Seems par for the course since our adaptive immune system is based on an old viral/transposon recombinase.

Transposon Molecular Domestication and the Evolution of the RAG Recombinase

https://pmc.ncbi.nlm.nih.gov/articles/PMC6494689/

Here is the actual study:

Escape of the BC200 gene to a human poxvirus reveals its persistent transposition in primates

https://www.science.org/doi/10.1126/science.aeh3441

Is VDJ recombination based on viruses or transposons?

It's the first time I hear this. Can't yet say much about it until I can verify that.