The impact of new technologies on vaccines

Vast changes are taking place in vaccinology consequent to the introduction of new technologies. Amongst the vaccines included in the Expanded Program me of Immunization (EPI), the pertussis vaccine has been replaced by acellu lar purified fractions devoid of side-effects. Non-pathogenic but immunogen ic mutants of tetanus and diptheria toxins are likely to replace the toxoid s, An effective Vaccine against hepatitis B prepared by recombinant technol ogy is in large-scale use. Conjugated vaccines against Haemophilus influenz ae b, S, pneumococcus and meningococcus are now available, as also vaccines against mumps, rubella and measles, Combination vaccines have been devised to limit the number of injections. Vaccine delivery systems have been deve loped to deliver multiple doses of the vaccine at a single contact point. A genetically-engineered oral Vaccine for typhoid imparts better and longer duration of immunity. Oral vaccines for cholera and other enteric infection s are under clinical trials,The nose as a route for immunization is showing promise for mucosal immunity and for anti-inflammatory experimental vaccin es against multiple sclerosis and insulin-dependent diabetes mellitus, The range of vaccines has expanded to include pathogens resident in the body su ch as Helicobacter pylori (duodenal ulcer), S, mutans (dental caries), and human papilloma virus (carcinoma of the cervix), An important progress is t he recognition that DNA alone can constitute the vaccines, inducing both hu moral and cell-mediated immune responses. A large number of DNA Vaccines ha ve been made and shown interesting results in experimental animals. Live re combinant vaccines against rabies and rinderpest have proven to be highly e ffective for controlling these infections in the field, and those for AIDS are under clinical trial. Potent adjuvants have added to the efficacy of th e vaccines, New technologies have emerged to 'humanize' mouse monoclonals by genetic en gineering and express these efficiently in plants. These recombinant antibo dies are opening out an era of highly specific and safe therapeutic interve ntions. Human recombinant antibodies would be invaluable for treating patie nts with terminal tetanus and rabies. Antibodies are already in use for tre atment of cancer, rheumatoid arthritis and allergies, An advantage of prefo rmed antibodies directed at a defined target and given in adequate amounts is the certainty of efficacy in every recipient, in contrast to vaccines, w here the quality and quantum of immune response varies from individual to i ndividual.