Okay, based on comparisons between the SR4 and SR5 core rulebooks on toxins and based on what the SR4 Runner's Companion had to say, this is the conversion of HMHVV III:
HMHVV III
Vector: Contact
Speed: 1 day
Penetration: -6
Power: 12
Nature: Retroviral
Effect: Pain, nausea, Essence loss, transformation
HMHVV III is responsible for the creation of ghouls, and is typically spread by unprotected contact with those creatures or their bodily fluids. Unlike the cases of other retroviruses in this genus, the subject is usually awake and aware during the metamorphosis. Every time the character fails the Disease Resistance Test, he loses 0.1 points of Essence. If his Essence falls to 0 or below, he dies.
The character should keep track of how many points of Essence he loses every time he is infected with HMHVV III. After losing 1.0 points of Essence in this fashion, the disease halts (if still ongoing). The character loses all Resonance and technomancer abilities and gains the Infected (Ghoul) quality
and a Magic attribute of 1 (or retains his own Magic attribute, if higher). Revitalization gene therapy cannot recover Essence lost to HMHVV III infection.
That's basically the HMHVV III description copied directly from the book.
This is what I came up with for the variants:
HMHVV III W-1
Vector: Contact
Speed: 3 days
Penetration: +12
Power: 0
Nature: Retroviral
Effect: None.
This is an initial attempt to weaponize HMHVV with the intent of it surviving outside of the human body for extended periods of time. While successful, the resulting virus is so weak that it cannot infect any human who does not have an immune system already completely destroyed by another disease. Even when it does infect another human, it lacks the capacity to affect their Essence due to its weaker nature.
HMHVV III W-2
Vector: Contact, Inhalation
Speed: 6 hours
Penetration: -3
Power: 6
Nature: Retroviral
Effect: Pain, nausea, Essence loss, transformation
A second attempt at weaponizing HMHVV. This version was altered to be capable of spreading through the air. However, the airborne spread of the disease decreases the viral load, causing it to be less effective at infecting people or penetrating protections. The virus also burns itself out quickly; within ten seconds of being released, any bit of the disease still airborne dies.
HMHVV III W-3
Vector: Contact, Inhalation
Speed: 1 day
Penetration: -3
Power: 12
Nature: Retroviral
Effect: Pain, nausea, Essence loss, transformation
An attempt at improving the W-2 variant to increase its power, remove the transformation, and increase the Essence loss. This variant, like normal HMHVV III, causes the infected to lose all Resonance and technomancer abilities and gains the Infected (Ghoul) quality and a Magic attribute of 1 (or retains his own Magic attribute, if higher) after losing 1.0 Essence. Unlike the normal version, the character loses 1.0 Essence each time they fail the Body roll, and this Essence loss continues even after they transform. Also, the character remains capable of spreading the disease, and thus becomes a danger to all around them due to being a mobile plague.
And here's what it's intended to look like, but which will never come about:
HMHVV III Weaponized
Vector: Contact, Inhalation
Speed: 1 day
Penetration: -6
Power: 12
Nature: Retroviral
Effect: Pain, nausea, Essence loss
Every time the character fails their Body roll, they lose 1.0 Essence. They remain capable of spreading the disease, being a mobile plague as the disease replicates and spreads from them to any nearby.
Those are just general summary write-ups. Anything I need to correct?
Edit: And the final product also being a potential nightmare epidemic is intentional on my part. The corp, whoever is developing this, is not fully thinking through potential consequences.