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. 2005 Jun;79(12):7641–7647. doi: 10.1128/JVI.79.12.7641-7647.2005

FIG. 3.

FIG. 3.

TR− supernatants contain rare TR− genomes packaged in infectious particles. (A) Infection of 293-E1 cells. One million 293-E1 cells were infected with 1 ml of 293/2089 or 293/TR− supernatants. Target cells were incubated with untreated supernatants or with supernatants pretreated with DNase I or with a neutralizing antibody directed against gp350. Similar numbers of GFP-positive cells were observed with or without pretreatment with DNase I of 293/TR− and 293/2089 supernatants. This shows that DNase treatment had no influence on the infectious process and excludes that 293/E1 cells acquired the TR− genome through direct transfer of naked DNA. In addition, pretreatment of both types of supernatants with a gp350-specific neutralizing antibody markedly reduced the number of GFP-positive cells. We therefore conclude that 293/TR− supernatants contain rare infectious particles that express gp350 at their surface. (B) Infection of Raji cells. One million Raji cells were infected with 1 ml of either 293/2089 or 293/TR− supernatants. Infected cells express GFP and can be detected upon exposure to UV light. Rare GFP-positive cells are visible after infection with 293/TR− supernatants.