Novel Vaccines to Human Rabies

Rabies, the most fatal of all infectious diseases, remains a major public health problem in developing countries, claiming the lives of an estimated 55,000 people each year. Most fatal rabies cases, with more than half of them in children, result from dog bites and occur among low-income families in Southeast Asia and Africa. Safe and efficacious vaccines are available to prevent rabies. However, they have to be given repeatedly, three times for pre-exposure vaccination and four to five times for post-exposure prophylaxis (PEP). In cases of severe exposure, a regimen of vaccine combined with a rabies immunoglobulin (RIG) preparation is required. The high incidence of fatal rabies is linked to a lack of knowledge on the appropriate treatment of bite wounds, lack of access to costly PEP, and failure to follow up with repeat immunizations. New, more immunogenic but less costly rabies virus vaccines are needed to reduce the toll of rabies on human lives. A preventative vaccine used for the immunization of children, especially those in high incidence countries, would be expected to lower fatality rates. Such a vaccine would have to be inexpensive, safe, and provide sustained protection, preferably after a single dose. Novel regimens are also needed for PEP to reduce the need for the already scarce and costly RIG and to reduce the number of vaccine doses to one or two. In this review, the pipeline of new rabies vaccines that are in pre-clinical testing is provided and an opinion on those that might be best suited as potential replacements for the currently used vaccines is offered

Electric pulses used in electrochemotherapy and electrogene therapy do not significantly change the expression profile of genes involved in the development of cancer in malignant melanoma cells

<p>Abstract</p> <p>Background</p> <p>Electroporation is a versatile method for <it>in vitro </it>or <it>in vivo </it>delivery of different molecules into cells. However, no study so far has analysed the effects of electric pulses used in electrochemotherapy (ECT pulses) or electric pulses used in electrogene therapy (EGT pulses) on malignant cells. We studied the effect of ECT and EGT pulses on human malignant melanoma cells <it>in vitro </it>in order to understand and predict the possible effect of electric pulses on gene expression and their possible effect on cell behaviour.</p> <p>Methods</p> <p>We used microarrays with 2698 different oligonucleotides to obtain the expression profile of genes involved in apoptosis and cancer development in a malignant melanoma cell line (SK-MEL28) exposed to ECT pulses and EGT pulses.</p> <p>Results</p> <p>Cells exposed to ECT pulses showed a 68.8% average survival rate, while cells exposed to EGT pulses showed a 31.4% average survival rate. Only seven common genes were found differentially expressed in cells 16 h after exposure to ECT and EGT pulses. We found that ECT and EGT pulses induce an HSP70 stress response mechanism, repress histone protein H4, a major protein involved in chromatin assembly, and down-regulate components involved in protein synthesis.</p> <p>Conclusion</p> <p>Our results show that electroporation does not significantly change the expression profile of major tumour suppressor genes or oncogenes of the cell cycle. Moreover, electroporation also does not changes the expression of genes involved in the stability of DNA, supporting current evidence that electroporation is a safe method that does not promote tumorigenesis. However, in spite of being considered an isothermal method, it does to some extent induce stress, which resulted in the expression of the environmental stress response mechanism, HSP70.</p

Muscle gene electrotransfer is increased by the antioxidant tempol in mice

Electropermeabilization (EP) is an effective method of gene transfer into different tissues. During EP, reactive oxygen species (ROS) are formed, which could affect transfection efficiency. The role of generated ROS and the role of antioxidants in electrotransfer in myoblasts in vitro and in Musculus tibialis cranialis in mice were, therefore, investigated. We demonstrate in the study that during EP of C2C12 myoblasts, ROS are generated on the surface of the cells, which do not induce long-term genomic DNA damage. Plasmid DNA for transfection (pEGFP-N1), which is present outside the cells during EP, neutralizes the generated ROS. The ROS generation is proportional to the amplitude of the electric pulses and can be scavenged by antioxidants, such as vitamin C or tempol. When antioxidants were used during gene electrotransfer, the transfection efficiency of C2C12 myoblasts was statistically significantly increased 1.6-fold with tempol. Also in vivo, the transfection efficiency of M. tibialis cranialis in mice was statistically significantly increased 1.4-fold by tempol. The study indicates that ROS are generated on cells during EP and can be scavenged by antioxidants. Specifically, tempol can be used to improve gene electrotransfer into the muscle and possibly also to other tissues

Enhanced Effect of DNA Immunization plus In Vivo Electroporation with a Combination of Hepatitis B Virus Core-PreS1 and S-PreS1 Plasmids ▿

To develop a novel, effective HBV therapeutic vaccine, we constructed two HBV DNA immunogens that contained PreS1, HBSS1, and HBCS1. Several delivery methods, such as intramuscular (i.m.) injection, intramuscular injection plus electroporation (i.m.-EP), and intradermal injection plus electroporation (i.d.-EP) were used in a murine model to analyze and compare the immune responses that were induced by the DNA immunogens. We found that i.d.-EP accelerated specific antibody seroconversion and produced high antibody (anti-PreS1, anti-S, and anti-C antibody) titers after HBSS1 and HBCS1 immunization. Combining the HBSS1 and HBCS1 DNA immunogens with i.d.-EP produced the strongest multiantigen (PreS1, S, and C)-specific cellular immune response and the highest specific PreS1 antibody levels. The results indicated that DNA immunization using HBSS1 and HBCS1 might be an ideal candidate, with its ability to elicit robust B and T cell immune responses against multiantigen when combined with optimized delivery technology. The present study provides a basis for the design and rational application of a novel HBV DNA vaccine