Techno-virus

In an alternate timeline where the Cybermen used Time Lord resources to conquer all of time and space, the "techno-virus" was the Ninth Doctor's term for an airborne virus that converted humans into Cyber-Warriors. (COMIC: Supremacy of the Cybermen)

Function
The techno-virus was comprised of invisible, microscopic robots which travelled through air and could perform extremely fast cyber-conversions; the virus would envelop its victims within the muscular Cyber-bodies of the Cyber-Warriors in a matter of seconds. This degree of efficiency allowed the Cyber-Warriors to convert the Earth of 2006 into the Cyber-Earth with the techno-virus within only three days.

In addition, the techno-virus was capable of at least partially converting non-human species, as the Ninth Doctor's right hand was partially converted after he used his sonic screwdriver to attack the microscopic robots comprising the techno-virus; the virus' attacking the sonic screwdriver also highlighted the techno-virus' ability to attack potentially dangerous technology. However, the techno-virus was unable to penetrate the particulate shield of the Doctor, Rose Tyler and Jack Harkness' flyer, although this would also result in the shield rejecting anybody partially converted by the virus, which would inflict severe pain and possibly death. (COMIC: Supremacy of the Cybermen)

History
In an alternate timeline where gave the Cybermen the means to conquer all of time and space, the Cybermen developed, and used, the techno-virus to cyber-convert the Earth of 2006 into the Cyber-Earth, fully conquering the planet and transforming humanity into Cyber-Warriors within only three days, as a experiment to assess the virus' efficiency in invading other worlds. The Ninth Doctor, Rose Tyler and Captain Jack Harkness investigated the planet, as the Doctor had analysed that such efficiency was beyond the Cybermen's natural capabilities.

After rescuing Jackie Tyler from a Cyberdog, the Doctor, Rose, Jack and Jackie flew a flyer into the Cyber-Warriors' base at St Paul's Cathedral; when their attempt to use the Doctor's TARDIS failed, the four fled to the crashed flyer, only for the techno-virus to instantly convert Rose, who then swiftly deleted Jack. Horrified and consumed with rage, the Doctor used his sonic screwdriver to attack the converted Rose, only for the techno-virus to begin grafting metal implants onto the sonic screwdriver and the Doctor's right hand. Jackie then brought the Doctor back to the flyer, where the Doctor recalibrated the flyer's particulate shield to seal out the techno-virus. However, this also caused the Doctor to experience severe pain, as his conversion had already begun and would soon complete.

In a desperate attempt to stop the Cybermen reusing the techno-virus on other worlds, the Doctor attempted to rupture the heart of the TARDIS, only for the power to be diverted into the Eye of Harmony of Gallifrey at the end of the universe, due to the efforts of the Cybermen invading Gallifrey at that point in time. This allowed the converted Rose to break into the TARDIS, who attempted to kill the Doctor and Jackie. However, the Twelfth Doctor and Rassilon's aversion of this timeline via the Eye of Harmony of Gallifrey at the end of the universe erased the techno-virus, as well as the timeline's events, from existence. (COMIC: Supremacy of the Cybermen)

Legacy
When Rose was subject to memory extraction by Addison Delamar, an attack by the Cybermen caused the machine extracting her memories to malfunction, causing Rose to regain her memories of being cyber-converted by the techno-virus. (COMIC: The Bidding War) These memories almost caused Rose to suffer an extreme mental shutdown, although the Doctor eventually cured her with the help of some Silurians. (COMIC: The Lost Dimension)