Is my client’s ongoing battle with depression caused by his Epstein-Barr virus infection lingering? If so, what can we do about this?

This indeed is another fine insight in making the connection here. It is an additional element. There are significant karmic issues in play as you know and have been working on. There is a history of spirit attachment bullying that has primed him to fear the worst about his future and then, in addition, the effects of the Epstein-Barr virus have perturbed his system to promote a state of emotional distress making him prone to depression. Continued work with the Lightworker Healing Protocol as well as prayers said on his behalf by the mother would be advisable here. What has been missing is the specificity to make the most effective requests of the divine realm for assistance and that you can provide with coaching.