H5N1 virus-like particle vaccine elicits cross-reactive neutralizing antibodies that preferentially bind to the oligomeric form of influenza virus hemagglutinin in humans.

Division of Viral Products, Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, MD 20892, USA.
Journal of Virology (Impact Factor: 4.65). 08/2011; 85(21):10945-54. DOI: 10.1128/JVI.05406-11
Source: PubMed

ABSTRACT Transmission of pathogenic avian influenza viruses (AIV) from wild birds to domestic poultry and humans is continuing in multiple countries around the world. In preparation for a potential AIV pandemic, multiple vaccine candidates are under development. In the case of H5N1 AIV, a clear shift in transmission from clade 1 to clade 2 viruses occurred in recent years. The virus-like particle (VLP) represents an economical approach to pandemic vaccine development. In the current study, we evaluated the humoral immune response in humans vaccinated with H5N1 A/Indonesia/05/2005 (clade 2.1) VLP vaccine manufactured in Sf9 insect cells. The VLPs were comprised of the influenza virus hemagglutinin (HA), neuraminidase (NA), and matrix 1 (M1) proteins. In an FDA-approved phase I/II human clinical study, two doses of H5N1 VLPs at 15, 45, or 90 μg HA/dose resulted in seroconversion and production of functional antibodies. Moreover, cross-reactivity against other clade 2 subtypes was demonstrated using virus neutralization assays. H5N1 whole-genome fragment phage display libraries (GFPDL) were used to elucidate the antibody epitope repertoire in postvaccination human sera. Diverse epitopes in HA1/HA2 and NA were recognized by postvaccination sera from the two high-dose groups, including large segments spanning the HA1 receptor binding domain. Importantly, the vaccine elicited sera that preferentially bound to an oligomeric form of recombinant HA1 compared with monomeric HA1. The oligomeric/monomeric HA1 binding ratios of the sera correlated with the virus neutralizing titers. Additionally, the two high-dose VLP vaccine groups generated NA-inhibiting antibodies that were associated with binding to a C-terminal epitope close to the sialic acid binding site. These findings represent the first report describing the quality of the antibody responses in humans following AIV VLP immunization and support further development of such vaccines against emerging influenza virus strains.

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Available from: Nitin Verma, Jul 24, 2015
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    • "Higher protein yields may be attributed to lower metabolic burden due to virus replication and to the higher susceptibility of the two Trichoplusia ni cell lines. To date, still many secreted glycoproteins are generated in Sf9 cells, such as influenza virus HA and various virus-like particles (Cox 2008; Khurana et al. 2011; Liu et al. 2013; Tretyakova et al. 2013). However, our findings suggest the high applicability of cell lines derived from Trichoplusia ni for recombinant protein expression, especially in the case of secreted proteins. "
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    ABSTRACT: Purpose of work: A comparative analysis of new and established insect cell lines, in regard to process relevant parameters, provide data that can be exploited for designing more robust and effective protein production processes. The baculovirus-insect cell expression system has been efficiently used for the production of heterologous proteins. Three different insect cell lines Tnao38, High Five and Sf9 were compared in terms of virus susceptibility, baculovirus production and product yield of an intra-cellularly (YFP) and extra-cellularly (influenza A virus hemagglutinin)-expressed recombinant protein. The Tnao38 and High Five cell lines exhibited higher (tenfold) susceptibility to baculovirus infection than Sf9 cells, whereas Sf9 cells showed a higher (100-fold) capacity for production of infectious virus particles. Analysis of recombinant protein expression revealed considerably higher product yields in Tnao38 and High Five cells as compared to Sf9 cells, for both model proteins. Overall, the two Trichoplusia ni-derived cell lines, High Five and Tnao38, were significantly more efficient in terms of secreting proteins such as the glycoprotein hemagglutinin of influenza A virus.
    Biotechnology Letters 12/2013; 36(4). DOI:10.1007/s10529-013-1429-6 · 1.74 Impact Factor
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    • "In addition, studies with A(H5N1) vaccines have generally required 2 × 90 ␮g unadjuvanted or lower doses of adjuvanted vaccine to achieve adequate levels of HAI antibodies in a majority of subjects. However, mouse immunogenicity studies of recombinant influenza A(H5N1) VLP vaccine were predictive of immunogenicity in man [9] [11]. Bright et al. [11] reported cross-clade protective immune response of an A(H5N1) VLP vaccine in mice. "
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    • "Virus-like particles (VLP) are a promising technology because they are non-infectious and present structurally native and highly antigenic protein conformations that induce robust antibody, as well as increased CD8þ and CD4þ T cell, responses (Bright et al., 2007; Kang et al., 2009; Quan et al., 2007). Preliminary data from clinical trials with a H5N1 influenza VLP vaccine further indicate immunogenicity and non-reactogenicity (Khurana et al., 2011). "
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