Preparation of quadri-subtype influenza virus-like particles using bovine immunodeficiency virus gag protein

Abstract

Influenza VLPs comprised of hemagglutinin (HA), neuraminidase (NA), and matrix (M1) proteins have been previously used for immunological and virological studies. Here we demonstrated that influenza VLPs can be made in Sf9 cells by using the bovine immunodeficiency virus gag (Bgag) protein in place of M1. We showed that Bgag can be used to prepare VLPs for several influenza subtypes including H1N1 and H10N8. Furthermore, by using Bgag, we prepared quadri-subtype VLPs, which co-expressed within the VLP the four HA subtypes derived from avian-origin H5N1, H7N9, H9N2 and H10N8 viruses. VLPs showed hemagglutination and neuraminidase activities and reacted with specific antisera. The content and co-localization of each HA subtype within the quadri-subtype VLP were evaluated. Electron microscopy showed that Bgag-based VLPs resembled influenza virions with the diameter of 150-200 nm. This is the first report of quadri-subtype design for influenza VLP and the use of Bgag for influenza VLP preparation.

Mono- and quadri-subtype virus-like particles (VLPs) containing H10 subtype elicit protective immunity to H10 influenza in a ferret challenge model

“…Preparation of mono-subtype H10 and quadri-subtype H5/7/9/10 VLPs was described in detail elsewhere [15]. Briefly, mono-subtype H10 VLPs were expressed in Spodoptera frugiperda (Sf9) cells using a baculovirus expression vector system (BEVS).…”

“…The rBV vector co-expressing H10, NA, and Bgag genes contained H10 gene derived from A/Jiangxi/IPB13a/2013 (H10N8) virus. Influenza HA, NA, and Bgag genes were cloned in tandem fashion, each gene within its own transcriptional cassette that included a polyhedrin promoter upstream from each gene, as described elsewhere [7, 15]. …”

“…In some cases, retrovirus gag was used in place of M1 [15]. The HA antigen is the major vaccine component, which induces neutralizing antibodies preventing infectious virus from entering cells [4, 16, 17].…”

“…Recombinant VLPs co-localizing three subtypes of HA protected ferrets, a highly sensitive to influenza infection animal model, from potentially pandemic viruses of H5, H7 and H9 subtypes [20, 21]. Recently, we have described a novel, quadri-subtype VLP design, which co-localized within a VLP the H5, H7, H9, and H10 hemagglutinins from influenza subtypes that have caused human infections in the past [15]. For preparation of the mono-subtype H10 and the quadri-subtype H5/H7/H9/H10 VLPs, we used the bovine immunodeficiency virus (BIV) gag protein (Bgag) as the inner core of the VLP in place of M1.…”

“…For preparation of the mono-subtype H10 and the quadri-subtype H5/H7/H9/H10 VLPs, we used the bovine immunodeficiency virus (BIV) gag protein (Bgag) as the inner core of the VLP in place of M1. Bgag has the advantage of a larger diameter providing more surface area to accommodate HA molecules [15]. The mono-subtype H10 VLPs that included H10 subtype have been also prepared.…”