I could SWEAR I had posted this last night, but right at this moment it's probably mystifying readers of a forum about using mayonnaise during foreplay. I'll try and remember what I said: something about human endogenous retroviruses beings sequences of viral DNA which have become incorporated into our own genome. Up to this point I had heard that only very few were capable of producing a viable viral particle, but this abstract talks about a " substantial fraction" which can reinfect the host, reinsert their DNA at random points, and alter gene expression. Not only that, but they can do this in response to stresses caused by infections, injury or environment, all of which have been posited as triggers for MS, (but let's face it: what hasn't?):
008 Feb 28 [Epub ahead of print]
ENDOGENOUS RETROVIRUSES IN SYSTEMIC RESPONSE TO STRESS SIGNALS.
Cho K, Lee YK, Greenhalgh DG.
Burn Research, Shriners Hospitals for Children Northern California, and Department of Surgery, University of California, Davis, Sacramento, California.
Infection of germline cells with retroviruses initiates permanent proviral colonization of the germline genome. The germline-integrated proviruses, called endogenous retroviruses (ERVs), are inherited to offspring in a mendelian order and belong to the transposable element family. Endogenous retroviruses and other long terminal repeat retroelements constitute ~8% and ~10% of the human and mouse genomes, respectively. It is likely that each individual has a distinct genomic ERV profile. Recent studies have revealed that a substantial fraction of ERVs retains the coding potentials necessary for virion assembly and replication. There are several layers of potential mechanisms controlling ERV expression: intracellular transcription environment (e.g., transcription factor pool, splicing machinery, hormones), epigenetic status of the genome (e.g., proviral methylation, histone acetylation), profile of transcription regulatory elements on each ERV's promoter, and a range of stress signals (e.g., injury, infection, environment). Endogenous retroviruses may exert pathophysiologic effects by infection followed by random reintegration into the genome, by their gene products (e.g., envelope, superantigen), and by altering the expression of neighboring genes. Several studies have provided evidence that ERVs are associated with a range of pathogenic processes involving multiple sclerosis, systemic lupus erythematosus, breast cancer, and the response to burn injury. For instance, the proinflammatory properties of the human ERV-W envelope protein play a central role in demyelination of oligodendrocytes. As reviewed in this article, recent advances in ERV biology and mammalian genomics suggest that ERVs may have a profound influence on various pathogenic processes including the response to injury and infection. Understanding the roles of ERVs in the pathogenesis of injury and infection will broaden insights into the underlying mechanisms of systemic immune disorder and organ failure in these patients.
PMID: 18317406 [PubMed -