[quote=@Sapphire]
<Snipped quote by Letter Bee>

So then the Jesus Fruit Baby Tree thing gives people a virus while healing them? 
[/quote]

Yes; Isabella could also have made a stronger strain of the virus, or a prion, but she didn't because she wanted a limited number of 'New Metahumans', as turning too many people into Metas would cause her to lose relevance.

In fact, anyone with enough power and resources can create a stronger strain of the virus, it would just lead to a Mutually Assured Destruction scenario if they did. 

[@Weird Tales], nope.