Safety and immunogenicity of an inactivated whole virus Vero cell-derived Ross River virus vaccine: a randomized trial

BACKGROUND

Ross River virus (RRV) is endemic in Australia and several South Pacific Islands. Approximately 5000 cases of RRV disease, which is characterized by debilitating polyarthritis, are recorded each year in Australia. This study describes the first clinical trial of a candidate RRV vaccine.

METHODS

An inactivated whole-virus Vero cell-derived RRV vaccine was tested in 382 healthy, RRV-naïve adults in a phase 1/2 dose-escalation study at ten sites in Austria, Belgium and The Netherlands. Subjects were equally randomized to receive 1.25 μg, 2.5 μg, 5 μg, or 10 μg aluminum hydroxide-adjuvanted or non-adjuvanted RRV vaccine, with a second dose after three weeks and a booster at six months. Vaccine immunogenicity was determined by measurements of serum IgG and neutralizing antibody titers. Vaccine tolerability and safety were monitored over the entire study period.

RESULTS

The optimal vaccine formulation was the adjuvanted 2.5 μg dose, as calculated using a repeated mixed model analysis of covariance comparing log-transformed RRV-specific IgG titers between different dose groups. Geometric means of RRV-specific serum antibodies measured 21 days after the third vaccination with the 2.5 μg adjuvanted formulation were 520.9 (90% CI 377.2-719.4) as determined by IgG ELISA and 119.9 (82.6-173.9) as determined by virus neutralization assay, resulting in seropositivity rates of 92.9% (82.6-98.0) and 92.7% (82.2-98.0), respectively. All vaccine formulations and doses were well tolerated after the first, second and third vaccination.

CONCLUSIONS

The adjuvanted, inactivated whole-virus Vero cell-derived Ross River virus vaccine is highly immunogenic in RRV-naïve adults and well tolerated at all dose levels.

Dilute acid hydrolysis of presscakes from silage and grass to recover hemicellulose-derived sugars

Grass and silage presscakes from various types of raw materials were hydrolyzed with dilute acid at moderate conditions to recover hemicellulose-derived sugars. Extracting the material with cold water prior to hydrolysis significantly increased the yield. The poor performance without extraction was due to the high buffer capacity of the material. The best results were obtained with extracted grass and silage from a permanent pasture and extracted clover/grass silage. The highest observed sugar yield was 16.43 g/100 g dry-matter, which represents approximately 25% of the available sugars and 60% of the hemicellulose fraction. Including the soluble sugar oligomers, the yields were even higher (up to 20 g/100 g dry-matter). A statistical experiment design with extracted clover/grass silage was performed to estimate the effects of temperature, time, and dry-matter concentration. Acid and dry-matter concentration had the highest effect on sugar yield, whereas temperature and acid concentration were mainly responsible for forming sugar degradation products. These findings agree with recent kinetic theories. Yields in this experiment were comparable to those of other lignocellulosic materials.

Effect of wood ash treatment on improving the fermentability of wood hydrolysate

Softwood hydrolysates were overlimed with wood ash to improve the fermentability of hydrolysates. It could be demonstrated in fermentation tests that wood ash treatment increases fermentability compared to the hydrolysates untreated and treated with alkaline compounds such as Ca(OH)(2), NaOH, and KOH, which are commonly used for overliming. The enhanced fermentability of the hydrolysate treated with wood ash is due to the reduction of the inhibitors of the fermentation such as furan and phenolic compounds and to nutrient effects of some inorganic components from the wood ash on the fermentation.

Thermophilic fermentation of hydrolysates: the effect of inhibitors on growth of thermophilic bacteria

Lignocellulosic biomass has great potential as a cheap feedstock in biological processes to produce biofuels or chemicals; however, dilute acid pretreatment at high temperatures produces undesirable compounds. Toxicity tests were done with inhibitors in standard media, to predict the growth-limiting effects on thermophilic strains. The 22 inhibitors included furfural, levulinic acid, acetic acid, and cinnamaldehyde. Neutralizing reagents and additional treatment steps have been tested.

Dilute-acid hydrolysis of sugarcane bagasse at varying conditions

Sugarcane bagasse, a byproduct of the cane sugar industry, is an abundant source of hemicellulose that could be hydrolyzed to yield a fermentation feedstock for the production of fuel ethanol and chemicals. The effects of sulfuric acid concentration, temperature, time, and dry matter concentration on hemicellulose hydrolysis were studied with a 20-L batch hydrolysis reactor using a statistical experimental design. Even at less severe conditions considerable amounts (>29%) of the hemicellulose fraction could be extracted. The percentage of soluble oligosaccharides becomes very low in experiments with high yields in monosaccharides, which indicates that the cellulose fraction is only slightly affected. For the sugar yields, acid concentration appears to be the most important parameter, while for the formation of sugar degradation products, temperature shows the highest impact. It could be demonstrated that the dry matter concentration in the reaction slurry has a negative effect on the xylose yield that can be compensated by higher concentrations of sulfuric acid owing to a positive interaction between acid concentration and dry matter contents.

Thermophilic production of lactic acid using integrated membrane bioreactor systems coupled with monopolar electrodialysis

The thermophilic Bacillus strain BS119 was selected for this study to demonstrate the long term performance of lactic acid production and simultaneous pre-purification. Integrated continuous cell recycle cultivation using ultra-filtration membrane bioreactor (MBR) systems was investigated. The permeate from the MBR was routed to an on-line electrodialysis (ED) to recover, pre-purify and concentrate lactate. The cultivation and ED was operated at 60 degrees C for more than 1,000 h at a pH of 6.5. At lower dilution rate (0.02 h(-1)), lactate concentration reached a maximum of 55 g l(-1) with clearly lower residual glucose levels. At 0.04 h(-1), lactate concentration was significantly lower at 35 g l(-1). Maximal volumetric productivities of 1.38 g l(-1) h(-1) were achieved. Under stable conditions, lactic acid yield on consumed glucose appeared stable at around 80%. It could be demonstrated that the addition of supplements like yeast extract and peptone severely influences product formation. Integration of mono-polar ED with the MBR systems yields lactate solutions with concentrations of up to 115 g l(-1). Because of the low substrate feed concentrations (less than 50 g l(-1)), lactate flux was rather poor, reaching a low maximum of 140 g m(-2) h(-1); nevertheless, stack energy consumption was positive with an average of 0.49 kWh kg(-1) lactate.

Thermophilic lactic acid production on hemicellulose hydrolysate

Lactic acid has many applications. It can be utilised as road-deicing agent, in the food industry or--after polymerisation--as a biodegradable plastic. The use of lignocellulose biomass will significantly increase the competitiveness of lactic acid-based polymers compared to conventional petroleum based plastics. The Institute for Agrobiotechnology in Tulln (IFA-Tulln) developed a process to apply renewable resources as cheap feedstock for production of lactic acid. The utilisation of thermophiles combined with a suitable pretreatment method enables a fermentation under non sterile conditions with detoxified hemicellulosic hydrolysates. This paper presents growth toxicity tests and batch experiments with bagasse hydrolysate, which were conducted to determine the fermentability of thermophilic wild type strains.