Comparison of enterovirus-specific cellular immunity in two populations of young children vaccinated with inactivated or live poliovirus vaccines

Enterovirus and type 1 diabetes: What is the matter?

A complex interaction of genetic and environmental factors can trigger the immune-mediated mechanism responsible for type 1 diabetes mellitus (T1DM) establishment. Environmental factors may initiate and possibly sustain, accelerate, or retard damage to β-cells. The role of environmental factors in this process has been exhaustive studied and viruses are among the most probable ones, especially enteroviruses. Improvements in enterovirus detection methods and randomized studies with patient follow-up have confirmed the importance of human enterovirus in the pathogenesis of T1DM. The genetic risk of T1DM and particular innate and acquired immune responses to enterovirus infection contribute to a tolerance to T1DM-related autoantigens. However, the frequency, mechanisms, and pathways of virally induced autoimmunity and β-cell destruction in T1DM remain to be determined. It is difficult to investigate the role of enterovirus infection in T1DM because of several concomitant mechanisms by which the virus damages pancreatic β-cells, which, consequently, may lead to T1DM establishment. Advances in molecular and genomic studies may facilitate the identification of pathways at earlier stages of autoimmunity when preventive and therapeutic approaches may be more effective.

On birth single dose live attenuated OPV and BCG vaccination induces gut cathelicidin LL37 responses at 6 week of age: a natural experiment

In a cross sectional study, we show that infants who received single dose of live attenuated OPV and BCG vaccines within 48h of birth, have higher excretion of human cathelicidin LL37 (p<0.05) in stool at 6wk of age. This response remained unchanged in multivariate analysis after adjusting for sex, mode of delivery, infant age, mother age birth weight and breast milk feeding pattern. This analysis also reveals that irrespective of vaccination, girl infants have higher human-beta-defencin2 (HBD2) and exclusively breastfed infants have higher total and anti-polio specific IgA to all three subtypes in stool (p<0.05). However, vaccination induces anti-polio IgA responses only to infants who are exclusively breastfed. Thus on-birth live attenuated vaccination may provide non-specific beneficial effect against infections while exclusive breastfeeding enhance protection by boosting vaccine induced IgA. The result also suggests that in polio endemic area, exclusive breastfeeding may be sufficient for mucosal anti-polio responses during early infancy.

Viral interference induced by live attenuated virus vaccine (OPV) can prevent otitis media

Background

The goal of this study was to evaluate whether a live attenuated poliovirus vaccine (OPV) has clinically relevant interfering effect with non-polio infections causing otitis media in young children.

Methods

Open trial in which the intervention group (64 children) received OPV at the age of 2, 3, 6 and 12 months. The control group (250 children) received IPV (inactivated polio vaccine) at the age of 6 and 12 months. Clinical symptoms were recorded by a questionnaire at the age of 3, 6, 12, 18 and 24 months.

Results

Otitis media episodes were less frequent in the OPV than in the control group. A significant difference was seen at the age of 6–18 months (IRR = 0.76 [95% CI 0.59–0.94], P = 0.011) and was particularly clear among children, who attended daycare (IRR 0.37 [95% CI 0.19–0.71], P = 0.003).

Conclusions

OPV provides some protection against otitis media. This effect may be mediated by viral interference with non-polio viruses.

Enteroviruses, type 1 diabetes and hygiene: a complex relationship

Type 1 diabetes (T1D) is an autoimmune disease in which the immune system mounts an attack on the host's insulin‐producing β cells. Because most cases of T1D cannot be attributed only to individual genetics, it is strongly inferred that there is a significant environmental contribution, such as infection, impacting disease development. The human enteroviruses (HEV) are common picornaviruses often implicated as triggers of human T1D, although precisely which of the numerous HEV may be involved in human T1D development is unknown. Experiments using non‐obese diabetic (NOD) mice, commonly used to model T1D, show that induction of T1D by HEV infection in NOD mice is a multifactorial process involving both the virus and the host. Interestingly, results demonstrate that HEV infection of NOD mice can also induce long‐term protection from T1D under certain conditions, suggesting that a similar mechanism may occur in humans. Based upon both experimental animal and observational human studies, we postulate that HEV have a dual role in T1D development and can either cause or prevent autoimmune disease. Whichever outcome occurs depends upon multiple variables in the host‐virus equation, many of which can be deduced from results obtained from NOD mouse studies. We propose that the background to the sharply rising T1D incidences observed in the 20th century correlates with increased levels of hygiene in human societies. Viewing T1D in this perspective suggests that potential preventative options could be developed. Copyright © 2009 John Wiley & Sons, Ltd.

Evaluation of poliovirus antibody titers in orally vaccinated semi-captive chimpanzees in Uganda

BACKGROUND

To understand immunological responses in chimpanzees vaccinated with live-attenuated vaccine (oral polio vaccine; OPV), serum neutralizing antibodies against poliovirus types 1, 2, and 3 were investigated over time.

METHODS

The neutralizing antibody titers against poliovirus types 1, 2, and 3 were determined by microneutralization test using 100 ID(50) of poliovirus types 1, 2, and 3 (Sabin strains).

RESULTS

Neutralizing antibodies against poliovirus types 1, 2, and 3 were detected in 85.7%, 71.4%, and 65% of the serum from 42 chimpanzees tested 9 years post-vaccination. The neutralizing antibody titers in chimpanzees were similar to the documented levels in human studies as an indicator of vaccine efficacy.

CONCLUSIONS

This study reveals persistence of neutralizing antibodies in chimpanzees for at least 9 years after vaccination with OPV. This first study in chimpanzees provides useful information for the evaluation of the success of vaccination with OPV in other captive apes.

A systematic approach to virus-virus interactions

A virus–virus interaction is a measurable difference in the course of infection of one virus as a result of a concurrent or prior infection by a different species or strain of virus. Many such interactions have been discovered by chance, yet they have rarely been studied systematically. Increasing evidence suggests that virus–virus interactions are common and may be critical to understanding viral pathogenesis in natural hosts. In this review we propose a system for classifying virus–virus interactions by organizing them into three main categories: (1) direct interactions of viral genes or gene products, (2) indirect interactions that result from alterations in the host environment, and (3) immunological interactions. We have so far identified 15 subtypes of interaction and assigned each to one of these categories. It is anticipated that this framework will provide for a more systematic approach to investigating virus–virus interactions, both at the cellular and organismal levels.

Childhood mortality after oral polio immunisation campaign in Guinea-Bissau

Though previous studies have suggested a non-specific beneficial effect of oral polio vaccine (OPV), there has been no evaluation of the mortality impact of national polio immunization days. On the other hand, studies examining the effect of OPV and diphtheria-tetanus-pertussis (DTP) vaccines, which are usually administered together in routine immunisation programmes in low-income countries, have found no beneficial or even a negative effect on infant survival. In 1998, we used the opportunity of two national immunisation days to examine the impact of OPV administered alone on survival for the 6103 children less than 5 years of age in the Bandim Health Project's study area in Guinea-Bissau. Survival was ascertained through regular surveillance from March 1998 until the beginning of the war on June 7, 1998, the end of 1998, or the end of 1999, respectively. The child register was linked with a register for the only paediatric ward in Bissau to determine the risk of hospitalisations. Among children under 5 years of age, 82% had received 1 or 2 doses of polio vaccines during the campaign. Though polio vaccination during the campaign was associated with slightly lower mortality, this difference was not significant for all children under 5 years of age (mortality ratio (MR)=0.46 (0.18-1.15)). However, oral polio vaccination was associated with a beneficial effect for children under 6 months of age at the time of the campaign, the mortality ratio being 0.09 (95% CI 0.01-0.85) in the 3 months before the war controlling for significant background factors, including routine immunizations, antenatal consultations, and arm circumference. The polio-vaccinated children aged 0-5 months had fewer hospitalisations than children who had not been polio vaccinated (RR=0.27 (0.10-0.76)). With longer follow-up to December 1998 or December 1999, the difference in mortality gradually disappeared, the MR for polio-vaccinated children being 0.61 (0.32-1.14) and 0.83 (0.51-1.34), respectively. Among children aged 6-59 months of age, measles vaccine was associated with a 56% reduction in mortality (MR=0.44 (0.28-0.69)) and no effect of oral polio vaccine was measurable in this age group. The effect of polio vaccine among children less than 6 months of age could be due to selection bias but might also represent a non-specific beneficial immune stimulation and there is nothing to suggest that OPV might have a negative effect on infant survival. Studies of the possible non-specific effects of oral polio vaccine are warranted before OPV is withdrawn.

Effect of dietary ribonucleotides on infant immune status. Part 2: Immune cell development

The objective of this study was to determine whether dietary ribonucleotides alter immune cell phenotypes or function in the first year of life. Newborn term infants in a double-blind, 12-mo, multicenter trial were randomized to cow milk formula groups with (FN, n = 138) or without (F, n = 147) 72 mg/L supplemental ribonucleotides. A nonrandomized HMF cohort (n = 192) was concurrently enrolled. Eighty-eight immune blood cell types were characterized by flow cytometry. Data were analyzed by multivariate ANOVA (MANOVA), ANOVA, and repeated measures analysis (RMA), with adjustments made for multiple comparisons. Ribonucleotide feeding changed subpopulations of T and natural killer (NK) cells. FN had higher numbers and percentages of memory/effector (M/E) cytotoxic/suppressor (CD45R0(+)CD8(+), RMA) T, Fas(+) M/E (CD45R0(+)CD95(+)CD3(+), 6 mo) T, and CD56(+)CD16(-) NK cells (CD56(+)CD16(-)CD3(-)CD8(-), 12 mo), and higher percentages of M/E helper (CD45R0(+)CD4(+), RMA) T, Tc1 (IFN gamma(+)CD4(-)CD3(+), RMA), total interferon (IFN)gamma T (IFN gamma(+)CD4(+/-)CD3(+), RMA), Th2 (IL-4(+)CD4(+)CD3(+), 7 mo), and CD57(+) NK-T cells (CD57(+)CD56(-)CD3(+), 6 mo, 7 mo) compared with F. Percentages of naive helper T (CD45RA(+)CD4(+), 12 mo) and numbers and percentages of CD56(+) NK-T cells (CD56(+)CD16(-)CD3(+)CD8(-), 2 mo, 6 mo) were lower in FN than F. Percentages of M/E cytotoxic/suppressor, Th2, and CD56(+)CD16(-) NK cells in FN were significantly higher than F but were not different from HMF, whereas F was significantly lower than HMF. Ribonucleotide supplementation of infant formula supported increased T-cell maturation and affected immunoregulatory NK cell subsets. These FN-associated immune cell profiles either did not differ from those infants fed HMF or tended to be more like those fed HMF than those fed F.

Oral polio vaccination and low case fatality at the paediatric ward in Bissau, Guinea-Bissau

Oral polio vaccine (OPV) and diphtheria-tetanus-pertussis (DTP) vaccines are given simultaneously in routine immunisation programmes in developing countries. It is therefore difficult to determine the separate effects of these vaccines on survival. We used the shortage of DTP vaccine in Bissau to examine the impact of OPV on the case fatality at the paediatric ward in Bissau. For 719 children less than 5 years of age whose vaccination card had been seen at admission and who had not yet received measles vaccine, having received OPV only was associated with a case fatality of 6% compared with 15% for children having received combined DTP and OPV vaccinations, the case fatality ratio (CFR) being 0.29 (95% confidence interval (CI) 0.11-0.77). Even if children fleeing the hospital were assumed to have died shortly after leaving the hospital, the case fatality would still be lower for children having received OPV only (CFR = 0.41; (95% CI 0.20-0.81)). The tendency was similar for children hospitalised with pneumonia, diarrhoea, and presumptive malaria. Control for background factors had no impact on the estimate. In areas with high mortality, OPV administered alone may have non-specific beneficial effects or DTP may have a negative effect for children who had received both DTP and OPV.

Diagnostic potential of parechovirus capsid proteins

To study humoral and cellular immunity against human parechovirus type 1 (HPEV1), the viral capsid proteins VP0, VP1, and VP3 were expressed and purified as glutathione S-transferase (GST)-tagged recombinant proteins. The fusion proteins were used to raise antisera in rabbits. VP0 and VP1 antisera specifically detected HPEV1-infected cells in culture by immunoperoxidase staining and immunofluorescence. Furthermore, antisera against the VP0 and VP1 proteins had neutralizing effects against HPEV1 infection. When the HPEV1 antibody titers of 20 adults and 55 children were determined by a microneutralization test, the prevalence of HPEV1 antibodies in the adult population was 96%, while 50% of children were seropositive. Selected sera were used to evaluate HPEV1 fusion proteins as antigens in an enzyme immunoassay. The VP3 capsid protein appeared to be suitable for the purpose, with specificity of 100% and sensitivity of 96% compared to the neutralization test. Furthermore, T-cell responses to the purified HPEV1 and HPEV1 capsid fusion proteins were studied in 20 adults. Sixty percent of the subjects had T-cell proliferation responses to purified HPEV1, and 90% of the subjects also had positive T-cell responses to at least one of the GST capsid proteins.

Induction of interferon-gamma and IL-4 production by mitogen and specific antigens in peripheral blood lymphocytes of Type 1 diabetes patients

A functional imbalance in cytokine production resulting in dominance of Th1 over Th2 type response has been suggested to play a critical role in the pathogenesis of type 1 diabetes. In this study the cellular responses to pokeweed mitogen and a panel of specific antigens were analysed by measuring the production of IFN-gamma and IL-4 cytokines at the levels of mRNA expression (expression index=antigen/medium) and protein secretion in culture supernatants. Two enterovirus preparates were included due to the suggested significance of these viruses in the aetiology of type 1 diabetes. The study included 22 children with newly-diagnosed type 1 diabetes, 15 children with longer duration of disease and 20 healthy children. Comparisons were made between age- and sex-matched groups. Newly diagnosed diabetic patients had significantly higher IFN-gamma mRNA expression index (p<0.02) but also higher IL-4 mRNA expression index (p<0.05) in tetanus toxoid stimulated peripheral blood mononuclear cells compared to healthy controls. Also the diabetic patients studied 3-72 months after the diagnosis of type 1 diabetes showed a tendency to higher IFN-gamma mRNA expression index compared to controls (0.05<p<0.1). Enhanced mitogen-stimulated IFN-gamma mRNA expression index was observed in children with newly-diagnosed type 1 diabetes when compared to subjects with longer duration of diabetes (p<0.05). No significant differences were observed in IFN-gamma produced into the culture supernatants. In conclusion, imbalance in both IFN-gamma and IL-4 mRNA levels was demonstrated between diabetic patients and healthy subjects.

Stimulation of the developing immune system can prevent autoimmunity

Both genetic and environmental factors contribute to the development of autoimmunity. Animals and humans exposed to natural infections have a reduced rate of autoimmune diseases. There is increasing evidence that immune stimulation prevents autoimmune diseases. Our hypothesis is that the process of the development of pathogenic cells involved in autoimmunity can be modulated by early stimulation of the immune system in autoimmunity prone individuals This allows for the upregulation of cytokines and growth factors that influence the generation of regulatory cells involved in autoimmunity. As we live in a 'cleaner environment' the decreasing chances of natural infection in the general population may contribute to the induction of autoimmunity because the developing immune system is not exposed to stimulation that may be necessary to generate regulatory cells involved in the modulation and prevention of autoimmunity. Immunization with certain vaccines may provide an alternative approach to stimulate the immune system to modulate or prevent the generation of pathogenic cells involved in autoimmunity by induction of regulatory cells.