Mini-HA Is Superior to Full Length Hemagglutinin Immunization in Inducing Stem-Specific Antibodies and Protection Against Group 1 Influenza Virus Challenges in Mice.

Seasonal influenza vaccines are updated almost annually to match the antigenic drift in influenza hemagglutinin (HA) surface glycoprotein. A new HA stem-based antigen, the so-called "mini-HA," was recently shown to induce cross-protective antibodies. However, cross-reactive antibodies targeting the HA stem can also be found in mice and humans after administration of seasonal vaccine. This has raised the question whether in similar conditions such a mini-HA would be able to show an increased breadth of protection over immunization with full length (FL) HA. We show in mice that in a direct comparison to H1 FL HA, using the same immunization regimen, dosing and adjuvant, a group 1 mini-HA has a higher protective efficacy against group 1 influenza virus challenges not homologous to the H1 FL HA. Although both antigens induce a similar breadth of HA subtype binding, mini-HA immunization induces significantly more HA stem-specific antibodies correlating with survival. In addition, both mini-HA and H1 FL HA immunization induce influenza neutralizing antibodies while mini-HA induces significantly higher levels of mFcγRIII activation, involved in Fc-mediated antibody effector functions. In agreement with previous findings, this confirms that more than one mechanism contributes to protection against influenza. Together our results further warrant the development of a universal influenza vaccine based on the HA stem region.

Continuously microscopically observed and process-controlled cell culture within the SlideReactor: proof of a new concept for cell characterization.

Certain cell types, especially primary human cells, favor a well-defined culture environment offering continuous supply of nutrients and oxygen and waste product removal. Several bioreactors based on special matrices or hollow fibers have been developed that provide such conditions. However, characterization of matrix re-organization or growth of tissue within these systems is possible only after culture termination. Evaluation of the influence of certain medium additives or culture conditions (e.g., temperature, oxygenation) on cell viability, expansion, and differentiation within these systems remains a challenging task. The SlideReactor, a miniaturized hollow fiber-based bioreactor, was developed to enable the observation of cells during culture. An operation concept offering predefined conditions for various cell types has been designed. For proof of concept, primary human cells (hepatocytes, fibroblasts, keratinocytes) and cell lines (HepG2, HuH7, C3A, WiDr, SkHep1) were cultured and observed. A series of experiments (n=40) showed the feasibility of the set-up; determination of process parameters and continuous observation is possible. The SlideReactor may serve as a simple and cost-efficient tool for cell characterization and optimization of cell-culture conditions.

The SlideReactor--a simple hollow fiber based bioreactor suitable for light microscopy.

Most bioartificial liver support systems are based on hollow fiber capillaries within modified dialysis cartridges or more sophisticated bioreactor constructions. Due to their design microscopic follow-up of reorganization and growth of tissue between the hollow fibers is not possible. The SlideReactor is a simple hollow fiber based bioreactor construction suitable for light microscopy and time-lapse video observation. The SlideReactor offers a cell compartment separated from a medium inflow and outflow compartment. Cell compartment access ports enable easy filling of the cell compartment with cell suspension, as well as fixation of the tissue. For more complex procedures or full access to all the cells, the bioreactor can be opened easily by cutting the silicone seal with a scalpel. Due to its simple design and the utilization of standard materials, it could serve as a suitable, cost-efficient tool to evaluate the behavior of cells cultured between hollow fiber capillaries. The paper describes the production process: similar to open source projects in software engineering, we would like to propose the concept as an open platform to anyone interested in hollow fiber based cell culture.

Characteristics and association with disease of two major subclones of Shiga toxin (Verocytotoxin)-producing strains of Escherichia coli (STEC) O157 that are present among isolates from patients in Germany.

Shiga toxin (Verocytotoxin) producing E. coli (STEC) O157 were isolated from 168 patients living in different parts of Germany. Most isolates were from sporadic cases and seven small outbreaks with STEC O157 were identified. The 168 strains were examined for phenotypic and genotypical traits in order to identify major types of STEC O157 occurring in Germany. Phage typing (PT) revealed PT8 (n = 54) and PT2 (n = 48) strains as most frequent (60.7%) among the isolates. Carriage of the stx(2) gene by STEC O157 was closely associated with hemolytic uremic syndrome (100%) and with bloody diarrhea (61.7%). The stx(2) gene was frequent in PT88, PT47 (both 100%), PT2 (91.5%) and PT4 (87.5%) strains and more rarely (33.3%) found in strains belonging to the other PTs. PT8 and PT2 strains formed two groups which differed from each other in their motility, stx-genotypes and the severity of the illness they caused. Pulsed-field gel electrophoresis of PT2 and PT8 strains and hybridization of XbaI digested DNA with stx(1) and stx(2) specific gene probes revealed similarities among epidemiologically unrelated strains belonging to the same PT. The results indicate that STEC O157 PT2 and PT8 strains form two distinct subclones which are dominating in Germany and other European countries.