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. 2012 May 8;3:87. doi: 10.3389/fimmu.2012.00087

Figure 2.

Figure 2

Infection or vaccination with pdmH1N1 induces a dominant antibody response targeting the HA stem. (A) mAbs to the HA stem fail to inhibit hemagglutination but a minority of mAbs inhibit hemagglutination by pdmH1N1. All mAbs were at 40 μg/ml and diluted 50% with virus in the first well. No detectable hemagglutination means that hemagglutination was not inhibited at 20 μg/ml. (B) Anti-HA stem mAbs inhibit binding of a mouse mAb (C179 (Okuno et al., 1993)) to the HA stem in a competition ELISA. Note that mAb I5-52, not using IGHV1-69, also inhibited C179 binding. (C) pH 5 pre-treatment of HA selectively decreases binding of anti-HA stem mAbs whether encoded by IGHV1-69 or other IGHV genes (like I5-52) but not anti-HA head mAbs like V2-36. (D) ELISA showing competitive inhibition of the indicated mAbs of the binding of biotinylated I5-24, which uses IGHV1-69 and binds to the HA stem. Note that V2-36 also inhibits binding of I5-24. Also shown is competitive inhibition of I5-24 binding by I14-2B7, which uses IGHV1-18 and IGKV2-30. KE5, an human anti-HCMV monoclonal antibody (McLean et al., 2005), was used as a negative control.