re infecting
The genetic relationship between infecting and re-infecting
RSV strains
t i iisolated
l t d ffrom young children
hild
att coastal
t lK
Kenya
Charles N. Agoti1, Clayton O. Onyango1,Graham F. Medley2, Patricia A. Cane3 and D.
12
J
James
N
Nokes
k 1,2
1 KEMRI-Wellcome
1.KEMRI
Wellcome Trust Research Programme,
Programme Kilifi
Kilifi, Kenya 2.
2 School of Life Sciences,
Sciences
University of Warwick, Coventry, UK 3. Health Protection Agency, Centre for Infections,
Colindale, London, UK [ Address correspondence to: cnyaigoti@kilifi.kemri-wellcome.org]
INTRODUCTION
METHODS/RESULTS
DISCUSSION
¾Five of the 54 cases appeared to
be persistent infections lasting for up
to seven weeks (figure 3)
Figure 1. Study design
¾Respiratory syncytial virus (RSV) is persistent
in the human population and a cause of
recurrent epidemics
p
¾Of the 49 remaining cases,
¾Individuals get RSV re-infected repeatedly
throughout life
if ((Henderson et al, 1979)) and
this is thought
g to play a major
j role in
persistence (Medley and Nokes, 2009)
¾29 were off th
the
heterologous group while
¾ 20 were of the
homologous group.
group
¾Despite
¾D
it implications
i
li ti
tto th
the effectiveness
ff ti
of future vaccines, the mechanism of RSV
re-infection is poorly understood
¾Two genetically and antigenically distinct
RSV groups exist
¾The homologous cases were of a
heterologous genotype except four.
Three of these four had amino acid
changes within the sequenced
region
off th
the G gene (figure
4A &
i
(fi
4B)
Figure 2. Enrolment and outcomes
¾A and B, and
635 Children recruited at birth
All followed up until @ experienced 3 RSV epidemics
Nasal sample
p taken whenever child had ARI & tested for RSV
¾within them multiple genotypes
occur
¾All confirmed re-infections with the
exception of two occurred in
separate epidemics
¾Most differences in RSV strains occur in the
attachment (G) protein which is
CONCLUSION
¾targeted by neutralizing
antibody responses
409 Infections identified by immunofluorescence
326 Primary
y infections
83 Repeat infections
The paired infections targeted for typing and sequencing
¾ under positive immune
selection (Cane,
(Cane 2007)
¾Characterizing in detail the genetic
characteristics
h
t i ti off infecting
i f ti
and
d re-infecting
i f ti
RSV strains can inform on the role of RSV
strain diversity in repeat infections
12 Specimens not located in the archives
22 Specimens gave a negative RT-PCR result
HYPOTHESIS
135 Infections typed into RSV A and B, and also
q
g
sequenced
in their G gene
RSV repeat infections are with different
genetic strains and persistence of this virus
in host populations is due to the presence
of genetically diverse strains that are
continuously evolving
¾It appeared that most RSV repeat
infections are with a genetically
different
d
e e strain
s a though
oug not
o
necessarily of the alternative group
level
¾Statistical analysis of the group
and genotype re-infection
re infection patterns
is currently on-going
¾ h
¾These
studies
t di complement
l
t our
investigations into the development
of RSV strain specific immunity - See
poster by Charles Sande
Excluded from analysis
29 pairs for which only a single RT-PCR
RT PCR result
was positive or available
ACKNOWLEDGEMENTS
OBJECTIVES
¾To determine if infecting and re-infecting
RSV strains are always genetically different
¾Tim Kinyanjui
54-paired
p
infections included in analysis
y of the genetic
g
relationship between infecting and re-infecting RSV strains
¾Ch l SSande
¾Charles
d
¾RSV Laboratory and field staff
¾To explore the patterns of RSV repeat
infections at group and genotype level and
the iinfluence
f
off group dominance
i
on the
patterns
Table 1. Sub-group re-infection patterns and the time interval (months) between consecutive infections
METHODS
¾The study
y design
g is detailed in figure
g
1&2
¾Positives were G gene sequenced and
t k
taken
through
th
h phylogenetic
h l
ti analysis
l i
¾Result interpretation will take into account
the prevalence of RSV A and B as depicted
b surveillance
by
ill
data
d t ffrom child
hild admissions
d i i
with RSV pneumonia to Kilifi District Hospital
over the same period (figure 3)
Pattern
Number of cases
Median duration
Mean duration
Range
A A*
A-A*
12
28
2.8
66
6.6
0 7 - 22.8
22 8
0.7
A-B
AB
19
14.1
14 1
15.3
15 3
8.0
8 0 - 24.1
24 1
BA
B-A
10
14 0
14.0
13 5
13.5
10 3 - 15.2
10.3
15 2
BB
B-B
13
10 4
10.4
13 6
13.6
6 8 - 23.0
6.8
23 0
Overall
54
12 2
12.2
12 6
12.6
0 7 - 24.1
0.7
24 1
¾The
e sstudy
udy pa
participants
c pa s
¾The Wellcome Trust for funding
(grant ref. nos 085882 &084633)
REFERENCE
Henderson FW, Collier AM, Clyde WA, Jr., Denny FW.
1979. Respiratory-syncytial-virus infections, reinfections
and
d immunity.
i
it A prospective,
ti
llongitudinal
it di l study
t d iin
young children. N Engl J Med 300: 530-4
Medley
y GF, Nokes DJ. 2009. Does viral diversity
y matter?
Science 325: 274-5
Cane P. 2007. Molecular Epidemiology and Evolution of
Respiratory Syncytial Virus.
Virus In Respiratory Syncytial Virus,
Virus
ed. P Cane, pp. 89-114: Elsevier
* Fi
Five off the
th re-infections
i f ti
iin this
thi category
t
may b
be iinterpreted
t
t d as single
i l infections
i f ti
that
th t were persistent
it t
RESULTS
Homologous group A to A reinfections
i f
i
Heterologous group A to B reinfections
i f
i
Indiv
viduall
60
Ken12
Ken11
Ken10
Ken09
Ken08
K 07
Ken07
Ken06
Ken05
Ken04
Ken03
Ken02
Ken01
Jan02
U
U
M
U
U
S
U
40
U
M M
M
U
SU
SU
20
UU
MU
U
S
S
Jan03
U
Jan04
Jan05
0
Ken29
Ken28
Ken4
Ken27
Ken26
Ken5
Ken25
Ken24
Ken23
Ken22
Ken21
Ken20
Ken19
Ken18
Ken17
Ken16
Ken15
Ken14
Ken13
Jan02
U
U
RSV A
U
U
M
U
S
U
U
60
M
U
RSV B
U
S
40
U
S
U
U
U
U
VS
U
M
M
S
U
M
S
U
U
U
Figure 4A
No of
o in-pa
atient cases
c
Figure 3
20
U
U
U
U
U
U
S
S
Jan03
Jan04
Jan05
0
Figure 4B
Heterologous group B to A reinfections
Homologous group B to B reinfections
60
Ken39
U
Ken38
Individ
dual
U
S
Ken37
U
S
Ken36
S
U
Ken34
Jan02
U
S
Ken32
Ken30
U
U
Ken33
40
M
U
Ken35
Ken31
U
20
M
S
M
U
S
Jan03
Jan04
Jan05
0
Ken52
Ken51
Ken50
Ken49
Ken48
Ken47
Ken46
Ken45
Ken44
Ken43
Ken42
Ken41
Ken40
Jan02
U
U
U
M
U
U
U
U
U
U
U
U
U
U
U
U
U
S
U
U
U
Jan04
Jan05
Date
Figure 3. Time course of RSV infections of each of the 52 children included in the final analysis. Dotted green lines represent the time from
bi th to
birth
t the
th first
fi t positive
iti sample.
l Each
E h symbol
b l represents
t a positive
iti sample
l for
f which
hi h genotyping
t i
has
h been
b
completed:
l t d ‘,
‘ GA2
GA2; ¯,
¯ GA5
GA5;
|, SAB1 and ½, BA. The letter above each sample represent the clinical status: U, upper respiratory tract infection; M, mild pneumonia; S,
severe pneumonia and VS , very severe pneumonia
pneumonia. The continuous red and blue lines represents the respective number of RSV A and
RSV B cases of under five-year olds admitted to Kilifi District hospital during the period.
Date
20
U
U
Jan03
40
U
M
U
No of in-pa tient ca
ases
U
60
0
Figure 4. Maximum likelihood phylogenetic trees of homologous group re-infections. Panel 4A shows
homologous group A to A re-infections based on sequences from 11 subjects and three reference
sequences Panel 4B shows homologous group B to B re-infections
sequences.
re infections based on sequences from 11
subjects and two reference sequences. The subject sequences are represented as follows: Ken#/xx
= unique
q
identifier/year
/y
of sampling.
p g The unfilled triangles
g
represent
p
first infections,, the filled red
trianges represent confirmed second infections while the purple were suspected to be prolonged
shedding cases. The summary of the observed genotype patterns is shown within each panel.