NEW YORK (TheStreet) -- Shares of BioCryst Pharmaceuticals (BCRX - Get Report) are jumping by 12.4% to $2.90 on heavy trading volume Monday afternoon, after the company's experimental antiviral drug showed promising results in mice infected by the Zika virus in a preclinical study.

BioCryst tested two doses of the BX443 drug, a placebo and antiviral ribavirin, on survival in immune-deficient mice infected with the virus.

Seven out of eight mice that received the standard dose survived, while no mice that received the placebo or ribavirin were alive after 28 days, according to a company statement.

Zika, which is transmitted through mosquito bites, can cause fever, rash and joint pain and has been linked to severe birth defects.

"BCX4430 is a broad spectrum antiviral that is being tested in a Phase 1 clinical safety and pharmacology study in healthy subjects. BCX4430 has demonstrated survival benefits in nonclinical studies against a variety of serious pathogens, including Ebola, Marburg, and Yellow Fever viruses," the Durham, NC-based company said in a statement.

The results will be presented at a World Health Organization (WHO) meeting scheduled for March 7 through 9 in Geneva, Switzerland.

About 4.11 million of the company's shares changed hands by this afternoon compared to its average volume of 1.89 million shares per day.

Separately, TheStreet Ratings Team has a "Sell" rating with a score of D- on the stock.

This is driven by some concerns, which should have a greater impact than any strengths, and could make it more difficult for investors to achieve positive results compared to most of the stocks covered.

The company's weaknesses can be seen in multiple areas, such as its unimpressive growth in net income, disappointing return on equity, generally disappointing historical performance in the stock itself and feeble growth in its earnings per share.

Recently, TheStreet Ratings objectively rated this stock according to its "risk-adjusted" total return prospect over a 12-month investment horizon. Not based on the news in any given day, the rating may differ from Jim Cramer's view or that of this articles's author.

You can view the full analysis from the report here: BCRX

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