Download CD4 T Cells

CD4 T Cells
All Aquiver
and
Poised for Action
One Year After the
STEP Vaccine
A quick immunology overview
HIV (or parts of HIV from a vaccine) are
Engulfed by Surveillance Cells
HIV, or vaccine components
Surveillance Cell
HIV (or parts of HIV from a vaccine) are
Engulfed by Surveillance Cells
HIV (or parts of HIV from a vaccine) are
Engulfed by Surveillance Cells
Surveillance Cells Cut Up Virus/Vaccine Parts
into Different Little Bits
Little Bits of Virus (or Vaccine Parts) are Presented
on the Surface of the Surveillance Cells
EPITOPES
(peptides-
15 amino
acids long)
CD4 T Cells become Excited (all aquiver and poised for
action) when Presented with their Epitope
CD4
CD4
EPITOPE
(peptide)
EPITOPE
(peptide)
CD4 T Cells are the Conductors of the
Immune Orchestra
CD4
CD4
IL2 cytokine
IL4 cytokine
IFNg cytokine
IL10 cytokine
TNFa cytokine
(polyfunctional)
CD4 T Cells are the Conductors of the
Immune Orchestra
CD4
CD4
IL2 cytokine
IL4 cytokine
IFNg cytokine
IL10 cytokine
TNFa cytokine
CD8
Killer CD8
T Cell
Killer Antibodies
Rationale
WHY CD4?
 CD4 T cells help optimize the killing activity of CD8 T cells
 CD4 T cells enhance antibody responses
WHY STEP?
 Important to work out what went right with this vaccine
regime
Need to Know Which Parts of the Vaccine
Excited the CD4 T Cells
Identifying CD4 Epitopes Using Gag Peptide Pools
Gag
Master pool
Maxipools
1&2
23&24
..............
Minipools 1
1.1, 1.2,
1.3, 1.4,
1.5
2
..............
23
23.1, 23.2,
23.3, 23.4,
23.5
2.1, 2.2,
2.3, 2.4,
2.5
24
24.1, 24.2, 24.3,
24.4, 24.5, 24.6,
24.7
Single
15mers
1,2,3,4,5,6,7,8,9,10..............111,112,113,114,115,116,117,118,119,120,121,122
overlapping by 11aa
Gag
gene
1.
2.
MGARASVLSGGELDR (epitope peptide)
ASVLSGGELDRWEKI (epitope peptide)
MGARASVLSGGELDRWEKI
............................................................
LTSLRSLFGNDPSSQ
A representative example of
identifying the epitope that elicited
a Gag-specific CD4 T cell response one
year post STEP vaccination
(PTID 13837)
Gag-specific CD4
DMSO
Gag Master Pool
epitope mapping
Pool
Positive?
Gag Master
Maxipool 1&2
Gag Maxipool 1&2
Gag Maxipool 9&10
Gag Maxipool 21&22
Gag Maxipool 23&24
5&6
7&8
IFN-g
3&4
9&10
11&12
13&14
15&16
17&18
19&20
21&22
23&24
IL-2
To Investigate Gag Maxipool 21 & 22
Overlapping
15mer Peptides
We need to test the
participant’s CD4
cells with the 10,
single 15mer
peptides that make
up this Maxipool
21.1
21.2
21.3
21.4
21.5
22.1
22.2
22.3
22.4
22.5
Positive?
To Investigate Gag Maxipool 21 & 22
Gag single 15mer
peptide, 22.2,
elicits no more
CD4 response
than the DMSO
negative control,
therefore is
negative.
IFN-g
DMSO
Gag single 15mer 22.2
IL-2
TNF-a
To Investigate Gag Maxipool 21 & 22
Gag single 15mer
peptide, 22.3,
elicits a higher,
CD4 response
than the DMSO
negative control,
therefore is
positive.
IFN-g
DMSO
Gag single 15mer 22.3
IL-2
TNF-a
To Investigate Gag Maxipool 21 & 22
DMSO
Gag single 15mer 22.4
IFN-g
Gag single 15mer
peptide, 22.4,
elicits a higher,
CD4 response
than the DMSO
negative control,
therefore is
positive.
IL-2
TNF-a
To Investigate Gag Maxipool 21 & 22
Gag single 15mer
peptide, 22.5,
elicits no more
CD4 response
than the DMSO
negative control,
therefore is
negative.
IFN-g
DMSO
Gag single 15mer 22.5
IL-2
TNF-a
To Investigate Gag Maxipool 21 & 22
Overlapping
15mer Peptides
21.1
21.2
21.3
21.4
21.5
22.1
22.2
22.3
22.4
22.5
Positive?
PTID 13837’s CD4 T Cell Gag Epitope
Gag 15mer peptide 22.4
Gag 15mer peptide 22.3
R429QANFLGKIWPSHKGRPGN447
Gag gene
Relative Positions of Gag CD4 Epitopes
(481)
(477)
(293)
(41)
(297)
(73)
(261)
(37)
Gag gene
(297)
(477)
(465)
(385)
(373)
(429)
(465)
Cytokine Profile of Epitope-Specific CD4 T Cells
One Year Post Vaccination
Vaccinated PTID 9952
 This participant had a vaccine-induced CD4 T cell
response to Gag epitope 24.5 and 24.6
(from maxipool 23 & 24).
 This participant then became infected with HIV.
 Will this vaccine-induced response still be
dominant after infection?
ag
G
9&
8
7&
6
5&
4
3&
2
1&
er
as
t
Stimulant
24
.7
24
.6
24
.5
24
.4
24
.3
24
.2
24
.1
10
11
&
12
13
&
14
15
&
16
17
&
18
19
&
20
21
&
22
23
&
24
M
Antigen Specific CD4 T Cell Response (%)
Infected, vaccinated PTID 9952
one year post vaccination
9952 CD4 Gag Responses IFNg & IL2 & TNFa
0.20
0.15
0.10
0.05
0.00
ag
G
9&
8
7&
6
5&
4
3&
2
1&
er
as
t
Stimulant
24
.7
24
.6
24
.5
24
.4
24
.3
24
.2
24
.1
10
11
&
12
13
&
14
15
&
16
17
&
18
19
&
20
21
&
22
23
&
24
M
Antigen Specific CD4 T Cell Response (%)
Infected, vaccinated PTID 9952
one year post vaccination
9952 CD4 Gag Responses IFNg & IL2 & TNFa
0.20
0.15
0.10
0.05
0.00
Conclusion
 Low, vaccine-induced Gag-specific CD4 T cell
responses were identified, at one year post vaccination,
in uninfected participants in the STEP vaccine trial
 Two responses in some participants
 Epitopes located along entire length of Gag gene
 Most common Gag-specific CD4 T cell response at one
year post vaccination was the release of two cytokines,
IL2 and TNFa – degree of polyfunctionality.
 Some vaccine-induced CD4 responses dominate after
infection
 Overall, data suggests utility of these vaccine-induced,
CD4 T cell responses.
Acknowledgements
 Trial participants and the CAB
 Repository technicians
 SAL
 Endpoints
 Evan Thomas and Janice Chen
 Nicole Frahm
 Steve de Rosa
 Julie McElrath
 National Health & Medical Research Council (NHMRC),
Australia