Multivalent HA DNA Vaccination Protects against Highly Pathogenic H5N1 Avian Influenza Infection in Chickens and Mice

Sustained outbreaks of highly pathogenic avian influenza (HPAI) H5N1 in avian species increase the risk of reassortment and adaptation to humans. The ability to contain its spread in chickens would reduce this threat and help maintain the capacity for egg-based vaccine production. While vaccines offer the potential to control avian disease, a major concern of current vaccines is their potency and inability to protect against evolving avian influenza viruses.The ability of DNA vaccines encoding hemagglutinin (HA) proteins from different HPAI H5N1 serotypes was evaluated for its ability to elicit neutralizing antibodies and to protect against homologous and heterologous HPAI H5N1 strain challenge in mice and chickens after DNA immunization by needle and syringe or with a pressure injection device. These vaccines elicited antibodies that neutralized multiple strains of HPAI H5N1 when given in combinations containing up to 10 HAs. The response was dose-dependent, and breadth was determined by the choice of the influenza virus HA in the vaccine. Monovalent and trivalent HA vaccines were tested first in mice and conferred protection against lethal H5N1 A/Vietnam/1203/2004 challenge 68 weeks after vaccination. In chickens, protection was observed against heterologous strains of HPAI H5N1 after vaccination with a trivalent H5 serotype DNA vaccine with doses as low as 5 microg DNA given twice either by intramuscular needle injection or with a needle-free device.DNA vaccines offer a generic approach to influenza virus immunization applicable to multiple animal species. In addition, the ability to substitute plasmids encoding different strains enables rapid adaptation of the vaccine to newly evolving field isolates

Novel chimeric gene promoters responsive to hypoxia and ionizing radiation

Despite being an adverse prognostic factor in radiotherapy, hypoxia represents a physiological difference that can be exploited for selective cancer gene therapy. In this study gene therapy vectors responsive to both hypoxia and ionizing radiation (IR) were developed. Gene expression was regulated by novel, synthetic promoters containing hypoxia responsive elements (HREs) from the erythropoietin (Epo), the phosphoglycerate kinase 1 (PGK1) and the vascular endothelial growth factor (VEGF) genes, and IR-responsive CArG elements from the early growth response (Egr) 1 gene. All chimeric promoters could be activated by hypoxia and/or IR-treatment, and selectively control marker gene expression in human T24 bladder carcinoma and MCF-7 mammary carcinoma cells. Importantly, enhancers containing combinations of HREs and CArG elements were able to respond to both triggering treatments, with the Epo HRE/CArG combination proving to be the most responsive and robust. The Epo HRE/CArG enhancer could effectively control a suicide gene therapy strategy by selectively sensitizing hypoxic and/or irradiated cells expressing the enzyme horseradish peroxidase (HRP) to the prodrug indole-3-acetic acid (IAA). These data indicate that the use of such chimeric promoters may effectively regulate therapeutic gene expression within the tumor microenvironment in gene therapy strategies aimed at addressing the problem of hypoxia in radiotherapy