No cure for mosaic virus

My ‘Moneymaker’ tomatoes were planted in good-quality growing bags. They started off well, but after a few weeks some of the leaves started going light green and yellow.

The leaves you sent appear to be infected with a mosaic virus. The pale markings are fairly typical and I’m afraid there is no cure. Your plants will be severely weakened and yields will be low.
‘Moneymaker’ is probably more susceptible than those bred with resistance. Also, the virus can be carried on seed gathered from infected plants.
Plant viruses cannot be cured and are extremely infectious. You should remove diseased plants completely and clean up the greenhouse. The virus is usually spread by aphids, but you can transfer it all too easily on your hands and tools, or even brushing past a plant with contaminated clothing.
No tomato variety is fully immune from virus infection but examples of those which have a level of resistance include ‘Cherry Wonder’, ‘Estrella’, ‘Nimbus’, ‘Shirley’ and ‘Sonatine’.
I would avoid growing cucumbers in the same glasshouse as tomatoes too, since cucumber mosaic virus can also spread to tomatoes.