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A.J. Almeida, 2007
VACCINATION STRATEGIES USING
MICRO- AND NANOPARTICLES
António J. Almeida
Research Institute for Medicines and Pharmaceutical Sciences (iMed.UL) Faculdade de FarmáciaUniversidade de Lisboa
Universidad de sevill, Facultad de Farmacia, 2007
A.J. Almeida, 2007
A BRIEF HISTORY
VACCINE – From the latin vacca (cow)
Edward Jenner (1749-1823)
2
A.J. Almeida, 2007
A BRIEF HISTORY
A.J. Almeida, 2007
A BRIEF HISTORY
3
A.J. Almeida, 2007
A BRIEF HISTORY
Louis Pasteur (1822-1895)
A.J. Almeida, 2007
A BRIEF HISTORY
XV cent. - In China healthy people acquired immunity against smallpox by sniffing powdered smallpox pustulles or by inserting them into small cuts in the skin (“variolation”).
1796 - Edward Jenner conducts the first clinical investigations on vaccination with cowpox and smallpox viruses.
1875-1930 - Louis Pasteur - first attenuation of vaccines.
Robert Koch - methodology, etiology, hypersensitivity, postulates.
Emil von Behring - antibodies and immunotherapy.
Paul Ehrlich - specific receptor-ligand binding, specific chemotherapy, antibody quantificaton.
By 1929 - Humoral immunologic phenomena described; Immunotherapy dominates the field; Credible and useful vaccines (smallpox and rabies, killed and/or attenuated typhoid, shigella, cholera, plague, diphtheria, tetanus, pertussis, and tuberculosis)
VACCINE – From the latin vacca (cow)
4
A.J. Almeida, 2007
TYPES OF TRADITIONAL VACCINES
Vaccines containing killed microorganismsPreviously virulent micro-organisms that have been killed with chemicals or heat (ex. vaccines against flu, cholera, bubonic plague, and hepatitis A).
Vaccines containing live, attenuated microorganismsLive micro-organisms that have been cultivated under conditions that disable their virulent properties. They typically provoke more durable immunological responses and are the preferred type for healthy adults (ex. yellow fever, measles, rubella, and mumps).
Toxoid-based vaccinesInactivated toxic compounds from micro-organisms in cases where these (rather than the micro-organism itself) cause illness (ex. tetanus and diphtheria).
Subunit vaccinesRather than introducing a whole inactivated or attenuated micro-organism to an immune system, a fragment of it can create an immune response (ex. vaccine against HBV and vaccine against Human Papillomavirus (HPV).
A.J. Almeida, 2007
INNOVATIVE VACCINES
Conjugate VaccinesLinking poorly immunogenic polysaccharide outer coats to proteins (e.g. toxins) so that the immune system can be led to recognize the polysaccharide as if it were a protein antigen (ex. Haemophilus influenzae type B vaccine).
Recombinant Vectors
Combining the physiology of one micro-organism and the DNA of the other, so that immunity can be created against diseases that have complex infection processes.
DNA Vaccination
It works by insertion (and expression, triggering immune system recognition) into human or animal cells, of viral or bacterial DNA. Some cells of the immune system that recognize the proteins expressed will mount an attack against these proteins and cells expressing them.
5
A.J. Almeida, 2007
VACCINES: BASIC FACTS
• Pure recombinant or synthetic antigens used in modern day vaccines are generally far less immunogenic than older style live or killed whole organism vaccines.
• There is a major need for improved and more powerful adjuvants for use in these vaccines.
• With few exceptions vaccines are delivered parenterally.
• The delivery of antigens at mucosal surfaces (nasal, oral, pulmonary, urogenital) stimulates protective immune responses in both systemic and mucosal compartments due to the dissemination of antigen-sensitised cells to other tissues.
A.J. Almeida, 2007
VACCINE FORMULATION
VACCINE
ANTIGENSInactivated organismsAttenuated organisms
Isolated and purified proteins, glycoproteins, and carbohydrates
IMMUNE POTENTIATORSBacterial productsToxins and lipids
Nucleic acids, cytokynes, peptidesPeptidoglycans, hormones
Carbohydrates,
Vaccine
Adjuvants
DELIVERY SYSTEMSMineral salts
Microparticles
Emulsions
Liposomes
6
A.J. Almeida, 2007
VACCINE ADJUVANTS
AdjuvantsFrom the Latin adjuvare, meaning "to help". Component that increases specificimmune responses to the antigen.
A very special type of excipients
Safely and effectively used since 1925 when they were discovered by G. Ramon who found that the antitoxin response to tetanus and diphtheria was increased by injecting these vaccines with additional compounds such as agar, tapioca, lecithin, starch oil, saponin, bread crumbs!
Ramon, G (1925) Bull Soc Cent Med Vet 101, 227-234.
A.J. Almeida, 2007
VACCINE ADJUVANTS: REQUIRED PROPERTIES
• Chemically pure and defined composition
• Act only to potentiate the vaccine
• Non-toxic or has a negligible toxicity at the dose range for effective adjuvanticity
• Stimulates a strong humoral and/or T cell immune response
• Provides good immunological memory or long-term immunity
• Does not induce autoimmunity
• Non-mutagenic, carcinogenic or teratogenic
• Non-pyrogenic
• Stable under broad ranges of storage time, temperature, and pH
• Biodegradable/biocompatible
Multi enim sunt vocati, pauci vero electiSt. Matthew’s Gospel, 22, 14
7
A.J. Almeida, 2007
VACCINE ADJUVANTS
PARTICULATE ADJUVANTS• Aluminium salts• W/O and O/W emulsions• Immunostimulating complexes (ISCOMs)• Liposomes• Microparticles and nanoparticles• Proteasomes/virosomes (IRIVs)
NON-PARTICULATE ADJUVANTS• Muramyl-dipeptide (MDP)• Non-ionic block copolymers (POE, POP)• Saponins (Quil-A, Quil-21)• Lipid A• Cytokines (IL1, IL2, IL4, γ-INF)• Carbohydrate polymers (mannan, glucan)• Bacterial toxins (CTB, LTB)
ADJUVANT COMBINATIONS• Freund’s adjuvant• Chiron MF59• Syntex adjuvant formulation (SAF)
A.J. Almeida, 2007
VACCINE ADJUVANTS: MODE OF ACTION
Immunomodulation Generally small molecules or proteins which modify the cytokine network.
Presentation Generally amphipatic molecules or complexes which interact with antigen in its native form.
CTL induction Particles which can entrap the antigen and fuse or disrupt cell membranes; w/o emulsions for direct attachment of peptide to cell surface MHC-1.
Targeting Particulate carriers which entrap the antigen and interact with APCs.
Carbohydrates that target lectin receptors on APCs.
Depot generation Microsphere, nanoparticles, w/o emulsions, alum.
8
A.J. Almeida, 2007
VACCINE ADJUVANTS
Adjuvants licensed for human use
• Aluminium salts (aluminum hydroxide, aluminum phosphate)
• Calcium phosphate
• MF 59 (squalene/water emulsion)
• IRIVs (imunistimulating reconstituted influenza virosomes)
A.J. Almeida, 2007
MICROSPHERES AS IMMUNOLOGICAL ADJUVANTS
Buffer (PBS)Empty microspheresTet/Vac/AdsMicroencapsulated (PLA/TT)
0 4 6 7 90.0
0.1
0.2
0.3
0.4
0.5
Time (weeks)
Imm
une
Res
pons
e (O
D 4
50 n
m)
Almeida and Alpar (1994). 2nd EUFEPS Congress
Immune response to i.m microencapsulated TT
9
A.J. Almeida, 2007 Almeida and Alpar (1994). 2nd EUFEPS Congress
Empty microspheresTet/Vac/Ads (0.1 µg)Tet/Vac/Ads (1.0 µg)PLA/TT (0.8 µm; 0.1 µg)PLA/TT (0.8 µm; 1.0 µg)PLA/TT (2.4 µm; 0.1 µg)PLA/TT (2.4 µm; 1.0 µg)PLA/TT (18.5 µm; 0.1 µg)PLA/TT (18.5 µm; 1.0 µg)
0 11 39 840.00
0.10
0.20
0.30
Time (days)
Imm
une
Res
pons
e (O
D 4
50 n
m)
MICROSPHERES AS IMMUNOLOGICAL ADJUVANTS
Immune response to i.m. microencapsulated TTinfluence of particle size
A.J. Almeida, 2007
MUCOSAL VACCINES
10
A.J. Almeida, 2007
MUCOSAL VACCINES
A.J. Almeida, 2007
THE COMMON MUCOSAL IMMUNE SYSTEM
Kyiono and Fukuyama (2004) Nat Rev Immunol
11
A.J. Almeida, 2007 Cheroutre and Madakamutil (2003). Nat Rev Immunol
ANTIGEN PROCESSING AFTER STIMULATION OF THE GALT
A.J. Almeida, 2007
SCLN
Kuper et al (1992). Immunol Today
PCLN
NALT
M
APC
Mucosal response
SIgA
Systemic response (possibly via the spleen)
PARTICLE UPTAKE AT THE NALT AND ANTIGEN PROCESSING
12
A.J. Almeida, 2007
VACCINE ADJUVANTS
PARTICULATE ADJUVANTS• Aluminium salts• W/O and O/W emulsions• Immunostimulating complexes (ISCOMs)• Liposomes• Microparticles and nanoparticles• Proteasomes/virosomes (IRIVs)
NON-PARTICULATE ADJUVANTS• Muramyl-dipeptide (MDP)• Non-ionic block copolymers (POE, POP)• Saponins (Quil-A, Quil-21)• Lipid A• Cytokines (IL1, IL2, IL4; γ-INF)• Carbohydrate polymers (mannan, glucan)• Bacterial toxins (CTB, LTB)
ADJUVANT COMBINATIONS• Freund’s adjuvant• Chiron MF59• Syntex adjuvant formulation (SAF)
MUCOSALADJUVANTS
?
A.J. Almeida, 2007
• Microspheres and nanoparticles• Liposomes• Virosomes (IRIVs)• Mutant live bacteria • Bacterial invasins• Lectins• Bioadhesive/mucoadhesive polymers• E. coli heat-labile enterotoxin B subunit• Cholera toxin B subunit (CTB)• Monoclonal antibodies• Vitamin B12• Vitamin E• Glycodeoxycholic acid• poly-ornithine• Dimethyl-β-cyclodextrin• Spermine
CARRIER SYSTEMS/ADJUVANTS FOR MUCOSALLY ADMINISTERED ANTIGENS
13
A.J. Almeida, 2007
CyDs IN VACCINE FORMULATION
A.J. Almeida, 2007
CYCLODEXTRINS AS PHARMACEUTICAL EXCIPIENTS (1)
Formation of inclusion complexes with various molecules.
Modification of physical and chemical properties of incorporated guest compounds.
• Stabilization of drugs and excipients during storage or processing.
• Taste and odour masking.
• Conversion of liquid materials to dry form.
• Improvement of drug solubility in water.
• Emulsification of drugs.
• Controlled release of drugs.
14
A.J. Almeida, 2007
• Peptide and protein carriers
Stabilization (chemical chaperones).
Protection against enzymatic degradation
Chemical modification of enzymes.
CYCLODEXTRINS AS PHARMACEUTICAL EXCIPIENTS (2)
CYDs as vaccine adjuvants ?
A.J. Almeida, 2007
CyDs ACT AS STABILISING AGENTS FOR MICROENCAPSULATED TT
Johansen et al (1998). Pharm Res 15: 1103-1110
Additive Encapsulation efficiency (%)
Type Content (%) Fluorimetry ELISA
- - 74.2 6.1
Trehalose 15 93.5 5.8
BSA 5 - 17.9
α−CD 10 75.7 3.3
β-CD 15 76.2 6.7
γ-HPCD 15 90.0 10.3
• Tetanus Toxoid (TT) - 150 KDa
• PLGA 50:50 microspheres
• Spray-drying of w/o emulsions
BSA
TRH
γ-HPCD
TT
15
A.J. Almeida, 2007
HP-β-CyD REDUCES HAEMOLYTIC ACTIVITY OF SAPONIN ADJUVANTS
Waite et al (2001). Vaccine 19: 3957-3967
• Evaluation of the safety and tolerance of saponin adjuvant QS-21
• In vitro haemolysis assay
Irie and Uekama (1999). Adv Drug Deliv Rev 36: 101-123
HP-β-CyD
A.J. Almeida, 2007
HP-β-CyDs AS PAIN REDUCING AGENTS IN VACCINE I.M. VACCINES
• Evaluation of the safety and tolerance of saponin adjuvant QS-21
• Double-blind, randomised trial
• 15 human volunteers
Waite et al (2001). Vaccine 19: 3957-3967
16
A.J. Almeida, 2007
SULFOLIPO-CyDs AS A VACCINE ADJUVANT
Hilgers et al (1999). Vaccine 17: 219-228
• Inclusion of sulfo-lipo CyDs in a O/W emulsion (squalane in water):
↑ physical stability of the formulation;
↑ adjuvanticity
↓ reactogenicity
Reactogenicity
A.J. Almeida, 2007
SULFOLIPO-CyDs AS A VACCINE ADJUVANT
Romera et al (2001). Vaccine 19: 132-141
• Sulfo-lipo CyDs/squalane/W• Inactivated Bovine Herpes Virus Type 1 (BHV-1)• Calves• I.m immunisation at days 0, 46 and 226
Immunisation Challenge
17
A.J. Almeida, 2007
SULFOLIPO-CyDs AS A VACCINE ADJUVANT
• Sulfo-lipo CyDs/squalane/W
• Pseudorabies virus DNA
• Pigs
• S.c immunisation at days 0, 28, 56, and 84
Romera et al (2001). Vaccine 19: 132-141
A.J. Almeida, 2007
• Peptide and protein carriers
Stabilization (chemical chaperones). Protection against enzymatic degradationChemical modification of enzymes.
• Absorption enhancers at the mucosal sites (mainly nasal)
CYCLODEXTRINS AS PHARMACEUTICAL EXCIPIENTS (2)
CyDs as mucosal vaccineadjuvants ?
18
A.J. Almeida, 2007 Kamphorst et al (2004). Eur J Pharm Biopharm 57: 199-205
IMMUNE RESPONSE OVA-CyD COMPLEXES
• Ovalbumin (OVA) - 43 KDa
• B6D2F1 mice
• Oral administration at days 1 and 14
• S.c. administration at day 1
oral
subcutaneous
A.J. Almeida, 2007 Alpar et al (2001). Adv Drug Deliv Rev 51: 173-201
CyDs AS PENETRATION ENHANCERS FOR NASALLY ADMINISTERED TT
• Tetanus Toxoid (TT) - 150 KDa
• BALB/c mice
• I.n. administration at days 1 and 49
• Dimethyl-β-cyclodextrin (CYC)
• Glycodeoxycholic acid (BS)
19
A.J. Almeida, 2007
CyDs AS PENETRATION ENHANCERS FOR NASALLY ADMINISTERED DT
• Diphtheria toxoid (DT) - 65 KDa
• BALB/c mice
• I.n. administration at days 1 and 49
• Dimethyl-β-cyclodextrin (CYC)
• Glycodeoxycholic acid (BS)
Alpar et al (2001). Adv Drug Deliv Rev 51: 173-201
A.J. Almeida, 2007 Kuper et al (1992). Immunol Today 13: 219-224
SCLNPCLN
NALT
M
APC
Mucosal response
SIgA
Systemic response (possibly via the spleen)
ANTIGEN UPTAKE AT THE NALT AND ANTIGEN PROCESSING
20
A.J. Almeida, 2007
• CyDs play an important role as chemical chaperones, thus preserving antigen integrity and
immunogenicity during storage or processing, which is certainly useful in vaccine
formulation.
• The inclusion of CyDs in emulsion or saponin-adjuvanted parenteral vaccines reduces
reactogenicity.
• CyDs may also control the rate of antigen release from microsphere vaccine formulations, thus influencing the depot effect.
• CyDs may be included in suitable vaccine formulations for immunisation purposes upon uptake at mucosal sites.
• Antigen uptake and translocation across the nasal mucosa may be significantly increased by CyDs, resulting in high specific systemic humoral immune responses.
• The role of CyDs as vaccine components is far from being fully understood. Further understanding would promote the optimisation of vaccine delivery systems.
SOME REMARKS ON CyDs AS VACCINE CARRIERS
A.J. Almeida, 2007
MUCOSAL VACCINATION AGAINST STRANGLES
21
A.J. Almeida, 2007
BACKGROUND
PLGA
PCL/Chi
SLN
SLN/SCF
SLM/SCF
Kyiono and Fukuyama (2004) Nat Rev Immunol
A.J. Almeida, 2007
STRANGLES
• Infection of the respiratory tract of equidae caused by nasopharyngeal infection by Streptococcus equi subsp. equi that spreads rapidly to the lymph nodes of the head.
• Characterised by an acute, febrile, suppurative, retropharyngeal and submandibularlymphadenitis, with abscess capsule formation that will drain pus to the nearest site of egress (skin or upper respiratory tract mucosa).
• Abscesses can form in other body organs and their rupture may be fatal.
• Morbidity may be as high as 100% and infection may be fatal.
• M-like protein is believed to induce both local and systemic immunity.
22
A.J. Almeida, 2007
• Antigens delivered intranasally avoid the proteolytic and
acidic environment of the stomach, encountered by orally
administered antigens.
• Immune responses elicited by intranasal vaccination are
generally stronger than those induced by the same antigens
delivered orally.
• Systemic immune responses, are generally easier to
achieve by intranasal delivery than by oral delivery.
• The respiratory tract is less colonised by commensal
microrganisms than the gut, thereby decreasing
interference of vaccine-strain uptake by ecological
competition.
THE NASAL ROUTE OF IMMUNISATION
A.J. Almeida, 2007
Safety concerns, due to reactions including nasal discharge, abscessation of lymph nodes and other sites, allergic reactions, and purpura-like signs.
IMMUNISATION AGAINST STRANGLES
Name Antigen Adjuvant Route Company
Equivac® S Bacterial lysate i.m Pfizer
Strepvax II® SeM-based Aluminiumhydroxide
i.m. BoehringerIngelheim
Strepguard® SeM-based Havlogen® i.m. Intervet
Equilis Strep E® Live mutantS. equi
- submucosalinjection
Intervet
Pinnacle® Live attenuatedS. equi
- intranasal FortDodge
23
A.J. Almeida, 2007 http://www.wyke-equine.co.uk/equine_nebulisers.htm
Regular vaccination program:S. equi M-like protein (SeM) rich extracts associated with nanoparticulate carriers.
IMMUNISATION AGAINST STRANGLES: AIMS
A.J. Almeida, 2007
Vaccine Adjuvants Tested
• Aluminium hydroxide (Hoffman et al, 1991)
• Freund’s complete adjuvant (Jean-François et al, 1991)
• Monophosphoryl lipid A / trehalose 6,6’-dimycolate (Timoney and Guan, 1996)
• Havlogen® (polyacrylate cross-linked with polyallylsucrose) (Sheoran et al, 1997)
• Sucrose acetate isobutyrate (Nally et al, 2001)
• Cholera toxin (Sheoran et al, 2002)
• E. coli heat-labile enterotoxin B subunit (Flock et al, 2004)
• PLGA microspheres (Azevedo et al, 2006)
• ISCOM’s (Flock et al, 2006)
IMMUNISATION AGAINST STRANGLES
24
A.J. Almeida, 2007
Production and characterisation of an effective mucosal vaccine against strangles,
prepared by association of S. equi antigens in micro / nanoparticles.
Nasal route
Oral route
Specific SIgA
IMMUNE RESPONSE AFTER NASAL DELIVERY OF S. equi ANTIGENS
i.m. routeSpecific IgG
A.J. Almeida, 2007
Streptococcusequi
Fermentation(30 l)
Inactivation(formaldehyde) Disruption
Enzymaticextraction
IMMUNE RESPONSE AFTER NASAL DELIVERY OF S. equi ANTIGENS
Freeze-dryingCharacterisation(physical, chemical,
pharmaceutical)
Micro/Nanoparticles
Subunit antigen(SeM)
In vivo studies
25
A.J. Almeida, 2007 Azevedo et al (2006) Eur J Pharm Biopharm
MICROENCAPSULATION OF S. EQUI ANTIGENS
66.2 KDa
45.0 KDa
1 2 3 4 5
010203040506070
0 5 10 15 20 25 30
Time (day)
Prot
ein
rele
ased
(%)
Disrupted S. equi(6.0 μm; 80%EE)
Enzymatic extract(2.1μm; 23% EE)
Whole-killed S. equi(6.0 μm; 100% EE)
A.J. Almeida, 2007
SERUM IMMUNE RESPONSE AFTER NASAL DELIVERY OF S. equi ANTIGENS
WKSePLGA-WKSeSe lysatePLGA-Se lysate
0.0
0.1
0.2
0.3
0.4
0 28 42Time (day)
IgG
Titr
e (O
D 4
05 n
m)
Nasal route
0.0
0.4
0.8
1.2
1.6
0 28 42Time (day)
IgG
Titr
e (O
D 4
05 n
m)
i.m. route
Azevedo et al (2006) Eur J Pharm Biopharm
(n=5 per group; pooled samples)
26
A.J. Almeida, 2007 Almeida and Alpar (1997). In: Antigen Delivery Systems
MUCOSAL IMMUNE RESPONSE UPON IMMUNISATION WITH PLGA-TT
• Tetanus Toxoid (TT) in PLGA microspheres
• BALB/c mice
• Intranasal, oral and im. Immunisation at days 1 and 49
A.J. Almeida, 2007
Challenge with a virulent strain of S. equi(according to J.F.Timoney, U.S. Patent 5,183,659, 1993)
PROTECTION AFTER NASAL DELIVERY OF S. EQUI ANTIGENS
Azevedo et al (2006) Eur J Pharm Biopharm
Group Preparation Route Morbidity (%) Survival (%)
1 WKSe-PLGA microspheres nasal 20 100
2 WKSe-PLGA microspheres i.m. 20 100
3 Se-lysate-PLGA microspheres nasal 20 100
4 Se-lysate-PLGA microspheres i.m. 20 80
5 Free WKSe nasal 100 0
6 Free WKSe i.m. 100 0
7 Free Se-lysate nasal 100 0
8 Free Se-lysate i.m. 100 0
(n=5 per group)
27
A.J. Almeida, 2007 http://www.ifisica.uaslp.mx/~elias/projects_fichiers/ProteinPoly/2Proteinpoly.jpg
PROTEIN ADSORPTION ONTO MICRO / NANOPARTICLES
• Association to colloidal carriers avoiding harsh formulation procedures
• A way of increasing the loading of the antigen-containing nanoparticles.
• Protection from degradation after administration
• Avoid the possible degradation of protein antigens caused by the contact with organic solvents
• Slow-release of antigen
ADSORPTION AS A VACCINE FORMULATION STRATEGY
ANTIGEN ADSORPTION
• Standard procedure to formulate aluminium-adjuvanted vaccines
A.J. Almeida, 2007
Recovered particles
PROTEIN ADSORPTION ONTO PLA MICROSPHERES
Centrifugation, washing and
drying
Incubation in a shaking water
bath (25ºC/o.n.)
Microspheres + protein in PBS
Adsorption Procedure
28
A.J. Almeida, 2007
PROTEIN ADSORPTION ONTO PLA MICROSPHERES
A.J. Almeida (1993); Alpar et al (1994) Eur J Pharm Biopharm
T.A. Barber (1993)
Adsorption Process
160120804000
2
4
6
8
10
12
14
16
Equilibrium concentration (µg/ml)
Am
ount
ads
obed
(µg/
mg)
160120804000
2
4
6
8
10
12
14
16
C/(x
/m) (
mg/
ml)
Equilibrium concentration (μg/ml)
Tetanus Toxoid
γ-Globulin
80060040020000
20
40
60
80
100
120
Equilibrium concentration (µg/ml)
x/m
(µg/
mg)
(mg/
ml)
800700600500400300200100000
2
4
6
8
10
Equilibrium concentration (μg/ml)
C/(x
/m) (
mg/
ml)
(mg/
ml)
17501500125010007505002500
0
20
40
60
80
100
120
140
Equilibrium concentration (µg/ml)
Am
ount
ads
orbe
d (µ
g/m
g)
175015001250100075050025000
2
4
6
8
10
12
14
Equilibrium concentration (μg/ml)
C/(x
/m) (
mg/
ml)
BSA
A.J. Almeida, 2007 Almeida et al (1993) J Pharm Pharmacol
IMMUNE RESPONSE AFTER INTRANASAL DELIVERY OF TETANUS TOXOID
PBSSoluble TT (60 µg) PLA-adsorbed TT (60 µg)
0 2 4 7 15101
102
103
104
105
Time (week)
Imm
une
Res
pons
e (Ig
Gtit
re)
29
A.J. Almeida, 2007
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
0 18 26 39
Time (day)
IgG
Titr
e (a
dsor
bed
CTB
/free
CTB
)
Free CTB (10 μg/dose)
Adsorbed CTB (0.25 μg/dose)
Cholera toxin B subunit (0.8 μm PLA particles)
Almeida et al (1992). Biochem Soc Trans
IMMUNE RESPONSE TO ORALLY DELIVERED CTB
A.J. Almeida, 2007
PLA AND PCL NANOPARTICLES
1 2 3 4 5 6 7 8
1 2 3 4 5 6 7 8 9
Adsorption of S. equi Enzymatic Extract
PLA/CS (+) PLA/PVA (-)
VMD (nm) 719.9±2.18 414.4±3.57
Zeta potential (mV) +21.2±1.23 -29.9±3.21
Loading efficiency (%) 12.6±0.8 14.9±0.9
PVA/CSLV
Total Protein amount (μg/mg particles)
87
100
96
72
0 50 100 150 200PVA/PVA
PCL
PLA
Florindo et al (2005). MicroBiotec’05
30
A.J. Almeida, 2007
POLY-ε-CAPROLACTONE MICROSPHERES
(-) Microspheres PCL/PVA
(+) Microspheres PCL/chitosan
+37,2±1,72,08±0,91(+)-PCL/chitosan
-31,2±2,02,27±1,56(-)-PCL/PVA
Zeta Potencial (mV)Size (μm)Formulation
Adsorption of S. equi Enzymatic Extract
Florindo et al (2005). MicroBiotec’05
Seru
msp
ecifi
cIgG
10
100
1000
45 Days 90 Days 180 Days
PCL-PVAPCL-CHITOSAN
FREE
Seru
msp
ecifi
cIgG
10
100
1000
45 Days 90 Days 180 Days
PCL-PVAPCL-CHITOSAN
FREE
A.J. Almeida, 2007
PLA AND PCL NANOPARTICLES
Adsorption of S. equi Enzymatic Extract
PLA/CS (+) PLA/PVA (-)
VMD (nm) 719.9±2.18 414.4±3.57
Zeta potential (mV) +21.2±1.23 -29.9±3.21
Loading efficiency (%) 12.6±0.8 14.9±0.9
Florindo et al (2007). Proceed Int Symp Cont Rel Bioact Mater.
Uptake of PCL/chitosan/FITC-BSA nanoparticlesby macrophages (J774A1 cell line)
80 min0 min
Immunisation studies• S. equi enzymatic extract adsorbed
onto PCL and PLA nanoparticlesenhanced serum specific IgG, IgG1 and IgG2a as well as mucosal IgAresponses.
• Antibodies and citokine titers (IL-2, IL-4, IL-6, IFN-γ) predict protection.
31
A.J. Almeida, 2007
CONCLUSIONS
• The successful development of mucosal particulate vaccines depends on the understanding of their physico-chemical and biological properties.
• Association of particulate systems with other adjuvants or absoprtion enhancers (e.g. CTB, CyDs) plays an important role is certainly useful in vaccine formulation.
• Further understanding the role absorption enhancers would promote the optimisation of particulate mucosal vaccine delivery systems.
• Microencapsulated S. equi lysates or whole-killed cells given by the intranasal and intramuscular caused full protection against a virulent strain upon experimental infection.
• Adsorption of S. equi enzymatic extract onto PCL microspheres enhanced serum specific IgG antibody responses, even 180 days after a single dose administration.
• The delivery of S. equi antigens is receiving further attention in order to fully understand the mechanisms responsible for their strong activity upon association to microspheres/nanoparticles.
A.J. Almeida, 2007
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