In this regard, vaccines prevent more than three million deaths each year with an estimated

positive economic impact over a billion dollars per year [1]. The global vaccination program and effort has successfully eradicated one Modulators infectious disease (smallpox) with another one (polio) expected soon [2]. Although substantial progress has been made selleckchem in the prevention of many important infectious diseases (such as polio, measles, whooping cough, hepatitis A and B, etc.) by vaccination, infectious diseases still cause substantial morbidity and mortality and thus, there remains an urgent need for the development of new or improved vaccines [1]. This is particularly true for organisms that cause devastating diseases such as HIV, malaria and tuberculosis. In addition, the recent surge in emerging and re-emerging microbial

pathogens and the ERK inhibitor mounting incidence of antimicrobial resistance are major concerns in the clinical management of infectious diseases, fueling the urgency for new and improved vaccines. A number of different strategies have been used in the development of vaccines. Vaccines made from live, attenuated microorganisms are usually very effective but the risk of reversion and limited self-replication makes this strategy less than ideal and these vaccines are usually considered unsafe for use in humans [3]. Similar regulatory concerns plague recombinant protein and live vector vaccines. Vaccines based on killed, whole pathogen cells are somewhat effective but these could potentially contain toxic molecules such as lipopolysaccharides or be contaminated with live pathogens [4]. The safety of DNA vaccines have also come into question since there are concerns about

insertion into the host genome and possible mutagenic and oncogenic potential as well as the potential to trigger pathogenic anti-DNA autoimmune antibody responses [5]. Subunit vaccines, on the other hand, do not have these safety concerns as they only contain purified antigens rather than whole organisms and are, therefore, Liothyronine Sodium not infectious. As such, they can be safely given to immunosuppressed people and are less likely to induce unfavorable immune reactions. However, these advantages are tempered by the fact that purified antigens are often less immunogenic and they require the use of strong adjuvants to increase immunogenicity. Adjuvants can be classified into one of two broad categories: they are either immunostimulatory molecules like CpG oligonucleotides (ODN), bacterial toxins and cytokines or they are delivery vehicles that have inherent immunostimulatory activity like liposomes, microparticles and emulsions. Licensing adjuvants for use in human vaccines has been a difficult undertaking, typically due to the safety profile of these substances [6]. There are very few adjuvants currently approved for human use. In fact, in the United States, alum is still the only adjuvant approved for human vaccination.