Science - USA (2022-03-04)

fig. S1). By contrast, heterologous booster vac-
cination with mRNA-1273 led to a much larger
(86-fold) increase in S-specific serum IgG bind-
ing responses (Fig. 1B and fig. S1). Correspond-
ingly, ChAdOx1 prime immunization elicited
weak serum IgG binding activity to recombinant
receptor binding domain (RBD), N-terminal

domain (NTD), and prefusion-stabilized S2

subdomains [geometric mean areas under

the curve (AUCs) ranging from 67 to 321], and

homologous and heterologous booster immu-

nization enhanced these responses by two- to

fourfold and 25- to 77-fold, respectively (Fig. 1,

CtoE).

Cross-reactive MBCs induced by seasonal

b-coronaviruses are activated and expanded

after primary SARS-CoV-2 infection and mRNA

vaccination ( 13 , 14 ). To determine whether

ChAdOx1:ChAdOx1 and/or ChAdOx1:mRNA-1273

vaccination elicited similar recall responses,

we assessed serum IgG binding to recombinant

1042 4 MARCH 2022¥VOL 375 ISSUE 6584 science.orgSCIENCE

Fig. 1. Serum binding and neutralizing
activity after homologous and
heterologous prime-boost vaccination.
(A) Immunization and blood draw
schedule. (BtoG) Serum IgG binding
to (B) recombinant SARS-CoV-2 S
(1:1 mixture of WT S and S-2P antigens),
(C) NTD, (D) RBD, (E) prefusion-stabilized
S2, (F) HKU1 S, and (G) OC43 S, as
assessed with enzyme-linked immuno-
sorbent assay. Binding of prepandemic
donor sera (n= 17 donors) is shown
forcomparisonin(F)and(G).Geometric
mean AUC values are shown below
data points. (HtoJ) Serum neutralizing
activity against (H) authentic SARS-CoV-2
D614G and (I) Beta/B.1.351 measured
with plaque reduction assay (n=27or
28 donors from each cohort) and
(J) Delta/B.1.617.2 measured with cyto-
pathic effect (CPE)–based colorimetric
microneutralization assay (n=10donors
from each cohort). Plotted values
represent 50% serum neutralizing titers.
Values below the dotted line indicate
the percentage of samples with serum
neutralizing titers below the limit of
detection. (K) Serum neutralizing activity
against authentic Omicron/B.1.1.529/BA.1
measured with 100% CPE inhibition
(n= 10 donors from each cohort). Values
below the dotted line indicate the
percentage of samples with serum
neutralizing titers below the limit
of detection. Statistical comparisons
between prime and boost were
determined by means of Wilcoxon
pair-matched rank sum test.
Statistical comparisons across
groups were determined by means
of two-tailed Mann WhitneyUtest
with Bonferroni correction [(B) to (E)]
and (H) to (K)] or two-sided Kruskal
Wallis test by ranks with subsequent
Dunn’s multiple comparisons [(F) and
(G)]. P< 0.05, P< 0.01, P< 0.001,
****P<0.0001. P, Prime; B, Boost;
AUC, area under the curve; LOD, limit
of detection; ns, nonsignificant. All data
are representative of at least two
independent experiments.

7–9 days

mRNA-1273

(n=27)

7–9 days

ChAdOx1

(n=28)

ChAdOx1

(n=55)

65-87 days

PBPB

100

101

102

103

104

105

106

Anti-SARS-CoV-2 S IgG (AUC)

961

(^47721433)
123254
ChAdOx1:
ChAdOx1
ChAdOx1:
mRNA-1273
Anti-RBD IgG (AUC)
PBPB
100
101
102
103
104
105
106
258
(^476243)
6102
ChAdOx1:
ChAdOx1
ChAdOx1:
mRNA-1273
Anti-NTD IgG (AUC)
PBPB
100
101
102
103
104
105
106
103
195
67
5081
ChAdOx1:
ChAdOx1
ChAdOx1:
mRNA-1273
Anti-S2 IgG (AUC)
PBPB
100
101
102
103
104
105
106
295 1156 260
12519
ChAdOx1:
ChAdOx1
ChAdOx1:
mRNA-1273
PBPB
101
102
103
104
105
106
Anti-HKU1 S IgG (AUC)
ChAdOx1:
ChAdOx1
ChAdOx1:
mRNA-1273
Pre-
pandemic
4410 43354037 5098
1562
ns ns
PBPB
101
102
103
104
105
106
Anti-OC43 S IgG (AUC)
ChAdOx1:
ChAdOx1
ChAdOx1:
mRNA-1273
Pre-
pandemic
ns ns
2826 6231 58635645 7244
PBPB
101
102
103
104
Serum Neutralization IC
50
(1/dilution)
ChAdOx1:
mRNA-1273
ChAdOx1:
ChAdOx1
18 82 19 1595
(89%)(21%) (85%)
D614G
PBPB
101
102
103
104
Serum Neutralization IC
50
(1/dilution)
ChAdOx1:
mRNA-1273
ChAdOx1:
ChAdOx1
<20 56 <20 854
(100%)(40%) (100%)
Delta
PBPB
101
102
103
104
Serum Neutralization IC
50
(1/dilution)
ChAdOx1:
mRNA-1273
ChAdOx1:
ChAdOx1
<24 37 <24 727
(100%)(50%) (96%)
Beta
B
C
D
NTNTDD E
SARS 2 S RBD
S 2 G
HKU1HKU1SS
OC43OC43SS
H I J K
PBPB
101
102
103
Serum Neutralization IC
100
(1/dilution)
ChAdOx1:
mRNA-1273
ChAdOx1:
ChAdOx1
<10<10<10 27
(100%)(100%) (100%)(20%)
ns
Omicron
A
F
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