Lactic acid bacteria (LAB) are a group of beneficial microorganisms utilized in various food products and have potential biomedical applications, particularly as vaccine delivery vehicles. LAB can colonize human cavities and enhance the immune response due to their acid resistance and absence of lipopolysaccharides, minimizing risks associated with traditional vaccines. Current research is focused on developing genetically engineered LAB strains for vaccines against multiple pathogens, while addressing safety and environmental concerns.

1. Lactic acid bacteria (LAB)
By Mehwish Manzoor

2. Contents...
• Lactic acid bacteria (LAB)
• Potential biomedical LAB applications
• LAB as Vaccines
• Steps of medical translation of live L. lactis-based
vaccines
• Benefits of LAB based Vaccines
• Future perspectives

3. Lactic acid bacteria (LAB)
• Represent a group of different gram-positive
microorganisms,
• non sporulating bacteria
• This group is distinguished by the ability to carry out
• fermentation of carbohydrates to form lactic acid
• Beneficial role played by these microorganisms in the
humans and other animals

4. Cont……..
• Present in many foods and are frequently used as
probiotics
• to improve some biological functions in the host

5. Lactic Acid Bacteria (LAB) or Lactics applications
• plants, meat, and dairy
• Dairy products - acidophilus milk, yogurt, buttermilk,
and cheeses
• The Lactics are also important commercially in the
processing of meats (sausage, cured hams), alcoholic
beverages (beer, fortified spirits), and vegetables
(pickles, and saukerkraut).

6. Potential biomedical LAB applications
• LAB as adjuvants,
• immunostimulators, or
• Therapeutic drug delivery systems
• Factories to produce therapeutic molecules

7. Why we choose LAB as vaccines?
• Lactobacillus genus, are able to colonise cavities
such as the mouth, the urogenital or the
gastrointestinal tracts, where they play a critical role
in maintaining a balanced normal micro flora •
Preventing or lowering the incidence or recurrent
urinary or digestive tract infections

8. Cont…..
• LAB are quite acid resistant and certain strains are
able to effectively survive passage through the
stomach
• • Absence of LPS in their cell wall virtually eliminates
the risk of
• endotoxic shock

9. Lactic acid bacteria (LAB)
• Important genera of (LAB) Lactococcus,
Lactobacillus, Leuconostoc, Streptococcus and
Pediococcus.
• Therapeutically used species L. acidophilus , L.
brevis, L. casei, L. bulgaricus and L. bifidus.

10. Exploitation of LAB
• Live vaccine or vaccine delivery vehicle
• The evolution of genetic engineering techniques
• Expressing heterologous proteins in different cellular
compartments
• improving their antigenic potential for the
production of vaccines against viruses, bacteria, and
parasites.

11. LAB as vaccine delivery vehicle
• The use of bacteria as vaccine delivery vehicles
implies construction of recombinant strains that
contain the gene cassette encoding the antigen
• Several genera of LAB are being tested as vaccine
delivery vehicles

12. Cont……
• Vaccines deliver vehicle
• Expresses an antigen from another species
• The vaccine component to be delivered can be
either protein or DNA
• Use of live viral or bacterial vectors for the
production of replicative particulate antigens in vivo

14. LAB as live vaccine
• As Live bacterial vaccines
• Designed to induce an immune response Itself
• To develop LAB as live vaccines, they have to be
genetically transformed

16. Recent developments
• Lactococcus lactis - Brucella abortis and Helicobacter
pylori
• Streptococcus gordonii prototype vaccines against
HIV and measles
• With Lactobacillus, prototype vaccines against
anthrax and rotavirus are under development, and
have already been obtained against tetanus

17. Benefits of LAB based Vaccines
• Eg: Lactococcus lactis
• Lactococcus lactis is a GRAS (generally regarded as
safe) bacterium that is widely used in the food
industry
• Intensive genetic and molecular research potential
new biomedical applications –vaccine delivery, –gene
delivery, –heterologous protein expression and –
therapeutic drug delivery

18. Future perspectives
• No or few lactococcal vaccine candidates are
currently under clinical investigation
• The use of biological containment strategies may be
necessary to prevent survival of genetically modified
vaccine strains in the environment
• The ultimate aim will be to develop environmentally
safe, multi-valent LAB vaccine vectors against a
variety of different pathogens