I have believed the specificity of viruses to their host species, based on the protein-protein interaction. But now am reading some papers suggesting that transmission across kingdoms is possible, as they could detect some plant viruses in humans who consumed infected fruit or salads, yes that is possible, also that the humans displayed symptoms. is this really justifiable, or is it only that humans had other secondary reactions and the symptoms should not be directly linked to the virus?

Their justification is that because these plant viruses belong to the same families with some human and insect viruses. (the three families, Bunyaviridae, Rhabdoviridae and Reoviridae contain viruses known to infect plant, animal and human)