Suspicious of virus
 

I have had this isolated cattleya for two years because after two weeks of opening the flowers begin to appear with necrotic stripes but it is a very strong plant, it blooms in spring and autumn with spectacular blooms, now it has twenty, three unopened, beautiful , large and fragrant. This is not sad?

Beautiful! I'm glad you're able to keep alive and not toss it!

I don't see problems on the flowers. But if you are concerned, you can get some test strips, the only sure way to test for virus. The flowers are beautiful, though... even if it tests positive, if you can keep it away from other plants then keep it. But knowledge is power. Test it. (I have a big, beautiful Blc. Porcia 'Cannizaro' that is virused - the whole grex is - I just put it under a tree away from other orchids and it blooms like crazy every year. )

Beautiful! If there were no issues for 2 weeks, then that's a a bit of a win. Two weeks of no blemishes is pretty good.