A therapeu*c nanopar*cle vaccine against Trypanosoma cruzi in a mouse model of Chagas disease
Meagan A. Barry1,2,3, Qian Wang4, Kathryn M. Jones1,4, Michael J. Heffernan4, Eric Dumonteil5, & Peter J. Hotez1,3,4 1Na*onal School of Tropical Medicine, 2Medical Scien*st Training Program, 3Program in Transla*onal Biology and Molecular Medicine, 4Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA.
5Laboratory of Parasitology, Universidad Autonoma de Yucatan, Merida, Mexico.
VACCINE FORMULATION
Chagas disease is a neglected tropical disease of great importance in the Americas, with 7-‐8 million people infected. The causa*ve agent is Trypanosoma cruzi (T. cruzi), and results in an acute febrile illness that progresses to chronic chagasic cardiomyopathy in 30% of pa*ents. Current pharmacological treatments are plagued by significant side effects, poor efficacy, and are contraindicated in pregnancy. There is an urgent need for new treatment modali*es. A therapeu*c vaccine for Chagas disease has poten*al advantages that include cost savings, reduced adverse effects, and the poten*al to be used as a replacement for current therapies or when paired with chemotherapy. Prior work in mice has iden*fied an efficacious T. cruzi an*gen (Tc24). We hypothesize that the recombinant Tc24, when delivered in a poly(lac<c-‐co-‐glycolic acid) (PLGA) nanopar<cle delivery system with CpG mo<f-‐containing oligodeoxynucleo<des (ODN) as an immunomodulatory adjuvant, will induce a TH1-‐mediated CD8+ T cell immune response, ul<mately resul<ng in decreased parasitemia, increased survival, and reduced cardiac pathology in our murine model.
ACKNOWLEDGEMENTS
Our nanopar*cle vaccine, comprised of Tc24 and CpG ODN encapsulated in PLGA nanopar*cles, produced a robust TH1-‐baised immune response. When tested for therapeu*c efficacy in T. cruzi infected BALB/c mice, improved survival was seen. Addi*onally, there was a significant reduc*on in the number of parasites in the cardiac *ssue, sugges*ng protec*on from parasite-‐driven cardiac damage. These data demonstrate the immunogenicity and efficacy of a Tc24/CpG ODN nanopar<cle vaccine and are convincing evidence for a poten<al new therapeu<c vaccine against Chagas disease.
We thank Coreen M. Beaumier and Brian P. Keegen for their invaluable help. Meagan Barry, e-‐mail: [email protected]
Baylor College of Medicine, 1 Baylor Plaza, Houston, TX 77030
MEDICAL SCIENTIST TRAINING PROGRAM
M.D./PH.D.
OO
O
Ox y
• Flagellar Ca2+ binding protein
• Expressed in all developmental stages
• Highly immunogenic
An*gen: Tc24
Delivery System: PLGA nanopar*cles
• Biocompa*ble • Biodegradable • FDA approved as an
excipient
Study Groups PLGA[Tc24]
Alum with Tc24
Soluble Tc24
0 5 10 15 20 250
50
100
150
200
Days post-injection
Perc
ent
of in
itial
flu
ores
cenc
e in
tens
ity PLGA[Tc24]Alum with Tc24Soluble Tc24
AF660-‐labeled Tc24
In vivo Imaging
Inject SQ
BALB/c
IMMUNOGENICITY
KINETICS OF ANTIGEN DISPERSAL
500 T. cruzi H1 trypomas*gotes
Study Groups
PLGA[Tc24] +PLGA[CpG]
Unvaccinated
PLGA[Tc24]
PLGA[CpG]
0 10 20 30 40 500
50
100
Perc
ent s
urvi
val
Days
PLGA[Tc24] + PLGA[CpG] UnvaccinatedPLGA[Tc24]PLGA[CpG]
d0 d24 d7 d14 d1 d3 d5 d2 d10 d19
FINDINGS: The PLGA nanopar*cle serves as a depot, similar to alum, allowing a prolonged release of protein over *me
Soluble Tc24
Tc24 + Alum
PLGA
[Tc24]
10min 4hr 1d 10d
Study Groups
Group Name A B C D E F
Nanopar*cles (mg) 2 1 0.5 0.25 0.13 -‐
Tc24 (ug) 14.4 7.2 3.6 1.8 0.9 -‐
CpG (ug) 7.6 3.8 1.9 0.95 0.48 -‐
Immunize SQ
BALB/c d0 d56 d28
FINDINGS: A sta*s*cally significant TH1-‐biased immune response with increased dose
Representa*ve Mice Dispersal of Fluorescently Labeled Tc24 Over Time
Tc24-‐specific IFN-‐γ Producing Cells Tc24-‐specific IgG2a An*body Titers
Infect IP
Immunize SQ
d0 d50 d14 d7
THERAPEUTIC EFFICACY
Survival Through Acute Phase of Disease Parasite Burden In Cardiac Tissue
Cardiac Tissue
: Vaccinated
INTRODUCTION
CONCLUSIONS
FINDINGS: The vaccine results in improved survival and significant reduc*on in parasites in the cardiac *ssue
Am
astig
ote
Nes
ts in
car
diac
tiss
uepe
r 20
mic
rosc
ope
field
s (4
00x)
PLGA[Tc2
4] + P
LGA[CpG]
Unvacc
inat
ed
PLGA[Tc2
4]
PLGA[CpG]
0
100
200
300p < 0.01
Key
Alive at d50 post-infectionDead at d50 post-infection1.90
1.95
2.00
2.05
2.10
Alive at d50 post-infectionDead at d50 post-infection
Legend
Am
astig
ote
Nes
ts in
car
diac
tiss
uepe
r 20
mic
rosc
ope
field
s (4
00x)
PLGA[Tc2
4] + P
LGA[CpG]
Unvacc
inat
ed
PLGA[Tc2
4]
PLGA[CpG]
0
100
200
300p < 0.01
Cardiac Tissue
: Unvaccinated
• Short, synthe*c DNA that contains CpG mo*fs
• Toll like receptor (TLR) 9 agonist
Adjuvant: CpG ODN
Poly(lac*c-‐co-‐glycolic acid)
Characteriza*on of Nanopar*cles
• Morphology & size • Size distribu*on • Loading efficacy
A B C D E F
Study Groups
A B C D E F
Study Groups
BALB/c