Introduction: There are no specific antivirals designed for many viral infections. Inosine pranobex (PI) is a purine nucleoside that is involved in a wide variety of intracellular biochemical processes. The mechanism of action in human body is still unclear but numerous studies have demonstrated that this drug inhibits viral replication and exhibit pleiotropic effect. We evaluated in vitro effect of inosine pranobex (PI) on replication of human viruses: parainfluenza viruses (HPIV-2, HPIV-4), entroviruses A (CA16, EV71) and adenoviruses C (HAdV-2, HAdV-5).
Materials and methods: In the present study, cytotoxic effect of inosine pranobex was assessed using A549 cell line exposed to different concentrations of compound (PI: 50-800 ig/mL) for 48 hours. Cytotoxic effect of inosine pranobex was assessed visually using light, inverted microscopy Olympus CK2 under 400x magnification and by the MTT colorimetric assay. Antiviral effect was estimated according to the reduction of virus titer. The yield reduction assay (YRA), which evaluates the ability of the PI (50-800 µg/mL) to inhibit virus multiplication in cell cultures, was applied. The cytopathic effect of the virus was evaluated 48 h after infection ofA549 cell cultures with viruses by means of light, inverted microscopy. The Reed-Muench statistical method was used to determine the 50% end point (IC50) (yield reduction assay, YRA) in the presence of inosine pranobex with the controlled one.
Results: There were no morphological changes, as assessed visually, in cell cultures treated with PI. MTT cytotoxicity assay confirmed microscopic observations. The viability of cells in the presence of the tested compounds was average 98, 36 %. After conducting the experiments and analyzing the results we noticed that higher concentrations of PI strongly inhibited multiplication of all viruses. PI weakly reduced the titer of infectious enteroviruses and HPIV-4 as compared with the control. Adenoviruses showed the highest sensitivity to the antiviral activity of PI, however, increasing concentrations of PI up to 800 µg /ml slightly enhanced the antiviral activity of 400 µg/ml PI.
Conclusions: Our study demonstrated that inosine pranobex shows no cytotoxic activity on the A549 cell line. In conducted study was observed that adenoviruses (HAdV-2 and HAdV-5) and HPIV-2 have the highest sensitivity to the antiviral activity of inosine pranobex from all tested viral strains.