔrmtB mutant. There was no significant difference in biofilm formation and motility among the three strains. In conclusion, the data presented here suggest that acquisition of the 16S rRNA methylase gene rmtB in E. coli can exact a fitness cost on the bacteria, subsequently reducing the growth rate slightly and decreasing the competitive capacity of the bacterium, whereas it does not affect biofilm formation or motility.