Liveattenuated pathogens as vaccine

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Live-attenuated pathogens as vaccine
Grow the pathogen in non-human cells.
Polio vaccine (Sabin) poliovirus grown in monkey
cells
Measles vaccine rubella virus grown in duck
embryo cells
TB vaccine (BCG) Mycobacterium bovis grown in
media with bile.
Attenuated pathogen induce immunity without
causing disease.
May regain virulence through mutation.
May cause disease in immunodeficient patients.
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Mucosal vaccine
Mucosal IgA
Systemic immunization give poor induction of
mucosal IgA.
Systemic IgG
Plasma cells induced in lymph nodes do not
express ?4?7 integrins and CCR10.
Problems of mucosal vaccine Degradation,
dilution Tolerance
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HIV
HIV (R5 strain) infects memory CD4 T cells.
receptor
CD4
gp120/gp41
CCR5
co-receptor
gp120
gp120 is covered with glycans.
Recessed CD4 binding site
CD4
gp120 trimer
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Co-receptor binding site on gp120 is formed after
CD4 binding.
gp41
gp120
Co-receptor binding
CD4 binding site
gp41
CD4
CCR5
CD4 T cell
Co-receptor binding
CD4 binding site
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gp120 HIV vaccine trial
(2003)
Vaxgen
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Antibody therapy
immunization
Isolate individual B cells
Activation of B cells that recognize different
epitopes.
Monoclonal antibody
Polyclonal antibody in serum
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Hybridoma
Immunized mouse
spleen
Myeloma (mouse tumor derived from plasma cells)
No Ig production
Ig production
Ig secretion apparatus
Short-lived in culture
Immortal
Fusion with PEG (polyethylene glycol)
Hybridoma
Ig production
Ig secretion apparatus
Immortal
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Hybridoma screening
De novo pathway (inhibited by HAT)
Plate cells into 96-well plates
Nucleotide synthesis
Salvage pathway (require HPRT)
myeloma
hybridoma
Splenocytes
de novo
de novo
de novo
Salavage
Salavage
HPRT-
HPRT
HPRT
HAT inhibits de novo pathway
hybridoma
Splenocytes
de novo
de novo
Most wells contain a single hybridoma.
Salavage
Salavage
HPRT
HPRT
Short-lived in culture
Screen culture supernatant with ELISA
hybridoma
de novo
Salavage
HPRT
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Monoclonal antibody in cancer therapy
Monoclonal antibody Against tumor antigen
Immunize mice
Tumor antigen
Cancer cell
ADCC
Cancer patient
Macrophages NK cells
Complement activation
Cancer cell
BCG-CFA
lymphoma
mice
Anti-TNP IgG
51Cr
TNP-conjugated lymphoma
Activated M?
ADCC
Lysis
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Anti-tumor function of mAb requires Fc?R.
14-17 days
melanoma
Count lung metastasis
/- mAb against melanoma Ag
UPC10 control mAb TA99 anti-melanoma mAb
Deletion of inhibitory Fc?RIIB enhances
anti-tumor activity of mAb.
Human breast Cancer carcinoma
Follow tumor development
Nude mice
Herceptin (anti-breast cancer)
No thymus No graft rejection
Loss of Fc?RIIB enables mAb to inhibit tumor at
low dose.
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Humanizing mAb for clinical application
Chimeric antibodies
Tumor antigen
hybridoma
Mice
mVH
mCH
Mouse Ig gene
mVL
mCL
Mouse mAb
Replace mouse Ig constand region with human Ig
constant region
mVH
hCH (C?1, C?3)
Chimeric Ig gene
mVL
hCL
chimeric mAb
The same antigen binding specificity
Human IgG1 and IgG3 for ADCC and
complement activation
Transfect chimeric Ig gene into myeloma.
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Humanized mAb
hybridoma
Tumor antigen
Mice
mVH
mCH
Mouse Ig gene
mVL
mCL
Mouse mAb
Introduce CDRs from mouse Ig gene into human Ig
gene
hVH
hCH
hVL
Humanized Ig gene
hCL
Humanized mAb
The same antigen-binding specificity as mouse mAb
Transfect humanized Ig gene into myeloma.
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Human mAb
Transgenic mice with human Ig genes.
Human IgH locus
Mouse IgH knockout
Mouse IgL knockout
Human IgL locus
breeding
Immunize with tumor antigen
hybridoma
Human mAb
Human IgH, IgL
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Phase III clinical trial of trastuzumab
(Herceptin)
Humanized mAb against HER2/NEU (epidermal growth
factor receptor). HER2 is over-expressed in
25-30 of breast cancer.
2 mg/kg weekly iv infusion of mAb
Complete response disappearance of detectable
tumor Partial response gt 50 decrease in the
sum all lesions
Kaplan-Meier plot
Disease progression gt 25 increase in lesion
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Phase III clinical study of combined trastuzumab
and chemotherapy
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Rituximab anti-CD20 chimeric mAb for B cell
lymphoma.
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Improving the efficacy of mAb
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Cancer vaccine
Clinical trials in National Cancer Institute
(1995-2004)
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Outside of NCI
Objective response rate 3.8
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Immune evasion by tumors
Tumors induce Treg cells.
Tumor free mouse
Tumor free mouse
Analyze HA-T cells
HA-T cells
CD4 T cells specific for tumor antigen (HA)
Immunize with HA
Mouse with tumor
Analyze HA-T cells
Mouse with tumor
HA-T cells
-Tumor
Tumor
Thy1.1
CD4
Cell
CFSE
Less cell division in the presence of tumor
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HA-T cells stimulated in vitro with HA APC.
HA-T cells from tumor mice do not proliferate
and produce IFN-?.
tumor
- tumor
tumor
-tumor
HA-T cells express FoxP3 and IL-10.
Tumor-induced Treg (TMTreg)
TMTreg suppress the activation of Th1 effector
cells.
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tumor
-tumor
TMTreg are induced from CD4CD25-GITR- T cells by
tumor.
CD4CD25-GITR- T cells
tumor
Th1
Tumor-induced Treg
Suppress anti-tumor effector T cells
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Treg number increases in tumor.
Ovarian carcinoma
Treg number in tumor correlates inversely with
survival of patients with ovarian carcinoma.
Low lt 131 per field
Medium 131-346 per field
High gt 346 per field
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DCs may induce T cell tolerance to tumors.
Tumor cells
infection
Tumor cells
IL-10
IL-10, VEGF
inflammation
Lack of inflammation
IL-10R
Tolerogenic DC
STAT3
Down regulation of co-stimulation
Tumor-induced Treg
effector T cells
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Defective DC maturation in cancer patients
DCs from control or patients
Activation of normal T cells through allogenic MHC
Increased immature DCs in cancer patients
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Reduction of immature DCs after removal of tumor.
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Tumor cells could lose class I MHC to evade CTL.
Tumor cells secrete soluble MICA to evade NK
cells and CTL.
Tumor cell
NK
NKG2D
Soluble MICA induces endocytosis and degradation
of NKG2D.
NKG2D
CD8 T