Table 2.

Replication of rA2ΔM2-2 and rA2 in mice and protection against wild-type RSV A2 challenge

Immunizing virusVirus replicationa (mean log10 PFU/g of tissue ± SE) in:RSV A2 replication after challengeb (mean log10 PFU/g of tissue ± SE) in:
Nasal turbinatesLungsNasal turbinatesLungs
rA23.72 ± 0.334.0 ± 0.13<1.4<1.4
rA2ΔM2-2<1.4<1.4<1.4<1.4
None (control)<1.4<1.43.53 ± 0.174.10 ± 0.13
  • a Groups of 12 BALB/c mice were immunized intranasally with 106 PFU of the indicated virus on day 0. The level of infected virus in the indicated tissues was determined by a plaque assay at day 4, and the mean log10 titer ± standard error per gram of tissue was determined.

  • b Groups of 6 BALB/c mice were challenged intranasally with 106 PFU of RSV A2 on day 21 and sacrificed 4 days later. The replication of wild-type RSV A2 in tissues was determined by a plaque assay, and the mean log10titer ± standard error per gram of tissue was determined.