What is a Vaccine?
In the most simplified terms, a vaccine is a biological preparation that provides active acquired immunity against a certain disease. Usually a vaccine consists of a biological agent that represents the disease-causing microorganism. It is often made from a weakened or killed form of the microorganism, its toxins or one of its surface protein antigens. An individual that has been vaccinated produces antibodies against the protein antigen that protect him/her from contracting the disease upon attack from the pathogenic microorganism.
What are the approaches for Vaccine Development?
Scientists take many approaches to design vaccines against a pathogenic microorganism. These choices are dictated by the nature of pathogen and the infection as well as practical considerations about the use of the vaccine. Some of the options include live attenuated vaccines, inactivated vaccines, DNA vaccines and recombinant subunit vaccines. See schematic below for an overview of the various approaches used to make a vaccine. This technical note discusses the basics of research and production of recombinant vaccines.
Figure 1: Various approaches for Vaccine Development
What is a Recombinant Vaccine?
Vaccine generated using recombinant DNA technology is called recombinant vaccine. While there are various types of vaccines made possible by recombinant DNA technology, recombinant vaccines can be classified into two major categories.
- DNA vaccines
- Recombinant (protein subunit) vaccines
These vaccines usually consist of synthetic DNA containing the gene that encodes the disease-agent protein. Usually, the plasmid DNA used as vaccine is propagated in bacteria such as E. coli and they are isolated and purified for injection. This “naked” DNA is usually injected intramuscularly or intradermally. The principle behind a DNA vaccine is that the antigen can be expressed directly by host cells in a way that simulates viral infection and invokes an immune response from the host. This is similar to GenScript's
DNA Immunization Technology which is a powerful tool that aids in custom antibody production against membrane proteins, other problematic antigens, as well as for early DNA vaccine development studies. DNA immunization technique allows antigen production to occur in vivo, bypassing the need to produce and purify protein antigen in vitro. Click
here to learn more about how GenScript's DNA immunization service can help you succeed in your next DNA vaccine development project. Schematic below illustrates concept of DNA vaccine.
Figure 2: Principle of DNA vaccine.
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GenScript is a world leader in synthetic DNA technology and its rush gene synthesis service helped Novavax develop a vaccine candidate for avian influenza A/H7N9 in record time of 289 days, less than 6 weeks after initial reports of infections in April 2013. Click
here to learn more about how GenScript
gene synthesis services can accelerate your vaccine research.
Recombinant (protein subunit) Vaccines
These are subunit vaccines containing only a fraction of the pathogenic organism. Often time these are synthetic peptides that represent the protein component that induces an immune response. But they can also consist of protein subunits (antigens) expressed in a heterologous expression system (E. coli, yeast, insect etc.) using recombinant protein expression technologies. Most of the vaccines under investigation today are based on such purified recombinant proteins or subunits of antigens. One of the best examples of recombinant protein vaccine currently in use in humans is the vaccine against Hepatitis B Virus (HBV).
Figure 3: Recombinant Hepatitis B Vaccine Production Summary.
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GenScript Services for Recombinant Vaccine Research
E. coli expression is routinely used for the production of high quality recombinant protein used in vaccine research applications.
Baculovirus expression is also widely used given its applicability to a wide variety of proteins, their authentic modifications (resembling antigenic protein) and also for cost reasons. To see an overview of recombinant protein expression systems, click
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