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Measles protective immunity
Annecy Symposium on
Correlates of Protective Immunity
September 21, 2010
Diane E. Griffin
Johns Hopkins Bloomberg School of Public Health

athogenesis of
measles
Target cells:
Epithelial cells
Endothelial cells
Monocyte/macrophages
T and B lymphocytes
CD4
CD8
10
Days after infection
20

How complete/rapid is clearance?
Studies in Zambian children
• MV cannot be cultured from any site after
the rash has cleared
• However, RT-PCR analysis of
nasopharyngeal washings, urine and
PBMCs shows:
– MV RNA is still detectable after recovery
• 50% positive at some site 1 month after discharge
• 35% positive at 3 months
Permar et al, J Infect Dis 183:532, 2001; Riddell et al, J Clin Virol 39:312, 2007

Current understanding of measles
protective immunity
• Natural measles infection confers lifelong
protection from re-infection
• Parenteral delivery of the live attenuated measles
virus vaccine can also induce long term
protection
• Epidemiologic studies (e.g. Chen et al. JID 162:1036,
1990) show that vaccine-induced protection
correlates with the level of neutralizing antibody:
– >120 mIU/ml: Protection from disease (rash)
– >1052 mIU/ml: Protection from infection (Ab rise)

Measles virus
Neutralizing antibody
Moss & Griffin, Nat Rev Microbiol 4:900, 2006

Rhesus macaque model for measles
rash
intra-tracheal
WT measles virus
Auwaerter et al JID, 1999; Lin et al, unpublished

Why study measles protective
immunity?
• The relative contributions of antibody, T
cells and MV-specific antigen
responses to protection are not known
• Interest in new vaccine approaches to:
– decrease the need for cold chain, needles
and syringes
– increase the ability to deliver 2 doses
through routine programs

Probing measles protective immunity
through studies of vaccinated macaques
• Lessons from old and new vaccines
– formalin-inactivated vaccine
– experimental DNA and virus-vectored vaccines
expressing individual proteins (H and F)
– live attenuated virus delivered by parenteral injection
and by aerosol
• These vaccines provide 4 levels of protection:
– None/enhanced disease
– From rash, but not viremia or infection
– From rash and viremia, but not infection
– From rash, viremia and infection

Immune responses to formalin-inactivated
and live measles virus vaccines
Neutralizing antibody Cytotoxic T cells
Inactivated
vaccine
Live vaccine
Level of protection
1:30
Live vaccine
1:10
Inactivated vaccine
1:15
Polack et al Nat Med 5:629, 1999

Antibody responses to challenge
Antibody amount
DNA
live
inactivated
naive
Antibody avidity
DNA
inactivated
live
naive
Polack et al., Nat Med 9:1209, 2003

Ability of antibody to neutralize MV
infection of different cells
Vero cells (CD46) B95-8 cells (SLAM)
H-DNA inactivated
naive
live
live
naive
H-DNA
inactivated
Polack et al., Nat Med 9:1209, 2003

Enhanced disease after challenge
Lesson: Quantity & quality of Ab is important
Measles Atypical measles
No immunization
Previous immunization with
formalin-inactivated vaccine
Polack et al Nat Med 6:629:1999

New DNA MV vaccines
A. PLG-formulated (Chiron)
Alphavirus promoter (SINCP) - H
• Coating plasmid DNA onto PLG (poly-lactide
glycolide) biodegradable and efficiently
phagocytosed particles
B. Vaxfectin-formulated (Vical)
CMV promoter, codon-optimized - H + F
• Potent adjuvant for DNA vaccines

Immune responses after MV DNA vaccination in
juvenile monkeys
Pan et al, Clin Vaccine Immunol 15:697 & 1214, 2008

Challenge of PLG & Vaxfectin/DNA-vaccinated
monkeys: Viremia
PLG/SINCP-H Vaxfectin/H+F
Pan et al, Clin Vaccine Immunol 15:697 & 1214, 2008

Rashes in PLG-DNAimmunized
monkeys
Control/naive
Low dose, i.d.
(enhanced)
Pan et al, Clin Vaccine Immunol
15: 697, 2008

DNA vaccines: lessons learned
• DNA vaccines expressing H or H+F can
induce protective immunity
• Protection is associated with high titer,
high avidity, durable neutralizing antibody
• Enhancement is associated with shortlived,
low avidity antibody and increased
virus replication

Recombinant Alphavirus replicon-based MV
vaccines (Chiron/Novartis)
• SIN
• Uses the replicon machinery of Sindbis virus with
greatly amplified expression of antigen
• VEE/SIN
• Similar to SIN, but has Venezuelan equine
encephalitis (VEE) backbone that enhances
expression.

Neutralizing antibody responses to
SIN-H particles
Protective level
10 6
Pan et al PNAS 102:11581, 2005
10 8

Viremias after challenge of
SIN-H particle-immunized monkeys
10 6 - rash
10 8 – no rash
naïve - rash
Pan et al, PNAS 102:11581, 2005

unstimulated
H peptides
T cell responses are biphasic
Pan et al, PNAS 102:11581, 2005
IFN-g ELISPOT assay
Days after challenge
viral RNA detected
by qRT-PCR

SIN-H lessons
• Neutralizing antibody alone does not protect
from viremia, but does protect from rash
• ? differential protection from infection of
some cells (e.g. epithelial cells) and not
others (e.g. lymphoid cells)
• there can be late recrudescence of viral RNA

Responses to VEE/SIN-H or H+F vaccination
Antibody responses
T cell responses
VEE/SIN-H and H+F animals protected from rash and viremia
Pan et al., J Virol, 84:3798, 2010

Recrudescence of virus replication after challenge
H-specific T cell responses MV RNA by qRT-PCR
Pan et al., J Virol, 84:3798, 2010

VEE/SIN-H+F lesson
• Protection from viremia and rash does not
necessarily indicate protection from infection
• ? Need to prime immune responses to other
viral antigens

Cellular and humoral immune responses after aqueous
delivery of current vaccine by different routes
Lin et al, unpublished

Priming the T cell response does not protect
from infection or rash
rashes
Lin et al, unpublished

Virus clearance is accelerated when animals
have pre-existing MV-specific memory T cells
Lin et al, unpublished

Conclusions
• Neutralization of lymphoid cell infection by wild type strains of
virus requires high avidity antibody
• T cells do not protect from rash or viremia, but accelerate virus
clearance
• Three levels of protective immunity can be identified:
– protection from disease (rash) – high titer neutralizing antibody
– protection from rash and viremia – Ab + T cells specific for at least H
and F
– protection from rash, viremia and infection – Ab + T cells, may
require T cell functions or MV specificity in addition to H+F
• Further study is needed to
– understand the mechanism and importance of the late appearance
of viral RNA in monkeys protected from disease
• e.g. where is virus, why is there late failure of control?
– understand the immune response to aerosol vaccination

• Paul Auwaerter
• Fernando Polack
• Robert Adams
Acknowledgments
• Chien-Hsiung (Peter)
Pan
• Wen-Hsuan (Wendy)
Lin
Funding from the NIAID and The Bill and Melinda Gates Foundation