The French drugs giant Sanofi-Aventis is buying the British vaccine-maker Acambis for £276m in the latest round of consolidation in the biotech sector.
The agreed deal, described as a "mutually beneficial logical step" by Wayne Pisano, the head of Sanofi's vaccine unit, sees the French group offering Acambis investors 190p a share.
The two companies are already developing vaccines together against Japanese Encephalitis, West Nile virus and Dengue fever.
Peter Fellner, Acambis's chairman, welcomed the offer yesterday. "Sanofi Pasteur, which is one of the world's largest vaccines companies, will benefit strategically not only from Acambis's pipeline and technologies but also from its significant US-based R&D and manufacturing infrastructure," he said.
The UK firm won a 10-year contract, worth $425m (£213m), to supply the US government with smallpox vaccine earlier this year. It is also working on vaccines against the hospital superbug C. difficile, flu and genital herpes.
Acambis stock rose 1p to 116p in London yesterday before the agreed offer was unveiled. Goldman Sachs and Invesco, which together own more than 40 per cent of Acambis's shares, have already agreed to accept the offer.
Large pharmaceutical firms have been scrambling to buy biotechs recently in an attempt to secure drug pipelines. The offer comes hot on the heels of a record $44bn bid by the Swiss drugs group Roche to buy out the US biotech Genentech.