A Swedish computer company has developed a vaccine to combat computer virus.

The vaccine, called TCELL, is said to be the first commercially available protection against contamination by the computer virus.It also can be used to simplify reconstruction of an already contaminated system, the developers say.

Computer virus is the popular name for the information that can be smuggled into a data-processing system in order to destroy, alter or completely eradicate the information stored there. The illicit information is introduced into the normal, legal program of a software system.

Once introduced, the illicit information - the virus - has the ability to reproduce itself.

When the legal program is run, the virus automatically begins to copy itself into all other programs it comes into contact with, just as a biological virus spreads in humans.

When contamination is detected it may be necessary to halt normal use of the entire data-processing system.

The vaccine TCELL can monitor a data-processing system network and detect faults in the electronic seal of each data file.

It is normally installed in the system as a process but can also be used as a patroling guard that warns security personnel when a contaminated file is detected.

With the new vaccine system, not all files are monitored at the same time, since this would harm system performance as a whole. TCELL selects a number of files at random, which are constantly monitored, and controls other files from time to time.

The system TCELL is available in the standard version as a software package for VAX/VMS and UNIX. It can be tailored for installation in all other operation systems.

Contact: Mrs. Viiveke Fak, or Mr. Jan-Olof Bruer, Aectra - Secure Transmission AB, Teknikringen 2, S-583 30 Linkoping, Sweden. Telephone: Int +46 13 212050.