Vaccines classes

Vaccines may be considered as representing live microorganisms, killed miciooiganisms or purified bacterial and viral components (component vaccines). These vaccine classes have been deseribed in detail in Chapter 15. Some additional points about their use are diseussed below. 

Another example that can be included in the subunit vaccine class is the use of bacterial toxoids. Many bacteria produce toxins which play an important role in the development of the disease caused by a particular organism. Thus, vaccines against some agents, for example tetanus and diphtheria, consist of the toxin inactivated with formaldehyde conjugated to an adjuvant. Immunization protects from disease by stimulating antitoxin antibody which neutralizes the effects of the toxin. 

Polio is the only disease, at present, for which both hve and killed vaccines compete. Since the introduction of the killed vims (Salk) in 1956 and the live attenuated virus (Sabin) in 1962 there has been a remaikable decline in the incidence of poliomyelitis (Fig. 16.1). The inactivated polio vaccine (TPV) contains formalin-killed poliovirus of all three serotypes. On injection, the vaccine stimulates the production of antibodies of the IgM and IgG class which neutrahze the vims in the second stage of infection. A course of three injections at monthly intervals produces long-lasting immunity to all three poliovirus types. 

Schumacher R, Adamina A, Zurbriggen R, et al. Influenza virosomes enhance class I restricted CTL induction through CD4+ T cell activation. Vaccine 2004 22 714. 

When new vaccines are developed, new pharmaceutical delivery systems and additives with properties suitable for this new class of vaccines must be developed. Promising additives and delivery systems have to be evaluated regarding their efficacy and toxicity. These vaccine formulations do not simply act as carriers but are also used to enhance the immune response against the administered antigen (as an... 

Aseptic techniques are used to avoid the possibility of infection of the animals or ceU cultures. These include the preparation of the vaccines and spleens under aseptic conditions in a class 100 clean room equipped with a laminar airfiow hood, sterilization of instruments, and treatment of work surfaces with disinfectant before and after use, washing of the investigator s hands with an antiseptic surgical scrub preparation, and wearing of sterile gloves, face mask, and eyeglasses. 

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