Biotechnology and genetic engineering in the new drug development. Part II. Monoclonal antibodies, modern vaccines and gene therapy.

Monoclonal antibodies, modern vaccines and gene therapy have become a major field in modern biotechnology, especially in the area of human health and fascinating developments achieved in the past decades are impressive examples of an interdisciplinary interplay between medicine, biology and engineering. Among the classical products from cells one can find viral vaccines, monoclonal antibodies, and interferons, as well as recombinant therapeutic proteins. Gene therapy opens up challenging new areas. In this review, a definitions of these processes are given and fields of application and products, as well as the future prospects, are discussed.

Oral immunogenicity of tomato-derived sDPT polypeptide containing Corynebacterium diphtheriae, Bordetella pertussis and Clostridium tetani exotoxin epitopes.

DPT vaccine, designed to immunize against diphtheria, pertussis, and tetanus, has been shown to be effective in humans. Nevertheless, dissatisfaction with the whole-cell preparations is due to the reactogenicity, which has to lead to the development of new safer formulations. Previously, we described the expression in tomato of a plant-optimized synthetic gene encoding the recombinant polypeptide sDPT, containing mainly immunoprotective epitopes of the diphtheria, pertussis and tetanus exotoxins and two adjuvants. In this study, we examined whether the ingestion of tomato-derived sDPT protein induces specific antibodies in mice after three weekly doses scheme. A positive group immunized with DPT toxoids was included. Specific antibody levels were assessed in serum, gut and lung. Sera tested for IgG antibody response to pertussis, tetanus and diphtheria toxin showed responses to the foreign antigens; interestingly, the response to diphtheria epitope was similar to those observed in the positive group. We found higher IgG1 than IgG2a responses in serum. A modest IgG response was observed in the tracheopulmonary fluid. High response of IgA against tetanus toxin was evident in gut, which was statistically comparable to that obtained in the positive group. The levels of response in these groups were higher than those in mice that received wild-type tomato. These findings support the concept of using transgenic tomatoes expressing sDPT polypeptide as model for edible vaccine against diphtheria, pertussis, and tetanus.

Generation of plant-derived recombinant DTP subunit vaccine.

The current diphtheria-tetanus-pertussis (DTP) pediatric vaccine is produced from the corresponding pathogenic bacteria Corynebacterium diphtheriae, Clostridium tetani and Bordetella pertussis; five injected doses of DTaP (acellular) vaccine are required for every child in the standard US vaccination schedule. Because the vaccine is derived from native live sources, adverse effects are possible and production is complex and costly. To address issues of safety, ease of renewability and expense, we used recombinant technology in an effort to develop a subunit DPT vaccine derived in non-pathogenic plant expression systems. Expression of diphtheria toxin (DT), tetanus fragment-C (TetC) and the non-toxic S1 subunit of pertussis toxin (PTX S1) antigenic proteins in soluble form in low-alkaloid tobacco plants and carrot cell cultures allowed efficient downstream purification to levels suitable for intramuscular injection in BALB/c mice. At working concentrations of 5mug per dose, these preparations induced high levels of antigen-specific IgGs in mouse sera. Our results clearly support the feasibility of producing recombinant pediatric vaccine components in plants.

Innovative vaccine production technologies: the evolution and value of vaccine production technologies.

This review paper provides an overview of innovative technologies designed to produce bacterial, viral, recombinant subunit, and polysaccharide vaccines, as well as combination vaccines. Advances in this field are illustrated by vaccines against DTP (diphtheria-tetanus-pertussis), influenza, hepatitis B (HepB) and typhoid fever. In addition, technological trends regarding antigens, adjuvants, and preservatives in vaccines are discussed. The progress achieved in vaccine production technologies is especially important for improving the protection of vulnerable populations against infectious diseases. These at-risk groups include infants, the elderly and immunocompromized individuals, as well as people living in developing countries or emerging economies.

Global DTP manufacturing capacity and capability. Status report: January 1995.

A recently completed survey of 63 manufacturers of diphtheria-tetanus-pertussis (DTP) vaccine and its components in 42 countries shows that there is potentially a large excess installed capacity for DTP production. However, many manufacturers are not producing to capacity, and demand and supply for this vaccine are not matched in individual countries. About half of all countries producing DTP vaccine and its components do not have fully functional national control systems, and some countries are performing none of the critical functions for an effective control of quality. Thus, potential for export of excess capacity is limited. The data collected indicate much homogeneity in the preparation of diphtheria and tetanus toxoids. Nearly all manufacturers use the same seeds and similar purification methods, but there is variability in whether purification is done before or after conversion of toxin to toxoid. About 10% of all manufacturers do not meet WHO-defined standards of purity for these toxoids. There is much more heterogeneity in the pertussis seed strains and the methods of purification used. The formulation of DTP vaccine differs considerably among producers. Potency testing is not being done by the WHO-recommended method by about 50% of manufacturers on lots of diphtheria and tetanus toxoids for release. Testing of irreversibility of conversion of toxin to toxoid, a WHO-specified safety test, is also not being done on each lot of diphtheria toxoid by 15% of manufacturers surveyed nor on each lot of tetanus toxoid vaccine by 30% of manufacturers surveyed. Access to technology to develop new DTP-based combination vaccines will be delayed if these manufacturers cannot ensure consistent high quality vaccine for their target populations. The results and conclusions suggest areas for future activities to strengthen the supply and quality of DTP and DTP-based combination vaccines.

Vacunación contra difteria, tosferina y tétanos / Vaccines against diphtheria, whooping cough and tetanus

La difteria, la tosferina o pertusis y el tétanos son tres importantes problemas de salud pública que tienen en común que pueden ser específicamente prevenidas con el uso de una sola preparación vacunal, conocida como vacuna triple bacteriana o DPT (difteria, pertusis y tétanos). La vacuna DPT es una preparación combinada que contiene los toxoides diftérico, tetánico y la vacuna pertusis adsorbidos a un adyuvante, generalmente hidróxido o fosfato de aluminio, ambos de calidad para uso por vía parenteral. Este biológico y las vacunas BCG (bacilo de Calmette y Guérin), toxoide tetánico, antisarampión y antipoliomielítica forman el grupo de las vacunas recomendadas en el Programa Ampliado de Inmunizaciones (PAI) que la Organización Mundial de la Salud ha recomendado para ser aplicado a toda la población mundial menor de 5 años. En México, esta actividad recibe el nombre de Programa Nacional de Inmunizaciones, con la enorme ventaja de que es el único de América Latina que tiene la capacidad de elaborar las vacunas correspondientes. En este capítulo se hará una breve descripción de las tres enfermedades, los agentes etiológicos, los procedimientos de producción de los componentes de la vacuna y sus perspectivas de desarrollo, así como de otras combinaciones de los componentes vacunales