title: Gene expression profiling of Cecropin B-resistant Haemophilus parasuis.
abstract: Synthetically designed antimicrobial peptides (AMPs) present the potential of replacing antibiotics in the treatment of bacterial infections. However, microbial resistance to AMPs has been reported and little is known regarding the underlying mechanism of such resistance. The naturally occurring AMP cecropin B (CB) disrupts the anionic cell membranes of Gram-negative bacteria. In this study, CB resistance (CBR) was induced in Haemophilusparasuis SH0165 by exposing it to a series of CB concentrations. The CB-resistant H.parasuis strains CBR30 and CBR30-50 were obtained. The growth curves of SH0165 and CBR30 showed that CBR30 displayed lower growth rates than SH0165. The result of transmission electron microscopy showed cell membranes of the CB-resistant CBR30 and CBR30-50 were smoother than SH0165. Microarrays detected 257 upregulated and 254 downregulated genes covering 20 clusters of orthologous groups (COGs) of the CB-resistant CBR30 compared with SH0165 (>1.5-fold change, p < 0.05). Sixty genes were affected in CBR30-50 covering 18 COGs, with 28 upregulated and 32 downregulated genes. Under the COG function classification, the majority of affected genes in the CB-resistant CBR30 and CBR30-50 belong to the category of inorganic ion transport, amino acid transport, and metabolism. The microarray results were validated by real-time quantitative reverse transcription PCR. This study may provide useful guidance for understanding the molecular mechanism underlying H.parasuis resistance to CB.
authors.affiliation: State Key Laboratory of Agricultural Microbiology, Division of Animal Infectious Disease, Huazhong Agricultural University, Wuhan, PR China.
authors.forename: Chunmei
authors.initials: C
authors.lastname: Wang
authors.forename: Fangzhou
authors.initials: F
authors.lastname: Chen
authors.forename: Han
authors.initials: H
authors.lastname: Hu
authors.forename: Wentao
authors.initials: W
authors.lastname: Li
authors.forename: Yang
authors.initials: Y
authors.lastname: Wang
authors.forename: Pin
authors.initials: P
authors.lastname: Chen
authors.forename: Yingyu
authors.initials: Y
authors.lastname: Liu
authors.forename: Xugang
authors.initials: X
authors.lastname: Ku
authors.forename: Qigai
authors.initials: Q
authors.lastname: He
authors.forename: Huanchun
authors.initials: H
authors.lastname: Chen
authors.forename: Feiqun
authors.initials: F
authors.lastname: Xue
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002462:Cell Membrane / Q000648:ultrastructure; D024881:Drug Resistance, Bacterial; D020869:Gene Expression Profiling; D044137:Haemophilus parasuis / Q000187:drug effects* / Q000235:genetics* / Q000254:growth & development / Q000648:ultrastructure; D019476:Insect Proteins / Q000494:pharmacology*; D046228:Microarray Analysis; D046529:Microscopy, Electron, Transmission; D009154:Mutation; D020411:Oligonucleotide Array Sequence Analysis; D060888:Real-Time Polymerase Chain Reaction
chemical_list: D000900:Anti-Bacterial Agents; D019476:Insect Proteins; C031162:cecropin B protein, Insecta