Bars indicate mean titers ± SD for 3 replicates and those labeled with different letters are significantly different (p < 0.05) while those with the same letter are not (p > 0.05). Apinductokine activitiy removed by Proteinase-K treatment Proteinase-K treatment of Gilteritinib 5 kDa membrane filtrates from C6/36 cultures acutely infected with DEN-2 removed their ability to induce apoptosis in C6/36 cells persistently infected with DEN-2 (Figure 5). As with viprolaxikine, apinductokine inactivation occurred whether proteinase-K activity

was removed from the treated filtrate by heating plus 5 kDa filtration or by 5 kDa filtration only. These tests indicated that apinductokine was also a small polypeptide. Figure 5 Photomicrographs showing

removal selleck screening library of apoptosis induction activity by proteinase K treatment. A = Untreated, cells persistently infected with DEN-2 (cf Fig. 3A); B = Positive immunofluorescence for apoptosis marker (green) in cells persistently infected with DEN-2 and exposed to untreated 5 kDa filtrate from C6/36 cells acutely-infected with DEN-2; C = As in B, but with proteinase-K treatment and showing little positive fluorescence (green) for the apoptosis marker. Conclusion In conclusion, this communication has revealed that extracts from C6/36 cell cultures infected with Dengue

virus contain previously unknown cytokine-like substances that can alter the host insect cell response to Dengue virus. It is the first report of an antiviral substance induced in insect cells by infection with buy Temsirolimus a virus in the family Flaviviridae. The fact that the cell sources and activities of the substances differed and that their activities were removed by treatment with proteinase-K suggested that at least two different, low molecular-weight polypeptides were responsible, one for protection of naïve cells against DEN-2 infection and the other for induction of apoptosis in C6/36 cells persistently infected with DEN-2. Further work is needed to characterize these cytokine-like substances (including check details molecular structure) to allow comparison with other low molecular weight polypeptides, to study their mechanism of action and to test their range of activities with several viruses and cell types. Methods Insect cell lines and viral inoculum Aedes albopictus C6/36 cells (a single cell-type clone obtained from the American Type Culture Collection under catalogue number CRL-1660) were grown in Leibovitz’s (L-15) medium containing 10% heat-inactivated fetal bovine serum (FBS), 10% tryptose phosphate broth (TPB) and 1.2% antibiotic (Penicillin G and Streptomycin).