Table 3.

Comparative neutralization of the assay and animal challenge stocks of‚ÄČSIVsmE660

Animal no.aNab titer measured with SIVsmE660b:
Cell viabilityReduction in p27
Assay stockChallenge stockChallenge stock
B51,0821,3402,118
B61,8417,5027,405
C1470384181
  • a Plasma samples were obtained 28 weeks post-intravenous inoculation with SIVsmE660.

  • b Neutralization was measured with the assay stock of SIVsmE660 grown in CEMx174 cells and the animal challenge stock of the same virus grown in macaque PBMC. Assays were performed with CEMx174 cells as described in the text with one modification: cells exposed to the animal challenge stock of virus were washed three times with growth medium 1 day after the addition of cells in order to remove the virus inoculum and residual anti-p27 antibodies. Culture supernatants were harvested for p27 quantification at the time cells were stained for viability. Neutralization titers are the reciprocal plasma dilution where either 50% of cells were protected from virus-induced killing or p27 synthesis was reduced 90% relative to virus control wells (no plasma sample). The average amount of p27 present in the virus control wells was 95 ng/ml.