** PolyNovo's shares PNV.AX drop about 5.5%, giving up most of their 8.2% gains in the previous session

** The medical device maker says medical devices are not currently exempt from U.S. import tariffs

** US sales accounted for about 78% of PNV's total sales in March

** The jump on Monday came after a 16% slide in a 4-session losing run; stock has now lost about 51% YTD

(Reporting by Nichiket Sunil in Bengaluru)

((nichiket.sunil@thomsonreuters.com))