首页 | 本学科首页   官方微博 | 高级检索  
     


Adaptation of Haemophilus influenzae to acquired and innate humoral immunity based on phase variation of lipopolysaccharide
Authors:Weiser J N  Pan N
Affiliation:Department of Pediatrics, University of Pennsylvania School of Medicine, Philadelphia 19104-6076, USA. weiser@mail.med.upenn.edu
Abstract:Phase variation in colony morphology has been associated with the pathogenesis of infection caused by Haemophilus influenzae. This study shows that differences in colony opacity in non-typeable H. influenzae (NTHi) strain H233 involve phase changes in the lipopolysaccharide (LPS) and depend on the expression of licl and lic2, which contain translational switches based on intragenic tandem repeats of 5'-CAAT-3'. Genetic analysis showed that opaque organisms have an out-of-frame number of repeats in both licl, required for the expression of phosphorylcholine (ChoP), and lic2, a putative galactosyl transferase that adds the terminal galactose on Galalpha1-4Gal. Defined variants in these loci were used to examine the contribution of individual LPS structures to resistance to serum bactericidal activity mediated by antibody and C-reactive protein (CRP). The addition of ChoP by licl was the only factor in serum killing involving CRP and complement. The terminal galactose moiety, in contrast, conferred resistance to killing by naturally acquired antibody and complement present in human serum. As Galalpha1-4Gal is also found on human glycolipids, it appears that decoration of the cell surface with this host-like antigen blocks antibody-mediated serum bactericidal activity. Genetic analysis of NTHi within the human respiratory tract demonstrated that Galalpha1-4Gal may not be expressed during carriage but may be advantageous for the organism in inflammatory states such as pneumonia.
Keywords:
本文献已被 PubMed 等数据库收录!
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号