TABLE 2.

Correlation between the frequency of epitope-specific CD8+ T cells, the level of protection measured by VV challenge, and the time after priming with MCMV-wt, MCMV-NP, or influenza virusa

Priming (PFU)nSpearman rank correlation of factor vs factor
Frequency of specific cells vs time after priming (P)Frequency of specific cells vs level of pro- tection (P)Time after priming vs level of pro- tection (P)
MCMV (103)400.841 (<0.001)0.521 (0.001)0.483 (0.002)
MCMV-NP230.702 (<0.001)0.507 (0.014)0.513 (0.012)
Influenza virus23−0.882 (<0.001)0.760 (<0.001)−0.736 (<0.001)
Overall860.566 (<0.001)
  • a Mice were primed with the indicated virus, and the frequency of epitope-specific CD8+ T cells was monitored in the blood by tetramer staining. Frequencies used for calculation were measured 0 to 3 days before challenge. At 4 days after challenge, the VV titers were measured in the ovaries. The level of protection was calculated as described in Materials and Methods to correct for variation between different challenge experiments. Numbers indicate the correlation coefficients that were calculated with the Spearman's rank correlation using logarithmic scales for all variables. Two-tailed P values for each correlation are indicated in parentheses. Data from one to three experiments per virus and time point were included in the analysis.