Lactococcus lactis as Vaccine-vectors

The food-grade Lactococcus lactis is a potential vector that can be used as a living vehicle for the delivery of heterologous proteins for vaccine and pharmaceutical purposes. It has great potential as a vaccine platform, especially through mucosal routes of administration. This organism has a well-established history of safe use in the food industry and is well suited for genetic manipulation, so many systems are currently available for efficient production of heterologous proteins.

Introduction of Lactococcus lactis

Lactococcus lactis (L. lactis) is a non-invasive facultative and mesophilic heterofermentative GRAS (generally regarded as safe) bacterium. This species has been used in industry for many years and is essential for the fermentation of large quantities of dairy products and other foods, especially in the production of cheese. Currently, L. lactis is the most characteristic member of Lactic acid bacteria (LAB) and is considered to be the model organism of this group, not only because of its economic importance but also because of the following features: (i) it has a fully sequenced genome; (ii) it is genetically easy to manipulate; (iii) many genetic tools have been developed for this species. These features allow L. lactis to be genetically engineered to efficiently produce and secrete different proteins, which are utilized to deliver therapeutic proteins to mucosal tissues, particularly through the intranasal, oral or genital mucosal surfaces.

Why Can Lactococcus lactis Be Used as Vaccine-vectors?

Since many pathogens enter the body through the mucosal surface, the establishment of specific mucosal immunity by mucosal (oral, intranasal, vaginal or rectal) vaccination can effectively prevent and eliminate early infection. In addition, mucosal vaccination can elicit mucosal and systemic immune responses, and the relative ease of mucosal vaccine administration ensures better patient compliance. L. lactis is non-invasive and non-symbiotic and therefore is less likely to cause immune tolerance or side effects during prolonged use. Furthermore, the safety of L. lactis has been well demonstrated, and it has good safety as a mucosal vaccine delivery vehicle for both humans and animals. The presentation of antigen to the immune system in the context of particulate Lactococcus cells avoids the development of host immunotolerance which is usually induced by oral administration of soluble antigens. In conclusion, L. lactis has great application value as a live vaccine carrier for delivering therapeutic DNA or protein.

The Design of Lactococcus lactis as Vaccine-Vectors

• Cloning vectors for heterologous protein expression

  Identification and isolation of wild-type plasmids from L. lactis made it possible to develop various cloning vectors. Using molecular biology techniques, Creative Biolabs manipulated these plasmids to make them an effective tool for cloning and studying genes of interest from both prokaryotes and eukaryotes. These engineered plasmids include (i) origin of replication (ori), (ii) selection markers (genes) for antibiotic resistance, and (iii) a multiple cloning sites (MCS).

• Expression and targeting of heterologous proteins

  Several inducible systems have been developed for protein expression in L. lactis which include the use of the lac operon, the T7 promoter or explosive gene expression systems. However, the nisin-controlled expression (NICE) system is particularly well characterized and is the most widely used induction system in L.lactis. Recently, a new expression system called P_Zn zitR was developed in L. lactis using the consensus signal peptide SPE_xp4, which allows efficient production of Nuc and β-galactosidase. The expression of heterologous proteins in L. lactis has been promoted both by advances in genetic knowledge and by new developments in molecular biology techniques. To obtain increased levels of heterologous proteins and control their production, various vectors have been developed in Creative Biolabs and currently form the basis of all expression systems in L. lactis and other LABs.

• Genetically modified L. lactis strains

  Selection markers (antibiotic resistance genes) present in cloning and expression vectors are widely used in the laboratory to select and maintain cells carrying recombinant plasmids. However, their use in the food and pharmaceutical industries is considered unacceptable due to antibiotics and environmental contamination in the final product. Currently, Creative Biolabs overcomes this problem by constructing auxotrophic bacterial strains, which is compensated for by including the wild-type gene in a cloning or expression vector. They can be used to produce proteins directly in food or large-scale fermentation without the need for selection markers.

Due to its good properties, the use of food-grade Lactococcus lactis as a vaccine carrier has become increasingly important. Creative Biolabs has developed several delivery systems that target heterologous proteins to specific cellular locations (i.e., cytoplasm, cell walls, or extracellular medium) and efficiently transfer DNA to eukaryotic cells. If you have any need for L. lactis as a delivery vehicle, we are your best choice.

All of our products can only be used for research purposes. These vaccine ingredients CANNOT be used directly on humans or animals.