محمدرضا علی رمائی

  The genus of Lactococcus lactis belonging to the lactic acid bacteria (LAB) group, is a gram positive, faculative anaerobic, non-spore forming and non-motile bacterium. The aims of this paper are to introduce Lactic acid bacteria especially non-pathogenic, non-invasive and safe Lactococcus lactis, to study the previous studies and to investigate the advantages, limitations, promotion methods and future prospects of oral vaccine based on this bacterium as a promising strategy for vaccine production and prevention of some infectious diseases.

In this review article, 62 articles related to Lactococcus lactis and its application in producing oral vaccines were collected via data bases such as PubMed, Google Scholar, Scopus since 1981-2020.

Lactococcus lactis, as a safe microorganism (GRAS) widely used in the food industry. Live recombinant Lactococcus lactis as a "biologic drug" is orally administered as one of the live vaccines expressing viral and bacterial antigens.

Recombinant Lactococcus-based vector can be suitable substitutes for live attenuated vaccines and can be considered as a safe and food-grade host for producing the desired products of human consumption over other systems. It also has a high potential for vaccine delivery, especially through mucosal methods to prevent or treat certain diseases.

Helicobacter pylori is a gram-negative and microaerophilic bacterium. About half of the human population in the world is infected with this bacterium. Helicobacter pylori is known to be one of the main causes of stomach ulcers and gastric cancer. The increased antibiotic resistance, the high cost of combined treatments and adverse side effects have led to an increase in the tendency to alternative methods such as the use of antioxidants, anti-inflammatory agents, probiotics and herbal medicines.

In this study the published articles on the effects of 29 plant families, including 69 Iranian plant species against H. pylori in vitro and in vivo conditions were reviewed and categorized.

According to the obtained results, plants such as Mentha Piperita, Zataria multiflora, Salvia mirzayanii, Geum Iranicum, Rhus coriaria , Commiphora myrrha, Heracleum persicum, Trachyspermum amm, Artemisia absinthium, Glycyrrhiza glabra L, Olea europaea and Punica granatum are the most affected plants against Helicobacter pylori in vitro condition. Discussion and

The observed antibacterial effects of the tested herbs in this study suggest that these herbs have the potential to be used as a viable alternative treatement for of the H. pylori infections but antibacterial activity evaluation of herbal extracts against H. pylori should be evaluated both in vitro and in vivo conditions. Also, determining the effective ingredient can help further research in this regard. The effectiveness of the same plant species should be evaluated in the different regions and ultimately concluded in the field of their effect. It is clear that the obtain outcome of the antibacterial effect of the same herbal extract on different strains of a bacterial species might be different so the standard strain of H. pylori must be use.

Legionella pneumophila is a cause of pneumonia in human beings. The purpose of this study was to separate L.pneumophila from stagnant and waste water, city squares, coolers and faucets and evaluation of the immuno-protective efficiency of its whole killed cells in mice model. Water samples were prepared, concentrated and then cultured on selective (GVPC) media. After identification of L.pneomophila the biomass of the organism was fixed with 0.5% formalin in sterile saline at 37ºC for 24 hours in order to prepare whole killed cells. Four groups of female BALB/c mices (each group consisted of 15 mices) were selected. Two groups of mice were immunized by three intraperitoneal administrations of prepared antigen in a dose of 4×108 CFU from whole killed cells at two week intervals and control groups received only sterile saline injections. Two weeks after the last injection, one group of immunized mice and one of the control groups were challenged with the lethal dose of virulent strain of L.pneuophila and also the two other groups of mice were challenged six weeks after the last immunization. From 120 water samples 27 samples were contaminated with L.pneumophila. Challenge results showed that the immune efficiency of whole killed cell was 93.33% after two weeks of the last immunization, and 86.66% after six weeks of the last immunization. This study showed that, stagnant water had the highest rate of contamination with L.pneumophila and the whole killed cell of L.pneumophila is a proper candidate for L.pneumophila vaccine studies.