** Shares of Gilead Sciences GILD.O rise 3.1% to $110.69 in morning trade

** U.S. Supreme Court rules in favor of Obamacare preventive care task force

** The task force helps guarantee that health insurers cover preventive care such as cancer screenings at no cost to patients

** Cancer test makers such as Exact Sciences EXAS.O up 4.8% at $54.32 and Guardant Health GH.O up 1.6%

** Labcorp Holdings LH.N, which offers cancer tests, is up 1.5% at $260.73

** The justices in a 6-3 decision reversed the lower court's ruling on Friday which will likely help in allaying investor fears on insurance coverage for PrEP or pre-exposure prophylaxis drugs

** PrEP drugs are approved in the U.S. to prevent HIV infection which are made by Gilead and by ViiV Healthcare, a joint venture of GSK GSK.L, Pfizer PFE.N and Shionogi 4507.T

** Including session's move, GILD up 17.3%, EXAS down 3.9%, LH up 13.5%, GH up 65% YTD

(Reporting by Siddhi Mahatole)

((siddhi.mahatole@thomsonreuters.com))