Figure 1

C6/36 cells protected against DEN-2 by 5 kDa membrane filtrate from cell cultures persistently infected with DEN-2. A = Unchallenged, naïve cells showing no immunofluorescence for DEN-2; B = Untreated, naïve cells challenged with DEN-2 and showing a high prevalence DEN-2 immunopositive cells (green) at 24 h post challenge; C = Naïve cells pre-exposed to the 5 kDa filtrate from C6/36 cells persistently infected with DEN-2 prior to DEN-2 challenge and showing few DEN-2 immunopositive cells at 24 h post challenge; D = Naïve cells treated with the wash from the upper side of the 5 kDa filter but not challenged with DEN-2 stock and showing a high prevalence of DEN-2 immunopositive cells at 24 h post challenge with viral particles in the supernatant solution from the persistently-infected culture. Green = anti-DEN and Red = pseudocolor for T0-PRO-3 iodide staining of DNA (nuclei).