It is notable that there is a discrepancy between patients for serum MN titers, the severity of disease, and the frequency of plasmablasts expressing neutralizing antibodies (Table I and Fig. 3 ). For example, patient EM, despite having the worst disease course, had the greatest HAI and MN serum titers. This may be caused by the time from infection (day 31), allowing full conditions that were previously published (Wrammert et al., 2008; Smith et al., 2009) . Variable genes were determined using in-house analysis software compared with the Immunogentics V gene dataset and the IMGT search engine (Ehrenmann et al., 2010; Lefranc et al., 2009 ). Background mutation rates by this method is 1 base-exchange per 1,000 bases sequenced (based on sequences of constant region gene segments). Comparisons were made to historical data, some of which was previously published (Zheng et al., 2005; Wrammert et al., 2008; Duty et al., 2009) .