Well first off, you need to decide what kind of tone you want this story to be in and what tone this main character is. He's what the story hinges on right now. Is this guy a hero or a villain? and what kind? Make a character profile for him to figure him out properly, much of his actions will write themselves, especially in the beginning.
As for what actually happens in the beginning, well it's always good to start with something exciting, something that gets the story going straight away. There's no reason you can't start with him making and releasing the virus and then through conversations and actions and other techniques, we slowly figure out why he did it, and how he's a rounded and proper character. That's how I would do it.
If you really don't want to start straight with the virus, you can start with how he came to be a furry, or perhaps some day in his life where all the problems of being the only furry show themselves. Like a day in his life, where it shows why he's unhappy with the way the world is, and so he starts on his work, but a lot of things get in his way. His personal life, his professional life and also the issues between furries and humans. It makes it a kind of thriller as the audience watches his struggle and wonders if he will get caught. Eventually... say at the start of the second act or maybe the third, the virus gets released and the last chunk of the book deals with the consequences of that, both to the world and to the relationship he has with it all, and the relationships he has with particular people. Also show the response the world has to this and his response to their response.
I'm totally going on rolling tangents with your story but hey, I'm just throwing ideas at you. You can take what you want from it all.
I hope I've helped.