Formaldehyde vaccine manufacture

Toxoid vaccines. Toxoid vaccines are preparations derived fiom the toxins that are seereted by eertain species of bacteria, hi the manufacture of such vaccines, the toxin is separated fiem the bacteria and treated in a way that eliminates toxicity without eliminating immunogenicity. Formalin (ca. 38% of formaldehyde gas in water) is used for this purpose and consequently the treated toxins are often referred to as formol toxoids. Toxoid vaccines are veiy effective in the prevention of those diseases such as diphtheria and tetanus in which the harmful effects of the infecting bacteria are due to the deleterious action of bacterial toxins on physiology and biochemistry. 

Composition and Methods of Manufacture. The diseases of diphtheria and tetanus are caused by toxins synthesized by the oiganisms Coynebacterium diphtheriae and Clostridium tetanic respectively. Diphtheria and tetanus vaccines contain purified toxins that have been inactivated by formaldehyde to form toxoids. 

Cell cultures provide infected fluids that contain little debris and can generally be satisfactorily clarified by filtration. Because most viral vaccines made from cell cultures consist of live attenuated virus, there is no inactivation stage in their manufacture. There are, however, two important exceptions inactivated poliomyelitis virus vaccine is inactivated with dilute formaldehyde or (3-propiolactone and rabies vaccine is inactivated with (3-propiolactone. The preparation of these inactivated vaccines also involves a concentration stage — by adsorption and elution of the virus in the case of poliomyelitis vaccine and by ultrafiltration in the case of rabies vaccine. When processing is complete the bulk materials may be stored until needed for blending into final vaccine. Because of the lability of many viruses, however, it is necessary to store most purified materials at temperatures of —70°C. 

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