title: Effect in virulence of switching conserved homologous capsular polysaccharide genes from Klebsiella pneumoniae serotype K1 into K20.
abstract: The capsular polysaccharides in different serotypes of Klebsiella pneumoniae (KP) coded by the (CPS) gene cluster are characterized by a conserved and a hyper-variable region. We performed a virulence study by switching genes in the highly conserved region of the CPS cluster between strains. Six genes in the CPS conserved region in serotype K20, including galF, acidPPc, wzi, wza, wzb and wzc, were knocked out and replaced by the homologous genes from serotype K1. Compared to the parental K20 strain, the mutants showed a decline in lethality (LD50) in mice from 10-fold to > 105-fold and were categorized in terms of the effect on virulence as low (L) for galF and acidPPC, moderate (M) for wzi, and high (H) for wza, wzb and wzc. Although substituting the acidPPC gene from K1 for acidPPC in the K20 strain fully restored virulence, substitution with the wzi, wza, wzb or wzc homologs from K1 did not. The restoration with wzi from K1 led to a partial restoration of virulence, with the LD50in mice changing from 104to 103CFU.For the wza, wzb and wzc genes, Complementation of K20 wza, wzb and wzc from K1 resulted in varied degrees of lethality in mice. Variable improvement in serum killing and phagocytosis was observed when the knockout mutants were compared with the gene-switched strains. In conclusion, homologous genes for capsule synthesis failed to exhibit the same functionality when switched between serotypes and virulence was decreased in different degree in according to the genes' homology.
authors: a School of Respiratory Therapy , College of Medicine, Taipei Medical University , New Taipei City , Taiwan.|b Division of Pulmonary Medicine, Department of Internal Medicine , Shuang Ho Hospital, Taipei Medical University , New Taipei City , Taiwan.
authors: Chii-Lan
authors: CL
authors: Lin
authors: c Division of Infectious Diseases and Tropical Medicine, Department of Internal Medicine , Tri-Service General Hospital, National Defense Medical Center , Taipei , Taiwan.
authors: Fei-Hsu
authors: FH
authors: Chen
authors: d National Institute of Infectious Diseases and Vaccinology , National Health Research Institutes , Miaoli , Taiwan.
authors: Li-Yueh
authors: LY
authors: Huang
authors: d National Institute of Infectious Diseases and Vaccinology , National Health Research Institutes , Miaoli , Taiwan.
authors: Jen-Chang
authors: JC
authors: Chang
authors: e Department of Medical Laboratory Science and Biotechnology , Yuanpei University , Hsinchu , Taiwan.
authors: Jiun-Han
authors: JH
authors: Chen
authors: d National Institute of Infectious Diseases and Vaccinology , National Health Research Institutes , Miaoli , Taiwan.
authors: Yu-Kuo
authors: YK
authors: Tsai
authors: c Division of Infectious Diseases and Tropical Medicine, Department of Internal Medicine , Tri-Service General Hospital, National Defense Medical Center , Taipei , Taiwan.
authors: Feng-Yee
authors: FY
authors: Chang
authors: c Division of Infectious Diseases and Tropical Medicine, Department of Internal Medicine , Tri-Service General Hospital, National Defense Medical Center , Taipei , Taiwan.
authors: Jung-Chung
authors: JC
authors: Lin
authors: c Division of Infectious Diseases and Tropical Medicine, Department of Internal Medicine , Tri-Service General Hospital, National Defense Medical Center , Taipei , Taiwan.|d National Institute of Infectious Diseases and Vaccinology , National Health Research Institutes , Miaoli , Taiwan.|f PhD Program for Aging , College of Medicine, China Medical University , Taichung , Taiwan.
authors: L Kristopher
authors: LK
authors: Siu
mesh_terms: D000818:Animals; D016667:Bacterial Capsules / Q000235:genetics*; D001426:Bacterial Proteins / Q000235:genetics; D055786:Gene Knockout Techniques; D005816:Genetic Complementation Test; D007710:Klebsiella Infections / Q000382:microbiology; D007711:Klebsiella pneumoniae / Q000145:classification / Q000235:genetics* / Q000472:pathogenicity*; D007928:Lethal Dose 50; D008100:Liver Abscess / Q000382:microbiology; D051379:Mice; D005810:Multigene Family; D009154:Mutation; D011135:Polysaccharides, Bacterial / Q000235:genetics*; D065288:Serogroup; D014774:Virulence; D037521:Virulence Factors / Q000235:genetics*
chemical_list: D001426:Bacterial Proteins; D011135:Polysaccharides, Bacterial; D037521:Virulence Factors
keywords: Klebsiella pneumoniae; capsule and virulence; liver abscess