Replication-Competent Foamy Virus Vaccine Vectors as Novel Epitope Scaffolds for Immunotherapy
Fig 9
Activation of SIINFEKL-specific CTL by pCF-Bet-Ova8 infected EL4 cells is not due to external peptide loading.
HEK293T cells were transiently transfected with pCF-7 or pCF-Bet-Ova8. After 2 d, cell culture supernatants were harvested, cleared, and passed through a 100-kDa centrifugal filter. A) The filtrate (dotted bars) and retentate (striped bars) fractions were applied onto EL4 cells. After 4 d, EL4 cells were harvested and co-cultured with OVA-specific CTLs in an ELISpot assay. Plates were probed after 24 h of co-cultivation for the presence of secreted IFNγ. EG7 cells were used as positive control (black bar). EL4 cells, either untreated or infected with wild-type FFV, and corresponding filtrate fractions were used as negative controls (white bars). Results are shown as number of IFNγ spots per 12500 CTLs/well. ** represents a p-value of less than 0.01 when compared to pCF-7. B) Viral titers were determined for the retentate and filtrate fractions, confirming absence of viral particles in the filtrates.