You are right that no biotech is required to find terrible viruses from history. Access to those viruses is pretty well controlled though: you can get a stern letter from the CDC if you try to order DNA that looks like smallpox or RNA that looks like the 1918 Spanish flu. It's happened to my roommate during his virology research--they do monitor these things[1].

BUT, more importantly--you don't even need fancy biotech to engineer a terrible virus. No sequencing, recombinant DNA, fancy BSL-4 labs, well-educated virologists, none of that. All you need is a captive population, something any self-respecting evil warlord should be able to get. (Certainly the North Koreans, the Taliban, etc. have access to plenty of prisoners.)

The same simple mechanism used by Fouchier (the guy who created the controversial bird/ferret superflu) can be applied to humans: serial passage. Put any moderately bad flu virus in a certain number of prisoners, then expose them via air circulation to other prisoners. Take the sickest people from the second group and expose them to another uninfected group via air circulation. After five or six passages the virus in the last group will show extraordinary virulence and transmissive capabilities because you've applied artificial selection.

To seed the virus and start an attack, you take a few of these prisoners, expose them to the worst virus, and put them on planes to your target country while they are still in the incubation/transmissive period.

Obviously, this is a nightmare scenario that I hope never happens, but the idea that terrorists or evil dictators need fancy science to engineer superbugs is false. The same methods farmers have used for centuries to grow taller corn and leafier lettuce can be applied to viruses by anybody with enough prisoners and moral depravity.

[1]: It should be noted that in-house synthesizing costs are coming down, though, and we won't be able to rely on the safeguard of companies automatically BLASTing ordered sequences against a CDC blacklist for much longer.

I have been thinking exactly this. And one can't help wondering... hasn't this already been attempted?

because it's probably more effective just to use chemical weapons (or other WMD tech) that already exists.

I'd also add that the risk of "friendly fire" with bioweapons is very high.

Thanks for injecting some actual peer reviewed research into this discussion. As I mentioned elsewhere, I was mostly responding to the notion that one can engineer a virus with specific properties as opposed to relying on natural pathogens. No argument that there are no shortage of naturally occurring bugs that can kick our butts.

Can you comment on the models that are used for simulating outbreaks? Do they factor in natural evolutionary pressure and change of the virus? In the case of smallpox, you have something fairly stable, but influenza is highly variable over time. I can't imagine how one does that but it would be cool to know if it's possible.

        Do they factor in natural evolutionary pressure and change of the virus?

Not at all. Meta population models use some type of stochastic discrete PDEs and agent based models just infection probabilities. This is an over simplification but just so you have an idea. You can get the gritty details in the papers above.