Targeting HIV-1 entry and reverse transcription by vaccination
Author: Zuber, Bartek
Date: 2002-12-04
Location: Hillarpsalen, Retzius väg 8, Solna
Time: 9.00
Department: Mikrobiologiskt och Tumörbiologiskt Centrum (MTC) / Microbiology and Tumor Biology Center (MTC)
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thesis.pdf (1.530Mb)
Abstract
Human immunodeficiency virus type I (HIV-1) is a complex retrovirus,
which uses the CD4 receptor and chemokine receptors to infect its target
cells. The chemokine receptor CCR5 is essential for primary HIV-1
infection. The hallmark of retroviruses is the enzyme reverse
transcriptase (RT), which transcribes the virus genome from RNA to DNA.
RT is a major target for HIV drugs but antiviral treatment often selects
for drug resistant virus variants. RT lacks proofreading, which accounts
for a great deal of the high variability of HIV-1 genomes. The aim of
this thesis was to evaluate the RT gene and the CCR5 gene as immunogens
and to develop an animal model for HIV- I drug resistance.
The human CCR5 gene was used together with the adjuvant granulocyte
macrophage colonystimulating factor (GM-CSF) for immunization of mice and
monkeys (cynomolgus macaques). Immunization with the CCR5 gene induced
antibody responses in both mice and monkeys. The macaques were boosted
with CCR5 peptides in the rectal mucosa. This potentiated local IgA
responses as well as systemic IgA and IgG antibody responses to human and
macaque CCR5 peptides. The detected CCR5 antibodies demonstrate that we
were able to break tolerance and immunize against the endogenous CCR5
receptor. Interestingly, the CCR5 peptide boost abolished or decreased
CCR5 gene-induced antibody responses towards native CCR5. Sera from
vaccinated animals blocked infection of peripheral blood mononuclear
cells (PBMC) with HIV-1 and with simian immunodeficiency virus sooty
mangabey (SIVsm) in vitro. Regrettably none of the CCR5-immunized monkeys
were protected from SIVsm challenge. In one vaccinated animal the virus
surprisingly evolved and started to use the CCR5 receptor more
efficiently than before. Thus CCR5 immunization may lead to the evolution
of viruses with new properties which may be negative for the patient.
This has to be investigated further.
Different immunization strategies were tested in order to induce strong
RT specific immune responses. The adjuvant effect of bacterial DNA
(CpG-oligodeoxynucleotides, ODN) was evaluated in this context. A prime
with the RT gene followed by protein with CpG-ODN boost induced the most
potent cellular immune responses in both mice and macaques. After
challenge of mice with HIVI/murine leukemia virus (HIV-1/MuLV), cellular
immune responses in splenocytes were equal in the groups: receiving a)
DNA followed by protein with CpG-ODN or b) protein with CpG-ODN. In both
these groups protection from challenge was observed in some of the
vaccinated mice. Consequently the evaluated three-component vaccination
strategy induced potent humoral and cellular immune responses to RT and
provided partial protection from HIV-1. RT may therefore be an important
component of an HIV- I vaccine.
HIV-1 drug resistance mutations found in vitro do not always correlate to
the mutations found in vivo in treated patients. An in vivo model for the
study of resistance development in macaques was constructed. The
occurrence, type and duration of RT mutations during treatment with the
nonnucloside inhibitor nevirapine were analyzed over time. We found a
good correspondence of mutation pattern and kinetics between the monkey
model and known data from nevirapine treated patients. Mutation K103N
found in the drug treated monkeys was infrequently selected by nevirapine
in cell culture. This indicates that the monkey model might be used to
detect mutations that are difficult or impossible to predict in vitro.
This model can also be used to study new vaccines targeted to RT with
drug-induced mutations.
In conclusion we were able to induce immune responses to both the CCR5
and the RT gene products. CCR5 specific antibodies induced unpredicted
virus evolution to a higher receptor affinity. RT specific immune
responses partially protected mice from HIV-1/MuLV infection. A primate
model for HIV-1 drug resistance was successfully developed. This model
may be used in future studies of vaccines directed to RT with
drug-induced mutations.
List of papers:
I. Zuber B, Hinkula J, Vodros D, Lundholm P, Nilsson C, Morner A, Levi M, Benthin R, Wahren B (2000). "Induction of immune responses and break of tolerance by DNA against the HIV-1 coreceptor CCR5 but no protection from SIVsm challenge. " Virology 278(2): 400-11
Pubmed
II. Zuber B, Vodros D, Morner A, Nilsson C, Walther-Jallow L, Ten Haft P, Heeney J, Wahren B (2002). "CCR5 gene immunization may select for SIV that uses CCR5 more efficiently." (Manuscript)
III. Zuber B, Kjerrstrom Zuber A, Makitalo B, Rollman E, Ljungberg K, Hinkula J, Klingstrom J, Eriksson LE, Mathiesen I, Isaguliants MG, Oberg B, Wahren B (2002). "Potent and protective immune responses to the HIV-1 RT gebe/protein aided by CpG-ODN in a prime-boost regimen." (Submitted)
IV. Zuber B, Bottiger D, Benthin R, ten Haaft P, Heeney J, Wahren B, Oberg B (2001). "An in vivo model for HIV resistance development. " AIDS Res Hum Retroviruses 17(7): 631-5
Pubmed
I. Zuber B, Hinkula J, Vodros D, Lundholm P, Nilsson C, Morner A, Levi M, Benthin R, Wahren B (2000). "Induction of immune responses and break of tolerance by DNA against the HIV-1 coreceptor CCR5 but no protection from SIVsm challenge. " Virology 278(2): 400-11
Pubmed
II. Zuber B, Vodros D, Morner A, Nilsson C, Walther-Jallow L, Ten Haft P, Heeney J, Wahren B (2002). "CCR5 gene immunization may select for SIV that uses CCR5 more efficiently." (Manuscript)
III. Zuber B, Kjerrstrom Zuber A, Makitalo B, Rollman E, Ljungberg K, Hinkula J, Klingstrom J, Eriksson LE, Mathiesen I, Isaguliants MG, Oberg B, Wahren B (2002). "Potent and protective immune responses to the HIV-1 RT gebe/protein aided by CpG-ODN in a prime-boost regimen." (Submitted)
IV. Zuber B, Bottiger D, Benthin R, ten Haaft P, Heeney J, Wahren B, Oberg B (2001). "An in vivo model for HIV resistance development. " AIDS Res Hum Retroviruses 17(7): 631-5
Pubmed
Issue date: 2002-11-13
Rights:
Publication year: 2002
ISBN: 91-7349-309-0
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