UPDATE 1-Nabi to sell staph vaccine to Glaxo for $46 mln

* Nabi to get initial cash payment of $20 mln

* Deal expected to close year-end 2009

* Shares up 9 percent after market

Aug 6 (Reuters) - Nabi Biopharmaceuticals (NABI.O) said it agreed to the sell PentaStaph, its experimental vaccine for staph infections and related assets to GlaxoSmithKline Plc (GSK.L) for up to $46 million.

Upon closing of the deal, expected before year-end 2009, Nabi will receive an initial cash payment of $20 million, plus an additional $26 million upon four milestone accomplishments, the company said in a statement.

Nabi expects to close the sale before year-end 2009 and complete the milestones within the next 18 months.

PentaStaph is Nabi's five-component vaccine candidate against S. aureus infections.

Shares of the company rose as much as 9 percent at $2.75 in after-market trade. They closed at $2.53 Thursday on Nasdaq.

For the alerts, please double-click [ID:nWNBB1273] (Reporting by Shailesh Kuber in Bangalore; Editing by Anil D'Silva)