I think I've come to the conclusion that Cryptovirus is just another very common virus that easily infects people with ME, just like HHV-6 does. Although it was found in a high percentage of ME/CFS patients, these patients were all based in the same locality, South East Queensland, and there doesn't seem to have been any healthy control samples tested for the same virus. As far as I can see, a paper on Cryptovirus was never published, so the research does not have a particularly solid basis. Cryptovirus and the SER (swine) strain of PIV-5 share some identical protein strands of their genome, so it is possible that Cryptovirus is a human isolate of the SER strain, meaning that Cryptovirus would be a zoonotic virus (a species crossover). But it hasn't been confirmed that Cryptovirus is the same as SER in anything that I've read and it seems to be speculation rather than fact. It seems probable that Cryptovirus is a human variant of PIV-5, as there has been research published which describes Cryptovirus as a human variant of PIV-5. At the very least, Cryptovirus sits within the Rubulavirus genus (virus categorisation) along with PIV-5 and mumps, and so at the very least, it is very closely related to PIV-5 and mumps.