Vaccines to combat the neglected tropical diseases

Abstract

Summary The neglected tropical diseases (NTDs) represent a group of parasitic and related infectious diseases such as amebiasis, Chagas disease, cysticercosis, echinococcosis, hookworm, leishmaniasis, and schistosomiasis. Together, these conditions are considered the most common infections in low- and middle-income countries, where they produce a level of global disability and human suffering equivalent to better known conditions such as human immunodeficiency virus/acquired immunodeficiency syndrome and malaria. Despite their global public health importance, progress on developing vaccines for NTD pathogens has lagged because of some key technical hurdles and the fact that these infections occur almost exclusively in the world’s poorest people living below the World Bank poverty line. In the absence of financial incentives for new products, the multinational pharmaceutical companies have not embarked on substantive research and development programs for the neglected tropical disease vaccines. Here, we review the current status of scientific and technical progress in the development of new neglected tropical disease vaccines, highlighting the successes that have been achieved (cysticercosis and echinococcosis) and identifying the challenges and opportunities for development of new vaccines for NTDs. Also highlighted are the contributions being made by non-profit product development partnerships that are working to overcome some of the economic challenges in vaccine manufacture, clinical testing, and global access.

Helminth Infections and Host Immune Regulation

“…Indeed, classic immunity reminiscent of protection against viral and bacterial pathogens is rarely observed, with protection against helminth infection taking years to develop and seldom achieving sterile cure (5). However, effective immunity that significantly reduces the parasite burden is possible, as demonstrated by irradiated larval or cercarial vaccines in animal models of schistosomiasis, hookworm infection, and filariasis (178) as well as the more recent recombinant antigens (27). Hence, the generation of immunity is deficient in humans exposed to natural helminth infection.…”

Assessment of Protection Induced by DNA and Live Vaccine Encoding Leishmania MHC Class I Restricted Epitopes against L. major Challenge in Balb/c Mice Model

“…However debilitating effects reflected as DALY (disability adjusted life year) remark NTDs as serious global health problem more than ever. Unfortunately, effective vaccine is still lagging behind due to some challenges as antigen discovery, pre-clinical development, clinical trials in resource-poor countries and intricacies of host-parasite interaction [1,2].…”

Ancylostoma ceylanicum metalloprotease 6 DNA vaccination induces partial protection against hookworm challenge infection

“…Current human hookworm vaccine development has been hampered by allergic complication (Zhan et al 2012). The vaccine trials of leading vaccine candidate for ancylostomiasis were held due to unacceptable toxicities, including generalized urticarial reactions in several volunteers (Bethony et al 2011). The risk of an allergic reaction seems to be lower in the case of DNA immunization.…”