جستجوی مقالات مرتبط با کلیدواژه « لاکتوکوکوس لاکتیس » در نشریات گروه « پزشکی »

Oral vaccines in infectious diseases, whose agents enter the body through the mucous membrane, will induce the innate immune pathway. The neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) have been documented as biomarkers of Brucella systemic inflammation. The purpose of this study is to investigate the effect of oral administration of the Lactococcus lactis probiotic vaccine carrying Brucella abortus BLS antigen on the ratio of blood leukocytes as biological biomarkers in mice with brucellosis compared to the control group.

60 mice with brucellosis (challenged) and 60 healthy mice (non-challenged) were included in the study. The challenge group was divided into 6 subgroups and 6 types of intervention including 1) L. lactis/pNZ8148-Usp45-BLS, 2) L. lactis-pNZ8148, 3) L. lactis, 4) IRIBA Vac, 5) pNZ8148 and 6) PBS received by gastric gavage in all groups except IRIBA Vac. Serum was used to check hematological parameters. C-reactive protein (CRP) level was measured. The number of neutrophils and lymphocytes was determined using a complete blood cell count. PLR and NLR were calculated.

In this study, the level of CRP in the mice of the challenge group increased significantly compared to the non-challenge group. (P<0.0001) The mice receiving oral vaccine L. lactis/pNZ8148-Usp45-BLS were able to inhibit the infection and reduce the concentration of CRP in They were basic level. Mice with brucellosis have lower levels of NLR and PLR than the control group, and after receiving the recombinant vaccine, an increase in leukocytes was observed (P˂0.0001).

The mice of the challenge group and the non-challenge group showed a statistically significant difference in terms of PLR and NLR as well as CRP. These parameters can be useful markers in evaluating the systemic inflammation of brucellosis.

Listeria monocytogenes leads to listeriosis in humans through the consumption of ready-to-eat foods. Older adults, immunocompromised patients, pregnant women, and newborns are at the highest risk for this infection. To detect probiotic bacteria with an inhibitory activity against L. monocytogenes, we evaluated the inhibitory effect of Lactococcus lactis on the growth and invasion of L. monocytogenes.

In this study, we used the L. monocytogenes ATCC 7644 strain and the L. lactis PTCC 1336 probiotic strain. To investigate the inhibitory effects of L. lactis on the growth of pathogenic L. monocytogenes, we employed the well diffusion agar method, and to investigate its inhibitory effect on invasion by this bacterium, we conducted a co-culture with Caco-2 human enterocyte cells.

The results showed that L. lactis in concentrations of 0.25, 0.5, and 1 had antimicrobial properties against L. monocytogenes. With increasing concentration, the inhibitory effect on this pathogen increased. In addition, L. lactis showed an inhibitory effect on the L. monocytogenes invasion of Caco-2 cells. Therefore, in the concentration of 1, L. lactis decreased the number of bacteria by reducing the invasion of the cells by Listeria from log 108 to log 102; in the concentration of 0.5, from log 108 to log 103; and in the concentration of 0.25, from log 108 to log 105.

L. lactis has antimicrobial and inhibitory properties against the invasion of L. monocytogenes and can be considered an option to inhibit invasion and gastrointestinal infections caused by this bacterium.

Vaccination is an efficient and cost-effective way to control brucellosis. This study aims to generate recombinant Lactococcus lactis (L. lactis) with Brucella abortus (B. abortus) BLS cytoplasmic protein.

The target vector, gene, and signal peptide (pNZ8148-Usp45-BLS) were developed and made in this study. Cloning accuracy was verified by PCR, enzyme digestion, and sequencing. Top10 F Escherichia coli was transformed using the recombinant expression vector. The column plasmid extraction kit selected and eliminated chloramphenicol-effected bacteria from an agar plate. In electroporation, Lactococcus lactis bacteria received the recombinant vector. Both SDS-PAGE and RT-PCR confirmed the transition.

To confirm the correctness of cloning and to confirm the presence of the BLS gene in the pNZ8148 vector, PCR and enzymatic digestion were performed. Observation of the BLS gene fragment with a length of 477 bp and plasmid pNZ8148 - Usp45 without the BLS gene fragment with a length of 2997 bp, the cloning of the BLS gene fragment was confirmed. Also, in the study conducted by the nanodrop device, the concentration of the extracted plasmid was estimated at 848.9 ng/µl and the degree of purity was 2.07. The results of RT-PCR indicated the success of the BLS gene transformation of Brucella abortus in L. lactis bacteria. Also, a single protein band of 18 kDa was observed in transformed L. lactis.

The present study showed that the BLS gene of the probiotic L. lactis transfected with pNZ8148-Usp45-BLS is expressed by electroporation.

In all species of Brucella bacteria, the Omp10 gene sequence is conserved. The high antigenic property of this gene product stimulates the host's immune system. Using the probiotic Lactococcus lactis bacterium as a live carrier, in addition to being safe, is suitable for the production of recombinant proteins and gene transfer to eukaryotic cells. Omp10 is one of the surface lipoproteins in brucella’s outer membrane with high immunogenicity which has a substantial role in up-taking nutrition, signaling, adherence, and antibiotic resistance. This protein has antigenic properties and can play an adjuvant role when attached to other antigens. Therefore, the purpose of this research is to create the probiotic bacteria Lactococcus lactis to produce the Omp10 protein of Brucella abortus.

Brucella abortus Omp10 gene with Usp45 peptide signal was synthetically cloned in the pNZ8148 vector. The recombinant vector was first reproduction in Escherichia coli strain TOP10 and then purified by plasmid extraction kit. The concentration of extracted plasmid was measured by nanodrop. The recombinant pNZ8148-Usp45-Omp10 vector was then transformed into Lactococcus lactis bacteria through electroporation. Cloning and gene expression assessment and verification were done by SDS-PAGE, enzyme digestions, and RT-PCR techniques.

The results showed the successful expression of the target gene Omp10 in the Lactococcus lactis probiotic bacteria. The recombinant protein was well expressed in probiotic bacteria.

The present study showed that the Omp10 protein is expressed in the probiotic bacterium Lactococcus lactis transformed by electroporation with the recombinant pNZ8148-Usp45-Omp10 vector. Lactococcus lactis transformed in the present study can be suitable as an oral subunit vaccine to prevent brucellosis in future studies.

The sequence of Omp25 is conserved in all Brucella species. The high antigenicity of the product of this gene stimulates the host’s immune system. Using engineered probiotic bacteria is an appropriate method for vaccine transport. The aim of this study was to express the Omp25 of the Brucella abortus pathogenic bacterium in Lactococcus lactis probiotic bacterium.

In this experimental study, the required vector was designed and synthesized to include the gene of interest and a signal peptide (pNZ8148-Usp45-Omp25). E. coli strain TOP10F was transformed using the pNZ8148-Usp45-Omp25 expression vector based on induction by nisin. The recombinant plasmid was extracted from the transformed bacteria using a plasmid extraction kit. The L. lactis was transformed by pNZ8148-Usp45-Omp25 vector using electroporation. Evaluation of the expression of Omp25 gene at the RNA level was assessed by reverse transcription method and confirming the presence of recombinant Omp25 protein in the engineered bacteria using SDS-PAGE method.

Successful expression of B. abortus Omp25 in L. lactis was verified by RT-PCR. Subsequently, the proteins were separated based on molecular weight using sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS-PAGE). The protein expression analysis showed the expression of Omp25 as a 25kDa extra band in transformed L. lactis compared to the L. lactis receiving the vector lacking the target gene.

This study shows that Omp25 is expressed in L. lactis transformed via pNZ8148-Usp45-Omp25 by electroporation. Transformed L. lactis can be successfully used as a subunit oral vaccine in prevention of Brucellosis.

  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.

Clostridium difficile bacterium is the leading cause of clinical infection and pseudomembranous colitis. Toxin B (TcdB) of C. difficile is regarded as one of the main virulence factors of this bacterium. Moreover, the receptor binding domain (RBD) of this toxin which is known as an immunogenic domain attaches to its receptor in intestine. This study aimed to clone and express the immunogenic domain of the Toxin B in Lactococcus lactis to provide a safe oral vaccine against colitis caused by C. difficile as an alternative treatment in future studies based on Lactococcus.

In order to clone this segment, at first, the DNA was extracted from C. difficile, and then, the RBD gene segment was amplified by the PCR method using designed primers. The amplified segment was attached to pTZ25R/T plasmid and transformed into Escherichia coli. Subsequently, the RBD segment was extracted from pNZ9418 plasmid using restriction enzymes, such as SacI and NcoI, and then it was purified in this study. Following that, the RBD segment was cut in pNZ8149 plasmid using the same enzymes and was attached under the proper condition. The pNZ8149 plasmid with segment was transformed into L. lactic competent cells by electroporation method.

After the screening of electro-transformed colonies, the accuracy of cloning was verified using PCR, enzyme digestion on the extracted recombinant plasmid, and sequencing.

According to the results, L. lactic which produces the immunogenic domain can be used as a safe oral vaccine and can be considered as an alternative therapy to reduce the incidence of Clostridium difficile infection in further investigations.

Probiotics are beneficial microorganisms that have been used in food production as well as health promotion over the centuries. Recombinant probiotics are used to express and transfer native or recombinant molecules to mucosal surface of digestive tract to promote efficiency in nutrition and health. Lactococcus lactis is a potential candidate for the production of useful biological proteins. Since there is not any vector nominated for this bacterium to show the extracellular protein secrition properties, therefore the aim of this study was to increase the efficiency of expression and secretion of recombinant proteins by adding transmission signal peptide usp45 to pBU003.
usp45 signal peptide has 81 nucleotides and previous studies indicated that it can also cause increase in the gene expression. In this study, after synthesising usp45 signal sequence, it was ligated into pBU003. Then the vector was transformed to Ecoli (MC1061). The recombinant plasmid named pFUM003 after “plasmid Ferdowsi University of Mashhad 003”.
Sequencing of recombinant plasmid containing usp45 showed that the plasmid had correct construction and the inserted sequence had exact match with the reference sequence (EU382094.1) reported in NCBI's GenBank.
The recombinant plasmid was named pFUM003. This recombinant plasmid structurally was correct and can be used to transmit into probiotics make them to benefit from extracellular protein production properties.

Lactococcus lactis (L. lactis) is one of the most important microorganisms used in dairy industry for production of fermented milk products. Bacteriophages which attack L. lactis are a serious threat to the dairy industry because of their negative effects on fermentation processes. Samples of raw milk were examined for the presence of lactococcal bacteriophages. Samples were centrifuged and then filtered through 0.45µm pore size filters. The filtrates were added to early-exponential cultures of Lactococcus lactis subspp. Lactis (PTCC 1336). Overlay method was used to detect the formation of plaques. After isolation and concentration of phages, serial dilutions of phage stock were used to determine titer of phage in concentrated sample. Electron Microscopy was used for observation and characterization of structural details of bacteriophages. Two phages were isolated; one of them had a hexagonal head of 45×30 nm in diameter and a flexible non-contractile tail of 70nm long which belonged to Siphoviridae. The other had a short tail and a hexagonal head of 53×60 nm in diameter which was a member of Podoviridae family. In this study, for the first time, two phages were isolated from milk. This does not reduce the significance of phage control in different stages of the production. The spread of the phages in the production plant can be very harmful.

Background and Dairy products often associated with problems such as short shelf life and poor hygiene control. A novel approach is to utilize bacteriocin or bacteriocin producer strains, to control undesirable micro flora as Listeria monocytogenes and Bacillus cereus in foods. Hence, we studied the effect of nisin like producing Lactococcus lactis against Listeria monocytogenes and Bacillus cereus, in order to compare the isolated strain within different countries. In this research we studied the effect of nisin like producing Lactococcus lactis, with producer spot test method. We also used supernatant from 24 h culture of Lactoccus lactis. Moreover, we studied the effect of bacteriocin on Listeria monocytogenes and Bacillus cereus growth curves. The growth of both strains was inhibited by the bacteriocin. According to our results, the bacteriocin could be used in liquid food with bacteriocin added directly or as a starter culture in fermentation. This would inhibit the growth of Listeria monocytogenes furthermore, Bacillus cereus is used to reduce food poisoning for fermented food products.