Antiviral properties of yolkin in a homologous hen model.

Eggs are among the most nutritious and accessible products that have been an important part of human diets for thousands of years. Well digestible proteins belong to the main nutritional components of eggs. Evolutionary old vitellogenin in serum of laying hens is enzymatically degraded to vitally important proteins, including phosvitin and yolkin. The latter protein has documented immunoregulatory properties and improves cognitive function. Yolkin isolated from hen eggs was tested for its potential virucidal and antiviral properties against Rous-associated virus-2 (RAV-2) using DF-1 hen fibroblasts, defined as a reduction in virus titer and the cytopathic effect, following 96 h culture in DF-1 infected cells. The mixing of yolkin with the virus led to concentration-dependent virus inactivation by 2-log at 50 µg/mL - and by 1-log at 10 µg/mL of yolkin - virucidal properties. On the other hand, the treatment of infected DF-1 cells with yolkin caused a diminution of the virus titer by 3-log for a concentration of 50 µg/mL and by 1-log at 10 µg/ml of yolkin - an antiviral effect. The results indicate that yolkin may exhibit both a direct virucidal property and the capability to interfere with virus replication in the homologous model. The involvement of ERK/MAPK signaling in RAV-2 replication in DF-1 cells, by using specific inhibitor PD98059, was also demonstrated. In conclusion, yolkin may play an antiviral role in the development of bird embryos. The accumulated data on the actions of yolkin in rodent models strongly suggest benefit of egg consumption in human everyday diet.