Table 2.

Infection of chimpanzees with rA2ΔNS1 or rA2ΔM2-2 induced significant protection against subsequent challenge with wild-type RSV A2 in the upper and lower respiratory tracts

Immunizing virusInoculum dosea (log10PFU/ml)No. of animalsReplication of RSV challenge virus at the indicated sitebMean peak rhinorrhea score
NasopharynxTrachea
Mean no. of days of shedding ± SEMean peak titerc ± SEMean no. of days of shedding ± SEMean peak titer ± SE
rA2ΔNS15.042.8 ± 0.751.7 ± 0.461.0 ± 0.411.8 ± 0.731.0
rA2ΔM2-25.043.5 ± 0.872.3 ± 0.711.0 ± 0.711.7 ± 0.631.0
rA2ΔNS2d 4.04ND1.9 ± 0.30ND2.2 ± 0.771.0
cpts248/404e 4.723.5 ± 0.502.3 ± 0.250<0.71.0
Nonee 28.5 ± 0.505.0 ± 0.356.0 ± 1.04.8 ± 0.303.0
  • a Each virus was initially administered at the indicated dose in a 1.0-ml inoculum given intranasally and intratracheally.

  • b On day 56, chimpanzees were challenged with wild-type RSV A2 administered at a dose of 104 PFU/ml in a 1.0-ml inoculum given intranasally and intratracheally. Nasopharyngeal swab samples were collected daily for 12 days, and tracheal lavage samples were collected on days 2, 5, 6, 8, and 12. ND, not determined.

  • c Mean peak titers (log10 PFU/ml) were calculated by using the peak virus titer achieved in each animal.

  • d Data from the study of Whitehead et al. (29).

  • e Historic control animals from the study of Crowe et al. (10) were used.