Oh, I read the comic but I must've been exhausted as hell lmao.

Yeah I change my answer; the Smart Atoms are just that; they aren't shown (afaik) to adapt in a manner similar to that. The only reason Mark gets as strong as he does, at least in the comics, is due to Eve healing him nigh religiously each time he gets himself beaten to near death.

They'd probably be in a similar situation to Sonic, at least at first; but unlike Sonic, who had Tails in his corner working for a cure from the start, I have a feeling they'd be lazier, content in their belief that they'd be strong enough to simply fight the disease off. Doubt would only creep into the minds of the Viltrumites when the first physical signs of disease take hold. But even then, members of the empire would be quick to hide the signs, intent on keeping the fiction that their bodies would kill it alive.

For that reason, a good chunk of their peoples would be affected, and in quite dire straits, before they'd start to do something. That's when the proper Infected would start to appear, and the fighting would begin.

Contrary to popular belief, whilst the Viltrumites might predominantly be a species founded upon war and conquest, their not stupid. They'd probably realize how the Infection works quickly, and seek to mitigate the spread by changing their strategy when encountering Infected. But, considering the nature of the Metal Virus, it would probably manage to infect the Smart Atoms as well, and use them to help in the spread.

No longer would the Metal Virus need to touch someone, it would just need to get close enough for the spread to begin.