Fig. 4.

shows a representative Western blot of the PrP and PrP-res pattern of cultured cells infected with different TSE agents. N2a58 cells infected with 22L scrapie and Japanese FU-CJD agents (lanes labeled N₂) show a very different pattern than GT1 cells, infected with these same agents, as well as with a variety of other TSE agent strains. Despite these cell-type differences in PrP band pathology in cultured cells, neither the 22L nor the FU agents were modified. The FU and 22L agents, but not cell-type PrP-res patterns, bred true as shown by re-inoculation of mice [Arjona et al., 2004; Nishida et al., 2005; Liu et al., 2008]. PK+ lanes for PrP-res are indicated. The Japanese CJD isolates FU and YAM (lane labeled YA) show the same 13kd band in both undigested and digested samples, and this band distinguishes these geographic isolates from all the other agents in GT1 cells. Since this band is not visible in infected brain, it is a cell type-specific band that can be induced only by Asiatic CJD agents. The undigested vCJD lane (labeled vCJ) also shows a doublet at 19kd that corresponds to the thicker 19kd band in the PK+ lane, as well as to the 19kd band found in brain (see Fig. 3). This 19kd doublet was consistently observed after infection with donor brain samples from 1° and 2° passages of vCJD propagated in all the different host genotypes (Tga20, NZW and CD-1). All the other agents induced the 21kd PrP band in GT1 cells. Note that PrP and PrP-res profiles are the same after infection with the markedly different 263k and 22L scrapie agents. Chandler-RML scrapie infection resulted in a greater sensitivity of PrP to limited PK digestion.