Barnyard Week: We really dont need to worry about PERVs

Posted by ERV on May 26, 2011
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I LOVE talking about PERVs on ERV.

PERVs.

PERVs.

EVEN MOAR PERVs.

I LOVE PERVs!

Well… PERVs as in Piggie Porcine Endogenous Retroviruses. Not pervs as in Catholic Priests and Teh Popes advisers. Thats a different story.

Because the need for organs for transplants is so high, and because pigs are pretty great sources for transplants in humans, and because of recent successes with minimal PERV-pigs down-under, a lot of research has gone into PERVs to really try to nail down just how big of a threat they are to humans.

The problem is, PERVs can ‘infect’ human cells. But as some of you who have been following the XMRV story might note— being able to infect the cells of a creature in tissue culture, or the creature itself, might not be a big deal in and of itself. For a virus to be ‘bad’, its got to be able to infect the creature, that creature needs to get sick in some non-treatable way, and the creature needs to be able to spread that virus to other creatures.

A few recent papers have pointed out that, while yes, PERVs can ‘infect’ human cells, in real life, its just not an issue we need to worry about.
1– PERVs are restricted by human APOBECs.

Restriction of porcine endogenous retrovirus by porcine APOBEC3 cytidine deaminases.

Repression of porcine endogenous retrovirus infection by human APOBEC3 proteins.

This is just like what has been observed with XMRV. Yes, you can ‘infect’ cells, but the cell basically becomes the cockroach-hotel, as in ‘cockroaches check in, but they dont check out’. PERVs infect human cells, but they dont check out.

2– PERVs are not found in transplant recipients

Long-term absence of porcine endogenous retrovirus infection in chronically immunosuppressed patients after treatment with the porcine cell-based Academic Medical Center bioartificial liver.

Multiplex high resolution melting assay for estimation of Porcine Endogenous Retrovirus (PERV) relative gene dosage in pigs and detection of PERV infection in xenograft recipients.

There are a few settings where people have been allowed to get transplants from pigs in situations where PERVs might be transmitted. Despite the fact these patients are on immunosuppressive drugs to help the transplant take hold, PERVs are not popping up in these patients. PERVs are also not showing up in lab workers involved with these transplants.

Science: It can turn fears that were once rational (PERVs from pig xenographs might infect humans and cause a new world-wide pandemic a la HIV-1) into silliness, or turn fears into facts you need to address.

Its starting to become silly to worry about PERVs.

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Comments

  1. #1 Jaketoadie
    May 26, 2011

    But, what if the PERVs homologusly recombinaltion tiniker us, then can we be scared of PERVs again?

  2. #2 Levi
    May 26, 2011

    ERV,

    Thats great news. I will tell my cardiologist that you have green-lighted that new pig heart valve to replace my leaky original because its silly to worry about xenograft issues.

    I am no scientist virology student, but this gets me wondering about what would happen if several rhesus macaques were hypothetically innoculated with ultra-megadoses of cultivated PERV retrovirus particles at lethal challenge levels. What would you imagine those poor devils would present in terms of viremia and which tissues, if any, would still be riddled with PERV’s after several months?

    Of course, we would not really want to actually sacrifice our primordial cousin’s for such a study. My guess is that you feel that restiction factors would keep the retrovirus in check, and it would not be replication competent in those animals.

  3. #3 ERV
    May 26, 2011

    Its been done. The non-human primates have been fine (at least rhesus macaques, pig-tailed macaques, and baboons).

  4. #4 Levi
    May 26, 2011

    Its been done. More non-human primates sacrificed for the cause. If I get a pig-valve installed, I will make an eco-donation to a primate conservation non-profit in their honor. Do you have a linky for this PERV/primate research? It sounds interesting in a morbid sort of way.

  5. #5 Levi
    May 26, 2011

    ERV,

    Strike that last request for a linky. It see it here in the related citations of your original linked articles:
    http://www.ncbi.nlm.nih.gov/pubmed/19243559

  6. #6 Levi
    May 27, 2011

    OIC ERV,now I understand why you qualified your response and limited it to rhesus macaques, pig-tailed macaques, and baboons. They have a gene that restricts susceptibility to PERV’s and may be sub-optimal species for PERV research about human xenograft issues. Apparently, had they used African Green Monkey’s and treated them with tunicamycin, they may have gotten a different result. Or not, who knows?
    http://www.ncbi.nlm.nih.gov/pubmed/20949092

    Boy, this science stuff is complicated, what with all those white lab coat folks taking pot-shots at each others work. . .seems silly.

  7. #7 yaoi_myantidrug
    May 27, 2011

    There’s a joke about PORN (progressive outer retinal necrosis)somewhere in there….

  8. #8 Childermass
    May 27, 2011

    Off topic, but I know ERV will just love this. Login to Facebook, or have a friend login if you don’t do FB, and click:

    https://www.facebook.com/#!/notes/yonah-ward-grossman/for-over-one-hundred-years-americans-knew-pit-bulls-for-what-they-did-best-babys/213698638654712

    Title: “For over a hundred years Americans knew pitbulls for what they did best. Babysitting.”

    The note appears to be visible for all users. Since the author is not by “friend” nor a “friend of a friend” and I can see it.

  9. #9 Poodle Stomper
    May 27, 2011

    PERVs aren’t harmless to primates. I mean look at the poor rhesus macaques! One exposure to PERVs and they turn into , pig-tailed macaques (coincidence…I think not!)! WPI has spoken!