Multiple sclerosis and inflammatory bowel diseases: what we know and what we would need to know!

Multiple sclerosis (MS) is a demyelinating disorder of the central nervous system (CNS) but the causes have not been defined. The disease process appears to involve interplay between environmental factors and certain susceptibility genes. It is likely that the identification of the exact etiological mechanisms will permit the development of preventive and curative treatments. Evaluation of several diseases found to be more often associated than by chance alone may reveal clues to the etiology of those disorders. An association between MS and inflammatory bowel diseases (IBD) was suggested by the observation of an increased incidence of IBD among MS patients. A problem in the interpretation of the data rests, in part, with the observation that abnormal findings in brain magnetic resonance imaging (MRI) may be reported as MS in IBD patients. Defining the limits between incidental MRI findings and findings compatible with MS has resulted in further exploration of this possible association.

Insights into origins of Human T-cell Lymphotropic Virus Type 1 based on new strains from aboriginal people of Canada.

The causes of the worldwide distribution of Human T-cell Lymphotropic Virus Type 1 (HTLV-1) remain incompletely understood, with competing hypotheses regarding the number and timing of events leading to intercontinental spread on historical and prehistoric timescales. Ongoing discovery of this virus in aboriginal populations of Asia and the Americas has been the main source of evidence for the latter. We conducted molecular phylogenetic and dating analyses for 13 newly reported HTLV-1 strains from Canada. We analyzed two full-length proviral genomes from aboriginal residents of Nunavut (an autonomous territory in Northern Canada including most of the Canadian Arctic), 11 long-terminal-repeat (LTR) sequences from aboriginal residents of British Columbia's Pacific coast, and 2 LTR sequences from non-aboriginal Canadians. Phylogenetic analysis demonstrated a well-supported affinity between the two Nunavut strains and two East Asian strains, suggesting the presence of an Asian-American sublineage within the widespread "transcontinental" subgroup A clade of HTLV-1 Cosmopolitan subtype a. This putative sublineage was estimated to be 5400-11,900 years in age, consistent with a long-term presence of HTLV-1 in aboriginal populations of the Canadian Arctic. Phylogenetic affinities of the other 11 Canadian HTLV-1 aboriginal strains were diverse, strengthening earlier evidence for multiple incursions of this virus into coastal aboriginal populations of British Columbia. Our results are consistent with the hypothesis of ancient presence of HTLV-1 in aboriginal populations of North America.