The intent of prime-boost vaccination is to induce different types of immune responses and enhance the overall immune response, a result that may not occur if only one type of vaccine were to be given for all doses. This approach has been employed in trials with,

for example, TB, CMV, malaria and HIV candidate vaccines. For example, in studies on new TB vaccines, subjects already primed with the live, attenuated BCG vaccine have been boosted with a subunit adjuvanted vaccine (see Tuberculosis). Respiratory syncytial virus is a common cause of bronchiolitis and pneumonia in infants, and exacerbations of chronic obstructive pulmonary disease in the elderly. The development of an effective vaccine has been challenging; natural immunity to RSV infection is incomplete and re-infections occur in all age groups. Moreover, the primary target population for vaccination is newborns and young infants, and they are this website a challenging population selleckchem as they have relatively immature immune systems and the presence of maternal antibodies may interfere with vaccination of the young

infant (see Chapter 2 – Vaccine immunology). The initial efforts to develop a formalin-inactivated cell culture-derived RSV vaccine resulted in an unanticipated enhancement of natural RSV disease in some of the RSV-naïve infants who received the vaccine in a clinical trial and subsequently were exposed to RSV. The exacerbated disease is thought to be due to an exaggerated T helper type 2 cell immune response (see Chapter 2 – Vaccine immunology). Safety STK38 concerns regarding the potential of vaccines to trigger or prime for immunopathological responses has resulted in a cautious approach to the development of RSV vaccines. The vaccine candidates most advanced in clinical development use two different approaches – one uses a live, attenuated virus with a gene deletion deliberately targeted to minimise

immunopathological responses. The other approach uses a live viral vector to deliver only a key RSV surface antigen, thereby avoiding the risk of an immunopathological response arising from exposure to the RSV virus itself. Infectious illnesses exert a major burden of disease in developing countries. The greatest burden is caused by diseases for which we currently have no vaccines, eg taeniid cestode parasites are associated with high human morbidity and losses in livestock. Global efforts to reduce these infections in humans are ongoing through the use of antihelminthics and the implementation of lifestyle changes, but this is having little effect. However, substantial progress has been made towards developing veterinary vaccines which encourages investigation of the potential use of similar vaccines in humans to prevent, for example, hydatid disease (arising from infection with Echinococcus granulosus) and cysticercosis (from infection with Taenia solium).