The Infectious Virus, or IV, is a breed of viruses that sneak into programs throughout shared codes or data files. Usually IVs sneak into files shared through Zans or Zan2.0s. Then when a Zan needs repair, an "infected" Zan may be the source of model code for a Ran. Then the copied code spreads the virus. The virus may eventually sneak into a CP and take control. After taking control, the IV copies itself with the data stolen from the CP. The life cycle then begins again.
Although very dangerous, IVs can be very easy to spot by AVs or DPs. However, AVs are hardly effective to IVs at all, besides the ObsidianSVD.