Thank you, very interesting. Viruses of course are packets of genetic material that then highjack the host cells to reproduce and to manufacture the various proteins that are coded for by the virus genome, so you are right they get the host to produce these proteins. As to superantigens, they are mostly associated with bacteria but some viruses also produce them such as rabies and EBV but the most studied is the Mouse Mammary Tumor Virus Superantigens.
What is also important to realise that the host response to these superantigens can also be variable due to genetic, environmental and other factors so that not everyone who is exposed to superantigens would react in the same way with a cytokine storm, or also weather the effects of such a storm. This is why the severity of the disease is different according to age, sex, ethnic background and comorbidities.