Shares of pharmaceutical giant Gilead Sciences (GILD) - Get Report fell on Wednesday after the company reported weaker-than-expected fourth-quarter earnings amid a drop in sales of some of its better-known drugs, even as Chinese researchers explored patenting one of Gilead's experimental drugs to combat the novel coronavirus outbreak.

The Foster City, Calif.-based company said it earned $1.7 billion, or $1.30 an adjusted share in the fourth quarter, down from $1.9 billion, or $1.44 a share, a year earlier and short of analysts’ average estimates of $1.67 a share.

Revenue was $5.9 billion, up 1.4% from a year earlier and higher than the $5.71 billion analysts had been expecting.

Affecting the quarter were sales of some of the company’s top-selling drugs, including its HIV medications, which came in at $4.6 billion vs. $4.1 billion a year ago, and sales of its hepatitis C treatments, which fell to $630 million from $738 million in the fourth quarter of 2018.

At the same time, Chinese researchers reportedly have applied for a local patent on an experimental Gilead drug that they believe could help fight the novel coronavirus outbreak - and also significantly bolster Gilead's bottom-line going forward.

The Wuhan Institute of Virology – based in the central Chinese city at the epicenter of the epidemic – has applied for a patent in China for the use of Remdesivir, an antiviral therapy used to treat infectious diseases including Ebola and SARS.

The application was made on Jan. 21 along with a military academy, according to a Feb. 4 statement on the institute’s website.

Beijing has moved aggressively to contain the infection that has killed almost 500 people and infected nearly 25,000. If granted, Gilead will need to get Chinese patent owners on board when it wants to sell the drug for treating the novel coronavirus infection outside China.

Among the U.S. drug companies exploring a potential treatment: AbbVie (ABBV) - Get Report, Johnson & Johnson (JNJ) - Get Report, Moderna (MRNA) - Get Report and Novavax (NVAX) - Get Report.

Shares of Gilead were down 4.41% at $64.43 in morning trading on Wednesday.