caries vaccine

1. Caries Vaccine
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CONTENTS
History
Prevention of dental caries by immunization
Mechanism of action of caries vaccine
Active immunization / vaccination
Passive immunization
Routes of administration
1. Oral
2. Systemic (subcutaneous)
3. Active gingio-salivary
4. Intranasal
5. Tonsillar
6. Minor salivary gland
7. Rectal
Barriers to use of vaccine
Recent advances in Caries Vaccine production:
1. Sub-unit vaccines
2. DNA vaccines
3. Adjuvant – Cholera toxin, Salmonella toxin
4. Liposomes
5. Biodegradable micro spheres
6. Bio-adhesives
7. Plantigens and Plantibodies
8. Advances in route and time of vaccine administration.
Conclusion
Reference

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HISTORY
- Edward Jenner was the pioneer in the field of immunization. He developed a
vaccine against small pox.
- Louis Pasteur succeeded in developing vaccine against anthrax and rabies.
Based on the above concepts, vaccine for dental caries was also tried out.
The first caries immunization experiments were performed in the 1930s,
lactobacillus was used as an antigen. Immunization against lactobacillus was only
partially successful and could not provide adequate protection against caries, this
was because it was a more a consequence than cause of caries initiation and was
present only in deep carious.
Hence, streptococcus mutans became the target in virtually all immunization
experiments after their redetection in 1960. It colonizing ability in early dental
plaque.
Prevention of dental caries by immunization :
As dental decay fulfils the criteria of an infections disease, the possibility of
preventing it by vaccination has been pursued.
- The rationale is that immunization with MS should induce an immune
response which might prevent the organism from colonizing the tooth
surface and thereby prevent decay.
The attractions of this approach were
- A vaccine could be administered before the deciduous dentition has erupted
(6 mns of age) it would prevent the disease in the children, who show the
greatest incidence of caries.

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- The vaccine could be given at the same time as that against diphtheria and
tetanus.
Immunity could be boosted at intervals there after to provide life long
protection.
- Individual parents would make the decision whether to have their child
vaccinated the principle of individual freedom would not be violated.
- The existing delivery system of immunization could be used, without any
financial border being incurred.
Mechanism of action of caries vaccine :
As with any other immunization mechanism, caries immunization can be
active as passive.
(i) Active immunization / vaccination
- Vaccination involves administration of antigen into the host, stimulating
host immune response to produce antibodies against the antigen.
- Either whole antigen or subunit vaccines can be administered. Attenuated
whole streptococcus mutans can be administered as antigen.
- The disadvantage of this is that the antigen may contain the fimbrial M
protein, which cross reacts with heart tissue
- Active immunization can be administered either to stimulate systemic
antibody production or mucosal antibody production.
- Earlier studies of mucosal immunization were done by injecting MS cells or
purified GTF into salivary gland region to induce IgA secretion. This had the
disadvantage of altering the function of the gland.
- Advantage of active immunization is that is results in enhanced immune
responses with possibilities of longer periods of protection.

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- Disadvantage is that it cannot be used in immune compromised individuals.
ii) Passive immunization :
- In this route, ready made antibodies against streptococcus mutans antigens
are isolated and administered to provide immediate protection against caries.
- It can be achieved in the following ways.
a) Local route :
- Topical application of mouse monoclonal antibodies to Ag I/II to cleaned
tooth surfaces.
b) Systemic route :
- By administering milk containing IgG antibodies from Cows and Egg Yolk
antibodies.
- Advantages of passive immunization are that immediate protection can be
achieved.
- Can be employed in immune compromised patients also.
Disadvantages :
- Transient protection
- Repeated administration is needed for effective vaccination.

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Routes of administration :
In general and routes of immunization have been used with S. mutans
i) Oral
ii) Systemic (subcutaneous)
iii)Active gingio-salivary
iv) Intranasal
v) Tonsillar
vi) Minor salivary gland
vii) Rectal
i) Oral :
- May of the earlier studies relied on oral induction by immunity in the gut
associated lymphoid tissue (GALT) to elicit protective immune responses.
- Here the antigen was applied by oral feeding, gastric intubation or in form of
vaccine containing capsules or liposomes.
Disadvantages :
- Not ideal for reasons including detrimental effects of stomach acidity on
antigen.
- Inductive sites are relatively distant
- The rise in secretary antibodies produced was of short and duration
- Immunological memory is secretary IgA responses is rather limited and this
may curtail the value of oral immunization.
- The immunological response initiated is predominantly by IgA antibodies.

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ii) Intranasal :
- More recently attempts have been made to induce protective immunity in
mucosal inductive sites that are in closer anatomical relationship to the oral
cavity.
- Intranasal installation of antigen, targets the nasal-associated lymphoid
tissue (NALT).
iii) Tonsillar :
- Tonsillar tissue contains elements of immune induction of both secretary
IgA and IgG responses.
- Palatine tonsils especially the nasopharyngeal tonsils have been known to
contribute precursor cells to mucosal effector sites such as salivary glands.
iv) Minor salivary gland :
- Minor salivary glands that populate the lips, cheeks, and soft palate can be
potential routes for mucosal induction of salivary immune responses.
- Because of short, broad secretary ducts that facilitate retrograde access of
bacteria and their products.
Advantages :
- Lower doses of antigen are required as degradation of the antigen by
protealytic enzymes and denaturated by acid is lower than the GIT.
- Induces both systemic and mucosal immunity
- Administration is relatively easy.
v) Rectal :
- More remote mucosal sites have also been investigated for inductive
potential.

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- Colorectal region as an inductive site has been suggested because of the fact
that this site has the highest concentration of lympho follicles in the lower
intestinal tract.
- Thus use of vaccine suppositories as one alternative for children in whom
respiratory ailments preclude use of intranasal application of vaccine.
vi) Subcutaneous route :
- It was used successfully in animal trials and elicited predominantly serum
IgG, IgM, and IgA antibodies.
- Transport of antibodies, complement, sensitized lymphocytes access via the
blood supply to the gingiva and then through the junctional epithelium into
crevicular fluid.
Disadvantages :
- May induce antibodies to heart muscle
v) Topical gingivo salivary immunization :
- This route has been exposed in order to exclude any potential systemic side
effects and to localize the immune response to the oral cavity.
- A prerequisite for successful gingival immunization was preparation of a
smaller molecular weight streptococcal antigen, as high molecular weight
antigen can’t penetrate the crevicular epithelial barrier.
Barriers to use of vaccine :
- Challenge presented by complex diet.
- Shift to other cariogenic serotypes or organisms
- Cross-reaction with heart tissue.

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- Dental caries is not considered a life threatening disease to warrant the use
of a vaccine for its prevention.
- Dental caries is considered a multifactorial disease of which microorganisms
are only one of the various factors.
Recent advances in Caries Vaccine production:
1. Sub-unit vaccines
2. DNA vaccines
3. Adjuvant – Cholera toxin, Salmonella toxin
4. Liposomes
5. Biodegradable micro spheres
6. Bio-adhesives
7. Plantigens and Plantibodies
8. Advances in route and time of vaccine administration.
1. SUB-UNIT VACCINES:
Previously, the whole vaccine was introduced into the host to produce an
antibody response. This had a potential disadvantage of cross-reaction with heart
muscle. Here a particular protein antigen of the organism is used as an antigen.
Syntheticpeptide vaccines based on putative functional domains of glucosyl
transferase are developed as sub-unit vaccines. They have the advantage of
specifically attacking the antigenic surfaces. Antigenic proteins of a different
disease causing organism can be designed to induce immunity to more than one
infection.

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2. DNA vaccines
The purpose of DNA vaccines is to make the antigenicity more specific and
long lasting. The basis for such DNA vaccines is that when a specific DNA is
administered into the system, the host can synthesize protein component coded by
the DNA. Cell wall protein antigen, of MS is considered a virulence factor because
it may mediate initial attachment of the organism to tooth surface. Anti caries
DNA vaccine is developed to express cell wall protein.
Lower number of carious lesions and high levels of salivary Ig A and serum
Ig G were observed experimental animals following a targeted salivary gland
administration of this DNA vaccine. However, the possibility of the induced DNA
to cause damage to the host genetic components has not been completely ruled out.
Thus further research is warranted to detect the safety of these vaccines.
3. Adjuvant
Adjuvants are molecules to which antigentic peptides are added to achieve a
potent immune response. Adjuvant enhances the antigenecity of the antigen by the
following ways;
- It acts as a deposit or reservoir, where the antigen can be released
progressively.
- The adjuvant is able to present the antigen directly to immune competent
cells.
- Some adjuvant acts as chemical immune stimulators of lymphoid cells.

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Common adjuvant that has been tried for a long time are;
a. Freund’s incomplete adjuvant – aluminum hydroxide or phosphate.
b. Freund’s complete adjuvant – Freund’s incomplete adjuvant with a suspension
of killed tubercule bacilli.
c. Silica particles, Beryllium sulfate.
d. Endotoxins.
However, important adjuvants used with caries vaccine antigens in the recent
research are ;
a. Mucosal adjuvants eg cholera toxin.- A1 subunit of cholera toxin is replaced
with chosen protein antigen segment and cholera toxin becomes a chimeric
immunogen.
b. Coupling with carrier microparticles.
c. Live bacterial vectors eg Attenuated Salmonella, BCG, normal oral flora etc.
oral administration with recombitant-streptococcus lactis IL1403
carrying S.mutans MT8148 surface protein antigen gene has been tried in
mice.
d. Live viral vectors eg Vaccina, adenovirus, polio replicons.
Thus the addition of adjuvant and antigen together are a significant
improvement in the caries vaccination research.
4. Liposomes
Liposomes are lipid vesicles lined by external liposomal membranes
composed of same lipids as the cell membrane. Any liposoluble antigen can be
incorporated to the lipid membrane and any hydro soluble antigen can be included

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in the internal cavity of the liposome. Studies in rats show doubling in the efficacy
of orally administered vaccine from 40% to 80% with the use of liposomes.
Changing lipid composition can modify particle size of liposomes. A first
population of small lipososme can deliver the antigen rapidly, while a second
population of larger liposome delivers antigen slowly. Thus sustained release of
antigen can be achieved.
5. ISCOM
ISCOM are solid particles generated by combining an antigen with a
biocompatible detergent and adjuvant, giving rise to minute structures of 35 nm.
Protein antigens of caries vaccine can be incorporated in them.
6. Biogradable Micro-spheres
Composition of microspheres is similar to surgical sutures. Antigens can be
incorporated into microspheres and released by non-enzymatic rapid hydrolysis.
Microspheres can be placed inside the host tissue and sustained long-term release
of antigen can be obtained.
7. Bio-adhesive
Bio-adhesive poly D,L-lactide-coglycolide (PLGA) microparticles can also
be used to incorporated antigens.
Liposomes, biospheres and bioadhesives have emerged out as effective
method to deliver antigen to the host system.
8. Plantigens and plantibodies

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Plants cells have protein synthesis machinery similar to humans. Thus plants
can be used to synthesise plantigens (antigens) and plantibodies (antibodies).
Researchers with transgenic plants started in 1983 with the use Tobacco
Plants. Later it was extended in various plants producing fruits and vegetables.
Thus eating a transgenic plant derived fruit will not only provide nutrients but also
provide protection against infectious diseases.
CARO Rx TM10 is the first clinically tested plantibody. Immediately after
professional cleaning of teeth with oral antiseptic solution, it ws applied several
times over two week period. Antibody treatment prevents adhesion of S.mutans to
teeth while colonization of other oral bacteria occurs unimpeded. Subjects treated
with this, remained caries free for about 6 months in the phase I clinical trials.
Phase II clinical trials are in progress now.
Advantages are large quantities of antibodies can be derived from plants.
Antibodies in apples, bananas makes the vaccination procedure feasible and
attractive to the general population.
Plantigens have a potential disadvantage of Rhizosecretion of antigen which
may contaminate the soil. Accidental transfer of genes to other plants via pollen
grains is also of great concern.
9. Advances in route and time of administration
Previously the exact time at which caries vaccine could be administered
remained a matter of confusion. Now it is proposed that it is better given at 6
months to one year of age after teeth have begun to emerge but before the mutans
streptococci bacteria have begun to colonize.

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Present studies state that mucosal immunization with antigens administered
through oral or intra-nasal routes and passive immunization with application and
use of transgenic plants can be effective in protection against and eradication of
dental caries.
10. Strain replacement therapy
It is a novel approach to prevent microbial diseases where a harmless
effector strain is permanently implanted in the host’s microflora. Naturally
occurring strain of S. mutans JH1000 has the property to presumptively colonize
the human oral cavity and aggressively displace indegeous wild strain by secreting
Mutacin 1140 a bacteriocin. It is an antibacterial substance produced by MS to
inhibit the growth of other bacteria.
CONCLUSION:
Though caries vaccine and replacement therapy are still in research state
now, they will become a reality in managing, preventing and eradicating this
disease. The present day dental practice is mainly concentrated on management of
carious lesions. As caries vaccine and caries eradication measures are introduced in
the clinical practice, in future, the work of the dentist will transform from caries
management to mere caries prevention methods.
REFERENCES
 AC Krithika, D Kandaswamy and V Gopi Krishna – Caries Vaccine – I ;
Today’s Myth!. JPHD 2004 : 4 ; 21 – 25.

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 B Krasse, CG Emilson and L Gahnberg – An anticaries vaccine ; Report
on status of research. Caries Res 1987; 21: 255 – 276.
 DJ Smith – Dental Caries Vaccines: Prospects and Concerns. Crit Rev
Oral Biol Med 2002 ; 13 : 335-349.
 MW Russell, G Hajishengallis, NK Childers and SM Michalek –
Secretory Immunity in Defense against Cariogenic Mutans Streptococci.
Caries Res 1999; 33: 4 -15.
 WM Edgar – Prevention of Caries : Immunology and Vaccination.
Prevention of Oral Diseases. 2nd Edition. Pg 109 – 114.