Cross-Reactive Neuraminidase Antibodies Afford Partial Protection against H5N1 in Mice and Are Present in Unexposed Humans
Figure 1
NA-Specific Antibody Responses to Immunization
Serum was collected from BALB/cJ mice after two injections with plasmid encoding the NA of human H1N1 influenza strain A/New Caledonia/20/99 (huN1) or saline only. Antibody reactivities with huN1 and the NA of H5N1 influenza strain A/Vietnam/1203/04 (avN1) were determined by ELISA.
(A) Between the huN1 DNA and saline-only treatment groups there was a statistically significant difference in mean IgG titers against huN1 (p < 0.001).
(B) IgG titers detected against avN1 were not significantly different between the treatment groups (p = 0.092). The antibody titer against each target was defined as the reciprocal of the highest serum dilution that produced an ELISA signal twice as intense as the signal from equivalently diluted naïve serum. The lower limit of detection was a titer of 20.