T Hovi1. 1. Enterovirus Laboratory, National Public Health Institute, Helsinki, Finland. Tapani.Hovi@ktl.fi
Abstract
BACKGROUND: Several lines of evidence suggest that enterovirus infections may be involved in the etiology of the insulin-dependent diabetes mellitus (IDDM). Often in the literature, a reference is given to specifically diabetogenic strains of enterovirus but there is no systematic assessment about the generation of such strains in the course of evolution or about their abundance among the 64 enterovirus serotypes pathogenic to man. If enteroviruses truly are involved in the etiology of IDDM, a possibility to prevent the disease with enterovirus vaccines might become feasible. In such a situation it would be important to know which serotypes and strains are the most important ones, and whether there would be differences between the strains as regards the pathogenetic mechanisms involved. OBJECTIVE: To present a brief summary of the basic biology of enteroviruses, on existing data of genetic variation of enteroviruses, and on molecular epidemiology of human enteroviruses with special reference to the different epidemiological modes of their putative involvement in the pathogenesis of IDDM. CONCLUSIONS: Like RNA viruses in general, enteroviruses exist as a quasispecies, a mixture of genetic microvariants with a vast potential to adapt to new environments. This means that specifically beta cell-tropic and potentially diabetogenic variants could, in theory, emerge sporadically during systemic infection of any individual. The patterns of genetic diversification of enteroviruses, cocirculation of separate genetic lineages in the human populations, and the assumed geographical restrictions of endemic transmission of the lineages, allow one to hypothesize that populations with a high persisting IDDM incidence might be endemically infected by some specific strains of enteroviruses. However, so far, there is no systematically collected data supporting this hypothesis.
BACKGROUND: Several lines of evidence suggest that enterovirus infections may be involved in the etiology of the insulin-dependent diabetes mellitus (IDDM). Often in the literature, a reference is given to specifically diabetogenic strains of enterovirus but there is no systematic assessment about the generation of such strains in the course of evolution or about their abundance among the 64 enterovirus serotypes pathogenic to man. If enteroviruses truly are involved in the etiology of IDDM, a possibility to prevent the disease with enterovirus vaccines might become feasible. In such a situation it would be important to know which serotypes and strains are the most important ones, and whether there would be differences between the strains as regards the pathogenetic mechanisms involved. OBJECTIVE: To present a brief summary of the basic biology of enteroviruses, on existing data of genetic variation of enteroviruses, and on molecular epidemiology of human enteroviruses with special reference to the different epidemiological modes of their putative involvement in the pathogenesis of IDDM. CONCLUSIONS: Like RNA viruses in general, enteroviruses exist as a quasispecies, a mixture of genetic microvariants with a vast potential to adapt to new environments. This means that specifically beta cell-tropic and potentially diabetogenic variants could, in theory, emerge sporadically during systemic infection of any individual. The patterns of genetic diversification of enteroviruses, cocirculation of separate genetic lineages in the human populations, and the assumed geographical restrictions of endemic transmission of the lineages, allow one to hypothesize that populations with a high persisting IDDM incidence might be endemically infected by some specific strains of enteroviruses. However, so far, there is no systematically collected data supporting this hypothesis.