The Shanti Virus is a debilitating and possibly deadly virus that was first contracted by Shanti Suresh, the sister of Mohinder Suresh and was thus named after her.
During volume 1, the only time the virus was spoken of was in the case of Molly Walker, whom Mohinder was able to heal by injecting antibodies contained in his own blood.
Later on in volume 2, it was discovered that a certain strain of the virus was used by The Company to suppress powers when it was injected into several super humans such as Sylar. Mohinder's blood, along with Claire Bennet's blood made a potent anti-serum that killed this strain of the virus once it infected a person.