When compared with more-established methods, DNA vaccines have an altogether different approach.
Neither attenuated nor killed pathogens are involved, nor are pathogen subunits isolated. Instead, DNA
vaccines utilize the genetic material from the virus or bacteria to elicit an immune response. To create a
DNA vaccine, scientists first isolate a gene from the target pathogen. They then splice the viral gene into
a double-stranded DNA vector. This vector, also known as a bacterial plasmid, is a circular genetic
structure that can be replicated and purified in a laboratory. Once the plasmid is established, the vaccine
is ready to be injected. In some cases, plasmid is layered on the outside of gold beads or particles. It is
then shot directly into tissue through a “gene gun,” which uses high-pressure gas to insert particles into
living tissue.
Research indicates that scientists are also attempting to convert the DNA vaccine into a liquid form that
could be used as nasal spray. After the DNA vaccine is injected into the body, it accomplishes two goals:
creating a strong cellular response and building a potent humoral, or antibody, response. Once injected,
DNA vaccinations prompt helper T cells and B cells to multiply and produce memory cells, as well as
activate cytotoxic “killer” T cells, which are the toughest pathogen fighters. This type of dual cellular and
humoral response gives long-lasting immunity, similar to what most live attenuated vaccines achieve;
however, they are much safer than a live-virus vaccine. Attenuated vaccines, though very effective, are
capable of occasionally causing the illness they are meant to provide protection against. Because DNA
vaccine plasmids are not living, and thus nonreplicating, there is no risk that they may cause an illness.
For these reasons, DNA vaccines hold enormous promise in the development of both prophylactic
vaccines, such as those that target a pathogen, as well as therapeutic vaccinations, which fight cancer.
Because of the advantages of DNA vaccines, their release to the public is highly anticipated. However,
unfortunately, virtually all remain in clinical trials. So far, in clinical trials with human patients, DNA
vaccines have shown mixed results. While they are both cost effective and well tolerated by patients,
some concerns hamper their advancement. In particular, these are related to their ability to disrupt
cellular processes and produce anti-DNA antibodies, resulting in too low a level of immunogenicity. This
essentially means that they are not effective enough. It is worthwhile to note, however, that the
technology for improving the vaccines’ efficacy has advanced by leaps and bounds since the 1990s.
Though DNA vaccines are not yet established in a vaccination schedule or routinely given to HIV or
cancer patients, it is likely that this will change in the relatively near future. If global market reports are
any indication, scientists foresee continued breakthroughs in the vaccines sooner rather than later. The
global DNA vaccine market was valued at nearly $244 million in 2013 but is expected to grow to $2.7
billion by 2019, according to some market research. In addition, new biotechnologies and
nanotechnologies are helping to improve the vaccines. Scientists are in uncharted waters with the
development of DNA vaccines, but they are hopeful that in the not-so-distant future, advancements will
lead to the eradication of currently incurable illnesses.
1. Which type of vaccines is currently considered the outer frontier of vaccination?
A) Live attenuated vaccines
B) Inactivated vaccines
C) Subunit vaccines
D) DNA vaccines
2. What is the key difference between DNA vaccines and more-established methods?
A) DNA vaccines utilize attenuated pathogens.
B) DNA vaccines utilize killed pathogens.
C) DNA vaccines utilize isolated pathogen subunits.
D) DNA vaccines utilize the genetic material from the virus or bacteria.
3. What is the purpose of splicing the viral gene into a double-stranded DNA vector in DNA vaccine
production?
A) To isolate pathogen subunits.
B) To activate cytotoxic "killer" T cells.
C) To create a strong cellular response.
D) To create a DNA vaccine ready for injection.
4. Which method is NOT mentioned as a way to administer DNA vaccines?
A) Injection
B) Nasal spray
C) Gene gun
D) Oral ingestion
5. What advantage do DNA vaccines offer over live attenuated vaccines?
A) They are cost-effective.
B) They produce a stronger immune response.
C) They are safer and do not cause illness.
D) They are well tolerated by patients.
6. What is one concern related to DNA vaccines' efficacy?
A) Their ability to disrupt cellular processes
B) Their cost-effectiveness
C) Their ability to produce anti-DNA antibodies
D) Their level of immunogenicity
7. According to market research, what is the expected growth of the global DNA vaccine market by
2019?
A) $244 million
B) $2.7 billion
C) $500 million
D) $1 billion
KEY: CABDCDB
