Volume 11, Number 8—August 2005
Letter
SARS Vaccine Protective in Mice
Table
Immunogen* | Neutralization titer† |
Virus replication upon challenge‡ |
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Lungs |
Nasal turbinates |
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2 wk post 1st dose | 2 wk post 2nd dose | 2 wk post 3rd dose | No. infected/ no. tested | Mean (± SE) virus titer§ | No. infected/ no. tested | Mean (± SE) virus titer§ | |
PBS | <1:8 | <1:8 | <1:8 | 4/4 | 6.3 ± 0.3 | 3/4 | 2.8 ± 0.35 |
MF59 | <1:8 | <1:8 | <1:8 | 4/4 | 6.1 ± 0.13 | 3/4 | 3.0 ± 0.58 |
Influenza A (5 μg) | <1:8 | <1:8 | <1:8 | 4/4 | 6.3 ± 0.07 | 3/4 | 2.9 ± 0.36 |
Influenza A (5 μg) + MF59 | <1:8 | <1:8 | <1:8 | 4/4 | 6.0 ± 0.19 | 4/4 | 3.0 ± 0.11 |
BPL-SARS-CoV (5 μg) | <1:8 | <1:8 | 1:64 | 1/4 | 2.0 ± 0.0¶# | 0/4 | ≤1.8 ± 0**†† |
BPL-SARS-CoV (5 μg) + MF59 | <1:8 | 1:91 | 1:645 | 0/4 | ≤1.5 ± 0¶** | 0/4 | ≤1.8 ± 0**†† |
*The indicated immunogens or control preparations were administered to mice by subcutaneous injection on 3 occasions 2 weeks apart; PBS, phosphate-buffered saline.
†Neutralization titers were determined as described (8).
‡Mice were challenged with 104 50% tissue culture infectious doses (TCID50) SARS-CoV intranasally.
§Virus titers are expressed as log10 TCID50/g of tissue.
¶p<0.00001 in a 2-tailed Student t test, compared to titers seen in mice that were immunized with PBS.
#Indicates the titer of a single animal. The remaining 3 mice had no detectable levels of virus.
**Virus not detected; the lower limit of detection of infectious virus was 1.5 log10 TCID50/g in a 10% wt/vol suspension of lung homogenate and 1.8 log10 TCID50/g in a 5% wt/vol suspension of nasal turbinates.
††p = 0.025 in a 2-tailed Student t test, compared to titers seen in mice that were immunized with PBS.
1These authors contributed equally to this work.