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Assessment of a new DNA vaccine candidate against urinary tract infection

Abstract number: O152

Fallah Mehrabadi J., Hoseini Moghaddam M., Najafi S., Khoramabadi N., Mahdavi M.

Objective: Urinary Tract Infection (UTI) is one of the most common infectious diseases and the major agent of UTI is Uropathogenic Escherichia coli (UPEC). Most of the time, it has affinity to attached to the vaginal and urinary tract mucosa tissue. UPEC has intracellular propagation, when do invasion of bladder epithelial cells. Therefore, cellular immune response is so important in this case. In our research, a genetic construct for inducing of cellular immune system was designed and immune response of immunized mice was evaluated.

Materials and Methods: Chromosomal DNA extracted from E. coli 35218 as a positive type I pili strain and fimH gene amplified by using this template in PCR. The PCR product inserted to pBluescript cloning vector and sequenced. Then, the fimH gene sub cloned to pVax eukaryotic expression vector. The recombinant vector sequenced again. COS7 cell line transfected with a complex of pVax/fimH and ExGen 500 poly cationic polymer. Three groups of BALB/c mice immunized with recombinant DNA construct. The first group injected intramuscularly (i.m) with two doses (100 mg for every injection during two weeks) of purified pVax/fimH. The second group injected with the same amount of pVax vector and the third group injected with PBS as negative control. All mice challenged, one week following the second injection, with uropathogenic Escherichia coli strain 35218. Moreover, lymphocytes isolated from spleen of immunized mice and cultured for cytokines assay.

Results: The sequence of E. coli 35218 fimH gene in our research showed more than 97% identity to other fimH sequence reports in GenBank. Expression of fimH gene in transfected COS7 was confirmed by RT-PCR. The result of challenge showed 100 times reduction of E. coli colonization in bladder tissue of first group mice. Additionally, IFN-g titer got rise in first group on compression with others groups.

Discussion: fimH gene has a little variation among type I pili positive strains but it has less variation on amino acid sequences. Hence, it was detected more than 97% identity of E. coli 35218 fimH sequence with others. Expression of fimH in pVax/fimH cassette was confirmed by RT-PCR. Consequently, induction of cellular immune response was showed by increasing of INF-g titration in immunized mice. So, DNA vaccination has a potential candidate for limiting recurrent urinary tract infection.

Session Details

Date: 10/04/2010
Time: 00:00-00:00
Session name: Abstracts 20th European Congress of Clinical Microbiology and Infectious Diseases
Subject:
Location: Vienna, Austria, 10 - 13 April 2010
Presentation type:
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