<i>De novo</i> generated PrP<sup>Sc</sup> is infectious, producing a new clinical disease.

<p>(A) Groups of 5 hamsters were <i>intra-cerebrally</i> (i.c.) inoculated with similar quantities of PrP<sup>Sc</sup> from either <i>de novo</i> generated protein (PGP-h1) or three well-established hamster prion strains, including 263K, HY and DY. Clinical signs were monitored weekly as described in <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1000421#s4" target="_blank">Materials and Methods</a> and when the signs progressed up to the level 4 of our scale, animals were considered sick and sacrificed to avoid excessive pain. This time is recorded as incubation period and is represented in the figure as days post-inoculation (d.p.i.). Differences on the incubation periods produced by the diverse sources of infectious material were analyzed by one-way ANOVA and were found highly significant (P<0.001). The significance of the differences between PGP-h1 and each of the other hamster prion strains were evaluated by the Dunnett Multiple Comparison post test. All differences were statistically significant (P<0.001). Behavioral alterations during the clinical phase of the disease in animals inoculated with various prion strains were assessed by an open field test, as described in <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1000421#s4" target="_blank">Materials and Methods</a>. Hamsters at mid stages of the disease (around 1 week after the first clinical signs were observed) were placed in a corner of the field and its behavior recorded for five minutes. We measured and analyzed total distance traveled during 20 s intervals (B), time that animals spent in vertical activity (C) and inactive time (D). The last two parameters are represented as a percentage of the total time. Tests were done twice for each animal and the result showed in the figure correspond to the average of the two determinations. Behavioral data was analyzed by one-way ANOVA with the Dunnett multiple comparison post-test. Statistical probability that the differences between PGP-h1 and control animals or hamsters inoculated with the other strains are different is indicated in the figure.</p>