Couple of Questions about Viruses

[Varine]

I think I posted a few questions on here in the past, but the liklihood of anyone remembering me is very minor so I'll start off again by saying that I know nothing about biology except the research I've done (most of which I didn't understand) involving wikipedia and the library and there's a kid in one of my classes who is majoring in biology that I use for information, but I don't think he likes me very much so generally he's not very helpful.

So basically you might need to break things down Barney style for me.

Anyway, to the point of the question I work for an indie game development team and we're working on a few stories, and one of them is a kind of zombie apocalypse. Well not really zombie, but we've been talking about the effects of some viruses and bacterias, and what I've been focusing on is rabies.

So first off, is it possible to combine viruses or isolate the effects of one? Such as rabies, would it be possible at all to isolate properties and remove them or hinder their progression? Like, could you say, limit the speed at which it produces or the delay it takes before really becoming noticeable (like instead of rabies taking a few weeks to months, could you speed it up so that it takes affect in hours)?

And as for combining, say some biological engineers took rabies and infected a bacteria like toxoplasmosa gondii with rabies after having engineered the virus to limit it's replication so that it doesn't kill the host as quickly as it does usually. Would that be possible at all either?

The reason I'm using those two specifically is because for the most part they have the symptoms that we're looking for, which would cause hallucinations, lesions on the skin, extreme agitation and possibly dementia, and as I understand it, possibly a kind of schizophrenia. Does that make any sense to anyone?

[JackBean]

well, yes, you could theoretically combine the properties as you like, because by some mutation you can get various responses. Question is, whether something like that could evolve in the nature. How will it survive between the standard virus/bacteria? How will it spread? etc.

But you cannot change the host just like that. I think that rabbies infect mammals and probably are not able to infect bacteria, you would have to look to the mechanism of infection and proceeding to see, whether there could be some analogy with bacterial host.