Transmissible spongiform encephalopathies (TSEs) are incurable, fatal diseases. The dye Congo Red (CR) can cure cells infected with agents of the sheep TSE, scrapie, but is not used as a therapeutic or prophylactic agent in vivo, as its effects are small, possibly due to low blood-brain barrier permeability, and complicated by its intrinsic carcinogenicity. In this paper, the development is described of a structure-activity profile for CR by testing a series of analogues of this dye for their ability to inhibit the formation of the protease-resistant prion protein, PrP-res, a molecular marker for the infectious agent, in the scrapie-infected, SMB cell line. It was found that the central benzidine unit in CR, which gives the molecule potential carcinogenicity, can be replaced by other, less toxic moieties and that the sulphonate groups on the core molecule can be replaced by carboxylic acids, which should improve the brain permeability of these compounds. However, detailed dose-response curves were generated for several derivatives and they revealed that, while some compounds showed inhibition of PrP-res accumulation at high concentrations, at low concentrations they actually stimulated levels of PrP-res above control values.

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Chicken kidney (CK) cell cultures have historically proved useful for the assay of a number of viruses including coronaviruses. A technique for the preparation of such cell cultures, using a combination of manual and trypsin disaggregation of kidneys dissected from 2- to 3-week-old birds is described. This technique routinely gives high cell yield together with high viability and the resultant adherent primary cultures can be used for virus growth and plaque formation.

Chicken tracheal organ cultures (TOCs), comprising transverse sections of chick embryo trachea with beating cilia, have proved useful in the isolation of several respiratory viruses and as a viral assay system, using ciliostasis as the criterion for infection. A simple technique for the preparation of chicken tracheal organ cultures in glass test tubes, in which virus growth and ciliostasis can be readily observed, is described.

Chicken tracheal organ cultures (TOCs), comprising transverse sections of chick embryo trachea with beating cilia, have proved useful in the isolation of several respiratory viruses and as a viral assay system, using ciliostasis as the criterion for infection. A simple technique for the preparation of chicken tracheal organ cultures in glass test tubes, in which virus growth and ciliostasis can be readily observed, is described.