The presentation and delivery of antigens is crucial for inducing immunity and, desirably, lifelong protection. Recombinant viral vectors – proven safe and successful in veterinary vaccine applications – are ideal shuttles for delivering foreign proteins to induce an immune response with protective antibody levels, by mimicking natural infection. Some examples of viral vectors are adenoviruses, measles virus or poxviruses. The required attributes to qualify as a vaccine vector are: Stable insertion of coding sequences into the genome, induction of a protective immune response, a proven safety record and the potential for large scale production.The need to develop new vaccines for infectious diseases, increase vaccine accessibility, reduce health costs and simplify overloaded immunisation schedules has driven the idea to combine antigens from the same or various pathogens. To protect effectively some vaccines require multiple antigens of one pathogen, or different pathogen serotypes/serogroups in combination (multivalent or polyvalent vaccines). Future multivalent vaccine candidates are likely to be required for complex diseases like malaria and HIV. Other novel strategies propose antigen combination of different pathogens to protect against several diseases at once (multidisease or multipathogen vaccines).
Multivalent and multipathogen vaccines delivered by viral vectors.