TABLE 1.
Antibody isotype titers specific to influenza virus A/PR8 at different time pointsa
| Time (immune sera) | Antibody isotype titer (103)
|
|||
|---|---|---|---|---|
| IgG1 | IgG2a | IgG2b | IgG3 | |
| 0 wk (preimmune) | 0.5 ± 0.1 | 0.05 ± 0.1 | 0.05 ± 0.02 | 0.05 ± 0.01 |
| 2 wk (primary) | 2 ± 0.5 | 2 ± 0.5 | 1 ± 0.3 | 0.05 ± 0.01 |
| 5 wk (first boost) | 16 ± 2.4 | 16 ± 1.8 | 2 ± 0.5 | 0.5 ± 0.01 |
| 8 wk (second boost) | 32 ± 2.5 | 32 ± 2.2 | 32 ± 3.6 | 1 ± 0.1 |
| 5 mo postimmunization | 64 ± 4.2 | 64 ± 3.4 | 32 ± 3.2 | 1 ± 0.1 |
a
IgG subclass serum antibodies specific to influenza virus PR8 were determined at week 0, 2, 5, 8, and 5 month postimmunization (at week 27) in the group of mice that were intranasally immunized with 10 μg of HA VLPs. Titers are expressed as the highest dilution of serum having a mean optical density at 450 nm greater than the mean plus 2 standard deviations of similarly diluted naïve serum samples.