Table 1

Antibodies elicited by infection

VirusEndpoint dilution titerEndpoint dilution titer with urea
A/PR/8/193424,300a24,300b
A/FM/1/194772,90072,900
A/Den/1/19572,700300
A/TX/36/19912,700900
A/NC/20/19992,700900
A/Bris/59/20072,700900
A/CA/07/200972,90024,300
  • a Average endpoint dilution titer of anti-rHA, A/CA/07/2009, from sera collected 3 months after each infection.

  • b Average endpoint dilution titer against rHA in an HA-specific urea displacement ELISA.