Biomedical Engineering Reference
In-Depth Information
13.4 Vaccine technology
The application of vaccine technology forms a core element of modern medicinal endeavour. It
plays a central role in both human and veterinary medicine and represents the only commonly em-
ployed prophylactic (i.e. preventative) approach undertaken to control many infectious diseases.
The current (annual) global vaccine market stands at in excess of US $3 billion. Immunization pro-
grammes, particularly those undertaken on a multinational scale, have served to reduce dramati-
cally the incidence of many killer/disabling diseases, such as smallpox, polio and tuberculosis.
Continued/increased emphasis upon the implementation of such immunization programmes is
likely. This is true not only of poorer world regions, but also amongst the most affl uent nations. An
estimated 500 000 adults die annually in the USA from conditions that could have been prevented
by vaccination. These include pneumococcal pneumonia, infl uenza and hepatitis B.
Vaccination seeks to exploit the natural defence mechanisms conferred upon us by our immune sys-
tem. A vaccine contains a preparation of antigenic components consisting of, derived from or related to
a pathogen. In most instances upon vaccine administration, both the humoral and cell-mediated arms of
the immune system are activated. The long-term immunological protection induced will normally pre-
vent subsequent establishment of an infection by the same or antigenically related pathogens. Although
some vaccines are active when administered orally, more are administered parenterally. Normally, an
initial dose administration is followed by subsequent administration of one or more repeat doses over
an appropriate time-scale. Such booster doses serve to maximize the immunological response.
Traditional vaccine preparations have largely been targeted against viral and bacterial patho-
gens, as well as some bacterial toxins and, to a lesser extent, parasitic agents, such as malaria.
However, an increased understanding of the molecular mechanisms underlying additional human
diseases suggests several novel applications of vaccines to treat/prevent autoimmune conditions
and cancer (discussed later). Despite such potentially exciting future applications, recent scientifi c
surveys indicate that the most urgently required vaccines are those that protect against more mun-
dane pathogens (Table 13.5). Although the needs of the developing world are somewhat different
to those of developed regions, an effective AIDS vaccine is equally important to both. Approaches
to development of such AIDS vaccines are discussed later in this chapter. Of particular conse-
quence to developing world regions is the current lack of a truly effective malaria vaccine. With
an estimated annual incidence of 300-500 million clinical cases (with up to 2.7 million resulting
deaths), development of an effective vaccine in this instance is a priority.
13.4.1 Traditional vaccine preparations
For the purposes of this discussion, the term 'traditional' refers to those vaccines whose devel-
opment predated the advent of recombinant DNA technology. Approximately 30 such vaccines
Table 13.5
Some diseases against which effective/more effective
vaccines are urgently required. Diseases more prevalent in developing world
regions differ from those that are most common in developed countries
Developing world regions
Developed world regions
AIDS
AIDS
Malaria
Respiratory syncytial virus
Tuberculosis
Pneumococcal disease
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