Production of immunogenic one-component avian H7-subtype influenza virus-like particles

Virus-like particles (VLPs) are a highly effective type of subunit vaccines because they mimic the viral capsid without the presence of infectious viral genetic material. In this study, hemagglutinin (HA) alone and in combination with matrix 1 (M1) were highly expressed in Hi-5 insect cells for the production of one-component (containing HA) H-VLP and two-component (containing HA and M1) influenza MH-VLP. The H-VLP or MH-VLP expressed in culture supernatant was purified in fractions with a strong hemagglutination response. Transmission electron microscopy analysis confirmed that the morphology of both H-VLP and MH-VLP was similar to that of authentic influenza virions. After 4 weeks of vaccination, hemagglutination inhibition (HAI) titers induced by either one dose (2 μg of HA) or two doses (a dosage of 0.5 or 0.2 μg of HA) of both types of VLPs in chickens were all more than 97, well above 16, the predictive protective HAI titer in chickens. These results confirm the effectiveness of insect cell-derived H-VLP and MH-VLP in avian influenza vaccine design. Most importantly, VLPs comprising HA alone provide a simple and fast platform for avian influenza vaccine manufacturing.