Live Attenuated Chimeric Yellow Fever Dengue Type 2 (Chimeri Vax -DEN2) Vaccine: Phase 1 clinical trial for safety and immunogenicity

A randomized double-blind Phase I Trial was conducted to evaluate safety, tolerability, and immunogenicity of a yellow fever (YF)-dengue 2 (DEN2) chimera (ChimeriVax™-DEN2) in comparison to that of YF vaccine (YF-VAX®). Forty-two healthy YF naïve adults randomly received a single dose of either ChimeriVax™-DEN2 (high dose, 5 log plaque forming units [PFU] or low dose, 3 log PFU) or YF-VAXâ by the subcutaneous route (SC). To determine the effect of YF pre-immunity on the ChimeriVaxTM-DEN2 vaccine, 14 subjects previously vaccinated against YF received a high dose of ChimeriVax™-DEN2 as an open-label vaccine. Most adverse events were similar to YF-VAX® and of mild to moderate intensity, with no serious side-effects. One hundred percent and 92.3% of YF naïve subjects inoculated with 5.0 and 3.0 log10 PFU of ChimeriVaxTM-DEN2, respectively, seroconverted to wt DEN2 (strain 16681); 92% of subjects inoculated with YF-VAX® seroconverted to YF 17D virus but none of YF naïve subjects inoculated with ChimeriVax-DEN2 seroconverted to YF 17D virus. Low seroconversion rates to heterologous DEN serotypes 1, 3, and 4 were observed in YF naïve subjects inoculated with either ChimeriVax™-DEN2 or YF-VAX®. In contrast, 100% of YF immune subjects inoculated with ChimeriVax™-DEN2 seroconverted to all 4 DEN serotypes. Surprisingly, levels of neutralizing antibodies to DEN 1, 2, and 3 viruses in YF immune subjects persisted after 1 year. These data demonstrated that 1) the safety and immunogenicity profile of the ChimeriVax™-DEN2 vaccine is consistent with that of YF-VAX®, and 2) pre-immunity to YF virus does not interfere with ChimeriVaxTM-DEN2 immunization, but induces a long lasting and cross neutralizing antibody response to all 4 DEN serotypes. The latter observation can have practical implications toward development of a dengue vaccine.

Modelling broccoli development, yield and quality

Broccoli is a vegetable crop of increasing importance in Australia, particularly in south-east Queensland and farmers need to maintain a regular supply of good quality broccoli to meet the expanding market. A predictive model of ontogeny, incorporating climatic data including frost risk, would enable farmers to predict harvest maturity date and select appropriate cultivar – sowing date combinations. To develop procedures for predicting ontogeny, yield and quality, field studies using three cultivars, ‘Fiesta’, ‘Greenbelt’ and ‘Marathon’, were sown on eight dates from 11 March to 22 May 1997, and grown under natural and extended (16 h) photoperiods at the University of Queensland, Gatton Campus. Cultivar, rather than the environment, mainly determined head quality attributes of head shape and branching angle. Yield and quality were not influenced by photoperiod. A better understanding of genotype and environmental interactions will help farmers optimise yield and quality, by matching cultivars with time of sowing. The estimated base and optimum temperature for broccoli development were 0°C and 20 °C, respectively, and were consistent across cultivars, but thermal time requirements for phenological intervals were cultivar specific. Differences in thermal time requirement from floral initiation to harvest maturity between cultivars were small and of little importance, but differences in thermal time requirement from emergence to floral initiation were large. Sensitivity to photoperiod and solar radiation was low in the three cultivars used. This research has produced models to assist broccoli farmers in crop scheduling and cultivar selection in south-east Queensland.

A prospective randomized trial of long term azithromycin (AZM) versus placebo in cystic fibrosis (CF): Impact on clinical, laboratory and quality of life (QOL) outcomes

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