The document discusses genetic engineering as a transformative technology for vaccine production, highlighting various types of genetically engineered vaccines, including subunit, DNA, recombinant, and RNA vaccines. It emphasizes both the advantages of these innovations and concerns over potential environmental risks associated with genetically modified organisms. The conclusion calls for increased research funding to address ecological impacts and enhance risk assessment methodologies in the field of genetic engineering.

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2. Contents Overview
 Introduction
 Genetic Engineering For Vaccine Production
 Genetically Engineered Vaccines
 Table: Some human disease agents for which rDNA vaccines
are being developed
 Genetically Engineered Vaccines and Their Potential Risks
 Advantages
 Conclusion
 References
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3. Introduction
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The use of new technology, popularly termed “genetic engineering,” has the
potential to change radically our approach to making some types of
vaccines. At present, acceptance of these new products is slow because of
the conservative attitude to releasing genetically modified organisms to the
environment. This careful approach should be applauded in the case of
recombinants of doubtful pedigree. However. Some may continue to be
impeded unnecessarily. Scientists can now isolate stretches of DNA
constituting individual genes. and analyze their base sequences. Hence
deducing the amino acid sequence of their protein products.
Pieces of DNA can be trimmed, sorted and multiplied, and removed from the
genome of one organism and inserted into the DNA of a heterologous
organism. Totally synthetic genes of any DNA base sequence, coding for any
peptide or protein, can be made. The manipulation of DNA in this manner is
commonly termed “genetic engineering”. Using this technology it is possible
to manipulate the genomes, and hence the phenotypic characteristics of
organisms. in novel and exciting ways.

4. Genetic Engineering For Vaccine
Production
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Useful vaccines can be made by transferring genes which code for immunizing
antigens into heterologous species which act as vectors in which the gene product
can be produced. This can be particularly useful where the pathogen for which a
vaccine is required is difficult to grow, slow growing, or dangerous. Suitable
vectors should be easy to grow and recombinant organisms should produce large
amounts of the required antigen.

5. Genetically Engineered Vaccines
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Subunit vaccines: They represent technologies ranging from the chemical
purification of components of the pathogen grown in vitro to the use of
recombinant DNA techniques to produce a single viral or bacterial protein,
such as Hepatitis B surface antigen for example. The disadvantage of such
vaccines is that immune responses, especially T-lymphocyte activation, are
too weak.
DNA vaccines: They employ genes encoding proteins of pathogens rather
than using the proteins themselves, a live replicating vector, or an
attenuated version of the pathogen itself. They consist of a bacterial plasmid
with a strong viral promoter, the gene of interest, and a
polyadenylation/transcriptional termination sequence. The plasmid is grown
in bacteria (e. coli), purified, dissolved in a saline solution, and then simply
injected into the host. In present versions only very small amounts of
antigens are produced within the vaccinated individual.

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Recombinant (DNA) vaccines: Made by isolation of DNA fragment(s)
coding for the immunogen (s) of an infectious agent/cancer cell, followed by
the insertion of the fragment(s) into vector DNA molecules (i.e. plasmids or
viruses) which can replicate and conduct protein-expression within bacterial,
yeast, insect or mammalian cells. The immunogen (s) may then be
completely purified by modern separation techniques. The vaccines tend to
give good antibody responses, but weak T-cell activation.
Naked DNA vaccines: They are engineered from general genetic shuttle
vectors and constructed to break species barriers. They may persist much
longer in the environment than commonly believed. Upon release or escape
to the wrong place at the wrong time. Horizontal gene transfer with
unpredictable long- and short-term biological and ecological effects is a real
hazard with such vaccines. There may be harmful effects due to random
insertions of vaccine constructs into cellular genomes in target or non-target
species.

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Live vector vaccines: These are produced by the insertion of the DNA
fragment(s) coding for an immunogen(s) intended for vaccination into the
genome of a ‘non-dangerous’ virus or bacterium, the vector. The insertion is
performed in such a way that the vector is still infectious ‘live’.
RNA vaccines: This involves the use of in vitro synthesized RNA (a single-
stranded relative of DNA). RNA are different from DNA vaccines in that there is
no risk of chromosomal integration of foreign genetic material.
Edible vaccines: These are produced by making transgenic, edible crop
plants as the production and delivery systems for subunit vaccines. Little is
known about the consequences of releasing such plants into the environment,
but there are examples of transgenic plants that seriously alter their biological
environment. A number of unpredicted and unwanted incidents have already
taken place with genetically engineered plants.

8. Table 1: Some human disease agents for which
rDNA vaccines are being developed.
Pathogenic agent Disease
Varicella-zoster virus Chicken pox
Hepatitis A and B viruses High fever, liver damage
Herpes simplex virus type 2 Genital ulcers
Influenza A and B viruses Acute respiratory disease
Rabies virus Encephalitis
Human immunodeficiency virus AIDS
Vibrio cholerae Cholera
Neisseria gonorrhoeae Gonorrhea
Mycobacterium tuberculosis Tuberculosis
Plasmodium spp. Malaria
Trypanosoma spp. Sleeping sickness

9. Genetically Engineered Vaccines
and Their Potential Risks
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 Synthetic and recombinant vaccines are produced under contained
conditions. Only a polypeptide which may confer protective immunity to a
given disease agent are brought out of the production unit and used as
vaccine. Such vaccines carry the same advantages and disadvantages
as traditional “killed” or “subunit” vaccines. It is conceivable that new
vaccine delivery systems and basic knowledge about immune system
interactions will make these vaccines more efficient in the near future. It
is difficult to imagine such vaccines posing ecological and environmental
risks.
 Genetically modified viruses and genetically engineered virus-vector
vaccines carry significant unpredictability and a number of inherent
harmful potentials and hazards.

10. Genetically Engineered Vaccines
and Their Potential Risks
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 RNA vaccines may have a far way to go before any of them find practical
use. Although easy degradation is a serious problem with RNA work in the
lab, RNA may be surprisingly resistant under natural conditions. At the
present time recombination between related RNA molecules has become
a real concern. RNA recombination is far more common than dogmatic
views held until recently.
 Naked DNA vaccines are engineered from general genetic shuttle vectors.
They are constructed to break species barriers. Naked DNA may persist
much longer in the environment than dogmas held just a short time ago.
Consequently, upon release or escape to the wrong place at the wrong
time, horizontal gene transfer with unpredictable long- and short-term
biological and ecological effects is a real hazard with such vaccines.
 Some environmental pollutants (xenobiotics, i.e. PCBs, dioxins, heavy
metals) may interact with genetically engineered vaccines, adding to their
unpredictability and the inability to perform meaningful risk assessments.

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In recent years, genetically engineered vaccine strategies have been
rushed into common use within such fields as medicine, veterinary
medicine and fish farming. Some scientists contend that such
vaccines are totally innocuous. But a recent and major research
report by Professor Terje Traavik reduces the ‘safe technology’ to
sheer naive optimism, and warns in conclusion that ‘many live,
genetically engineered vaccines are inherently unpredictable (and)
possibly dangerous.’ Changes in attitudes among scientists, medical
doctors as well as politicians are badly needed. Recent experiences
ought to call for humility with regard to environmental effects of
science and technology. In many cases, “experts” were proven wrong
after damage had been done. To the extent that any prior
investigations of damaging effects had been undertaken, methods
used were inadequate and only capable to reveal short-term effects,
whereas the long-term impacts were the most important and
serious.
Conclusion

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There is a most striking lack of holistic and ecological thinking with
regard to vaccine risks. This seems to be symptomatic for the real
lack of touch between research in medicine and molecular biology on
one hand, and potential ecological and environment effects of these
activities on the other. In order to make reliable risk assessments,
perform sensible risk management with regard to genetic
engineering in general, and genetically engineered vaccines in
particular, much pertinent knowledge is lacking. The prerequisite for
obtaining such knowledge is science and scientists dedicated to
relevant projects and research areas. It must be the responsibility of
the national governments and international authorities to make
funding available for such research. On one hand, this is obviously
not the responsibility of producers and manufacturers. On the other
hand, risk-associated research must be publicly funded in order to
keep it totally independent, which is an absolute necessity for such
activities.

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HL Yansura, DG Crea, R.Hirose, T Krugzewsk,
A Ikatura, K Riggs AD. Expression of
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110.
2. Goeddel DV Heyneker, HL Hozumi, T
Arrentren, R Ikatura, K Yansura, DG Ross,
MJ Miozzari, G Crea, R Seeburg PH. Direct
expression in Edierichiaroli of a DNA
sequence coding for human growth
hormone. Aurure 1979: 281; 544-545.
3. Righelato R. Business of biolog. Vature
1985: 316; 493.
References

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