Shares of a small biotech called Siga Technologies ( SIGA) shot up in premarket trading after it said a company it is acquiring filed for a patent in Denmark for a diagnostic system that it hopes to use to develop vaccines that could target the SARS virus. The shares were recently 64 cents, or 35%, to $2.45. The price action is increasingly typical in biotech penny stocks with news relating to severe acute respiratory syndrome, particularly in the pre- and post-market sessions. Dow Jones recently reported Siga's auditors appended a going-concern clause to its financial statements in a recent 10-Q. Siga said the patent covers a new proprietary method of "identifying and validating antigens, and the results obtained by analyzing the genetic variants of the SARS agent," adding that it hopes to use it with its delivery systems to "attempt to develop rationally designed vaccines against the coronavirus that is believed to be the causative agent of SARS." Siga said it agreed to acquire to acquire substantially all of the assets of Plexus, including the capital stock of Plexus Denmark APS, a wholly owned subsidiary of Plexus Vaccine Inc.