Rising Cellular Immune Response after Injection of pVax/iutA: A Genetic DNA Cassette as Candidate Vaccine against Urinary Tract Infection

Abstract

Background: Uropathogenic Escherichia coli (UPEC) are major bacterial agent of Urinary Tract Infection (UTI). This infection is more prevalent among women because approximately half of all women will experience a UTI in their life-time and near a quarter of them will have a recurrent infection within 6-12 months. IutA protein has a major role during UPEC pathogenesis and consequently infection. Therefore, the aim of current study was assessment of IutA protein roles as a potential candidate antigen based for vaccine designing.

Methods: This survey was conducted during 2014-2015 at the University of Tehran, Iran. Chromosomal DNA extracted from E. coli 35218 and iutA gene amplified by PCR. The amplicon cloned to pVax.1 eukaryotic expression vector and recombinant vector confirmed by sequencing. The iutA gene expression in genetic cassette of pVax/iutA was evaluated in COS7 cell line by RT-PCR. Then, injected to mouse model, which divided to three groups: injected with pVax vector, PBS and pVax/iutA cassette respectively in two stages (d 1 and 14). One week after the second injection, bleeding from immunized mouse was performed and IFN-gamma was measured.

Results: The mice immunized with pVax/iutA showed increased interferon-γ responses significantly higher than two non-immunized groups (P<0.05).

Conclusion: Cellular immune response has a main protective role against UTI. Raising this kind of immune response is important to preventing of recurrent infection. Moreover, the current DNA cassette will be valuable for more trying to prepare a new vaccine against UTI.

Keywords: Genetic vaccination; IutA; Uropathogenic Escherichia coli.

Fig. 1:

GFP expression in transfected COS7 as transfection positive control

Fig. 2:

The result of RT-PCR Lane 1 (Ladder l kb), Lane 2 (positive PCR for iutA), Lane 3 (RT-PCR of DNase treated RNA), Lane 4 and 5 (RT-PCR for 24 and 48h transfected cells), Lane 6 (Ladder 100 bp) Expression of iutA during 48h was more than 24h (lane 4 and 5), because the intensity of related band of lane 5 on agarose gel was more than the lane 4.

Fig. 3:

IFN-γ cytokine assay of immunized mouse groups Colume 1 showed the stimulation index of IFN-γ cytokine titration of mouse which injected with pVax/iutA genetic cassette. Colume 2 is related to groups whicg received pVax vector and Colume 3 represent of reaction of groupe which injected with PBS.