Development and characterization of a hemolysis inhibition assay to determine functionality of anti-Streptolysin O antibodies in human sera.

The high burden of disease and the long-lasting sequelae following Streptococcus pyogenes (Strep A) infections make the development of an effective vaccine a global health priority. Streptolysin O (SLO), is a key toxin in the complex pathogenesis of Strep A infection. Antibodies are elicited against SLO after natural exposure and represent a key target for vaccine-induced immunity. Here we present the setup and characterization of a hemolysis assay to measure functionality of anti-SLO antibodies in human sera. Assay specificity, precision, linearity, reproducibility, and repeatability were determined. The assay was demonstrated to be highly sensitive, specific, reproducible, linear and performed well in assessing functionality of anti-SLO antibodies induced by exposed individuals. Moreover, different sources of critical reagents, in particular red- blood cells, have been compared and had minimal impact on assay performance. The assay presented here has throughput suitable for evaluating sera in vaccine clinical trials and sero-epidemiological studies to gain further insights into the functionality of infection- and vaccine-induced antibodies.

Prospective study of the burden of rotavirus gastroenteritis in Danish children and their families.

This was the first study to characterize the total burden of rotavirus gastroenteritis (RVGE) at both hospital and general physician (GP) clinics in Denmark, and also the first to confirm rotavirus (RV) as the leading cause of acute gastroenteritis (GE) among children <5 years in GP clinics nationwide. Several aspects of RVGE were reported, including the impact of RVGE on family life by changes in HRQoL and by the number of days absent from day care. RV was detected in 225 (63.6%) children, and the median number of days absent from day care was 5 days. In 43.0% of the families, at least one family member, a total of 170 individuals, experienced symptoms of acute GE. Reduced health-related quality of life was observed both among children and parents. Our data suggested that RVGE indirectly as well as directly is a major public health burden in Denmark and comparable with data from other European countries.

G2P[4] the most prevalent rotavirus genotype in 2007 winter season in an European non-vaccinated population.

BACKGROUND: Recently, a high prevalence of G2P[4] rotavirus (RV) infection was reported from Brazil, and linked with the universal RV vaccination programme that used the G1P[8] live oral RV vaccine. OBJECTIVE: To determine the genotypes of RV co-circulating in a non-vaccinated population, in northern Portugal in the winter season of 2007. STUDY DESIGN: Prospective multicenter study of the genotypes circulating in the northwest region of Portugal during January to March 2007. Children with acute gastroenteritis, who attended the Pediatric Emergency Services of five Hospitals, were included in the study. The parents of the children completed a clinical and epidemiological data questionnaire and stool samples were collected. Stool samples positive in a RV enzyme immunoassay (EIA) were genotyped by reverse transcriptase-polymerase chain reaction. RESULTS: Stool samples were collected from 424 children. Two hundred and thirty-four (55.2%) stool samples were RV-positive. G2P[4] was the predominant RV type (68.6%), followed by G9P[8] (14.0%). CONCLUSIONS: Because our population was naïve for RV vaccine, the G2P[4] predominance cannot be explained by vaccination. Rather, this high prevalence of G2P[4] may be within the normal fluctuation of RV genotypes. RV strain surveillance programmes are important for informing RV vaccination programmes.

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.

Increase in viral gastroenteritis outbreaks in Europe and epidemic spread of new norovirus variant.

BACKGROUND: Highly publicised outbreaks of norovirus gastroenteritis in hospitals in the UK and Ireland and cruise ships in the USA sparked speculation about whether this reported activity was unusual. METHODS: We analysed data collected through a collaborative research and surveillance network of viral gastroenteritis in ten European countries (England and Wales were analysed as one region). We compiled data on total number of outbreaks by month, and compared genetic sequences from the isolated viruses. Data were compared with historic data from a systematic retrospective review of surveillance systems and with a central database of viral sequences. FINDINGS: Three regions (England and Wales, Germany, and the Netherlands) had sustained epidemiological and viral characterisation data from 1995 to 2002. In all three, we noted a striking increase in norovirus outbreaks in 2002 that coincided with the detection and emergence of a new predominant norovirus variant of genogroup II4, which had a consistent mutation in the polymerase gene. Eight of nine regions had an annual peak in 2002 and the new genogroup II4 variant was detected in nine countries. Also, the detection of the new variant preceded an atypical spring and summer peak of outbreaks in three countries. INTERPRETATION: Our data from ten European countries show a striking increase and unusual seasonal pattern of norovirus gastroenteritis in 2002 that occurred concurrently with the emergence of a novel genetic variant. In addition to showing the added value of an international network for viral gastroenteritis outbreaks, these observations raise questions about the biological properties of the variant and the mechanisms for its rapid dissemination.