The G virus is the mutation of the T virus and the Ebola virus. Once infected, the person will mutate into this:
Upon taking damage, the person will mutate into various forms which lend the highest amount of defensive and offensive power.
Second mutation:
Third mutation:
Fourth mutation:
Fifth and final mutation:
At this point the creature could devour and entire train. The proper method to combat this creature in any of its stages is located within my tagline.