Our results show that an oligonucleotide array incorporating thousands of probes representing genomes of multiple foodborne RNA viruses including multiple hepatitis A virus genotype strains and multiple coxsackievirus serotype (A and B) strains can be used to differentiate between virus members of either genus to identify the genotype/serotype of these viruses by array hybridization assay. Because the large number of probes can bind and detect labeled targets over a much larger area of the viral genomes, producing distinctive signal patterns for each genotype/serotype, the need for large scale sequencing is eliminated for this level of discrimination. Is the risk of multiple sclerosis related to the ‘biography’ of the immune system? Multiple sclerosis (MS) with onset in childhood offers a unique opportunity to study the infectious background of this disease but the immune reactions against infectious agents in such children have only recently been investigated. These and other epidemiological studies strongly implicate involvement of one or more infectious agents in the aetiology of MS, with Epstein-Barr virus (EBV) being the prime candidate. Rather than being the actual cause of MS, it is more probable that these agents are involved in the development of immunoregulatory pathways. These pathways, if disturbed by hygiene-related factors including an altered sequence of infections, may generate and maintain a deficit within the immunological network that facilitates, to particular early events in the development of MS, preceding the onset of MS disease by years or a decade. A framework that can serve as a guide for further epidemiological, immunologic and molecular biologic investigations is formulated. This approach may shed light on the complex natural history of MS and may lead to rational preventive and therapeutic strategies. It is possible that, in the future, MS could be prevented by vaccination against EBV in early childhood; the framework is of relevance to the design of an appropriate type of vaccine. The pathogenesis of multiple sclerosis (MS) is certainly complex and heterogeneous in nature [1] , involving an interplay between innate and environmental factors [2] [3] [4] and genetic factors, notably the polymorphism of HLA [5] . The epidemiology of this disease strongly indicates that it has emerged as a major neurological disorder in industrially developed nations over the last 150 years and is likely to be affected by hygiene-related factors [3, 6] .