Report of a collaborative study to assess the suitability of a reference reagent for antibodies to hepatitis E virus.

Several commercial and "in-house" assays have been developed for the detection of antibodies to hepatitis E virus, a major causative agent of enterically transmitted non-A non-B hepatitis. As these kits contain a variety of synthetic peptides or recombinant proteins, greater standardisation is required. A collaborative study was therefore carried out to assess the suitability of a freeze dried preparation designated 95/584 to serve as a reference reagent for hepatitis E virus serum IgG. Preparation 95/584, which is a serum from a previously infected individual, was assayed along with four coded samples, one of which D, was a coded duplicate of 95/584, and three individual sera, coded A, B and C. These preparations were sent to seven laboratories in five countries who tested them in eight different enzyme immunoassays. In most laboratories the coded duplicate gave a mean potency of within 20% of the candidate reference reagent despite the wide range of assays used. However, the potencies of the coded samples which were from different individuals gave somewhat variable potencies relative to the candidate reference reagent. This is not surprising as each sample will have varying proportions of antibodies against individual viral proteins and result in the variation in results observed. Nevertheless, this material will be of use in the standardisation of diagnostic tests for use in sero-prevalence studies and for assessing immunity. Preparation 95/584 was found to be suitable to serve as a reference reagent for hepatitis E serum IgG and has been established as an interim Reference Reagent for Human anti-hepatitis E serum. Each ampoule contains 50 Units per ampoule.     

Collaborative study to assess the suitability of a candidate International Standard for yellow fever vaccine

Yellow fever vaccines are routinely assayed by plaque assay. However, the results of these assays are then converted into mouse LD(50) using correlations/conversion factors which, in many cases, were established many years ago. The minimum required potency in WHO Recommendations is 10(3) LD(50)/dose. Thirteen participants from 8 countries participated in a collaborative study whose aim was to assess the suitability of two candidate preparations to serve as an International Standard for yellow fever vaccine. In addition, the study investigated the relationship between the mouse LD(50) test and plaque forming units with a view to updating the WHO recommendations. Plaque assays were more reproducible than mouse assays, as expected. Differences in sensitivities of plaque assays were observed between laboratories but these differences appear to be consistent within a laboratory for all samples and the expression of potency relative to the candidate standard vaccine improved the reproducibility of assays between laboratories. However, the use of potencies had little effect on the between laboratory variability in mouse LD(50) assays. There appears to be a consistent relationship between overall mean LD(50) and plaques titre for all study preparations other than sample E. The slope of the correlation curve is >1 and it would appear that 10(3) LD(50) is approximately equivalent to 10(4) plaque forming units (PFU), based on the overall means of all laboratory results. The First International Standard for yellow fever vaccine, NIBSC Code 99/616, has been established as the First International Standard for yellow fever vaccine by the Expert Committee of Biological Standards of the World Health Organisation. The International Standard has been arbitrarily assigned a potency of 10(4.5) International Units (IU) per ampoule. Manufacturers and National Control Laboratories are including the First International Standard for yellow fever vaccine in routine assays so that the minimum potency in IU of vaccines released for use and which meet the current minimum potency of 10(3) LD(50) in mouse assays, can be determined. These data will be analysed before a review of the WHO requirements, including the minimum potency per dose, is undertaken.     

Intercontinental differences in overweight of adopted Koreans in the United States and Europe

A greater proportion of the United States (US) population is overweight or obese (with BMI over 25 kg/m²) relative to all Western European populations, and it might be expected that migrants to either the US or Western Europe would develop patterns of overweight and obesity that reflect this difference. This paper examines the effects of obesogenic environments on Asians by reporting differences in rates of overweight (which is taken to include obesity in this analysis) among 261 adult South Koreans, which had been adopted in early-life into white middle class families living in the US and in Western European Nations. Data collected during an international adoption survey carried out for the Korean government in 2008 were analyzed. The prevalence of overweight of adopted Koreans raised in the US significantly exceeds the level among adopted Koreans in Europe by 11.3%. These intercontinental differences are statistically significant after controlling for sex, current age, age of adoption, and education. This paper supports the view that life-style factors are more detrimental for the weight status of people in the US than in Western Europe.     

A collaborative study to assess the proficiency of laboratory estimates of potency of live measles vaccines.

A collaborative study was undertaken to assess the variability in estimates of the potency of measles vaccines. Overall a median variation of 2.0 log10 between estimates was observed. This was reduced to a median of 1.0 log10 when the potencies were expressed relative to a reference vaccine. A difference in the sensitivity between plaque assays and TCID50 assays was also reduced when relative potencies were used. The benefit of including a common reference preparation in vaccine assays was therefore demonstrated. For the vaccines assayed in this study, it was not necessary to use a measles reference of the same strain as the vaccines tested. We therefore recommend that measles vaccines be assayed against a single international reference preparation.     

A collaborative model for large‐scale riparian restoration in the western United States

In 2009, a group of practitioners took action to restore 175 miles of riparian habitat impaired by invasive plants along the Dolores River in southwestern Colorado and eastern Utah. Recognizing the magnitude of ecological, jurisdictional, and management challenges associated with this large‐scale initiative, this group of managers built trust and relationships with key partners to foster collaboration across boundaries and cultivate consensus of a variety of perspectives and forms of knowledge. What emerged was a network of individuals, organizations, and agencies dedicated to restoring the Dolores River riparian corridor while sharing information and learning from one another. This public–private collaboration, called the Dolores River Restoration Partnership (DRRP), has been successful in creating a process by which financial, technical, and human resources are shared across boundaries to restore a riparian corridor. Specifically, the DRRP developed effective planning documents, a responsive governance structure, monitoring protocols, and a shared mindset for extracting lessons learned that have been instrumental in making progress toward its shared restoration goals and addressing a wide variety of restoration challenges. The tools developed by the partnership and lessons learned from their utility are outlined in this case study as a means to inform other collaborative restoration efforts.     

Independent emergence of Yersinia ruckeri biotype 2 in the United States and Europe

Biotype 2 (BT2) variants of the bacterium Yersinia ruckeri are an increasing disease problem in U.S. and European aquaculture and have been characterized as serovar 1 isolates that lack both peritrichous flagella and secreted phospholipase activity. The emergence of this biotype has been associated with an increased frequency of enteric redmouth disease (ERM) outbreaks in previously vaccinated salmonid fish. In this study, four independent specific natural mutations that cause the loss of both motility and secreted lipase activity were identified in BT2 strains from the United States, United Kingdom, and mainland Europe. Each of these was a unique mutation in either fliR, flhA, or flhB, all of which are genes predicted to encode essential components of the flagellar secretion apparatus. Our results demonstrate the existence of independent mutations leading to the BT2 phenotype; thus, this phenotype has emerged separately at least four times. In addition, BT2 strains from the United Kingdom were shown to have the same mutant allele found in U.S. BT2 strains, suggesting a common origin of this BT2 lineage. This differentiation of distinct BT2 lineages is of critical importance for the development and validation of alternative vaccines or other treatment strategies intended for the control of BT2 strains.     

Larval parasites ofOulema melanopus in Europe and their colonization in the United States

The cereal leaf beetle,Oulema melanopus (L.), of minor economic importance in Europe, was found in Michigan, USA, in 1959, and has caused increasing damage to small grains. Studies in Europe prompted the introduction into the United States, of 3 hymenopterous parasites of the larval stage:Tetrastichus julis (Walker),Diaparsis carinifer (Thomson), andLemophagus curtus Townes, as a multiplespecies biological control attempt. From 1964 to 1970, field collections in 10 European countries showed that parasitism averaged 12.3% byD. carinifer, 10.4% byT. julis, and 5.6% byL. curtus. Parasites are discussed with respect to life-history, distribution, constancy, hostrange, synchrony with host, and effects of encapsulation by the host larva. Techniques are described for parasite collection, rearing, shipment, overwintering in quarantine, field release, and recovery. Adult parasite releases in the USA (1964–1971) totaled 43,054D. carinifer, 31,123T. julis, and 3,109L. curtus. BothD. carinifer andT. julis are known to be established at several sites in Michigan, andT. julis is also established in Ohio.Lemophagus curtus was recovered in Michigan in 1972.