Nucleotide Sequence Analysis of the Legionella micdadei mip gene, Encoding a 30 Kilodalton Analog of the Legionella pneumophilia Mip Protein

After the demonstration of analogs of the Legionella pneumophila macrophage infectivity potentiator (Mip) protein in other Legionella species, the Legionella micdadei mip gene was cloned and expressed in Escherichia coli. DNA sequence analysis of the L. micdadei mip gene contained in the plasmid pBA6004 revealed a high degree of homology (71%) to the L. pneumophila mip gene, with the predicted secondary structures of the two Mip proteins following the same pattern. Southern hybridization experiments, with the plasmid pBA6004 as the probe, suggested that the mip gene of L. micdadei has extensive homology with the mip-like genes of several Legionella species. Furthermore, amino acid sequence comparisons revealed significant homology to two eukaryotic proteins with isomerase activity (FK506-binding proteins). The intracellular life-style of at least two Legionella spe-cies encountered in human infection, Legionella pneumo-phila and L. micdadei, is well established (13, 15, 16, 22, 25). When a human is the host organism, the bacteria are phagocytized by alveolar macrophages. Once inside, the bacteria prevent lysosome-phagosome fusion by a yet-un-known mechanism, thus evading one possible route o

Molecular characterization of isolates of Haemophilus paragallinarum from China by ribotyping

Ribotyping profiles were determined for 12 Page serovar A isolates of Haemophilus paragallinarum from five outbreaks of infectious coryza in Hebei province in the People's Republic of China. Four enzymes were used to generate restriction digests of chromosomal DNA: HaeIII, HindIII, HpaII and SspI. The digests were probed with a digoxigenin-11-dUTP-labelled DNA probe produced by PCR amplification of the 16S rDNA of the type strain of H. paragallinarum. Only one profile was seen among the 12 isolates when using either HindIII or SspI. Three different ribotype profiles were seen with HpaII, while four different profiles were detected with HaeIII. Cluster analysis of the profiles generated by HpaII and HaeIII corresponded with the known epidemiological history of the isolates. These results are the first molecular characterization of isolates of H. paragallinarum from China and confirm the existence of genetic diversity in the H. paragallinarum population in that country