"Terminal" by Kathy Reichs & Brendan Reichs
The fifth in the "Virals" series. Virals against Trinity. Chance Claybourne inherited the pharmaceutical company from his father. In a secret lab at the company he tried to duplicate the parvovirus experiment that infected Tori, Hi, Shelton, and Ben on Liri Island. He ended up infecting himself and another scientist, Will Speakman with a stronger version of the parvovirus. On a camping trip Will accidentally infects his roommate, Cole and Tori's friend Ella. After getting fired by Chance Will forms the "Trinity" with Cole and Ella and starts a war against Chance, Tory, and the other "Virals". They consider Chance a traitor (he's infected with the stronger version of parvovirus) and Tori responsible for it all (1st one infected with parvovirus).
Meanwhile there are "men in black" who do not know about any of these actual parvovirus infections wandering around town asking questions about Chance and Tori. In particular, strange happenings around Tori. And Chance has been testing the blood of himself and the "Virals" trying to develop some sort of serum they can use to reverse the effects of the parvovirus.
Susan