Figure 4. PCR screen of individual donor libraries for neutralizing mAbs and donor serology.

(a) PCR amplification of cDNA from each donor IgM⁺ memory B cell library using oligonucleotide pairs designed so their 3′ ends specifically anneal in the HCDR1 and HCDR3 regions. Donors are indicated at the top of the figure. The expected size of the amplified fragment is indicated with an arrow. The identity of the bands was confirmed by sequencing (b) Binding and neutralizing activity of donor serum collected at the same time as the B cells used for library construction (note serum was not available for donor 12). IgM and IgG ELISA reactivity was measured against rHA and neutralizing activity against H1N1 (A/Hong Kong/54/98) and H5N1 (A/Vietnam/1203/04). Donor 1020 who was PCR positive for the tested neutralizing mAbs is indicated in bold.