Species barrier

Human prion disease models have also been developed in mice [154,155]. Crossing the species barrier into an experimentally accessible animal system, the prions responsible for Creutzfeldt Jakob disease, new variant CJD, Gerstmann-Straussler-Scheinker disease, and fatal familial insomnia produce a reproducible time-dependent neuronal degeneration leading to death. 

Kocisko DA, Priola SA, Raymond GJ, Chesebro B, Lansbury PT Jr, Caughey B. Species specificity in the cell-free conversion of prion protein to protease-resistant forms a model for the scrapie species barrier. Proc Natl Acad USA 1995 92 3923-3927. 

Kellershohn N, Laurent M. Species barrier in prion diseases a kinetic interpretation based on the conformational adaptation of the prion protein. Biochem J 1998 334 539-545. 

Prion transmission between species is limited by a barrier. A species barrier restricts transmission of prion disease between different mammalian species. On primary passage of prions from species A to species B, usually not all inoculated animals of species B develop disease, and those that do have much longer and more variable incubation periods than those that are seen with transmission of prions within the same species. On second passage of infectivity to further animals of the species B, transmission parameters resemble within-species transmissions, with most if not all animals developing the disease with short and consistent incubation periods. Species barriers can therefore be quantified by measuring the fall... 

Bruce, M. etal. Transmission of bovine spongiform encephalopathy and scrapie to mice Strain variation and the species barrier. Philos. Trans. R. Soc. Bond. [Biol] 343 405-411, 1994. 

Fig. 1. Transmission mechanisms. Strain barrier PrPc (circle) interacts with different strains of PrPSc (square or triangle). The replicated PrPSc is similar to the template. The 3F4 epitope is not recognized when it is in PrPSc, but is exposed after pardal denaturation by GdnHCI so that it is detected by the antibody. Antibody reactivity depends on the particular strain of PrP (Safar et aL, 1998). Species barrier when the template PrPSc contains unfavorable residues at the binding interface, the transformation of PrPc to Pr l>Sr does not occur. In vitro replication 35S label of PrPc is detected in PrPSc after replication in a medium containing GdnHCI (Kocisko et aL, 1994).

To account for the species barrier of prion infectivity, it was proposed that the 109-112 epitope recognized by antibody 3F4 is localized at the... 

Warwicker, J. (1997). Species barriers in a model for specific prion protein dimerisation. 

Another virus, of the coronavirus type, has made headline news under the name SARS. It seems to be a disease that has crossed species boundaries, from animals to humans. This disease appears not to kill its victims directly but sets up a storm of immunochemicals in the body called cytokines. These are inflammatory materials and can be more deadly than the virus itself in large quantities. Influenza and pneumonia use the same technique.20 The bird flu of 1997 and 2004 seems to have crossed the animal-human species barrier and has created an urgent need for research into counteracting this problem. 

There is a hypothesis that the HIV vims might have jnmped the species barrier from monkey to people via a contaminated poho vaccine becanse the vaccine was manufactnred in primary monkey kidney tissne known to be sometimes contaminated with monkey vimses. The existing evidence, inclnding tests of pohovims seed stocks, more than 20 vaccine lots, and sernm samples from vaccine recipients makes this hjrpothesis highly improbable (6,7). 

The misfolded form, scrapie, results in a class of disease called spongiform encephalopathies, e.g., mad cow disease. Unlike other diseases caused due to protein misfolding, prion diseases are infectious. The infecting agent is the misfolded protein. Prionogenic diseases are transmitted across the species barriers, from cow to sheep to human beings, and are fatal. 

Recently a serious public health problem has arisen by showing that a prion disease in cattle can cross species barriers and infect humans. This occurred when cattle were fed meal made from sheep infected with scrapie. The cattle developed BSE (commonly called mad cow disease ). Subsequently, when people consumed prion-contaminated beef, a small number, primarily in Great Britain, developed a variant of CJD (vCJD) approximately five years afterward. The variant form of CJD is a unique form of prion disease occurring in a much younger population than would be expected from inherited or sporadic CJD. Both BSE and vCJD share many similar pathologic characteristics suggesting an etiologic link between human vCJD and cattle BSE. 

M. Horiuchi, S. A. Priola, J. Chabry, et al. Interactions between heterologous fortms of prion protein binding, inhibition of conversion, and species barriers. Proceedings of the Society of National Academy of Sciences (USA) 97,5836 (2000). 

CWD prions are highly contagious, at least for transmission within and between deer and elk populations. However, it is also of great interest to analyze the interspecies transmissibility or species barriers of CWD for several reasons. Such studies may enable determination of (1) the source of the CWD agent, (2) the possible distribution to carnivores feeding on infected carcasses and rodents as reservoir hosts, and (3) finally, the most important reason for such studies is to predict whether CWD might be transmissible to humans. 

Harrington RD, Baszler TV, O Rourke KI et al (2008) A species barrier limits transmission of chronic wasting disease to mink (Mustela vison). J Gen Virol 89 1086-1096... 

Keywords Quasi-species Species barriers Strains Transgenic models... 

Prion Strains, Species Barriers, and Transgenic Mouse Models. 80... 

---