Passive Immunization

1
Passive Immunization of Neonates Against Oral
Virus Challenge Ghent/International AIDS
Society/Clinical Trials Partnership Group on HIV
in Women an Children Prevention of HIV
Transmission through Breastfeeding Strengthening
the Research Agenda Ghent, Belgium - December
12-13, 2002 Ruth Ruprecht, M.D., Ph.D. Harvard
Medical School, Boston
2
Maternal HIV Transmission -Experimental Model of
Infection in vivo

• Virus of choice chimeric SHIV (encoding HIV env
  in SIV backbone)
• SHIV experimental model of infection allows
  evaluation of anti-HIV Env human antibodies in
  macaques
• Oral, non-traumatic exposure of Macaca mulatta
  (rhesus) neonates to SHIV within 5 days of birth

3
Neutralizing Anti-HIV Antibodies

• were isolated from HIV clade B- infected
  individuals
• were expanded as monoclonal antibodies
• were examined for their epitope specifity

4
Epitope Specificity
F105 and anti - CD4 binding siteb122G12 com
plex epitope on gp 120 dependent on correct
N-linked glycosylation2F5 linear gp41
epitope, ELDKWA 4E10 linear gp41
epitope, NWFDIT
5
NmAb Epitopes
Modified from Ferrantelli and Ruprecht, Curr
Opin in Immunol, 2002 14495-502.
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Selection Criteria for Human nmAbs

• targeted to conserved epitope
• relatively potent as single agent, including
  neutralization of primary HIV isolates
• synergistic interaction with other nmAbs in the
  combination regimen
• IgG subtype
• availability in sufficient amounts

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Passive Immunization of Neonatal Primates Summary

• Thus far, a total of 31 newborn rhesus monkeys
  have been treated with triple or quadruple
  combinations of human nmAbs against oral
  challenge with different SHIV strains

• All untreated controls were infected

• Of the 31 treated infants, 22 were completely
  protected (no virus at any time).

• No neutralization escape mutants were found in a
• nmAb-treated monkey that became infected.

Baba et al., Nature Medicine 2000
6200-6 Hofmann-Lehmann et al., J Virol 2001,
757470-80 Hofmann-Lehmann et al., J Med
Primatol, 2002, 31109-119 Ferrantelli et al.,
AIDS, in press and unpublished data
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Can human nmAb combinations protect neonatal
rhesus macaques against oral challenge with an
acutely pathogenic, chimeric SHIV that encodes
the env gene of a primary HIV isolate?
9
Will passive immunization with human nmAb
combinations still completely protect neonatal
macaques, even when given as post-exposure
prophylaxis (PEP)?
10
SHIV89.6P

• built from SIVmac239 backbone
• env was derived from HIV89.6, a primary,
  dualtropic strain isolated from an AIDS
  patient.
• replicates in rhesus macaque PBMC
• results in persistent infection in adult
  macaques.
• became acutely pathogenic after serial passage
  in rhesus monkeys. Typically, CD4 T cells
  drop precipitously 2 weeks post-inoculation.
  Most monkeys do not recover and die of AIDS.

Reimann et al., J Virol 1996 706922-6928.
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i.v. Neonatal PEP -Study Design
nmAb-treated b12, 2G12, 2F5, 4E10 _at_ 30 mg/kg ea
1 h PEP
12 h PEP
n 4
n 3
Controls
SHIV89.6P
oral
n 4
d0 wk 1 wk 2



mos
12

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i.v. Neonatal PEP -Viremia and CD4 T-Cell Counts
Control animals
MAb-treated animals -12h post-exposure
MAb-treated animals -1h post-exposure
A
B
C
8 6 4 2
8 6 4 2
8 6 4 2
RPs-8
REq-8
RAq-8
RQs-8
RFq-8
RQp-8
RYr-8
RPo-8
RWq-8
RSl-8
RYq-8
Log plasma viral load (copies/ml)
Log plasma viral load (copies/ml)
Log plasma viral load (copies/ml)
neg.
neg.
neg.
0 10 20 30
40 50
0 10 20 30
40 50
0 10 20 30
40 50
E
D
F
5 4 3 2 1
5 4 3 2 1
5 4 3 2 1
cells/ml)
3
cells (10

CD4
0 10 20 30
40 50
0 10 20 30
40 50
0 10 20 30
40 50
Weeks after challenge
Weeks after challenge
Weeks after challenge
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Optimization of Neonatal Post-Exposure
Prophylaxis (PEP) in Primates
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Towards Clinical ApplicationIncreased Safety
Intramuscular (I.M.) PEP

• Practical - nurses can administer PEP
• I.M. safer than i.v. - less concern about
  Ig-aggregates

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I.M. neonatal PEP -Study Design
n 4
n 4
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I.M. Neonatal PEP - Viremia and CD4 T-Cell
Counts
Controls nmAb-treated
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I.M. Neonatal PEP - Outcome of Challenge

• All untreated controls high plasma viremia and
  dramatic drops in CD4 T cells 3 out of 4
  infants died of AIDS within 6 weeks
• All nmAb-treated macaques were completely
  protected from infection (RT-PCR on plasma,
  DNA-PCR on PBMC and co-cultivations of PBMC no
  virus)

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Passive immunization A novel approach to
prevent mother-infant HIV transmission
in sub-Saharan Africa, especially milk-borne
virus transmission?
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Neutralization of 19 Primary HIV Clade C Isolates
and Clade B Strain HIV89.6 By the Quadruple
Combination of Mabs b12, 2G12, 2F5, and 4E10
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The Combination of nmAbs IgG1b12, 2G12, 2F5, and
4E10

• completely neutralized several HIV clade B
  primary isolates (1,2)
• 1 Xu et al., J Hum Virol 2001, 455-61
• 2 Zwick et al., J Virol 2001, 7512198-208

• completely neutralized 14 out of 20 primary HIV
  clade C isolates from different parts of the
  world, including all 4 Chinese isolates the
  remainder 6 isolates were neutralized 97.5 to 99
  (1)

• neutralized 4 out of 4 primary HIV clade A
  isolates gt99 (3)
• 3 Kitabwalla et al., AIDS Res Hum Retroviruses,
  in press

• neutralized 5 out of 5 primary HIV clade D
  isolates gt99 (3)

This quadruple nmAb combination has potently
neutralized primary HIV isolates of clades A, B,
C, and D
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ProspectivePhase I clinical trial of human
nmAbs (candidates F105, 2G12, 2F5, or 4E10) in
HIV-exposed human neonatesP.I. Dr. Hoosen
CoovadiaNelson Mandela School of Medicine,
Durban, South Africa
22
Human Neutralizing mAbs Used in Neonatal
Primates Phase I Testing in Humans
F105 tested in HIV-infected adults (Cavacini et
al., AIDS Res Human Retroviruses 1998
14545-550)2G12 tested in HIV-infected
adults (Armbruster et al., AIDS 2002 16
227-233)2F5 tested in HIV-infected
adults (Armbruster et al., AIDS 2002 16
227-233)IgG1b12 not yet tested 4E10 not yet
tested
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Questions to be Addressed

• Can passive immunoprophylaxis identify
• other epitopes that confer complete
  protection?
• Can vaccines be designed that preferentially
  generate neutralizing antibodies against
  epitopes known to yield complete protection?
• Can pregnant women be vaccinated with such
  antibody response-based vaccines, and will
  vaccine-induced nAbs cross the placenta?

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Conclusions

• Passive immunization with human nmAbs
  protected orally challenged newborn macaques
  from systemic infection and /or disease induced
  by SHIV89.6P
• Passive immunization promising tool to
  prevent mother-to-child HIV transmission intra-
  and post- partum
• Epitopes identified through passive
  immunization correlates of immune protection
  ideal targets for candidate AIDS vaccines

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Acknowledgements
DFCI / Harvard Medical School Flavia
Ferrantelli Weidong Xu Moiz Kitabwalla Regina
Hofmann-Lehmann Timothy Baba Robert
Rasmussen Tao Wang Agnes Chenine Pei-Lin
Li Vladimir Liska Beverly Smith-Franklin Alison
Williams Josef Vlasak Beth Israel-Deaconess
Medical Center Lisa Cavacini Marshall Posner
Duke University School of Medicine David
Montefiori
Institute of Applied Microbiology, Vienna,
Austria Hermann Katinger Gabriela
Stiegler University of Massachusetts Medical
Center Shan Lu
University of Texas, MD Anderson Cancer
Center Bruce Bernacky Tahir Rizvi Russell
Schmidt Lori Hill Michale Keeling
Yerkes National Primate Research Center Harold
McClure Stephanie Ehnert Daniel
Anderson
Harvard School of Public Health Janet
Andersen Yichen Lu
University of Nebraska Charles Wood Qiujiang Du
Jun He
Memorial Sloan-Kettering Cancer Center Ting-Chao
Chou
Univ. Teaching Hosp., Lusaka, Zambia Ganapati
Bhat Chipepo Kankasa
The Scripps Research Institute Dennis Burton