Hepatitis V, or Hep V for short, is a virulent and fatal strain of the Hepatitis D virus found on the HBO original series True Blood. Known to have been affecting vampires since the series' first season, Hepatitis V was created by humans using genetic engineering that modified the Hepatitis D virus. Ex-televangelist turned Buddhist Sarah Newlin's blood contains the only known cure. Anthropomorphically, Hep-V is the main antagonist for the series' seventh, and final, season.
The virus works by weakening its victims, and after a while induces the True Death. Dr. Overlark, head doctor at the Vamp Camp research prison, spearheaded the project which lead to the creation of the virus Hepatitis V. It is created by mutating the original vampires' temporary foe, the virus Hepatitis D. Hepatitis D is relatively harmless to humans, can cause vampires to be weak for some months and vampires usually just have to worry about being staked in that time. However, Hepatitis V has been created as Hepatitis D's fatal counterpart. Dr. Overlark and his team believe the new strain they have created can be spread through consumption, copulation (vaginal and anal), as well as injection and is highly contagious.
A vampire infected with the fatal strain of Hep V will begin weakening, losing their strength and even speed. Within an hour or so, the virus can be visibly seen spreading through the victims' skin, with their veins darkening to a blueish black color that slowly covers the victims. Over time, the veins will cover the victim's entire body appearing where major veins and arteries are held. The victim also experiences pain and discomfort which increases as the virus destroys its host from the inside out. Many hours after exposure to infection, the virus saps its victim's powers and strength completely, and they will begin to feel extremely hot all over their body which may perpetuate to a burning sensation all over as the victim comes near their true death. It appears the average victim will succumb to their affliction within 24-48 hours after first exposure to the virus, if delivered directly by injection. It is implied that other carriers can last much longer. It appears the virus in some ways reacts similarly against vampires blood much like silver; as the time comes for the victim's true death, they dissolve into a pile of blood and the blood will simmer and smoke for moments after the true death.
The virus is so powerful that not even Lilith's blood is able to cure its effects ("In the Evening"), and it is not yet proven whether Warlow's blood would be ineffective against the virus. Hep V weakens its victims before ultimately putting them to the True Death. It also accelerates the vampire's metabolism, causing them to need to feed excessively. This hunger tends to drive the vampires to savagery and brutality out of desperation that they would not normally exhibit.
The first vampire seen to be infected with the virus is Nora Gainesborough, the sister of Eric Northman and the progeny of Godric. She was injected with it as punishment to Eric for turning Truman Burrell's daughter Willa into a vampire. Nora dies within a day of being subjected to the virus. ("Don't You Feel Me")
"In the Evening"
The virus infects all the camp prisoners who drink the contaminated Tru Blood. Those who escape contamination include: Eric Northman, Willa Burrell, Tara Thornton, Pamela Swynford de Beaufort, Jessica Hamby, Violet Mazurski, James and Ex Fellowship of the Sun televangelist Steve Newlin. The virus also spreads to much of the world's vampire population when infected Tru Blood is distributed globally. ("Dead Meat")
The virus also infected Eric, in the second episode of the seventh season, "I Found You.", as well as Bill Compton at the end of the fifth episode, "Lost Cause". Bill was infected by Sookie Stackhouse, and the virus seems to have mutated into an accelerated form through her blood. While faerie blood in general when infected, may mutate the virus, the blood of a faerie or halfling of a powerful bloodline causes the virus to mutate at an exceedingly accelerated rate. As a distant descendant of Niall Brigant, King of the Fae, Sookie's blood caused Bill's condition to progress from Stage One to Stage Three in a matter of days. It is unknown whether Bill would have died from the hep-v that he got from Sookie due to her royal fairy blood. Like Nora, Bill became warm, but Sookie could also hear his thoughts near the end so it could have meant that he was turning more and more human instead of dying. However, due to Bill's wish to die anyway he had Sookie stake him before that opportunity was explored.