TABLE 3.
Protective efficacy of dk/Sing (H5N3) vaccine against lethal infection with HK/483 virus
| Vaccine group | Prechallenge antibody titera against:
|
Mean virus titer (log10 EID50/ml) ± SDb
|
No. protected/total no.c
|
|||||
|---|---|---|---|---|---|---|---|---|
| HK/156
|
HK/483
|
|||||||
| HI | Neutralization | HI | Neutralization | Lung | Brain | Infection | Death | |
| dk/Singd | 80 | 400 | 40 | 100 | 2.6 ± 0.6e | ≤0.8e | 7/10f | 12/12e |
| dk/Sing + alum | 1,280 | 8,000 | 320 | 1,600 | ≤1.2e | ≤0.8e | 8/8e | 12/12e |
| Alum | 10 | 25 | 10 | 25 | 6.3 ± 0.9 | 2.5 ± 1.0 | 0/7 | 0/10 |
a
Serum samples pooled from 10 mice per group were used.
b
Mean virus titers and protection from infection were determined on day 6 p.i. Titers represent means ± SD of 7 to 10 mice per group.
c
Mice were monitored for 14 days after challenge. Mice in the alum-vaccinated group died on day 6 or 7.
d
Mice were vaccinated with two doses of 10 μg of formalin-inactivated dk/Sing vaccine and challenged 4 months later with 50 LD50 of HK/483 virus.
e
P < 0.001 compared with alum-vaccinated group.
f
P < 0.01 compared with alum-vaccinated group.