UPDATE 1-BioCryst gives update on intravenous influenza drug

* Gives written response to HHS 'request for proposal'

* Co to also start late stage trials for serious influenza * Shares up 2.5 pct

Sept 30 (Reuters) - BioCryst Pharmaceuticals Inc (BCRX.O) said it delivered a written response to the U.S. Department of Health & Human Services' (HHS) 'request for proposal' on supplying its experimental intravenous influenza drug to treat critically ill patients.

The company said it would provide further update on the process, which operates under the Emergency Use Authorization, once it is completed.

BioCryst also said it was starting two late-stage trials testing the intravenous formulation of the drug peramivir to treat hospitalized patients with serious influenza.

While one late-stage study will test the drug's efficacy in combination with the current standard-of-care, the other study would test the safety and tolerability of the drug.

Expenses for these studies, which are intended to support regulatory approval, are covered under the recently modified $180 million HHS/Biomedical Advanced Research and Development Authority contract.

Shares of the company rose 2.5 percent to $8.45 in trading after the bell. They closed at $8.24 Wednesday on Nasdaq. (Reporting by Vidya L Nathan in Bangalore; Editing by Anthony Kurian)