68 • Impacts of Applied Genetics— Micro-Organisms, Plants, and Animals 
repair of nerve cells and thus could be sig- 
nificant for nerve restoration in surgery. 
• Erythropoietin, a glycopeptide that is large- 
ly responsible for the regulation of blood 
cell development. Its therapeutic applica- 
tions may range from hemorrhages and 
burns to anemias and other hematologic 
conditions. (See Tech. Note 5, p. 80.) 
Immunoproteins 
Immunoproteins include all the proteins that 
are part of the immune system— antigens, inter- 
ferons, cytokines, and antibodies. Since poly- 
peptides, the primary products of every molec- 
ular cloning scheme, are at the heart of immu- 
nology, developments made possible by recent 
breakthroughs will presumably affect the entire 
field. There is little doubt that applied genetics 
will play a critical role in developing a pharma- 
cology for controlling immunologic functions, 
since it provides the only apparent means of 
synthesizing many of the agents that will com- 
prise immunopharmacology. 
ANTIGENS (VACCINES) 
One early dramatic benefit should be in the 
area of vaccination, where genetic technologies 
may lead to the production of harmless sub- 
stances capable of eliciting specific defenses 
against various stubborn infectious diseases. 
Vaccination provides effective immunity by 
introducing relatively harmless antigens into 
the immune system thereby allowing the body 
to establish, in advance, adequate levels of anti- 
body and a primed population of cells that can 
grow when the antigen reappears in its virulent 
form. Obviously, however, the vaccination itself 
should not be dangerous. As a result, several 
methods have been developed over the past two 
centuries to modify the virulence of micro-orga- 
nisms used in vaccines without destroying their 
ability to trigger the production of antibodies. 
(See Tech. Note 6, p. 80.) 
Novel pure vaccines based on antigens syn- 
thesized by rDNA have been proposed to fight 
communicable diseases like malaria, which have 
resisted classical preventive efforts. Pure vac- 
cines have always been scarce; if they were 
available, they might reduce the adverse effects 
of conventional vaccines and change the meth- 
ods and the dosages in which vaccines are 
administered. 
Some vaccines are directed against toxic pro- 
teins (like the diphtheria toxin produced by 
some organisms), preparing the body to neutral- 
ize them. Molecular cloning might make it pos- 
sible to produce inactivated toxins, or better 
nonvirulent fragments of toxins, by means of 
micro-organisms that are incapable of seiz ing 
as disease-causing organisms. 
Immunity conferred by live vaccines invari- 
ably exceeds that conferred by nonli\ ing anti- 
genic material— possibly because a living micro- 
organism creates more antigen over a longer 
period of time, providing continuous "booster 
shots.” Engineered micro-organisms might be- 
come productive sources of high-potency anti- 
gen, offering far larger, more sustained, doses 
of vaccine without the side-effects from the con- 
taminants found in those vaccines that consist 
of killed micro-organisms. 
However, it is clear that formidable Federal 
regulatory requirements would ha\ e to he met 
before permission is granted for a no\ el li\ ing 
organism to he injected into human subjects. 
Because of problems encountered with li\ e \ ac- 
cines, the most likely application will lie in the 
area of killed vaccines (often using only parts of 
micro-organisms). 
It is impossible in the scope of this r('port to 
discuss the pros, cons, and conse(|U(‘nc(?s of de- 
veloping a vaccine for each viral disea.se. How- 
ever, the most commercially important are tin* 
influenza vaccines, with an a\'(M’age of 20.8 mil- 
lion doses given per year from 1973 to 197.'>— a 
smaller number than the 25.0 million doses |)er 
year of polio vaccine, hut moix^ profitable. 
Influenza is caused by a \ ii'us that has re- 
mained unconti'oll(;d larg(;ly because of the fre- 
quency with which it cati mutate and change its 
antigenic structures. It has h(‘(Mi suggested that 
antigenic protein genes for influenza could he 
kept in a "gene hank” and used w hen nec'ded Iti 
addition, the genetic code for several antigens 
could he introduced into an organism such as / 
