| Autor: |
Clemans, Daniel L., Marrs, Carl F., Patel, Mayuri, Duncan, Michelle, Gilsdorf, Janet R. |
| Zdroj: |
Infection and Immunity; February 1998, Vol. 66 Issue: 2 p656-663, 8p |
| Abstrakt: |
ABSTRACTAdherence of Haemophilus influenzaeto epithelial cells plays a central role in colonization and is the first step in infection with this organism. Pili, which are large polymorphic surface proteins, have been shown to mediate the binding of H. influenzaeto cells of the human respiratory tract. Earlier experiments have demonstrated that the major epitopes of H. influenzaepili are highly conformational and immunologically heterogenous; their subunit pilins are, however, immunologically homogenous. To define the extent of structural variation in pilins, which polymerize to form pili, the pilin genes (hifA) of 26 type a to f and 16 nontypeable strains of H. influenzaewere amplified by PCR and subjected to restriction fragment length polymorphism (RFLP) analysis with AluI and RsaI. Six different RFLP patterns were identified. Four further RFLP patterns were identified from published hifAsequences from five nontypeableH. influenzaestrains. Two patterns contained only nontypeable isolates; one of these contained H. influenzaebiotype aegyptius strains F3031 and F3037. Another pattern contained predominantly H. influenzaetype f strains. All other patterns were displayed by a variety of capsular and noncapsular types. Sequence analysis of selected hifAgenes confirmed the 10 RFLP patterns and showed strong identity among representatives displaying the same RFLP patterns. In addition, the immunologic reactivity of pili with antipilus antisera correlated with the groupings of strains based on hifARFLP patterns. Those strains that show greater reactivity with antiserum directed againstH. influenzaetype b strain M43 pili tend to fall into one RFLP pattern (pattern 3); while those strains that show equal or greater reactivity with antiserum directed against H. influenzaetype b strain Eagan pili tend to fall in a different RFLP pattern (pattern 1). Sequence analysis of representative HifA pilins from typeable and nontypeable H. influenzaeidentified several highly conserved regions that play a role in bacterial pilus assembly and other regions with considerable amino acid heterogeneity. These regions of HifA amino acid sequence heterogeneity may explain the immunologic diversity seen in intact pili. |
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