3.2 In vitro inhibitory effects of aprotinin on infections caused by various influenza A virus subtypes
Previous studies have minimal information on the spectrum of the anti-influenza viral activity of aprotinin. Therefore, we evaluated the effects of aprotinin treatment on the production of infectious particles of various IAV subtypes, including human and avian viruses, through time-based studies by determining the growth kinetics of the following viruses in MDCK cells: A/PR/8/34 (H1N1), A/CA/04/09 (H1N1), A/PH/2/82 (H3N2), A/AB/Kor/CN2/09 (H5N2), A/AB/Kor/CN5/09 (H6N5), and A/Ck/Kor/01310/01 (H9N2) viruses. We simultaneously added each virus and 60 nM aprotinin to the cell cultures and cultured without removing either virus or aprotinin throughout the incubation period. Culture supernatants were collected at different time points, and virus titers were determined by calculating the median TCID50 based on the hemagglutination assay. As shown in Fig. 3, aprotinin was able to significantly reduce the production of the tested human IAVs after more than 16 h post-infection, supporting the results of previous studies.[17,19] Especially, aprotinin had superior inhibitory effects on A/CA/04/09 (H1N1) and A/PH/2/82 (H3N2) viruses than oseltamivir. Aprotinin was also able to significantly reduce the production of the tested avian IAVs (Fig. 4). Aprotinin displayed weaker inhibitory effects on avian IAVs than oseltamivir at early time points post-infection but presented similar effects to oseltamivir at 64 h post-infection. These results indicate that aprotinin had inhibitory effects on infections of both human and avian IAVs.