Vivotif--a 'magic shield' for protection against typhoid fever and delivery of heterologous antigens.

The attenuated Salmonella typhi strain Ty21a is the main constituent of Vivotif, the only attenuated live oral vaccine against typhoid fever. In comparison with antibiotics, the 'magic bullets' which Paul Ehrlich was striving for to treat infectious diseases, this vaccine should be viewed as a 'magic shield', because rather than treating typhoid fever after the infection has started, immunisation with this vaccine strain prevents infection and disease by the induction of specific immune responses. Ty21a is also an attractive carrier for the delivery of heterologous antigens.

Vaccines against typhoid fever.

Because of high infectivity and significant disease burden, typhoid fever constitutes a major global health problem. Implementation of adequate food handling practices and establishment of safe water supplies are the cornerstone for the development of an effective prevention program. However, vaccination against typhoid fever remains an essential tool for the effective management of this disease.

Oral administration of specific antigens to allergy-prone infant dogs induces IL-10 and TGF-beta expression and prevents allergy in adult life.

Background: Oral administration of allergens can induce immune tolerance to specific allergens in rodents and hence might be a possibility to prevent and treat allergic diseases in human subjects. However, the gastrointestinal tract of mice is different from that of human subjects. The absorption of specific antigens and subsequent antigen presentation to intestinal T cells is different in both species, making it difficult to extrapolate results.

Experience with registered mucosal vaccines.

Most pathogens gain access to their host through mucosal surfaces. It is therefore desirable to develop vaccination strategies that lead to mucosal immune responses. Ideally, a vaccine should be administered mucosally in order to elicit mucosal protection.