June 6-11, 2010
Japanese Encephalitis (JE) is a disease primarily dominant in South East Asia, caused by the Japanese Encephalitis virus (JEV). It is responsible for an estimated 50,000 cases of the disease every year, of which around 10,000 are fatal and approximately 15,000 result in long term neurological sequelae (WHO 2006). Viral inactivation is a main feature in many vaccine manufacturing processes in order not only to inactivate the product itself but also any potential adventitious agents which may have been introduced during manufacture. Chemical inactivation using formaldehyde is one of the most common methods used for inactivated viral vaccines, yet due to the relatively unpredictable nature of the protein cross linking method by which inactivation occurs, antigen recovery rates can vary significantly (Fraenkel-Conrat & Mecham 1949, Metz et al. 2003). This poster will demonstrates a design of experiments based optimisation of the viral inactivation step of a JE vaccine. The current manufacturing conditions are non-optimal in terms of inactivation time and antigen recovery. Several key variables of the formaldehyde inactivation of JEV have been identified from the literature for investigation: temperature, pH, formaldehyde concentration and the presence of stabilisers (glycerol, sorbitol, lysine, glycine and PEG). As a factor screening experiment, a two level factorial design will be presented involving 36 experimental runs including 4 centre points. The measured effects will be antigen recovery by ELISA and virion size using a Nanosight. Complete inactivation of JEV will be determined by plaque assay. The data will determine which of the factors are the most significant and which factors contribute to interaction effects with regards to optimal inactivation of JEV for use in a vaccine. References: • Fraenkel-Conrat H., Mecham D. K.; 1949; The Reaction of Formaldehyde with Proteins VII – Demonstration of intermolecular cross-linking by means of osmotic pressure measurements J. Biol. Chem.; 177: 1-495 • Metz B., Kersten G. F. A., Hoogerhout P., Brugghe H. F., Timmermans H. A. M., Jong A., Meiring H., Hove J., Hennink W. E., Crommelin D. J. A., Jiskoot W.; 2004; Identification of Formaldehyde-induced Modifications in Proteins; J. Biol. Chem.; vol. 279; no. 8; pp6235-6243. • WHO position paper 2006 – Weekly epidemiological record 2006, 81, 325-340, No. 34/35.
Michael Hughson, "DESIGN OF EXPERIMENT BASED JAPANESE ENCEPHALITIS VIRUS FORMALDEHYDE INACTIVATION OPTIMISATION FOR A VERO CELL DERIVED VACCINE" in "Vaccine Technology III", John G. Auniņš,Merck, USA; Barry C. Buckland, BiologicB, USA; Kathrin U. Jansen, Pfizer, USA; Paula Marques Alves, IBET, Portugal Eds, ECI Symposium Series, (2010). http://dc.engconfintl.org/vaccine_iii/31