Cucumber mosaic virus?

[Nat1H]

I have some courgette plants in my greenhouse,that I am currently hardening off. One of them has 2 small bright yellow spots on one of the leaves. How do I know of it's mosiac virus or not? I really don't want it to spread to all my tomatoes and peppers! (If it hasn't already)
Thanks

I don't know how to tell by the leaves-but you could isolate these plants with some fine netting.