[P-man]

I need to clear this up: the difference between poisonous and infectous. Apparently, infectous agents are living organisms like viruses and bacteria, and poisonous substances are, well, substances. But, can't a virus be poisonous? That's where the line gets a bit fuzzy for me.

[sdekivit]

isn't this more chemical biology ?

In any case, the definition of an infectuous disease:

any change from a state of health in which part or all of the host body is not capable of carrying on its normal functions due to the presence of an micro-organism or its products (including viral diseases).

Thus in this case i wouldn't say a virus is poisonous, but infectuous. Same counts bacterial toxins.

[Equi]

Unless viruses produce toxins, they are not poisonous. Pathogenicity is usually caused by the vast amount of tissue lysis.

[Borek]

I wonder... looks to me like it is possible that proteins produced for virus can be toxic. Not that I have ever heard about such a case, but then my knowledge about viruses is rather small.

[P-man]

Thanks for clearing everything up. First science class: looking like an interesting year up ahead.

[Equi]

I wonder... looks to me like it is possible that proteins produced for virus can be toxic. Not that I have ever heard about such a case, but then my knowledge about viruses is rather small.

That may be a fluent border. Most are definitely immunogenic and cause local inflammation. At gram-negative blood sepsis the lipopolysaccharides on the outside membrane "break" off and cause toxic effects. Similar effects with allergens - not harmful, but sometimes dangerous.