How Could ERVs Cause MS and Schizophrenia?
Although MS and schizophrenia133 are two distinct diseases both tend to debut in 18—28-year-old persons. In both there is support both for genetic134 and for environmental, unevenly distributed, possibly infectious, etiological factors.135,136 Schizophrenia debuts often are seasonal.137 This is not an argument for a pathogenic role of HERVs which are present since conception in nearly all persons. The reasons for seasonality in viral infections are not entirely known. This epidemiological pattern is primarily connected with fecal-oral or airborne transmission. Such types of transmission are remote from currently known HERV biology. If HERVs, via a polymorphism or a reintegration event, would be the major etiological factors of MS and schizophrenia there should be a pronounced hereditary component and a minor environmental one. However, if HERVs modulate the disease by interaction with environmental factors, there could be equally important hereditary and environmental components of the
