Future directions in HIV basic
science research
The hunt for a cure
Future Directions
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A new vaccine approach.
Targeting and purging the latent reservoirs.
Targeting and removing integrated virus.
Stem cell based therapies.
Targeting and controlling immune activation.
A “new” vaccine approach- Use
another virus to “trick” the immune
response to SIV
• Rhesus Cytomegalovirus is a monkey
herpesvirus.
• They replaced genes in Rhesus
Cytomegalovirus with those of SIV.
Annual Reviews
Less restricted. Rhesus Cytomegalovirus that expresses SIV genes (strain 68-1 RhCMV)
expands the CD8+ T cell response to SIV.
N Goonetilleke, and A J McMichael Science 2013;340:937938
Published by AAAS
A new vaccine approach
• They found that vaccination with Rhesus
Cytomegalovirus containing SIV allowed
protection from SIV challenge in monkeys
(Rhesus Macaques)
• The immune responses in these animals were
not the same as the responses in animals
exposed to SIV without the vaccine = better
protection
Targeting and purging the latent
reservoirs
• HIV latency and persistence is the biggest
hurdle in a cure.
• Targeting and removing the latent reservoir
from the body remains an important
therapeutic target.
HIV persistence during therapy
Short-lived infected cell
Long-lived infected cell
(latently infected)
HIV persistence during therapy
Antiretroviral therapy
Short-lived infected cell
Long-lived infected cell
(latently infected)
HIV persistence during therapy
Short-lived infected cell
Long-lived infected cell
(latently infected)
HIV persistence during therapy
Antiretroviral therapy
•Latently infected CD4+ T lymphocytes are rare
in vivo:
•Approximately 1 per 106 total resting CD4+ T
cells
•Probably constitute around 105-106 cells per
patient
Formation of HIV latency
Anti-HIV Immunotoxin
Infected Cell
gp120
Anti-gp120
3B3:N31H/Q100eY(dsFv)-PE
McHugh et al.; 2002
Pseudomonas
Exotoxin
Prostratin or Bryostatin or ?
Activation/elimination strategy for clearing latently-infected cells:
Marsden and Zack (2010) Future Virol. 5(1): 97–109.
Targeting Integrated Virus
HIV Lifecycle
Structures of cleavage enzymes.
Schiffer J T et al. J. Virol. 2012;86:8920-8936
Targeted gene knockout by DNA-editing enzymes.
Schiffer J T et al. J. Virol. 2012;86:8920-8936
Integrated Virus Targeting
• Highly specific, efficient way of getting
integrated virus out of cell.
• Problems with delivery to the cell.
• Highly promising
Stem Cell Based Therapies
• Most include gene therapy to modify the
hosts genetic makeup to:
– Make cells that are resistant to HIV infection
And/or
– Make cells that can target and kill HIV infected
cells.
http://www.nytimes.com/2011/11/29/health/new-hope-of-a-cure-for-hiv.html?pagewanted=all
Stem cell based Anti-HIV Gene
Therapy
Containing
at least 1
anti-HIV
gene
Kitchen SG et al. Stem cell-based anti-HIV gene therapy. Virology. 2011
Multiple anti-HIV gene therapy
approach
Selected anti-HIV genes
1. Potent HIV inhibitors at early
stage of viral life cycle
2. Distinct anti-HIV mechanisms
Goals
1. Inhibit multiple HIVs
• CCR5 tropic HIVs
• CXCR4 tropic HIVs
• Multi-drug resistant HIVs
2. Prevent emergence of resistant
HIV mutants
CCR5-siRNA
Hu-TRIMcyp
C46 entry
inhibitor
HIV TCR
“Engineered Immunity”
Stem cell based approaches
Would allow direct genetic modification of progenitor
(“baby”) cells in the body
Would allow prolonged self-renewal of modified cells
that would have long life in the body
Cells would undergo normal development and be
recognized as part of the body
Engineering Antiviral Immunity
Goal: We are interested in using molecularly
cloned, HIV- specific T cell receptors (TCRs) from
HIV-specific CD8+ T cells and other HIV-targeting
molecules to modify human blood forming stem
cells to target and kill HIV in infected individuals
“Genetic Vaccination” to HIV
Stem cell
TCR 
TCR 
TCR 
TCR 
TCR 
TCR 
TCR 
TCR 
Viral Vectors
Containing Cloned
TCRs
T cell
T cell
Virus
Infected
cells
T cell
T cell
T cell
Humanized
Mouse
Model
of
HIV
Infection:
HLA-A*0201+
The NSG-CTL Model
Tissue
Fetal Liver
1. Sort CD34+
CD34+
4. Thaw and Transduce
with
Anti-HIV TCR
CD34+
Or Control TCR
Infect with
HIV-1NL4-3HSA-HA
CD34+
CD34+
CD34+
CD34+
2a. Viably freeze fraction
Irradiate
CD34+
CD34+
NSG
2. Transduce with
Anti-HIV TCR or
Control TCR
3. Combine with fetal
thymus tissue and
liver stroma, implant
under kidney capsule
NSG
3 weeks
5. Tail Vein Inject
6-12
weeks
6. Analyze
TCR
Expression/F
unction
HIV-Specific TCR suppresses of HIV in humanized mice
p=0.05
Copies vRNA/ml
1000000
100000
p=0.02
10000
1000
100
10
1
SL9-TCR
Control
TCR
Week 2
SL9-TCR
Control
TCR
Week 6
Kitchen et al., PLoS Pathogens 2012
GMP Level Closed System Gene Transduction and Cell Processing
Apheresis
Final Infusion Product
Cytomate
Gene Transfer Product
Isolex
Isolex
Culture
Targeting Immune Activation and HIV
• HIV activates the immune response during
infection
• HIV replicates in an active immune response
• We can target the virus (ARV), we need to also
target the immune response to make it better
able to clear HIV
• One way is to target specific molecules to
lower levels of immune activation to decrease
HIV levels.
HIV infection in the gut (Intestines, Colon) causes
problems with the immune response
Immune activation and inflammation in HIV‐1 infection: causes and consequences
There is a lot going on in HIV infection.
Like antiretroviral therapy and the HIV
lifecycle, if we can target multiple
events we may be able to allow
the immune response to clear HIV.
The Journal of Pathology
Volume 214, Issue 2, pages 231-241, 27 DEC 2007 DOI: 10.1002/path.2276
http://onlinelibrary.wiley.com/doi/10.1002/path.2276/full#fig1