ABSTRACT
Legionella pneumophila causes a severe form of pneumonia known as Legionnaires' disease especially in patients with impaired cellular immune response. In order to prevent the disease, immunogenicity and the level of the induction of protective immunity from the recombinant peptidoglycan-associated lipoprotein (rPAL) against Legionella pneumophila in BALB/c mice was examined. Mice immunized with (rPAL) rapidly increased an antibody response in serum and also displayed a strong activation of both innate and adaptive cell-mediated immunity as determined by antigen-specific splenocyte proliferation, an early production of pro-inflammatory cytokines in the serum and in the splenocyte cultures. Infection with a primary sublethal does of Legionella pneumophila serogroup 1, strain paris, caused resistance to a lethal challenge infection in the animals with 100% survival rate. However, mice treated with rPAL survived with 60% rate in 10 days after a lethal i.v challenge with L. pneumophila. All of the control animals receiving PBS died within 24â¯h. The present study indicates that recombinant protein PAL of Legionella pneumophila is strongly immunogenic and capable to elicit early innate and adaptive immune responses and lasting immunity against a lethal dose of Legionella pneumophila challenge. Antigenic characterization and immune protection of recombinant protein PAL would be of considerable value in comprehension the immune-pathogenesis of the disease and in development possible vaccine against the Legionella.
Subject(s)
Bacterial Vaccines/immunology , Immunity , Legionella pneumophila/immunology , Legionnaires' Disease/prevention & control , Lipoproteins/immunology , Peptidoglycan/immunology , Recombinant Proteins/immunology , Vaccines, Synthetic/immunology , Animals , Antibody Formation , Antigens, Bacterial/genetics , Antigens, Bacterial/immunology , Bacterial Vaccines/genetics , Cytokines/blood , Disease Models, Animal , Female , Immunity, Cellular , Immunity, Innate , Immunization , Legionella/immunology , Legionella/pathogenicity , Legionella pneumophila/genetics , Legionnaires' Disease/immunology , Lipoproteins/genetics , Mice , Mice, Inbred BALB C/immunology , Peptidoglycan/genetics , Survival Rate , Vaccines, Synthetic/geneticsABSTRACT
BACKGROUND: Against a variety of antimicrobial resistant pathogens, the scientists attempted substitution of antimicrobial medicine with various nanoparticles and plant-based antibacterial substances. OBJECTIVES: The aim of this study was to assess the antibacterial effects of silver nanoparticles solely and in combination with Zataria multiflora essential oil and methanolic extract on some photogenic bacteria. METHODS: Minimum inhibitory concentrations (MICs) and fractional inhibitory concentrations (FICs) of plant essential oil, methanolic extract, and silver nanoparticles against bacteria were evaluated using the broth microdilution method and check board microtiter assays. RESULTS: The results of the experiment showed that the MIC and minimal bacterial concentration (MBC) values of Ag-NPs against all strains were in the range of 15.625 - 500 µg/mL, and values for the essential oil and plant extract were in the range of 1.56 - 100 mg/mL. CONCLUSIONS: Silver nanoparticles were observed to have additive effects with essential oil against Staphylococcus epidermidis and S. aureus. The obtained results suggest the need for further investigations of the antibacterial effects of the combination of silver nanoparticles with other plant extracts and essential oils.
