Antiviral Activity of Esterified α-Lactalbumin and β-Lactoglobulin against Herpes Simplex Virus Type 1. Comparison with the Effect of Acyclovir and l-Polylysines

The antiviral activity of methylated α-lactalbumin (Met-ALA), methylated and ethylated β-lactoglobulins (Met- and Et-BLG) was evaluated against acyclovir (ACV)-sensitive and -resistant strains of herpes simplex virus type 1 (HSV-1) and compared to that of ACV and l-polylysines (4–15 kDa) using fixed or suspended Vero cell lines. Esterified whey proteins and their peptic hydrolyzates displayed protective action against HSV-1, which was relatively lower than that induced by ACV or l-polylysines. The higher activity of l-polylysines was maintained against an ACV-resistant strain of HSV-1, whereas ACV lost much of its activity. The mean 50% inhibitory concentration (IC50) was about 0.8–0.9 µg/mL for l-polylysines against ACV-sensitive and -resistant strains of HSV-1 when using two concentrations of virus (50% and 100% cytopathic effect, CPE). The IC50 values of ACV against the sensitive strain of HSV-1 were 3 and 15 µg/mL when using the low and high concentrations of virus, respectively. When using 50% CPE, I...