Vampires in V Wars are humans with an activated predator gene known as NH47.
The prion protein biomass was initially frozen in a glacier, when it was excavated the presiding team was exposed to it, and seemingly either turned, died or committed suicide. When Luther Swann and Michael Fayne went to check on the team, they became exposed to the prion. As Luther Swann does not possess the predator gene, exposure to prion only caused a temporary illness which, after it had passed, resulted in no alterations to his cells or genetic makeup. As Michael Fayne possesses the predator gene, this acted as a co factor in the resulting overhaul to his physiology, essentially making Fayne patient zero to the outbreak of the prion. This would subsequently lead to an uncontrollable spread of the prion protein, where in many individuals who possessed the predator gene would be exposed to others who are carriers of the prion, resulting in their transition into a blood. The increased number of Bloods also went hand in hand with a rise of serial and spree killings throughout the U.S. These violent actions, and the nature of how Bloods are created led to the implementation of concentration camps to control the spread of the prion, and to segregate Bloods from the human public.
Human beings can become a Blood if they are exposed to the prion and possess the predator gene. It appears as though the prion is airborne, so even just close proximity to a Blood will spread the prion and, if present, activate the predator gene. Period of transition from a human into a Blood is not instantaneous, and appears to vary with each individual. For Michael Fayne, transition appeared to take several weeks to complete, however with Fayne's dentist, transition took less than several days (Down With The Sickness). This suggests that transition occurs more quickly when exposed to individuals who possess the prion, as opposed to direct exposure to the prion protein biomass.
Transition into a Blood only occurs when someone with the predator gene is exposed to the prion protein, emphasis on the term predator. After transition into a Blood is complete, many will instantly succumb to their instincts, and their behaviour will adapt to their predatory nature. Most Bloods will viscously attack and kill humans in the first few days after they have transitioned, acting on their base nature to hunt and kill their prey. According to Calix Niklos, an increase in serial and spree killings had occurred as a result of the outbreak (Blood Brothers). Michael Fayne described the drive to hunt and consume blood to be "impossible to control", however he was eventually able to accept and control his newfound status and nature as a predator (Bad as Me).
Transition into a blood results in radical changes to the body, with Fayne describing the transformation as "faster, stronger, more powerful than you could feel in a lifetime" (Bad as Me). The digestive system is modified to allow for the ingestion and digestion of blood. If Humans ingest blood this would likely lead to an iron overdose, causing them to become violently sick, a blood's modified digestive system allows them to ingest blood, and gain nutritional value from it (Down With The Sickness). The regular consumption of blood allows them to maintain their abilities, and improves their rate of healing (Bad as Me). What appears to be an aid in the consumption of blood is their ability to extend their teeth in to wickedly sharp fangs, like some predatory species this is to make it easier to tear the flesh of their prey. When their fangs extend the throat will also adapt, allowing Bloods to cast animalistic vocalisations such as the the low guttural sound of a growl or snarl (Cold Cold Ground).
Bloods are beings endowed with immense physical strength, that greatly surpasses that of any Human being. They can easily overpower Humans, lift them several feet high off the ground, and launch them through the air without any visible strain. Bloods are able to exert extreme physical force, enough to snap standard issue police cuffs and restraints, easily toss around adult Humans and break porcelain sinks (Down With The Sickness). Bloods possess the physical capabilities to quickly and visciously tear and mutilate flesh (Blood Brothers), in fact, they are so strong that it took close to half a dozen police officers to overpower just one of them.
Bloods are more athletic than Humans, they can move and run fast enough to suddenly appear out of nowhere, and quickly disappear from sight. They are able to move fast enough to abruptly appear out of nowhere and savagely attack and mutilate multiple victims. Bloods can quickly hunt down their prey and suddenly disappear after attacking and killing their victims (Because I Could Not Stop for Death). Their athleticism allows them to move at great speeds without sacrificing accuracy, and move and leap with inhuman ease (Bloody but Unbow'd), however they do not possess the quickness to dodge bullets or shotgun rounds (Bad as Me).
Sensory capacities are augmented, with specifically hearing and vision surpassing the capabilities of the human sensory system. Their vision allows them to see further, and with greater clarity than any Human, even in dark areas or at night. A blood's hearing allows them to pick up on conversations from across a room, or even in a moving car, their hearing even allows them to hear a heartbeat. Their vision and hearing seem to work convectively, as Fayne appeared to use the sound of someone's heartbeat to see the blood pumping through their veins and blood vessels (Blood Brothers). Their olfactory and gustatory senses are affected as well; as Fayne was able to detect and identify food that Swann, a human could not, despite the fact that they were both in a quarantine sealed room (Down With The Sickness). Bloods also find any normal human food they eat to taste "off".
Possibly the most drastic improvement to their physiology is an increase in the effectiveness and the efficiency of their ability to heal from harm or injury. Bloods can rapidly heal from harm to their body, they can recover from bullet wounds in hours, and heal almost instantly from a taser burn (Down With The Sickness). Their regenerative capacities are capable of repairing sensory defects such as incorrective eyesight (Bloody but Unbow'd). Bloods' rate of recovery allows them to endure greater injuries than Humans, with many bloods having endured multiple gunshots, and continued to move and function. It is unknown if bloods are immune to other infections and diseases, however they are highly resilient to foreign contaminants like drugs. Despite their ability to endure greater injury, Bloods are still mortal beings and can be killed by conventional means (Bad as Me).