Fig. 2.

Summary of the tonsil biopsy results for sPMCA versus IHC. Of the 48 deer examined, sPMCA findings were consistent with IHC results in 27 individuals, 13 of which remained negative by both assays throughout the collection period. In 17/48 deer (35 %), sPMCA identified CWD infection at time points prior to conventional IHC, including four IHC-negative deer identified at necropsy. In 4/48 deer (8 %), IHC identified CWD infections in samples that did not amplify PrP^res using sPMCA, including three deer that were negative by sPMCA at the termination of the study. Statistical analysis showed that sPMCA could identify CWD PrP^res significantly earlier (2.78 months) than IHC. Deer are grouped by inoculum type (shown by shading or no shading) corresponding to the groupings in Table 1.