Could these streaks on phal leaf be a sign of virus?

[euplusia]

When the roots are bad, the growth of leaves can easily suffer.
I have carried out some virus tests on a few of my Phalaenopsis plants in January and was surprised how many tests were positive for one or two viruses. However some of my plants are growing strong and the leaves don't show any symptoms.
In my personal experience there is nearly no correlation between leaf symptoms, vigorous growth and virus carrier status.