Rotavirus vaccines: an update

A study on the protective effects of CpG oligodeoxynucleotide-induced mucosal immunity against lung injury in a mouse acute respiratory distress syndrome model

This study aims to determine the feasibility of using oligodeoxynucleotides with unmethylated cytosine-guanine dinucleotide sequences (CpG ODN) as an immunity protection strategy for a mouse model of acute respiratory distress syndrome (ARDS). This is a prospective laboratory animal investigation. Twenty-week-old BALB/c mice in Animal research laboratory were randomized into groups. An ARDS model was induced in mice using lipopolysaccharides (LPSs). CpG ODN was intranasally and transrectally immunized before or after the 3rd and 7th days of establishing the ARDS model. Mice were euthanized on Day 7 after the second immunization. Then, retroorbital bleeding was carried out and the chest was rapidly opened to collect the trachea and tissues from both lungs for testing. CpG ODN significantly improved the pathologic impairment in mice lung, especially after the intranasal administration of 50 μg. This resulted in the least severe lung tissue injury. Furthermore, interleukin-6 (IL-6) and IL-8 concentrations were lower, which was second to mice treated with the rectal administration of 20 µg CpG ODN. In contrast, the nasal and rectal administration of CpG ODN in BALB/c mice before LPS immunization did not appear to exhibit any significant protective effects. The intranasal administration of CpG ODN may be a potential treatment approach to ARDS. More studies are needed to further determine the protective mechanism of CpG ODN.

Information technologies for vaccine research

Vaccinology is a combinatorial science which studies the diversity of pathogens and the human immune system, and formulations that can modulate immune responses and prevent or cure disease. Huge amounts of data are produced by genomics and proteomics projects and large-scale screening of pathogen-host and antigen-host interactions. Current developments in computational vaccinology mainly support the analysis of antigen processing and presentation and the characterization of targets of immune response. Future development will also include systemic models of vaccine responses. Immunomics, the large-scale screening of immune processes which includes powerful immunoinformatic tools, offers great promise for future translation of basic immunology research advances into successful vaccines.

Detection of rotavirus in children with acute gastroenteritis in Porto Velho, Rondonia, Brazil

Rotavirus group A (RVA) infection was ascertained in 591 fecal samples from children 0 to 6 years old with acute gastroenteritis. The vaccination status was also verified in all 591 subjects, with 302 (51.0 % ± 4.0 %) participants fully vaccinated against rotavirus. Forty-two of the vaccinated children (13.9 % ± 3.9 %) tested positive for RVA infection. Of the 289 unvaccinated children (49.0 % ± 4.0 %), 61 (21.1 % ± 4.7 %) had stools positive for RVA. This study suggests that the proportion of acute diarrhea cases caused by rotavirus was low and that the incidence of rotavirus diarrhea decreased over the study period in both vaccinated and unvaccinated children.

Advances in pediatric dehydration therapy

PURPOSE OF REVIEW

To review the advances in the assessment, treatment, and evaluation of care for pediatric dehydration.

RECENT FINDINGS

Recent studies have added new information across the spectrum of care for dehydration. Advances in the assessment of dehydration allow more accurate clinical evaluation, but do not help predict the treatment outcomes. Antiemetics as an adjunct to oral rehydration therapy have been proven well tolerated, efficacious, and cost-effective. Rapid, large-volume intravenous rehydration for outpatients with dehydration did not show any benefit over more standard regimens. Clinical guidelines incorporate all these aspects of care; however, physicians show poor adherence to the guidelines despite the evidence that guidelines improve outcomes and reduce cost.

SUMMARY

Dehydration burdens the healthcare system worldwide. Through advances in its assessment, treatment with antiemetics and intravenous fluids, and standardization of practice with clinical guidelines, this burden could be reduced.

Development and validation of a pictorial nausea rating scale for children

OBJECTIVE

The lack of a widely used, validated measure limits pediatric nausea management. The goal of this study was to create and validate a pictorial scale with regular incremental levels between scores depicting increasing nausea intensity.

METHODS

A pictorial nausea scale of 0 to 10 with 6 faces (the Baxter Retching Faces [BARF] scale) was developed in 3 stages. The BARF scale was validated in emergency department patients with vomiting and in healthy patients undergoing day surgery procedures. Patients were presented with visual analog scales for nausea and pain, the pictorial Faces Pain Scale-Revised, and the BARF scale. Patients receiving opioid analgesics or antiemetic agents had their pain and nausea assessed before and 30 minutes after therapy. Spearman's ρ correlation coefficients were calculated. A Wilcoxon matched-pair rank test compared pain and nausea scores before and after antiemetic therapy.

RESULTS

Thirty oncology patients and 15 nurses participated in the development of the scale, and 127 patients (52, emergency department; 75, day surgery) ages 7 to 18 years participated in the validation. The Spearman ρ correlation coefficient of the first paired BARF and visual analog scale for nausea scores was 0.93. Visual analog scales for nausea and BARF scores were significantly higher in patients requiring antiemetic agents (P = .0001) and decreased significantly after treatment (P = .0002), while posttreatment VAS (P = .20) and FPSR scores (P =.47) for patients receiving only antiemetic agents did not [corrected].

CONCLUSIONS

We describe the development of a pictorial scale with beginning evidence of construct validity for a self-report assessment of the severity of pediatric nausea. The scale had convergent and discriminant validity, along with an ability to detect change after treatment.

Newer insights into the mechanism of action of Psidium guajava L. leaves in infectious diarrhoea

BACKGROUND

Psidium guajava L., Myrtaceae, is used widely in traditional medicine for the treatment of diarrhoea, dysentery, gastroenteritis, stomachaches, and indigestion. However, the effect of the leaf extract of P. guajava on the pathogenesis of infectious diarrhoea has not been studied. The present study evaluates the effect of a hot aqueous extract (decoction) of dried leaves of P. guajava on parameters associated with pathogenicity of infectious diarrhoea. The aim was to understand its possible mechanism(s) of action in controlling infectious diarrhoea and compare it with quercetin, one of the most reported active constituents of P. guajava with antidiarrhoeal activity.

METHODS

The crude decoction and quercetin were studied for their antibacterial activity and effect on virulence features of common diarrhoeal pathogens viz. colonization of epithelial cells and production and action of enterotoxins. Colonization as measured by adherence of enteropathogenic Escherichia coli (EPEC) and invasion of enteroinvasive E. coli (EIEC) and Shigella flexneri was assessed using HEp-2 cell line. The production of E. coli heat labile toxin (LT) and cholera toxin (CT) and their binding to ganglioside monosialic acid (GM1) were studied by GM1-ELISA whereas the production and action of E. coli heat stable toxin (ST) was assessed by suckling mouse assay.

RESULTS

The decoction of P. guajava showed antibacterial activity towards S. flexneri and Vibrio cholerae. It decreased production of both LT and CT and their binding to GM1. However, it had no effect on production and action of ST. The decoction also inhibited the adherence of EPEC and invasion by both EIEC and S. flexneri to HEp-2 cells. Quercetin, on the other hand, had no antibacterial activity at the concentrations used nor did it affect any of the enterotoxins. Although it did not affect adherence of EPEC, it inhibited the invasion of both EIEC and S. flexneri to HEp-2 cells.

CONCLUSION

Collectively, the results indicate that the decoction of P. guajava leaves is an effective antidiarrhoeal agent and that the entire spectrum of its antidiarrhoeal activity is not due to quercetin alone.

Estimated research and development costs of rotavirus vaccines

Diseases like rotavirus afflict both upper- and lower-income countries, but most serious illnesses and deaths occur among the latter. It is a vital public health issue that vaccines for these types of global diseases can recover research and development (R&D) costs from high-priced markets quickly so that manufacturers can offer affordable prices to lower-income nations. Cost recovery depends on how high R&D costs are, and this study attempts to replace high, unverified estimates with lower, more verifiable estimates for two new vaccines, RotaTeq (Merck) and Rotarix (GlaxoSmithKline or GSK), based on detailed searches of public information and follow-up interviews with senior informants. We also offer a new perspective on "cost of capital" as a claim for recovery from public bodies. Our estimates suggest that companies can recover all fixed costs quickly from affluent markets and thus can offer these vaccines to lower-income countries at prices they can afford. Better vaccines are a shared project between companies and public health agencies; greater transparency and consistency in reporting of R&D costs is needed so that fair prices can be established.

Incidence and risk factors for community-acquired acute gastroenteritis in north-west Germany in 2004

In developed countries, acute gastroenteritis (AGE) is a major source of morbidity. However, only a few studies have estimated its incidence and the associated medical burden. This population-based study determined the incidence of community-acquired AGE patients seeking medical care and the relative role of various pathogens. Stool samples from patients with AGE presenting to a general practitioner (GP), pediatrician, or specialist in internal medicine for that reason were screened for various bacterial and viral enteropathogens. A control group was established as well. Incidences were calculated by the number of positive patients divided by the general population. The study was performed in north-west Germany in 2004. The incidence of AGE patients requiring medical consultation was 4,020/100,000 inhabitants. Children (<5 years of age) were at the highest risk (13,810/100,000 inhabitants). Of the patients, 6.6% were tested positive for an enteropathogenic bacteria and 17.7% for a viral agent. The predominant pathogens were norovirus (626/100,000) and rotavirus (270/100,000). Salmonella was the most frequently detected bacteria (162/100,000). The results presented confirm AGE and, specifically, AGE of viral origin as a major public health burden in developed countries.

Gastroenteritis by rotavirus in Spanish children. Analysis of the disease burden

Rotavirus is one of the most common causes of gastroenteritis worldwide. With the commercialisation of effective rotavirus vaccines in Europe in sight, it is necessary to provide studies which evaluate the disease burden. The aim of this study is two-fold, on one hand, to determine the burden of the rotavirus disease in Spanish children under the age of five, and on the other, to estimate the economic cost of these hospitalizations. The study was undertaken during a 5 year period (2000-2004). The rotavirus hospitalization rate was determined using the Minimum Basic Data Set of the national hospital discharge register. The observed data were compared with those expected by applying a model developed by the Centers for Disease Control and Prevention (CDC) adapted for European Countries. The financial expense of these hospitalizations was estimated. Of all admissions coded as gastroenteritis, 31.6% were due to rotavirus. The hospitalization rate by rotavirus was 480 cases per 100,000 children under five. These data are within the confidence range proposed by the adapted CDC model. The financial expense due to hospitalizations reaches 123,262 euros yearly in a Spanish University Hospital. In conclusion, rotavirus contributes significantly to the hospitalization of acute gastroenteritis. The rate of hospitalization by rotavirus is higher compared to other studies carried out in Spain. In view of future commercialisation of rotavirus vaccines, more in-depth analysis considering direct and indirect costs are necessary.

IFN-gamma is the only anti-rotavirus cytokine found after in vitro stimulation of memory CD4+ T cells from mice immunized with a chimeric VP6 protein

CD4+ T cells are the only lymphocytes required for protection of mice against rotavirus shedding after mucosal immunization with chimeric VP6 (MBP::VP6) and the adjuvant LT(R192G). One possible effector of protection is CD4+ T-cell cytokines. To determine if memory CD4+ T cells of immunized mice produce cytokines with direct anti-rotavirus activity, an in vitro infection model was developed using mouse CMT-93 cells and rhesus rotavirus (RRV). Spleen and lamina propria (LP) cells, as well as purified splenic CD4T cells obtained after intranasal immunization of BALB/c mice with MBP::VP6/LT(R192G) released large quantities of two cytokines (IL-17 and IFN-gamma) into cell supernatants when stimulated with MBP::VP6. Production of these same cytokines is rapidly upregulated in intestinal lymphocytes after rotavirus inoculation of immunized mice. IL-17 pretreatment of CMT-93 cells had no effect on subsequent RRV replication, but IFN-gamma was the most potent inhibitor within a panel of nine cytokines tested. Supernatants obtained after in vitro stimulation of splenic CD4+ T cells of immunized mice had high levels of anti-RRV activity and their pretreatment with mAb against IFN-gamma caused essentially complete loss of activity. Thus, IFN-gamma was the only cytokine identified in stimulated CD4+ T cells from immunized mice that directly inhibited rotavirus replication.

Epidemiology of rotavirus in Portugal: G9 as a major cause of diarrhoea in non-hospitalised children

BACKGROUND

Rotavirus is a major cause of gastroenteritis in children worldwide, but there is no data available on the incidence of rotavirus gastroenteritis or on the strains circulating in Portugal.

METHODS

We determined prospectively the incidence of rotavirus infection in non-hospitalised children and the genotypes circulating during one winter season in the central region of Portugal.

RESULTS

Rotavirus was found in 45% of the samples tested. The peak incidence was in February (54% positive) and March (60% positive). Genotyping was performed in 195 samples; unexpectedly, G9P[8] was present in 90% of the cases, a much higher percentage than previously reported in other countries.

CONCLUSIONS

These results contribute to the assessment of the burden of disease attributable to rotavirus in Portugal and facilitate preparation for intervention by vaccination. The predominance of G9 in Portugal is unlikely to be a local phenomenon, and may be observed elsewhere in Portugal and Europe. The epidemiology of rotaviruses in Portugal should be monitored in subsequent years.

Rotavirus immunoglobulin levels among Indian mothers of two socio-economic groups and occurrence of rotavirus infections among their infants up to six months

Rotavirus specific immunoglobulin levels were estimated and compared between mothers undergoing delivery from two socio-economic groups (n = 56 each) by direct/capture ELISA. IgG geometric mean titers (GMTs) of cord blood/mothers serum at delivery were significantly higher in the higher socio-economic group (HSG) as compared to the lower socio-economic group (LSG) (P < 0.01). Thirty-four mother-infant pairs (17 from each group) were followed-up up to 6 months for the occurrence of rotavirus infections. All follow-up LSG infants were low birth weight as against none from the HSG. Detection of virus by ELISA/RT-PCR and considering IgM/IgA seroconversion as an index of infection, 11 and 17 infants from HSG and LSG respectively had rotavirus infections. Two infants from LSG were hospitalized for severe rotavirus diarrhea but none from the HSG. Lower IgG levels in the LSG mother-infant pairs as compared to those of HSG, suggests a possible role of under nutrition in development of antibodies and immunity. Infants from the HSG who did not have rotavirus infections had significantly higher IgG GMTs in cord blood and serum samples at 6 months, than those HSG infants who had symptomatic/asymptomatic rotavirus infections (P < 0.05). In conclusion, fewer rotavirus infections occur when cord blood contains higher level of IgG antibodies, suggesting a role of protective immunity.

Association of gamma interferon and interleukin-17 production in intestinal CD4+ T cells with protection against rotavirus shedding in mice intranasally immunized with VP6 and the adjuvant LT(R192G)

Mucosal immunization of mice with chimeric, Escherichia coli-expressed VP6, the protein that comprises the intermediate capsid layer of the rotavirus particle, together with attenuated E. coli heat-labile toxin LT(R192G) as an adjuvant, reduces fecal shedding of rotavirus antigen by >95% after murine rotavirus challenge, and the only lymphocytes required for protection are CD4+ T cells. Because these cells produce cytokines with antiviral properties, the cytokines whose expression is upregulated in intestinal memory CD4+ T cells immediately after rotavirus challenge of VP6/LT(R192G)-immunized mice may be directly or indirectly responsible for the rapid suppression of rotavirus shedding. This study was designed to identify which cytokines are significantly upregulated in intestinal effector sites and secondary lymphoid tissues of intranasally immunized BALB/c mice after challenge with murine rotavirus strain EDIM. Initially, this was done by using microarray analysis to quantify mRNAs for 96 murine common cytokines. With this procedure, the synthesis of mRNAs for gamma interferon (IFN-gamma) and interleukin-17 (IL-17) was found to be temporarily upregulated in intestinal lymphoid cells of VP6/LT(R192G)-immunized mice at 12 h after rotavirus challenge. These cytokines were also produced in CD4+ T cells obtained from intestinal sites specific to VP6/LT(R192G)-immunized mice after in vitro exposure to VP6 as determined by intracellular cytokine staining and secretion of cytokines. Although genetically modified mice that lack receptors for either IFN-gamma or IL-17 remained protected after immunization, these results provide suggestive evidence that these cytokines may play direct or indirect roles in protection against rotavirus after mucosal immunization of mice with VP6/LT(R192G).

Infection is the major component of the disease burden in aboriginal and non-aboriginal Australian children: a population-based study

BACKGROUND

Infection accounts for the majority of pediatric mortality and morbidity in developing countries, but there are limited data on the infectious diseases burden in children from developed countries. We investigated reasons for hospitalization before age 2 years in a birth cohort of Western Australian Aboriginal and non-Aboriginal children.

METHODS

Data on live births between January 1990 and December 2000, and corresponding deaths and hospitalizations in the first 2 years of life, were obtained through linked population-based data.

RESULTS

Almost half the cohort of 270,068 children were hospitalized at least once. Aboriginal children had significantly higher admission rates (2196 vs. 779 per 1000 live births), stayed longer and were more likely to die in hospital than non-Aboriginal children. Infections (mainly respiratory and gastrointestinal) were the most common reason for hospitalization, accounting for 34% of all admissions, with higher rates in Aboriginal (1114 per 1000 live births) than non-Aboriginal children (242 per 1000) (P < 0.001). Over time, admission rates for infections declined in Aboriginal children but increased in non-Aboriginal children. Aboriginal children were admitted 14 times more often for pneumonia than non-Aboriginal children.

CONCLUSIONS

Infections are the leading cause of hospitalization in children under 2 years of age. The continuing heavy burden of serious infections, borne disproportionately by Aboriginal children, needs to be alleviated. Public health interventions such as the development and universal implementation of vaccines for respiratory syncytial virus, rotavirus and influenza are needed, while adequate funding must be committed to Indigenous health services and training.

Genotypic characterization of rotaviruses and prevalence of serotype-specific serum antibodies in children in Kuwait

There are no data on the serotypes of rotaviruses prevalent in Kuwait, which has a large expatriate population and hence a focal point for transmission of pathogens. The serotype information will contribute to the fund of knowledge on the world epidemiology of rotavirus serotypes and will predict the outcome of vaccination in Kuwait. Of the 75 rotavirus-positive samples from 172 children (aged <5 years) with severe diarrhoea, 69 were genotyped. The distribution of genotypes was G1 (63.8%) followed by G9 (10.2%), G2 (7.3%), G4 (7.3%) and G3 (4.4%). Among the P types, P[8] was the most common type found across all G types. By fluorescent focus neutralization test, serum antibodies to genotypes G1 (94%), G4 (68%) and G9 (46%) were found in 120 other children. These results show that G1 is the predominant serotype in Kuwait and that a vaccine that contains G1 will be most effective.

A case-control study to determine risk factors for hospitalization for rotavirus gastroenteritis in U.S. children

OBJECTIVE

The objective of this case-control study nested within a surveillance study conducted at 3 hospitals (Cincinnati Children's Hospital Medical Center, Cincinnati, OH; Children's Hospital of New Orleans, New Orleans, LA; and Hasbro Children's Hospital, Providence, RI) was to identify risk factors for rotavirus gastroenteritis requiring hospitalization.

PATIENTS

Cases were children < or =59 months of age who were admitted with acute gastroenteritis (AGE) and found to have rotavirus infection. Controls were selected from a birth certificate registry (Cincinnati and Providence) or a registry of patients from a large practice consortium in 11 locations (New Orleans).

RESULTS

Three hundred forty-nine rotavirus-infected cases and 1242 control subjects were enrolled. Breast feeding was protective against hospitalization for rotavirus AGE for infants <6 months of age. (odds ratio [OR], 5.1; 95% confidence interval [CI], 1.2-13.2). Low-birth-weight (<2500 g) infants had increased risk for hospitalization even beyond the first few months of life (OR, 2.8; 95% CI, 1.6-5.0). Children in child care were more likely to be hospitalized for rotavirus AGE than those cared for at home, particularly those > or =24 months of age (OR, 3.0; 95% CI, 1.8-5.3). Other characteristics associated with rotavirus AGE hospitalization were children <24 months of age covered by Medicaid or without insurance (OR, 2.1; 95% CI, 1.4-3.2) and having another child in the house <24 months of age (OR, 1.6; 95% CI, 1.1-2.3). The data suggest that maternal age <25 years (OR, 1.4; 95% CI, 1.0-2.0) and a mother with less than a high school education (OR, 1.5; 95% CI, 1.0-2.3) may also increase risk of rotavirus hospitalization.

CONCLUSION

There are socioeconomic and environmental factors and aspects of the child's medical and dietary history that identify children at risk for hospitalization with rotavirus AGE.

An age-structured epidemic model of rotavirus with vaccination

The recent approval of a rotavirus vaccine in Mexico motivates this study on the potential impact of the use of such a vaccine on rotavirus prevention and control. An age-structured model that describes the rotavirus transmission dynamics of infections is introduced. Conditions that guarantee the local and global stability analysis of the disease-free steady state distribution as well as the existence of an endemic steady state distribution are established. The impact of maternal antibodies on the implementation of vaccine is evaluated. Model results are used to identify optimal age-dependent vaccination strategies. A convergent numerical scheme for the model is introduced but not implemented. This paper is dedicated to Prof. K. P. Hadeler, who continues to push the frontier of knowledge in mathematical biology.

Protection against rotavirus shedding after intranasal immunization of mice with a chimeric VP6 protein does not require intestinal IgA

Intranasal immunization of mice with chimeric VP6 and the adjuvant LT(R192G) consistently elicits >95% reductions in fecal rotavirus shedding following challenge. To determine the association between mucosal antibody and protection, we immunized BALB/c wt and J chain knockout (Jch-/-) mice with VP6 and either LT(R192G) or cholera toxin (CT). Both strains developed nearly equal levels of serum rotavirus IgG, but Jch-/- mice, which cannot transport dimeric IgA across epithelial cell surfaces, developed >4-fold higher levels of serum rotavirus IgA. Stool rotavirus IgA was present in wt but undetectable in Jch-/- mice. When challenged with rotavirus strain EDIM, reductions in rotavirus shedding were nearly identical in VP6-immunized wt and Jch-/- mice (i.e., 97% and 92%, respectively; P > 0.01). Th1 CD4 T cell responses were also detected in VP6-immunized animals based on high levels of IFN-gamma and IL-2 found after in vitro VP6 stimulation of spleen cells. Therefore, protection induced by intranasal immunization of mice with VP6 and adjuvant does not depend on intestinal rotavirus IgA antibody but appears to be associated with CD4 T cells.