Host-pathogen interactions in scrapie.

There are many strains of the agent which causes scrapie and these can be used singly or given as mixed infections to investigate the ways in which agent and host control mechanisms interact during the pathogenesis of the disease. Two genes in mice are described; one only affects the kinetics of the disease when extraneural injections are used, the other acts irrespective of the route of injection and it is suggested that it determines the structure of a multimeric agent-replication site, the number of such subcellular sites in the body being strictly limited.--Different agent strain/host genotype combinations give such a wide range of results that conventional quantitative analysis can yield little of predictive genetical value unless the major biological variables in host and agent can be specified.