Salmonella Enteritidis is the main cause of foodborne salmonellosis worldwide. The limited effectiveness of current interventions against this pathogen has been the main incentive to develop new methods for the efficient control of this infection. To investigate the use of DNA vaccines against S. Enteritidis in humans, immune responses stimulated by two plasmids containing the genes designated SEN1002, located in the pathogenicity island SPI-19 and encoding a Hcp protein involved in transport mechanisms, and SEN1395, located in the genomic island ΦSE14 and encoding a protein of a new superfamily of lysozymes, were evaluated. Humoral and cellular responses following intranasal immunization of two groups of BALB/c mice with the plasmids pV1002 and pV1395 plus adjuvant were evaluated and it was observed that the IgG2a/IgG1 ratios were sixfold higher than control groups. Both plasmids stimulated specific secretory IgA production. Increased proliferation of lymphocytes and IFN-γ production were detected in both experimental groups. DNA-vaccinated mice developed protective immunity against a virulent strain of S. Enteritidis, with nearly 2 logs of protection level compared to the negative control values in the spleen. Therefore, DNA vaccines are efficient at stimulating cellular and humoral immune responses at systemic and mucosal levels.

Advances over the last 20 years in immunology and molecular biology have provided many new tools for identifying the important antigens and new ways to achieve the appropriate immune responses to these antigens. These provide many more options to achieve the best immune response from deletion mutations, subunit antigens, vectors or DNA immunization. These tools are being adopted to screen, discover and produce the appropriate antigens and to deliver them by the optimal method and with novel adjuvants to achieve the appropriate immune response. These developments will result in vaccines for respiratory disease that are safer and more efficacious, and provide greater flexibility for use and administration.

Leishmania are protozoan parasites spread by a sandfly insect vector and causing a spectrum of diseases collectively known as leishmaniasis. The disease is a significant health problem in many parts of the world resulting in an estimated 12 million new cases each year. Current treatment is based on chemotherapy, which is difficult to administer, expensive and becoming ineffective due to the emergence of drug resistance. Leishmaniasis is considered one of a few parasitic diseases likely to be controllable by vaccination. The relatively uncomplicated leishmanial life cycle and the fact that recovery from infection renders the host resistant to subsequent infection indicate that a successful vaccine is feasible. Extensive evidence from studies in animal models indicates that solid protection can be achieved by immunisation with protein or DNA vaccines. However, to date no such vaccine is available despite substantial efforts by many laboratories. Advances in our understanding of Leishmania pathogenesis and generation of host protective immunity, together with the completed Leishmania genome sequence open new avenues for vaccine research. The major remaining challenges are the translation of data from animal models to human disease and the transition from the laboratory to the field. This review focuses on advances in anti-leishmania vaccine development over the recent years and examines current problems hampering vaccine development and implementation.

Vaccination against complex metazoan parasites has become a reality with the development and registration of recombinant protein-based vaccines against the cattle tick Boophilus microplus and the sheep cestode Taenia ovis. Progress towards the development of similar vaccines against gastrointestinal nematodes, primarily of ruminants, is outlined within a framework of defining the practical requirements for successful vaccination, antigen selection, recombinant protein production and antigen delivery, be it mucosal delivery or DNA vaccination. Antigen selection strategies include the fractionation of complex, but protective, parasite extracts, the use of antibody probes, evaluation of excretory-secretory components and gut-expressed hidden antigens as well as antigens targeted on the basis of function such as enzyme activity. The difficulties being encountered in recombinant protein production and their solution are discussed as are the requirements for successful antigen delivery. Recent technological developments such as the use of functional genomics to identify new vaccine candidates and DNA vaccination to present the selected antigen to the host immune system are discussed and are anticipated to have a profound effect on vaccine development in the future.