Article

An alternative method for preparation of pandemic influenza strain-specific antibody for vaccine potency determination

Division of Viral Products, Center for Biologics Evaluations and Research, Food and Drug Administration, 8800 Rockville Pike, Bethesda, MD 20892, United States.
Vaccine (Impact Factor: 3.62). 03/2010; 28(12):2442-9. DOI: 10.1016/j.vaccine.2009.12.079
Source: PubMed

ABSTRACT

The traditional assay used to measure potency of inactivated influenza vaccines is a single-radial immunodiffusion (SRID) assay that utilizes an influenza strain-specific antibody to measure the content of virus hemagglutinin (HA) in the vaccine in comparison to a homologous HA reference antigen. Since timely preparation of potency reagents by regulatory authorities is challenging and always a potential bottleneck in influenza vaccine production, it is extremely important that additional approaches for reagent development be available, particularly in the event of an emerging pandemic influenza virus. An alternative method for preparation of strain-specific antibody that can be used for SRID potency assay is described. The approach does not require the presence or purification of influenza virus, and furthermore, is not limited by the success of the traditional technique of bromelain digestion and purification of virus HA. Multiple mammalian expression vectors, including plasmid and modified vaccinia virus Ankara (MVA) vectors expressing the HAs of two H5N1 influenza viruses and the HA of the recently emerging pandemic H1N1 (2009) virus, were developed. An immunization scheme was designed for the sequential immunization of animals by direct vector injection followed by protein booster immunization using influenza HA produced in vitro from MVA vector infection of cells in culture. Each HA antibody was highly specific as shown by hemagglutination inhibition assay and the ability to serve as a capture antibody in ELISA. Importantly, each H5N1 antibody and the pandemic H1N1 (2009) antibody preparation were suitable for use in SRID assays for determining the potency of pandemic influenza virus vaccines. The results demonstrate a feasible approach for addressing one of the potential bottlenecks in inactivated pandemic influenza vaccine production and are particularly important in light of the difficulties in preparation of potency reagent antibody for pandemic H1N1 (2009) virus vaccines.

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    • "Although such assays might represent a major improvement over SRID in many regards, the experimental denaturation of HA during sample preparation for the assays or during the assays themselves makes the assays incapable of providing sufficient information on HA conformational integrity. Monoclonal antibody based assays (such as enzyme-linked immunosorbent assay [ELISA] [26] [27] and antibody-dependent surface plasmon resonance [SPR] [28]) can potentially measure conformational integrity. However these assays rely on a strain-specific monoclonal antibody panel that would need to be updated and calibrated along with a reference antigen that likely would be quantified with a conformationally insensitive biophysical assay. "
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