CARIES VACCINE

SEMINAR ON CARIES VACCINE
EVOLUTION, TYPES OF VACCINE AND SCOPE FOR FUTURE RESEARCH

1. Dr Divya Gaur Dept of Pedodontics and Preventive Dentistry CARIES VACCINE

2. INTRODUCTION ACQUISITION OF STREPTOCOCCUS MUTANS BIOFILM ROLE OF DENTAL PLAQUE IMMUNOLOGY OF DENTAL CARIES IN HUMANS TYPES OF IMMUNE RESPONSE NEED FOR CARIES VACCINE REQUIREMENTS OF DENTAL VACCINE MOLECULAR PATHOGENESIS OF DENTAL CARIES MOLECULAR TARGETS GLUCOSYLTRANFERASE GLUCAN BINDING PROTEINS ADHESINS

3. MECHANISM OF ACTION OF VACCINES TYPES OF VACCINES ROUTES OF IMMUNIZATION LOCAL SYSTEMIC PASSIVE ADJUVANTS AND DELIVERY SYSTEMS CLINICAL RESEARCH RISKS OF USING CARIES VACCINE PUBLIC HEALTH VIEW RECENT ADVANCES CONCLUSION

4. INTRODUCTION Dental caries is an infectious microbiologic disease of the teeth that results in localized dissolution and destruction of the calcified tissue 1 . Clifford MS. The art and science of Operative dentistry. 4th ed. Mosby Publications; 1995.

5. DENTAL CARIES SUBSTRATE HOST TIME MICRO- ORGANISMS STREPTOCOCCUS MUTANS LACTOBACILLUS ACIDOPHILUS ACTINOMYCES VISCOSUS EXTRINSIC CARBOHYRATES INTRACELLULAR POLYSACCHARIDES FOURTH FACTOR ADDED BY NEWBRUN SMOOTH SURFACES PITS AND FISSURES KEYES TRIAD AND NEWBRUN‘S TETRAD

6. MANAGEMENT OF DENTAL CARIES: EVOLUTION

7. STREPTOCOCCUS MUTANS WHAT IS IT? A gram + facultative anaerobe characterized by 8 serotypes. PREVALENCE: Most prevalent serotype: h HOW DOES IT CAUSE DENTAL CARIES? BIOFILM formation Aciduric and acidogenic . S. mutans S.Sobrinus S.Ratti S.Criceti S.Downei S.Ferus S.macacae

8. ACQUISITION OF STREPTOCOCCUS MUTANS CAUFIELD et al , «   window of infectivity « : children become permanently colonized with mutans streptococci between the middle of second year and the end of the third year . This window may open even earlier if maternal S. mutans infection levels are high , coupled with frequent exposures to dietary sucrose. DNA probe technology have suggested that low levels of mutans streptococci may be found in the oral cavity during the first year of life. Thus , data suggests that ‘ window of vaccine opportunity ’ could exist between 12 and 18 months for most populations.

9. BIOFILM A COMMUNITY OF BACTERIA ATTACHED TO SALIVARY COMPONENTS AND EMBEDDED IN A MATRIX OF GLUCAN OF HIGH MOLECULAR WEIGHT, PRODUCED BY STRETOCOCCUS MUTANS.

10. ROLE OF DENTAL PLAQUE Suggested by Williams in 1897. GV BLACK (1899): ‘the gelatinous plaque of caries fungus is a thin , transparent film that usually escapes observation and which is revealed only by careful search . It is not a thick mass of material alba frequently found upon the teeth , nor it is the whitish gummy material .’ Consists of salivary components ( acquired pellicle - glycoproteins ), desquamated epithelial cells and micro-organisms . Blayney (1942) Acidogenic streptococci : 86% of plaque Lactobacilli : 57%

11. ORAL CAVITY DEFENSE CAN BE OF 2 TYPES: NON- SPECIFIC: Lysozyme , lactoperoxidase and lactoferrin : active against many species of bacteria. SPECIFIC: Involves exposing the host to killed or attenuated forms of organism to instruct the host’s immunological memory. IMMUNOLOGY OF CARIES IN HUMANS

12. ANTIGEN – Any substance which stimulates production of antibody with which it reacts specifically and in an observable manner. ANTIBODY – Substance which appears in serum/tissue fluids which react with the antigen specifically and in an observable manner. IMMUNITY : It is defined as resistance offered by the host to the harmful pathogenic microbial infection. ANTIGEN AND ANTIBODY Specific Non-Specific Active Passive Natural Artificial Natural Artificial Innate Acquired

13. SECRETORY SALIVARY ANTIBODIES : IgA SERUM ANTIBODIES : IgG , IgM AND IgA ANTIBODIES IN THE MOUTH

14. THE PRIMARY RESPONSE: When an antigen is administered for the first time to an animal/ human. Latent period of induction : 3-10 days. Antibodies appear in the blood. First antibody to be elicited: IgM type. Antibody titre rises steadily during the next 2-3 days, reaches a peak level, and then declines almost as fast as it develops. if antigenic stimulus was sufficient, IgG appears in a few days. IgG reaches peak in 7-10 days and then gradually falls over a period of weeks or months. TYPES OF IMMUNE RESPONSE IMPORTANT OUTCOME OF PRIMARY RESPONSE: B and T lymphocytes produce “memory cells” or “ primed cells” that are responsible for immunological memory established after immunization.

15. THE SECONDARY (BOOSTER) RESPONSE: Also involves production of IgM and IgG antibodies . Brief production of IgM and much larger and prolonged production of IgG antibody. This accelerated response is attributed to immunological memory. TYPES OF IMMUNE RESPONSE Park K. Text book of preventive and social medicine. 17th ed. Bhanotidas Publication; 2004. Warren L, Ernest J. Medical microbiology and immunology. 6th ed. Lange Medical Publishing Division; 2000.

16. Immunobiological substance designed to produce specific protection against given disease. It is a suspension of attenuated or killed microorganisms, administered for the prevention or treatment of infectious diseases. They may be prepared from live modified organisms, inactivated or killed organisms, cellular fractions, toxoids or combinations of these. DENTAL CARIES VACCINE : The evidence of a specific bacterial cause of dental caries and the function of salivary glands as an effector site of the mucosal immune system has provided a scientific basis for developing a vaccine against this highly prevalent oral disease. VACCINE

17. EDWARD JENNER : pioneered in the field of immunology. LOUIS PASTEUR : developed vaccines against rabies and anthrax. 1930 : Caries immunizaition experiments were performed on lactobacillus. 1960 : Streptococcus mutans became the target . HISTORY OF VACCINES

18. Streptococcus mutans is a poor immunogen . Entry of S.mutans through junctional epithelium of gingiva not sufficient to elicit an immune response. T-cell response to S.mutans is of low order and needs boosting for sensitization. NEED FOR CARIES VACCINE

19. REQUIREMENTS OF A DENTAL CARIES VACCINE IDENTIFY THE TARGET. IDENTIFY THE COMPONENT OF IMMUNE SYSTEM THAT SHOULD BE STIMULATED/ INDUCED. SHOULD NOT HARM THE HOST

20. MOLECULAR PATHOGENESIS OF DENTAL CARIES Michalek and Childers : reviewed and demonstrated that experimental protection could be achieved by immunization with mutans streptococi . Then, attention was focused on immunologically intercepting properties of these organisms that led to disease.

21. MOLECULAR PATHOGENESIS OF DENTAL CARIES ANTIGEN I/II or Pac GLUCOSYLTRANSFERASES GTF-B AND GTF-C GTF provide scaffolding for aggregation of mutans and other oral streptococci through interaction with bacterial call- associated glucan binding proteins.

22. GLUCAN

23. MOLECULAR PATHOGENESIS OF DENTAL CARIES

24. MOLECULAR TARGETS

25. GLUCOSYLTRANSFERASE Moro I, Lehner T. Symposium report: Sixth International congress of mucosal immunology; Dental caries vaccine. J Dent Res July 23rd 1990. p. 1863-4. Russell RR. The application of molecular genetics to the microbiology of dental caries. Caries Res 1994;28:69-82.

26. Function of Glucans : provide scaffolding for the aggregation of mutans and other oral streptoccocci through interaction with bacterial cell- associated glucan binding proteins . Also, Glucans modify the porosity of the dental biofilm , thus increasing the availability of nutrients for continued bacterial metabolism. GLUCOSYLTRANSFERASE Moro I, Lehner T. Symposium report: Sixth International congress of mucosal immunology; Dental caries vaccine. J Dent Res July 23rd 1990. p. 1863-4. Russell RR. The application of molecular genetics to the microbiology of dental caries. Caries Res 1994;28:69-82. Three forms of GTF: Water insoluble glucan synthesizing enzyme: GTF-I Water insoluble and water- soluble glucan synthesizing enzymes: GTF-S-I Water- soluble glucan synthesizing enzymes: GTF-S

27. Hence active immunization with either S mutans or S sobrinus GTFs induced protective immune responses in dental caries. Induction of SIgA antibody in humans by oral or topical GTF administration is accompanied by interference with accumulation of S mutans ( smith & taubman 1987,1990) Passive administration of antibody to GTF in the diet can protect from dental caries. Thus presence of antibody to GTF in the oral cavity prior to infection can significantly influence the disease outcome. EXPERIMENTAL RESULTS

28. 3 distinct proteins with glucan binding activity: GBP-A, GBP-B and GBP-C. Only GBP-B has been shown to induce a protective immune response to experimental dental caries. GLUCAN BINDING PROTEINS

29. First described by Russell and Lehner . Bind acidic, mucin like glycoproteins found in saliva. 2 principal human pathogens: Antigens I/ II, Pac or P1 Streptococcus sobrinus : Spa-A or Pag . Antigens I/II : found in the culture supernatant as well as in S. mutans cell surface. Contains alanine -rich tandem- repeating region in the N-terminal third and a proline rich repeat region in the centre of the molecule. Antibody directed to the intact Ag I/II molecule or to its salivary binding domain blocked adherence of S. mutans of saliva-coated hydroxyapatite . CELL WALL ANTIGENS/ ADHESINS Smith DJ. Dental caries vaccines: Prospects and concerns. Crit Rev Oral Biol Med 2002;13:335-49.

30. SALIVARY IMMUNOGLOBULIN may interact with BACTERIAL SURFACE RECEPTORS, and inhibit colonization . May inactivate surface glucosyltransferases , which would reduce synthesis of extra cellular glucans resulting in reducing plaque formation. SECRETORY IgA from salivary glands due to direct immunization of gut associated lymphoid tissue (GALT): May prevent MS from adhering to the enamel surface. May also prevent formation of dextran by inhibiting the activity of glucosyltransferase (GTF). GINGIVAL CREVICULAR mechanism : All humoral and cellular components of systemic immune system, that exert its function at tooth surface. MECHANISM OF ACTION OF VACCINE Lehner T. Immunology of dental caries. Immunology of oral diseases. 3rd ed. Blackwell scientific publications; 1992. Wilton JM. Future control of dental disease by immunization: Vaccines and oral health. Int Dent J 1984;34:177-83. Lehner T, Challacombe SJ, Caldwell J. Immuologic basis for vaccination against dental caries in Rhesus monkeys. J Dent Res 1976;55:C166-80.

31. TYPES OF VACCINES SUB UNIT VACCINE RECOMBINANT VACCINE CONJUGATE VACCINE

32. ROUTES OF IMMUNIZATION

33. ACTION OF LOCAL IMMUNITY

34. Mucosal application of dental caries vaccines is preferred for induction of secretory IgA antibodies in salivary compartment. It has been shown that exposure of an antigen to a mucosally associated lymphoid tissue in the gut, nasal, bronchial, or rectal site can give rise to immune response not only in the region of induction but also in remote location. Several mucosal routes used to induce protective immune responses to dental caries vaccine antigens: Oral Intra Nasal Tonsillar Minor salivary gland Rectal COMMON MUCOSAL IMMUNE SYSTEM Russell MW, Hajishengallis G, Childers NK, Michalek SM. Secretory Immunity in defense against cariogenic Mutans streptococci. Caries Res 1999;33:4-15.

35. Early studies relied on oral induction of immunity in GALT to elicit protective salivary IgA response. Smith DJ (2002 ): applied antigen by oral feeding, gastric intubation, or in vaccine containing capsules or liposome. ORAL Smith DJ. Dental caries vaccines: Prospects and concerns. Crit Rev Oral Biol Med 2002;13:335-49.

36. Oral route failed to reduce caries significantly, as compared with subcutaneous immunization. The rise in secretory antibodies produced was small and of short duration. Immunological memory in secretory IgA responses is rather limited. Effect of stomach acidity on antigen, Inductive sites were relatively distant. ORAL

37. Recent attempts have been made to induce protective immunity in mucosal inductive sites that are in close anatomical relationship to the oral cavity. Intranasal installation of antigen targets the nasal associated lymphoid tissue (NALT) ( Brandtzaeg & Haneberg,1997 ). NALT is stimulated to produce antibodies against mutans streptococcal colonization and accumulation. INTRANASAL ROUTE Curtis R 3rd. 1984 Kreshover lecture: Genetic analysis of S. mutans virulence and prospects for an anticaries vaccine. J Dent Res 1986;65:1034-45.

38. INTRANASAL ROUTE By nasal spray : Vaccine is introduced into the mucosal immune system by nasal spray. Thus causing increased production of immunoglobulin IgA which fights tooth decay by interrupting the colonization of the bacterium S.mutans . Advantage: lower doses of ag needed easy adm induces both systemic & mucosal immunity

39. Has both IgA and IgG response: IgG is more dominant. Palatine tonsils and nasopharyngeal tonsils contribute precursor cells to mucosal effector sites: such as salivary gland. Experiments have shown that formalin- killed Streptococcus sobrinus cells in rabbit can induce a salivary immune response, which can significantly decrease the consequences of infection with cariogenic Streptococcus sobrinus . Repeated tonsillar application of a particulate antigen can induce the appearance of IgA antibodies in both major and minor salivary glands of rabbit. Smith DJ 2002. TONSILLAR ROUTE Smith DJ. Dental caries vaccines: Prospects and concerns. Crit Rev Oral Biol Med 2002;13:335-49.

40. Populate the lips, cheeks, and soft palate. Their short, broad secretory ducts facilitate retrograde access of bacteria and their products: potential routes for mucosal induction of salivary immune responses. Experiments with topical application of Streptococcus sobrinus GTF on lower lips of young adults : lower proportion of indigenous S. mutans / total Streptoccal flora in their whole saliva during a 6 week period following a dental prophylaxis, compared with a placebo group. Smith and Taubman , 1990 Used in children with respiratory ailments where intranasal application is not possible. MINOR SALIVARY GLAND ROUTE Smith DJ. Dental caries vaccines: Prospects and concerns. Crit Rev Oral Biol Med 2002;13:335-49.

41. Colorectal region as an inductive location for mucosal immune responses in humans: it has the highest concentration of lymphoid follicles in the lower intestinal tract. Preliminary studies have indicated that this route could also be used to induce salivary IgA responses to mutans streptococcal antigens such as GTF. RECTAL Smith DJ. Dental caries vaccines: Prospects and concerns. Crit Rev Oral Biol Med 2002;13:335-49.

42. ACTIVE PASSIVE TYPES OF IMMUNIZATION

43. Whole antigen or subunit Attenuated whole Streptococus mutans MS cells or purified GTFs injected into salivary gland region to induce TGA secretion- altering the function of the gland. ACTIVE IMMUNIZATION

44. For immediate protection Immunocompromised patients. Disadvantage: Transient protection PASSIVE IMMUNIZATION

45. Subcutaneous administration of S. mutans : elicited IgG , IgM and IgA antibodies. Antibodies reach oral cavity via gingival crevicular fluid. Whole cells, cell walls and the 185 KD streptococcal antigen have been administered on 2-4 occasions. IgG antibodies are well maintained at high titre , IgM progressively fall and IgA antibodies increase slowly in titre . IgG develop within months of immunization , reaching a titre of upto 1:1280. SYSTEMIC ROUTE OF IMMUNIZATION Lehner T. Immunology of dental caries. Immunology of oral diseases. 3rd ed. Blackwell scientific publications; 1992.

46. To limit potential side effects of other routes and to localize the immune response. Associated with increased IgG and IgA . Various modalities: Injecting lysozyme into rabbit gingiva : elicited local antibodies Brushing live S. mutans onto the gingiva of Rhesus monkeys, which failed to induce antibody formation. Using smaller molecular weight S. antigen, which resulted in better performance probably due to better penetration. ACTIVE GINGIVO-SALIVARY ROUTE Tandon S. Textbook of Pedodontics . 1st ed. Paras Publishing; 2001

47. External supplementation of antibodies. Approaches tried: Monoclonal antibodies: to surface antigen I/ II Bovine milk and whey: systemic immunization of cows with a vaccine using whole S. mutans led to bovine milk and whey containing polyclonal IgG antibodies. Egg- yolk antibodies: Hamada introduced using hen egg-yolk antibodies against cell- associated GTF of S. mutans . Transgenic plants: caries vaccine developed from a genetically modified (GM) tobacco plant. Vaccine is colourless and tasteless and can be painted onto the teeth rather than injected and is the first plant derived vaccine. PASSIVE IMMUNIZATION Tandon S. Textbook of Pedodontics . 1st ed. Paras Publishing; 2001. News. Genes .n. Greens: The future of oral medicine? Br Dent J 2002;192:674.

48. ADJUVANTS AND DELIVERY SYSTEMS News. Genes .n. Greens: The future of oral medicine? Br Dent J 2002;192:674.

49. CLINICAL RESEARCH IN THE FIELD OF CARIES VACCINE

50. CLINICAL RESEARCH IN THE FIELD OF CARIES VACCINE

51. All vaccines have risks. Immunologically cross reactive with human heart tissue and rabbit skeletal muscle myosin are found in cell membranes of S. mutans . Heart cross reactive Ab do not develop in Rhesus monkey or rabbits immunized with purified Ag I/II from S. mutans . Due to potential of S.mutans whole cells to induce heart – reactive Ab , the development of subunit vaccine for caries has been focused of intense research interest. RISK OF USING CARIES VACCINE

52. Although the prevalence of dental caries has declined according to a national epidemiological survey by US national institute of dental research, this oral disease is still a significant health problem that affects approximately 50% of 5-17 year old children. Developing countries without a water fluoridation system and where access to dental health education and treatment may not be available to everyone are in great need of a vaccine. PUBLIC HEALTH ASPECTS

53. Caries reduction could be attained if colonization of S. mutans could be prevented or reduced at the time of eruption of both primary and permanent teeth. Caries vaccine can be a successful adjunct to other caries-preventive measures. PUBLIC HEALTH ASPECTS

54. Identify virulence agents Design means to induce protective response Animal model Human tests Caries vaccines response requirements: -interfere with early colonization -not necessarily bactericidal -non-inflamatory response -persistent response -site directed response (oral cavity) PRODUCTION OF DENTAL CARIES VACCINE