Deane Donnigan and Antony Milford will oversee Axa Framlington's Biotechnology fund until the group finds a permanent replacement for the departing Gareth Powell.
Powell is joining Polar Capital in November, though he will continue to remain on the portfolio during his notice period.
He took over the £61m portfolio from Milford in April 2005, and will co-run a long-only healthcare fund with Dan Mahoney at Polar Capital.
Mahoney, from Morgan Stanley, will also join in November.
Meanwhile, Axa Framlington has added Gemma Game to the healthcare team. She will assume lead management responsibilities for the offshore WF Health portfolio.
At BlackRock, Game was a member of the global equities team, with specific responsibility for the healthcare sector.
Milford passed the Healthcare fund to Donnigan in 2005 as he approached retirement, but the group said he still works at least three days a week
Over one year to 30 July, the Biotech fund has produced a bid-to-bid return of 7.9%.