TABLE 2.

Passive transfer of immune serum protects naïve mice from replication of challenge virus in the respiratory tract

Expt no. and dose of SARS-CoV (TCID50)Passively transferred serumaNeutralizing antibody titer in serumbMean prechallenge neutralizing anti- body titer in re- cipient miceVirus replication in challenged mice
LungsNasal turbinates
No. of mice infected/no. testedMean virus titerc ± SENo. of mice infected/no. testedMean virus titer ± SE
1 (103)Immune1:2841:280/3≤1.5 ± 0d2/33.2 ± 0.72
Nonimmune≤1:4≤1:42/33.9 ± 1.212/32.4 ± 0.32
2 (104)Immune, undiluted1:1,0241:2310/3≤1.8 ± 0e*1/32.0 ± 0.17*
Immune, 1:10 dilution1:2741:221/32.0 ± 0.172/33.3 ± 0.73
Nonimmune≤1:4≤1:43/37.3 ± 0.143/35.6 ± 0.55
  • a Serum (200 μl) pooled from immunized or uninfected mice was administered to recipient mice by intraperitoneal injection in experiment 1, and 500 μl of the indicated serum preparation was administered to mice in experiment 2.

  • b Titer of antibody that neutralized infectivity of 100 TCID50 of SARS-CoV.

  • c Virus titers are expressed as log10 TCID50 per gram of tissue. *, P < 0.05 versus nonimmune control.

  • d Virus not detected; this value represents the lower limit of detection of infectious virus in a 10% suspension.

  • e Virus not detected; this value represents the lower limit of detection of infectious virus in a 5% suspension.