Rural environment and risk factors of amyotrophic lateral sclerosis: a case-control study.

The aetiology of sporadic ALS is still unknown. Links with several environmental factors have been suggested, and some epidemiological studies have shown an increased incidence of ALS in rural populations. This study was designed to investigate risk exposures in a well-delimited rural population and to assess whether rural residency or occupations, such as farming, were associated with an increased risk of developing ALS. A prospective case-control-study of 108 sporadic ALS cases matched by age and sex to 122 controls was performed in Brittany from 2006 to 2008. A strong association was found between agricultural activity and ALS (odds ratio: 2.919; p = 0.01), while rural residence itself did not influence the risk of the disease. Bulbar forms of onset prevailed among agricultural workers as compared with other occupations (55 vs. 26%; p = 0.009). These results suggest a potential role of exposure to agricultural chemicals or contact with animals linked to agricultural work. The prevalence of bulbar forms of onset in agricultural workers has not been reported before. In addition to variable methodological approaches, differences in agricultural practices could explain the discrepancy between these findings and other studies.

Inhibition of the interaction between the SARS-CoV spike protein and its cellular receptor by anti-histo-blood group antibodies.

Severe acute respiratory syndrome coronavirus (SARS-CoV) is a highly pathogenic emergent virus which replicates in cells that can express ABH histo-blood group antigens. The heavily glycosylated SARS-CoV spike (S) protein binds to angiotensin-converting enzyme 2 which serves as a cellular receptor. Epidemiological analysis of a hospital outbreak in Hong Kong revealed that blood group O was associated with a low risk of infection. In this study, we used a cellular model of adhesion to investigate whether natural antibodies of the ABO system could block the S protein and angiotensin-converting enzyme 2 interaction. To this aim, a C-terminally EGFP-tagged S protein was expressed in chinese hamster ovary cells cotransfected with an alpha1,2-fucosyltransferase and an A-transferase in order to coexpress the S glycoprotein ectodomain and the A antigen at the cell surface. We observed that the S protein/angiotensin-converting enzyme 2-dependent adhesion of these cells to an angiotensin-converting enzyme 2 expressing cell line was specifically inhibited by either a monoclonal or human natural anti-A antibodies, indicating that these antibodies may block the interaction between the virus and its receptor, thereby providing protection. In order to more fully appreciate the potential effect of the ABO polymorphism on the epidemiology of SARS, we built a mathematical model of the virus transmission dynamics that takes into account the protective effect of ABO natural antibodies. The model indicated that the ABO polymorphism could contribute to substantially reduce the virus transmission, affecting both the number of infected individuals and the kinetics of the epidemic.