Search

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.

Bovine spongiform encephalopathy (BSE) and its human equivalent, variant Creutzfeldt-Jakob disease (vCJD), are caused by the same strain of infectious agent, which is similar to, but distinct from, >20 strains of their sheep scrapie homologue. A better understanding of the molecular strain determinants could be obtained from cells in monoculture than from whole animal studies where different cell targeting is commonly a strain-related feature. Although a few cell types can be infected with different strains, the phenotypes of the emergent strains have not been studied. We have cured the scrapie-infected, clonal SMB cell line with pentosan sulfate, stably re-infected it with a different strain of scrapie and shown that biological properties and prion protein profiles characteristic of each original strain are propagated faithfully in this single non-neuronal cell type. These findings attest to the fact that scrapie strain determinants are stable and host-independent in isolated cells.

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.

The development of diagnostic tools for transmissible spongiform encephalopathies (TSEs) would greatly assist their study and may provide assistance in controlling the disease. The detection of an abnormal form of the host protein PrP in noncentral nervous system tissues may form the basis for diagnosis of TSEs. Using a new antibody reagent to PrP produced in chickens, PrP can be readily detected in crude tissue extracts. PrP from uninfected spleen had a lower molecular mass range than PrP from brain, suggesting a lower degree of glycosylation. A simple method for detecting the abnormal form of the protein, PrPSc, in ruminant brain and spleen has been developed. PrPSc was detected in sheep spleen extracts from a flock affected by natural scrapie and was also found in spleens from some, but not all, experimental TSE cases. In spleens from cattle with bovine spongiform encephalopathy (BSE) no PrPSc was detected. It is therefore suggested that there is differential targeting of PrPSc deposition between organs in these different types of TSE infection which, with other factors, depends on strain of infecting agent.