Ensilication Improves the Thermal Stability of the Tuberculosis Antigen Ag85b and an Sbi-Ag85b Vaccine Conjugate.

There is an urgent need for the development of vaccine thermostabilisation methodologies as the maintenance of a continuous and reliable cold chain remains a major hurdle to the global distribution of safe and effective vaccines. Ensilication, a method that encases proteins in a resistant silica cage has been shown to physically prevent the thermal denaturation of a number of model proteins. In this study we investigate the utility of this promising approach in improving the thermal stability of antigens and vaccine conjugates highly relevant to the development of candidate tuberculosis vaccines, including antigen 85b conjugated with the Staphylococcus aureus-protein based adjuvant Sbi. Here we analyse the sensitivity of these constructs to thermal denaturation and demonstrate for the first time the benefits of ensilication in conferring these vaccine-relevant proteins with protection against temperature-induced loss of structure and function without the need for refrigeration. Our results reveal the potential of ensilication in facilitating the storage and transport of vaccines at ambient temperatures in the future and therefore in delivering life-saving vaccines globally, and in particular to remote areas of developing countries where disease rates are often highest.

Recent trends in the prevalence and distribution of schistosomiasis in the Nile delta region.

In 1983, a survey of 71 villages in the Nile delta demonstrated that the overall prevalence of Schistosoma mansoni and S. haematobium infections was 39% and 5%, respectively. Recent increased availability of praziquantel, combined with Egyptian Ministry of Health-sponsored media efforts to educate the public about schistosomiasis, prompted us to determine the current status of S. mansoni and S. haematobium infections in the delta and evaluate any changes that may have occurred since the previous survey. The same villages that participated in the 1983 survey were resampled in 1990. Stool and urine samples were requested from all occupants over the age of two years in a 5% sample of houses within each village. Stool (Kato) thick smears and urine sediments were read qualitatively at the rural health station. Field-prepared Kato smears and a 20% sample of urine specimens were forwarded to the Ministry of Health Laboratory, where quantitative readings were also performed. Analysis of samples obtained from 17,310 persons revealed that S. mansoni prevalence had decreased to 23% and that S. haematobium prevalence had decreased to 3% (P < 0.001). The highest levels of schistosome infection were found in governates located in the eastern section of the delta. The observed changes in the prevalence of S. mansoni and S. haematobium suggest that control measures are having a favorable impact on schistosomiasis transmission in this region.