Salmonella as Vaccine-vectors

The ability of attenuated Salmonella vaccine strains to induce cellular and humoral immune responses in mucosal and systemic compartments makes them good candidates for delivery of heterologous antigens from unrelated bacterial, viral and parasitic pathogens to the immune system. Creative Biolabs has been committed to the development and production of new vaccine vectors for many years and provided many types of highly efficient Salmonella vaccine vectors to customers around the world. As a service provider, our goal is to provide the highest level of service, confidentiality and customer support.

Introduction of Salmonella

Salmonella is a rod-shaped gram-negative facultative anaerobe bacterium belonging to the Enterobacteriaceae family. The genus Salmonella is divided into two species, Salmonella enterica and Salmonella bongori. As a vaccine delivery system, attenuated Salmonella enterica serovar Typhi (S. Typhi) and Salmonella enterica serovar Typhimurium (S. Typhimurium) as live bacterial vaccine vectors have been used in many ways and shown obvious advantages for mucosal immunization. As pathogenic bacteria, Salmonella induces the immune response through their lipopolysaccharides and flagellin content on their surface that is recognized as pathogen-associated molecular patterns (PAMPs). The S. enterica virulence gene is primarily located in the Salmonella pathogenicity island (SPI). The two main SPIs are SPI1 and SPI2, which are involved in host cell invasion and intracellular host cell survival, respectively. Due to its significant pathogenicity, the mutant Salmonella has been developed as a DNA vaccine vector.

Our Strategies of Using Salmonella as Vaccine-Vectors

• Strains

Creative Biolabs has developed several attenuated mutant strains of Salmonella by recombinant DNA technology, including mutant S. typhi and S. typhimurium strains. These strains are well tolerated in clinical trials and have proficiently elicited strong systemic and local immune responses against the corresponding antigens. Moreover, several other manipulations have been studied in Creative Biolabs to improve the ability of Salmonella spp. as a vaccine carrier, including the manipulation of lipid A, outer membrane vesicles and engineering the dual-plasmid system and so on.

• Chromosomal integration of antigen cassettes

A given chromosomal locus is deleted to create an attenuated vaccine strain that is subsequently replaced by an expression cassette encoding the desired foreign antigen. Chromosomal expression of foreign antigens provides maximum genetic stability because chromosomal genes are rarely lost by spontaneous deletion. Chromosomal expression simplifies the construction of multivalent vaccines in which multiple chromosomal loci can be selected to express different antigens from the same or unrelated pathogens.

• Plasmid-based antigen expression

In addition to the chromosomal integration of genes encoding foreign antigens, plasmids can also be used. A variety of plasmid-based expression techniques are available for achieving sufficient production of antigen to produce the relevant immune response. Creative Biolabs has developed a variety of genetically stable expression plasmid systems based on the nature of the plasmid itself in nature, which enable more DNA sequence to be devoted to the expression of heterologous antigens, while minimizing the size and genetic instability of the replicons.

Advantages of Salmonella as Vaccine-vectors

These live attenuated Salmonella vaccines have several advantages for use as delivery systems, especially of mucosal pathogens.

• They mimic the natural infection of most mucosal pathogens, infecting their host through the mucosal surface.
• They are intracellular pathogens that are capable of surviving and replicating within antigen presenting cells, which facilitate the continual processing and presentation of the foreign antigens to the immune system.
• The vaccines are relatively inexpensive to produce or manufacture for large-scale mass-immunizations.
• Irreversible strains of attenuated Salmonella have been developed and these mutants cannot be restored to wild-type and thus can be safely used in humans.
• Bacterial vaccines are easily treated with antibiotics if adverse reactions occur during immunization.
• The oral route is more practical, socially acceptable, and reliable than other routes of vaccine administration.
• Salmonella bacteria can hold large amounts of foreign DNA (large multivalent antigen capacity) and thus can deliver one or more foreign antigens.
• Molecular tools and techniques developed for the genetic manipulation of E. coli can be readily applied to Salmonella vaccine operations.

The Salmonella-based vaccine delivery carrier provides an efficient platform technology for mucosal immunization and novel vaccination strategies. With years of experience and advanced vaccine development platform, Creative Biolabs has developed several delivery vectors for the stabilization of multicopy expression systems encoding foreign antigens in Salmonella live-vector vaccine strain. If you have any needs, 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.