Applvir is a virus created by Joe Dellinger in the early 1980's. It may have been created simultaneously with Elk Cloner, or even predate it.
Little information is available on the behavior of this virus. It is definitely some sort of boot sector virus, but few other details are available, or if they are, the terms used to describe it are different from the ones commonly used today. This is likely, as the virus was created before there was even a term for virus.
Dellinger coded a second and third variant of the virus. The first version of the virus was never released because it had some undesireable effects on the test computer. The second variant was released, but it was found to not meet its creator's expectations after its release.
He considered the third variant a success, as it caused no problems and was "effectively completely invisible". It may have also been responsible for some disks being immune to a potentially destructive version of the virus.
There may be a few more variants, as there was great interest in Dellinger's experiments in the Texas A&M, and many copies of the virus (and presumably source codes) were distributed to classmates who wanted to study the virus. Dellinger's own writings seem to confirm that other people created their own versions of the virus.
The original virus was never released, as it caused some problems on Dellinger's test computer. The second variant of the virus was released, which Dellinger also considered a failure, as it added 256 bytes to DOS, which caused problems with some programs.
This version spread to the University of Illinois at Urbana-Champaign when a Texas A&M student moved there to do graduate work. There, it caused the game "Congo" to stop working. A disinfection program was created to remove the virus. Some version of the virus was spreading at UUIC as late as 1984.
There is no official name for this virus. Some sources refer to it as simply the "Apple Virus" or "the Virus". It is unlikely that any antivirus products will even detect this virus, as it is so old and binaries seem unavailable (it is interesting to note though, that the German antivirus product Avira can detect Elk Cloner, so if any binaries become available, that product may be able to detect them). The Virus Encyclopedia has decided to name this one "Applvir", which comes close to violating the naming conventions, as it references the Apple platform. We believe this can be an exception since it is such a historic virus and we do not use the full name "Apple".
There are no exact dates for the creation of the viruses, but Dellinger says he wrote the first virus in 1981 December (presumably meaning that is when he started writing it) and completed it in early 1982. This would mean that it was created somewhat simultaneously with Elk Cloner.
Joe Dellinger. A (long) story about an (old) Apple II virus. 1990.04