Detection of enterovirus-specific total and polymeric IgA antibodies in serum using a synthetic peptide or heated virion antigen in ELISA

Maternal antibodies in breast milk protect the child from enterovirus infections

OBJECTIVE

Enterovirus infections are frequent in infants and may cause severe complications. We set out to assess whether breastfeeding can protect against these infections and whether such an effect is related to maternal antibodies in breast milk or in the peripheral circulation of the infant.

METHODS

One hundred fifty infants who were prospectively followed up from birth were monitored for enterovirus infections. The duration of breastfeeding was recorded, and maternal breast milk and blood samples were regularly taken at 3-month intervals for the detection of enterovirus antibodies and RNA. Maternal serum was available from early pregnancy, delivery, and 3 months postpartum.

RESULTS

Enterovirus infections were frequent and were diagnosed in 43% of infants before the age of 1 year and in 15% of the mothers during pregnancy. Infants exclusively breastfed for >2 weeks had fewer enterovirus infections by the age of 1 year compared with those exclusively breastfed for < or =2 weeks (0.38 vs 0.59 infections per child). High maternal antibody levels in serum and in breast milk were associated with a reduced frequency of infections. This effect was seen only in those infants breastfed >2 weeks, indicating that breast milk antibodies mediate this effect. Enterovirus RNA was not found in any of the breast milk samples.

CONCLUSIONS

These results suggest that breastfeeding has a protective effect against enterovirus infections in infancy. This effect seems to be mediated primarily by maternal antibodies in breast milk.

Isolation of enterovirus strains from children with preclinical Type 1 diabetes

AIMS

To develop methods for isolation of enterovirus strains from subjects with preclinical Type 1 diabetes and evaluate if their presence in stools is associated with beta-cell damage.

METHODS

The study subjects were participants of the Finnish Type 1 Diabetes Prediction and Prevention Study (DIPP). The prospectively followed birth cohort comprised 12 children who turned positive for diabetes-associated autoantibodies during the follow-up (case children) and 53 controls matched for date of birth, sex and HLA-DQB1 alleles. Altogether, 878 stool samples were analysed for the presence of enterovirus RNA by RT-PCR followed by virus isolation and partial sequencing of viral genome. Enterovirus antibodies and RNA were simultaneously analysed from serum.

RESULTS

Eleven enterovirus infections were diagnosed in case children and 42 infections in control children by the presence of viral RNA in stools. The proportion of children who were repeatedly enterovirus RNA-positive stools was higher among case than control children (42% vs. 11% of children; P=0.02). Combined serum (antibody and RT-PCR) and stool analyses indicated at least one enterovirus infection in 83% of the case children before the appearance of autoantibodies, while only 42% of the control children had infection by the same age (P=0.006). Twelve enterovirus strains were isolated from case children and 38 strains from control children.

CONCLUSIONS

This protocol makes it possible to isolate a large number of enterovirus strains from prediabetic subjects. The findings suggest that enterovirus infections may be associated with the beta-cell damaging process.

Synthetic peptides for diagnostic use

Synthetic peptides representing relevant B-cell epitopes are, potentially, ideal antigens to be used in diagnostic assays because of their superior properties with respect to quality control as compared to those of biologically derived molecules and the much higher specificity that sometimes can be obtained. It is thus not a surprise than an increasing number of synthetic peptide based diagnostic assays are being developed or already are commercially available. In this report methods to define useful synthetic peptides, and diagnostic systems that are under development or on the market are discussed.