Gilead Sciences (GILD 0.33%) is a long-standing leader in HIV treatment, but its sales of its hepatitis C drug Sovaldi that's driving the company's revenue surge.

While Sovaldi's sales are soaring, investors are right to wonder if the drug's break neck revenue pace can continue. If it can't, then investors will need Gilead to maintain its dominance in HIV treatment.

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In the following slideshow, you'll read three quotes from Gilead's top management that offer insight into the company's hepatitis C and HIV business and learn why those quotes may matter to investors.