Geluk F, Eijk P P, van Ham S M, Jansen H M, van Alphen L
Department of Medical Microbiology, Academic Medical Center, Amsterdam, The Netherlands.
Infect Immun. 1998 Feb;66(2):406-17. doi: 10.1128/IAI.66.2.406-417.1998.
The occurrence of fimbria gene clusters in nonencapsulated Haemophilus influenzae strains from chronic bronchitis patients (n = 58), patients with acute otitis media (n = 13), and healthy carriers (n = 12) was determined by DNA hybridization and PCR, based on sequences of fimbriate H. influenzae type b. Although an average of 18% of all nonencapsulated strains had a fimbria gene cluster consisting of hifA to hifE inserted in the chromosome between purE and pepN, differences in the frequency of fimbria cluster-positive strains were observed, depending on the source of isolates. The compositions of the fimbria gene clusters of seven strains from chronic bronchitis patients and one strain from an otitis media patient were analyzed in more detail. After enrichment for fimbria expression, the promoter of the gene cluster contained 10 TA repeats (n = 2), leading to optimal positioning between the -10 and -35 promoter regions. The promoter regions of five fimbria-negative strains were sequenced; four were found to have nine TA repeats, and one had only four TA repeats. The protein sequence of three ganglioside GM1-specific HifA adhesins consisted of conserved regions intermingled with regions of sequence diversity. hifA appeared to be flanked by intergenic regions that varied between strains and contained both direct and inverted DNA repeats. Since noncoding DNA between hifA and purE has not been found in H. influenzae type b, these DNA sequences are probably not essential for fimbria expression. An analysis of strains lacking the gene cluster revealed the presence of similar sequences in 13 of 15 strains from chronic bronchitis patients, 5 of 5 strains from otitis media patients, and 3 of 5 strains from healthy carriers. The lengths of these intergenic regions were the same for multiple isolates of strains obtained during persistent infections. The presence or absence and the composition of the fimbria gene cluster and other sequences between the flanking genes purE and pepN suggest that the fimbria gene cluster was originally contained on a mobile element.
基于b型有菌毛流感嗜血杆菌的序列，通过DNA杂交和聚合酶链反应（PCR），测定了慢性支气管炎患者（n = 58）、急性中耳炎患者（n = 13）和健康携带者（n = 12）中分离出的非包膜流感嗜血杆菌菌株菌毛基因簇的发生情况。尽管所有非包膜菌株平均有18%具有由hifA至hifE组成的菌毛基因簇，该基因簇插入在purE和pepN之间的染色体中，但根据分离株的来源，菌毛簇阳性菌株的频率存在差异。对来自慢性支气管炎患者的7株菌株和来自中耳炎患者的1株菌株的菌毛基因簇组成进行了更详细的分析。在富集菌毛表达后，基因簇的启动子含有10个TA重复序列（n = 2），从而使其在 -10和 -35启动子区域之间实现最佳定位。对5株菌毛阴性菌株的启动子区域进行了测序；发现4株有9个TA重复序列，1株只有4个TA重复序列。三种神经节苷脂GM1特异性HifA黏附素的蛋白质序列由保守区域与序列多样性区域相间组成。hifA似乎两侧是菌株间不同的基因间区域，且包含正向和反向DNA重复序列。由于在b型流感嗜血杆菌中未发现hifA和purE之间的非编码DNA，这些DNA序列可能对菌毛表达并非必不可少。对缺乏该基因簇的菌株进行分析发现，慢性支气管炎患者的15株菌株中有13株、中耳炎患者的5株菌株中有5株以及健康携带者的5株菌株中有3株存在相似序列。在持续性感染期间获得的菌株的多个分离株中，这些基因间区域的长度相同。菌毛基因簇的存在与否及其组成以及侧翼基因purE和pepN之间的其他序列表明，菌毛基因簇最初包含在一个可移动元件上。
