The Berserker Virus was a bioweapon developed by a scientist for Borvo the Hutt. It seemed to influence animals, making them go crazy.
A sample of the Berserker Virus, obtained from a courier
When local criminal Kritus Morven heard rumors of some new project of Borvo's, he paid a spacer to kidnap Borvo's scientist during a hunting expedition. Interrogating the scientist revealed that he was working on a bioweapon called the Berserker Virus. Shortly thereafter Morven got his hands on a sample of the virus when the spacer intercepted and killed the courier Dekker on his way to delivering the sample to Corellian buyers.
Around the same time, a courier was sent to deliver a datadisc to Damalia Korde in Dee'ja Peak which contained information about the Berserker Virus.
In the third and fourth mission for Kritus Morven in Star Wars Galaxies, the player has to escort Borvo's scientist to Morven and then kill the courier Dekker. The name of the virus is only revealed when the player examines the sample that is placed in his inventory after killing Dekker.
It is also mentioned by the NPC Damalia Korde at the end of a mission, when the player meets a courier and delivers a datadisc to her.