Today’s issue of Science1  has a number of letters that refer to things I’ve previously talked about here on Mystery Rays.

Immune System: Success Owed to a Virus?

More plausible than a “RAG transposon” is the insertion of an infectious DNA virus resembling a herpes virus adjacent to the RAG2 protein in a primordial deuterostome.

–David H. Dreyfus

Furher reading:

  • Sea urchin immune systems
  • I don’t think I’ve talked specifically about Dreyfus’s herpesvirus/RAG hypothesis yet (it’s queued up somewhere in my scattered reminders-to-self); it was published in PLoS One earlier this year.2

Immune System: “Big Bang” in Question

Immune memory, supposedly a characteristic of adaptive immunity and therefore of higher vertebrates, does in fact exist in invertebrates … The adaptive immune system never works on its own [a little-known fact first revealed 20 years ago (4) but subsequently neglected].

Thomas Pradeu

I heartily disagree with most of this letter.  First, the existence of immunological memory in invertebrates is at best debatable:

Second, far from being “neglected”, the essay that he claims is a “little-known fact” is probably the most famous  in immunology; the claim he thinks is neglected, is one of the most basic tenets of modern immunology:

Immune System: Promethean Evolution

We do not know precisely when the change from Epimethean (reacting) to Promethean (anticipating) took place, and there are no satisfactory intermediate forms (“missing links”) to indicate the steps along the way. But absence of proof is not proof of absence. We may with confidence recognize the Promethean “Big Bang” in immunology as one of the high points in the workings of Darwinian evolution.

Arthur M. Silverstein

Further reading:

  1. Science 24 July 2009: Vol. 325. no. 5939, pp. 392 – 393[]
  2. Paleo-Immunology: Evidence Consistent with Insertion of a Primordial Herpes Virus-Like Element in the Origins of Acquired Immunity
    David H. Dreyfus
    PLoS ONE. 2009; 4(6): e5778. doi: 10.1371/journal.pone.0005778 []