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Journal of Biomedicine and Biotechnology
Volume 2011 (2011), Article ID 174615, 11 pages
http://dx.doi.org/10.1155/2011/174615
Methodology Report

Bioactivity Determination of Native and Variant Forms of Therapeutic Interferons

1Biologics and Genetic Therapies Directorate, Health Canada, Tunney's Pasture, Ottawa, ON, Canada K1A 0K9
2National Institute for the Control of Pharmaceutical and Biological Products, Beijing, 100810, China
3Department of Experimental Medicine, Lady Davis Institute for Medical Research, McGill University, Montreal, QC, Canada H3A 2T5
4National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB, Canada R3E 3R2
5Department of Biochemistry, Microbiology & Immunology, University of Ottawa, Ottawa, ON, Canada K1H 8M5

Received 15 November 2010; Accepted 14 January 2011

Academic Editor: Andrei Surguchov

Copyright © 2011 Louise Larocque et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The traditional antiviral assays for the determination of interferon potency are reported to have considerable variability between and within assays. Although several reporter gene assays based on interferon-inducible promoter activities have been reported, data from comprehensive validation studies are lacking and few studies have been conducted to analyze the variant forms of interferons, which could have undesirable clinical implications. Here, a reporter gene assay employing a HEK293 cell line stably transfected with luciferase gene under the control of interferon-stimulated response element promoter was developed and validated. The assay was found to be more sensitive, with a larger detection range than the antiviral assay. Several cytokines tested did not interfere with the test, suggesting the assay possesses a certain degree of selectivity. Moreover, the robustness of the assay was demonstrated by minimal variations in the results generated by different analysts and cell passage number (up to 52 passages). Finally, the method was employed to analyze several interferon variants (interferon- 2a) and we found that the aggregated form has completely lost its potency; while a modest loss of bioactivity in oxidized interferon was observed (approx. 23%), the deamidated form essentially retained its activity.