No abstract

Almost 500 million people worldwide suffer from Type I allergy, a genetically determined immunodisorder which is based on the production of IgE antibodies against per se harmless antigens (allergens). Due to their worldwide distribution and heavy pollen production, grasses represent a major allergen source for approximately 40% of allergic patients. We purified Phl p 4, a major timothy grass (Phleum pratense) pollen allergen with a molecular mass of 61.3 kDa and a pl of 9.6 to homogeneity. Circular dichroism spectroscopical analysis indicates that Phl p 4 contains a mixed alpha-helical/beta-pleated secondary structure and, unlike many other allergens, showed no reversible unfolding after thermal denaturation. We show that Phl p 4 is a major allergen which reacts with IgE antibodies of 75% of grass pollen allergic patients (n=150) and induces basophil histamine release as well as immediate type skin reactions in sensitized individuals. Phl p 4-specific IgE from three patients as well as two rabbit-anti Phl p 4 antisera cross-reacted with allergens present in pollen of trees, grasses, weeds as well as plant-derived food. Rabbit antibodies raised against Phl p 4 also inhibited the binding of allergic patients IgE to Phl p 4. Phl p 4 may thus be used for diagnosis and treatment of sensitized allergic patients.

The objective of this study was to present, for the first time, an overview of the existing Panton-Valentine leukocidin (PVL)-positive methicillin-resistant Staphylococcus aureus (MRSA) strains in Austria and to compare the situation with that found in other countries. Between 2001 and 2006 we analysed 1150 MRSA isolates - from infections as well as from colonisation - for the presence of PVL genes. The most common multilocus sequence types of the 94 PVL-positive MRSA strains were ST8, ST152, ST30, ST80, and ST5; the ST22, and ST777 sequences were also detected. During 2005 and 2006, 3.7-7.7% of the isolates were PVL-positive. The age distribution of the patients revealed that nosocomial MRSA mainly occurs in elderly people, whereas PVL-positive MRSA mainly appears in younger people. We observed a relatively high prevalence of PVL-positive isolates. Several MRSA clones containing the PVL genes are spreading throughout Austria, including two strains not yet widespread in Western Europe.

The aim of this study was to provide an overview of predominant and sporadic methicillin-resistant Staphylococcus aureus (MRSA) strains in large regions of Austria, and to compare the results with those from other European countries. In total, 1439 MRSA isolates, collected routinely between January 1996 and June 2006 from five Austrian federal provinces, were investigated. The isolates were confirmed as MRSA using mecA/femA multiplex PCR assays. Genes encoding Panton-Valentine leukocidin (PVL), which are characteristic of community-acquired MRSA, were also detected by PCR. Subtyping was performed using SmaI macrorestriction digestion of genomic DNA, followed by pulsed-field gel electrophoresis (PFGE) and cluster analysis. Isolates that could not be assigned to clusters were further analysed by spa typing and/or multilocus sequence typing. The predominant clones detected in Austria were ST228 (southern German epidemic clone), ST5 (Rhine-Hessen MRSA), the ST8 Austrian clone and CC8/ST8. Whereas the frequencies of lineages corresponding to ST247, ST45 and ST22 remained comparably low, an increase in the frequency of lineages corresponding to ST5 and to ST228 was recorded. Overall, 20 different MRSA types and 321 subtypes were recognised according to PFGE analysis. The prevalence of different strains varied considerably in the different Austrian regions. When compared to other European countries, the situation in Austria was most similar to that found in Germany.

The recognition of conformational epitopes on respiratory allergens by IgE Abs is a key event in allergic inflammation. We report a molecular strategy for the conversion of allergens into vaccines with reduced allergenic activity, which is based on the reassembly of non-IgE-reactive fragments in the form of mosaic proteins. This evolution process is exemplified for timothy grass pollen-derived Phl p 2, a major allergen for more than 200 million allergic patients. In a first step, the allergen was disrupted into peptide fragments lacking IgE reactivity. cDNAs coding for these peptides were reassembled in altered order and expressed as a recombinant mosaic molecule. The mosaic molecule had lost the three-dimensional structure, the IgE reactivity, and allergenic activity of the wild-type allergen, but it induced high levels of allergen-specific IgG Abs upon immunization. These IgG Abs crossreacted with group 2 allergens from other grass species and inhibited allergic patients’ IgE binding to the wild-type allergen. The mosaic strategy is a general strategy for the reduction of allergenic activity of protein allergens and can be used to convert harmful allergens into safe vaccines.