Cell - 8 September 2016

lower levels of SHM at both the nucleotide and amino acid levels
in GLHL121 and MutHGLL121 B cells than the sequential protocol
(Figures 5A–5F;Figures S5G–S5I). We conclude that repeated
immunizations with one or two antigens fails to elicit the high
levels of mutation found after sequential immunization.

Neutralization by Monoclonal Antibodies

Antibodies from immunized mice showed somatic mutations

that were in some cases identical or similar to mutations in

PGT121, PGT122, PGT123, or 10-1074 (PGT121-like). Indeed,

there was a direct correlation between the total number of amino

Figure 2. Longitudinal Analysis of the Serum from Sequentially Immunized GLHL121 and MutHGLL121 Mice by ELISA
(A) Diagram of the sequential immunization protocol.
(B) Graphs show the results of ELISAs on serum (1:100 starting dilution) collected from naive and sequentially immunized GLHL121 (three mice) and MutHGLL 121
(three mice). ELISAs show reactivity against the immunogen and the boosting protein after each step. When indicated, ELISA binding of the human PGT121 bNAb
is also shown (1:100 starting dilution of a 500mg/ml solution = 5mg/ml). VLC = 5 different native-like SOSIPs.
See alsoFigure S2.

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