1. GlaxoSmithKline CEHS, Park Road, Ware, Hertfordshire SG12 0DP UK Tel. +44 1920 882968 Fax: +44 1920 884469 E-mail: richard.k.henderson@gsk.com, Corresponding author
2. GlaxoSmithKline, Research Triangle Park, North Carolina, USA
3. GlaxoSmithKline, Ulverston, Cumbria, UK
4. GlaxoSmithKline, Philadelphia, Pennsylvania, USA
5. Centre for BioProcess Engineering, Technical University of Denmark, Lyngby, Denmark