Hepatitis B is a highly infectious, potentially life-threatening virus affecting 400 million people worldwide.
It is entirely preventable with a series of three vaccinations.
Hep c and dating
Gilead is best known for its Sovaldi treatment for hepatitis C, heralded as a medical breakthrough for patients but at a price that has caused uproar in the US and abroad.
The ATF has previously claimed Gilead's profit margin had soared and its tax rate plummeted since the drug maker introduced its controversial $1,000-a-day treatment for hepatitis C.
"The profits are most likely in Ireland, a tax haven," ATF claimed in a submission to the SEC.
However, it provided no proof of its allegation that Gilead has benefited from any deal with the Irish government. The company employs more than 200 people here, and has a manufacturing plant in Cork.
The ATF submission came after the US markets regulator solicited views regarding the modernisation of certain business and financial disclosure requirements for public companies.
It could be a precursor to US companies having to reveal more details about their overseas tax affairs.ATF has claimed that moving some of its intellectual property to Ireland had allowed Gilead to cut its US tax bill by bn since 2013.ATF told the SEC that if Gilead is benefiting from a deal in Ireland, it could face a big tax assessment in the event of a European Commission investigation, similar to the current probe into tax paid here by Apple.The European Commission is currently probing whether or not Apple secured unfair tax arrangements in return for creating jobs in Ireland, a claim rejected by Apple and the Irish Government.Finance minister Michael Noonan has said the State here will fight any EU finding that tax wasn't properly charged here.The US Senate Finance Committee investigated Sovaldi's pricing last year and was harshly critical of Gilead.