Genetic Vaccines. Dr. Ziad Jaradat. INTRODUCTION.
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Dr. Ziad Jaradat
Killed vaccines: Vaccination with killed pathogen such as hepatitis A or antigens isolated from a pathogen such as parts of hepatitis B can not make their way into cells, they therefore give rise to primarily humoral responses and do not activate killer T cells.
Attenuated live vaccines: infiltrate cells. Even when non-living vaccines do prevent a disease, the protection often wears off after a time, consequently, recipients may need periodic booster shots.
1- Stansey and Parchkis (1955) and Ito et al (1957) performed DNA transfer experiments and were able to induce tumor and antibody formation.
To activate the cytotoxic T cells the following steps occur: complexes and “ a co-stimulatory molecule” found only on APCs.
Successful DNA vaccination has been demonstrated via a number of different routes including:
with the majority of DNA vaccines so far being administered through skin or muscle.
muscles rout of administration supports efficient transfection.
IL-2 : with the gene to enhance the immune response to genetic immunization. a potent stimulator of cellular immunity that induces proliferation and differentiation of T cells as well as B cell and NK cell growth.
Watanable et al...... reported a five fold increase in antibody response when IL-2 plasmid was co- injected with the plasmid encoding the antigen.
induces differentiation of T-helper cells into Th2 subtype, enhances B cell growth, and mediates Ig class switching. It was reported that injection of a plasmid encoding IL-4 3 days before immunization with a protein antigen increased Ag specific antibody levels compared to protein immunization alone.
However, studies showed that IL-4 inhibits Th1 mediated responses, thus put limitation on using it as adjuvant in viral or tumor vaccines or immunotherapy.
This cytokine increases production of granulocytes and macrophages and induces maturation and activation of APCs such as dendritic cells.
Thank you reversion to pathogenic state while replicating inside the host, DNA vaccines are safe and do not encode for genes that cause diseases