Here is a study that concludes TYLCV is not transmitted by seeds of tomatoes. I guess Fred is right, more research needed.
http://www.plantprotection.pl/PDF/47...06_Kashina.pdf
Seed transmission
Seeds were extracted from tomato fruits obtained from field- and graft-infected
tomatoes by blending the fruits in distilled water and separating them from the debris through several steps of washing with distilled water. The seeds were sown in
5 plastic pots of 30 cm in diameter (10 seeds per pot), and maintained in the screen
-
house.
Seed transmission
Typical TYLCV symptoms were not observed on any of the tomato seedlings
grown from seeds of infected plants, and no symptoms developed on indicator plants
following back-indexing.