[Optimization of gene expression and purification of Legionella pneumophila peptidoglycan associated lipoprotein recombinant protein]

There are many problems with most of the available diagnostic tests used to diagnose Legionella pneumonia, including inadequate sensitivity and specificity, and inability to provide a result in a clinically useful time period. Legionella pneumophila PAL protein has been considred as a target for detecting of Legionella infection from urine specimen, because it is conserved sequence and is secreted into the urine. The aim of this study was to optimize expression and purification of L. pneumophila PAL protein. In this experimental study, optimizing of 5 parameters [cell density, induction time, growth temperature, IPTG concentration and type of medium] was performed. After expression, periplasmic extract was prepared and recombinant PAL protein purified using Ni2+-charged resin column. Finally, recombinant PAL protein was verified by Western blotting. In terrific broth medium, the optimum condition of r-PAL protein induction was occurred at an OD600 of 0.6, 1mM IPTG concentration and 15 hours incubation at 25°C Recombinant periplasmic PAL protein was highly purified [>80%] using Ni-NTA column. Western blotting analysis showed that recombinant PAL protein was also specifically recognized by anti-His6-peroxidase antibody. By purification of recombinant PAL protein in purity greater than 80% it can be used to evaluate its capacity in diagnosis of Legionella infection and preparation of diagnostic kit

[Study of the CagA gene prevalence in helicobacter pylori strains isolated from patients with upper gastrointestinal disorders in Iran]

Helicobacter pylori commonly is associated with gastritis: but only sometimes it causes clinically significant diseases such as gastric and duodenal ulcer. The development of disease depends on the virulence of the infecting H. pylori strain, the susceptibility of the host, and environment co-factors. The cytotoxin associated protein encoded by cagA gene is an important virulence factor that is produced by some H. pylori strains, and has been used as virulence marker in some populations. The aim of the study was to examine the prevalence of cagA gene in the isolated strains of H. pylori from patients with dyspeptic disease and to investigate the association of cagA gene and the severity of H. pylori related diseases in Iran. In this study, biopsy specimens were obtained from the antrum of 180 patients. After isolation of H. pylori and its DNA by standard methods, polymerase chain reaction [PCR] technique was used for detection of cagA bacterial gene. 92 out of the 180 patients had H. pylori strains. 70% were cagA gene positive. All patients with peptic ulcer [100%] and 44 out of 72 [61%] patients with non-ulcer dyspepsia were cagA positive [p<0.01]. There was significant difference in frequency of cagA gene in peptic ulcer disease and non-ulcer dyspepsia [p<0.01]. It showed that the risk of PUD in patients with cagA+ H. pylori infection may be higher than in those with cagA- H. pylori infection