FIG. 4.

Induction of cytokine and chemokine mRNA expression by IFN-γ-treated and TMEV-infected SJL mouse microglia. RNA were isolated from unstimulated microglia, from microglia stimulated with IFN-γ for 24 h, and from microglia infected with viable or UV inactivated TMEV 48 h previously for time periods determined in preliminary experiments to be optimal for gene expression. The RNA for each microglia group was then analyzed by RT-PCR to determine IFN-α, IFN-β, IL-1β, IL-6, IL-10, IL-12, IL-18, TNF-α, iNOS, MIP-1α, IFN-γ, and HPRT mRNA expression levels. The products were separated on a 2% agarose gel and then analyzed for expression of the various cytokines relative to the HPRT expression levels (A). Similar results were observed in 10 separate experiments. (B) The mRNA levels for the various molecules are presented as percentages of the expression of HPRT based on densitometric scanning.