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PubMed1980

The antigenicity and immunogenicity of the intracellular and extracellular forms of vaccinia virus. I: The production of high-titre vaccinia extracellular virus and its antigenicity after inactivation.

Vaccinia extracellular virus, which until recently (Payne, 1979) had only been produced at low titre, 10(5)-10(6) pfu/ml, was produced at titres of up to 10(7.5) pfu/ml by selective combination of virus, cell and medium. It could be concentrated to 10(9)-10(9.3) pfu/ml by ultrafiltration without significant losses in quantity or quality. The final preparation was only contaminated to the extent of 25-50% with virus neutralizable by antiserum to intracellular virus, compared with the 70-90% found by other workers. When inactivated it produced good antibody titres in rabbits. In contrast, mice failed to produce antibody to extracellular virus, but did so to intracellular virus: they were also protected against a potentially lethal challenge with ectromelia virus.

Animals↗
PubMedDate not supplied

Zonal-centrifuged human diploid cell rabies vaccine.

In order to reduce the risk of allergic reactions, a purified human diploid cell culture rabies vaccine was developed. Pitman-Moore strain of rabies was propagated in WI-38 or MRC-5 cells. Both cell strains were found to be equally suitable for pro agation of rabies virus. The virus was purified and concentrated by continuous-flow sucrose density gradient ultracentrifugation. Virus peak fractions were diluted with a stabilized and then inactivated with BPL and freeze-dried. According to the standard NIH test for potency, the vaccine proved to be very potent and stable. The results of initial clinical applications of the vaccine will be presented.

Antibody Formation↗
PubMedDate not supplied

Differential growth response to exogenous calcium in normal and carcinogen-exposed primary human keratinocyte cell cultures.

The purpose of these studies was to examine an early carcinogen-induced change in primary human epithelial cell cultures and to attempt to reverse this change with retinoic acid. Primary cultures of human foreskin keratinocytes were prepared and exposed to the carcinogen, propane sultone. After each passage, a portion of cells were plated into medium containing increasing amounts of calcium. In a series of experiments it became evident that carcinogen exposed cells continued to grow in the presence of added calcium. Solvent control cell growth was decreased under such conditions. This new phenotype became apparent after the third subculture, but was pronounced after the fourth subculture. The addition of retinoic acid to the culture medium at each medium change reduced this effect and the keratinocytes grew more slowly, similar to control cells, in the presence of added calcium. The results suggest that carcinogen-exposed human keratinocytes acquire a resistance to calcium-induced differentiation or growth cessation and that retinoic acid can ameliorate this process. Although the mechanism of retinoic acid's inhibition remains unclear, these studies do provide a human cell model system which can be used to screen potential chemopreventive agents and for further mechanistic research.

Calcium↗