The rapidly increasing incidence of type 1 diabetes implies that environmental factors are involved in the pathogenesis. Enteroviruses are among the suspected environmental triggers of the disease, and the interest in exploring the possibilities to develop vaccines against these viruses has increased. Our objective was to identify enterovirus serotypes that could be involved in the initiation of the disease process by screening neutralizing antibodies against 41 different enterovirus types in a unique longitudinal sample series from a large prospective birth-cohort study. The study participants comprised 183 case children testing persistently positive for at least two diabetes-predictive autoantibodies and 366 autoantibody-negative matched control children. Coxsackievirus B1 was associated with an increased risk of β-cell autoimmunity. This risk was strongest when infection occurred a few months before autoantibodies appeared and was attenuated by the presence of maternal antibodies against the virus. Two other coxsackieviruses, B3 and B6, were associated with a reduced risk, with an interaction pattern, suggesting immunological cross-protection against coxsackievirus B1. These results support previous observations suggesting that the group B coxsackieviruses are associated with the risk of type 1 diabetes. The clustering of the risk and protective viruses to this narrow phylogenetic lineage supports the biological plausibility of this phenomenon.

CVB1 infections may contribute to the initiation of islet autoimmunity being particularly important in the insulin-driven autoimmune process.

Aims/hypothesis This case-control study was nested in a prospective birth cohort to evaluate whether the presence of enteroviruses in stools was associated with the appearance of islet autoimmunity in the Type 1 Diabetes Prediction and Prevention study in Finland. Methods Altogether, 1673 longitudinal stool samples from 129 case children who turned positive for multiple islet autoantibodies and 3108 stool samples from 282 matched control children were screened for the presence of enterovirus RNA using RT-PCR. Viral genotype was detected by sequencing.Results Case children had more enterovirus infections than control children (0.8 vs 0.6 infections per child). Timedependent analysis indicated that this excess of infections occurred more than 1 year before the first detection of islet autoantibodies (6.3 vs 2.1 infections per 10 follow-up years). No such difference was seen in infections occurring less than 1 year before islet autoantibody seroconversion or after seroconversion. The most frequent enterovirus types included coxsackievirus A4 (28% of genotyped viruses), coxsackievirus A2 (14%) and coxsackievirus A16 (11%). Conclusions/interpretationThe results suggest that enterovirus infections diagnosed by detecting viral RNA in stools are Electronic supplementary material The online version of this article

The infectious cycles of viruses are known to cause dramatic changes to host cell function. The development of microarray technology has provided means to monitor host cell responses to viral infection at the level of global changes in mRNA levels. We have applied this methodology to investigate gene expression changes caused by a small, icosahedral, single-stranded-RNA phage, PRR1 (a member of the Leviviridae family), on its host, Pseudomonas aeruginosa, at different times during its growth cycle. Viral infection in this system resulted in changes in expression levels of <4% of P. aeruginosa genes. Interestingly, the number of genes affected by viral infection was significantly lower than the number of genes affected by changes in growth conditions during the experiment. Compared with a similar study that focused on the complex, double-stranded-DNA bacterial virus PRD1, it was evident that there were no universal responses to viral infection. However, in both cases, translation was affected in infected cells.Over the past few years, microarray technology has been employed to probe the global effects of viral infection on host gene expression (26,27). The earliest microarray-based studies of host gene expression provided a very general, genome-wide picture of changes induced by viral infection. These studies, however, provided little information about the specific changes in individual genes across the entire host genome. Furthermore, investigations using this technology have largely focused on viral infections in animals and, to a lesser extent, in plants (21,30,35) or fungi (2, 3). Microarrays have been employed to detect phage-specific transcripts in infected cells (11,19), changes in the host genome (14,20), and changes in the transcriptional profiles of bacteria parasitized by lysogenic phages (7). However, to our knowledge, only two studies of virusinduced changes in host gene expression span the entire host genome. One of these studies involved a plant virus (21), and the other focused on an icosahedral, membrane-containing, double-stranded-DNA (dsDNA) phage, PRD1 (27).PRR1 is an icosahedral, single-stranded-RNA (ssRNA) phage (24) that is related to well-studied members (MS2, Qbeta, etc.) of the Leviviridae family (13). PRR1 is unique among members of the Leviviridae family in that it infects a wide range of gram-negative bacteria (8, 24), but only if they harbor an IncP-type conjugative plasmid. The PRR1 genome contains 3,573 nucleotides with only four protein-encoding genes, namely, those for the polymerase, the maturation and coat proteins, and the lytic factor (28). The PRR1 replication cycle and its effects on host cell physiology are described elsewhere (G. Daujotaitë, R. Daugelavièius, and D. H. Bamford, submitted for publication). The optimal bacterial host for PRR1 is Pseudomonas aeruginosa (24), a gram-negative, opportunistic human pathogen (15,16,18). At 6.3 million base pairs (containing 5,570 open reading frames [ORFs]), the P. aeruginosa genome is one of the largest bacterial genomes that ha...