Research on the procedure for recovery and species identification of Legionella from surface environmental water / 中华预防医学杂志

<p><b>OBJECTIVE</b>To establish a set of procedure for recovery and species identification of Legionella from the surface environmental water.</p><p><b>METHODS</b>Forty-four water samples were collected in eight parks of Guangzhou city from August to November in 2006. The bacteriologic examination was performed by cultivation on BCYEalpha plate, and 108 presumptive Legionella colonies were picked and their homogeneous relationship was analyzed by using an amplified fragment length polymorphism (AFLP) method. Species identification was carried out by latex agglutination test, biochemical characterization, analysis of cellular fatty acids composition, 16 S rRNA gene and mip gene sequencing.</p><p><b>RESULTS</b>Legionella was recovered among 27 (61.36%) samples of all eight parks, and 31 different strains were identified from those 108 presumptive Legionella isolates by AFLP method, including 20 strains of L. pneumophila, five strains of L. feeleii, four strains of L. longbeachae, one strain of L. oakridgensis and one strain of L. sainthelensi, and L. pneumophila could be easily differentiated by phenotypic and biochemical characteristics, latex agglutination test or analysis of the cellular fatty acids composition . However, uncertain factors were existing in those phenotypic identification methods as compared to the sequence analysis.</p><p><b>CONCLUSION</b>The taxonomic analysis of the Legionellae family should be dependent on the 16 S rRNA gene or mip gene.</p>

Epitope Tagging of the rpoS gene of Y. pestis by Recombineering Technique / 中国生物工程杂志

Objective: To facilitate the functional analysis of chromosomal genes and their products, the recombineering technique to epitope tagging of chromosomal genes of Y. pestis was adapted. Methods: The epitope tag was generated by primer annealing and then fused with resistance gene by fusion PCR. The epitope-resistance cassette was inserted into pBluecript, resulted in the template plasmid, pBS-MH. The tagging cassette for rpoS was obtained by PCR amplification from pBS-MH with primers containing homology specific to the target gene. PCR products were transformed into recombination competent cells and recombinants were selected. PCR and DNA sequencing were used to confirm the correct tagging event. The expression of the tagged protein was detected with Western blot by using monoclonal antibody to the epitope. Results: The template plasmid containing fusion of epitope and resistance gene was successfully constructed. The sigma factor gene, rpoS, was tagged with a myc-his tag at the COOH terminus. Expression of the tagged rpoS was successfully detected indirectly by the antibody against His tag. Conclusion: The chromosomal gene tagging by recombineering technique represents a powerful tool in the functional study of bacterial genes and their products.

Relationship between core promoter mutation, clinical features and virus replication in HBV carriers / 中华实验和临床病毒学杂志

<p><b>OBJECTIVE</b>To elucidate the relationship between HBV core promoter mutation and clinical features as well as its effects on serum e system and viral replication.</p><p><b>METHODS</b>Semi-nested mutation specific PCR (msPCR) was employed for detecting core promoter mutation at nt 1 762-1 764 in 97 patients with HBV infection.</p><p><b>RESULTS</b>The msPCR method was demonstrated to be specific and reliable for the mutation detection by sequencing the PCR products. The detection ratio of the mutation in patients with acute hepatitis, mild, moderate and severe chronic hepatitis and liver cirrhosis was 2/5, 7/43, 10/31, 1/3 and 7/15, respectively. The detection rate of the mutation in liver cirrhosis was significantly higher than that in light chronic hepatitis (P < 0.025). In 92 patients with chronic HBV infection, HBeAg positive rate in wild (25/92), mutant (42/92) and mixed (25/92) strain infection was 80.0%, 56.0% and 64.3%, HBV DNA level was (4.4 +/- 8.5) x 10(8), (1.1 +/- 1.6) x 10(9) and (1.4 +/- 1.8) x 10(9) copies/ml, the rate of abnormal ALT was 44.0%, 52.0% and 42.6%; ALT level was (58.6 +/- 79.0), (57.1 +/- 75.2) and (62.6 +/- 90.3) IU/L, respectively (P > 0.05).</p><p><b>CONCLUSIONS</b>The msPCR method for detecting core promoter mutation at nt 1 762-1 764 is specific and reliable. Core promoter mutation is associated with the severity of liver disease, but neither related to the status of e system in serum nor to the virus replication.</p>