the virus was created for use as a bioweapon - infecting the enemy with a disease that would cause them to turn on their own would prevent the need for invasion/direct warfare, as well as cripple their societal structure if civilians became infected. The plan was to also develop a cure/prevention that could be used as a bargaining tool; forcing those infected to surrender or fall to the disease. However, the government failed to understand just how deadly the disease would become - or how quickly it would spread beyond the sterile walls of the lab.

it's a hybrid of a severe strain of furious rabies and a highly contagious respiratory virus; it produces your typical aggressive biting behaviors seen in rabies, AND due to the sneezing/coughing symptoms from the respiratory virus, it is more likely to be passed through the air (due to infected drops landing in nearby people's eyes, noses etc).

1-2 days after exposure: reddening of eyes, runny/stuffy nose, redness/swelling and itching around wound (if bitten). it's unknown if the virus is contagious at this point

3-5 days after exposure: fever, coughing, sneezing. appears to be a bad flu, may be severe enough to cause airways to close, but death at this point is rare. believed to be contagious once sneezing/coughing appears. bite wounds will itch and leak (fluid from bites is highly contagious)

6-7 days: high fever, loss of appetite, confusion. aggression starts to appear. excessive foaming at the mouth, refusal to eat and drink, and loss of consciousness are common as it progresses.

7+ days: from here, the patient will either enter a coma, die, or enter a "zombie" like state - their brain is so damaged that they cannot function normally, but they are now alive solely to spread the virus. most, if not all, will eventually die, but it is not known for sure how long this takes (subjects have survived for years in this state in tests)

it should be noted that attacks caused by those infected are so vicious that they may outright kill those they bite. in these cases, the victim will not come back to life, but their body should be considered infected and should not be touched due to contamination risk.

the rabies vaccine will not treat or prevent this strain due to the immune system not recognizing it as rabies - the added DNA of the respiratory virus causes the body to view it as a completely new disease, rendering it unable to fight off the infection. It is unknown if a prior vaccination has any impact at all on symptoms or incubation period. death is 100% guaranteed after being infected.