Soil-Transmitted Helminth Vaccines: Are We Getting Closer?

Abstract

Parasitic helminths infect over one-fourth of the human population resulting in significant morbidity, and in some cases, death in endemic countries. Despite mass drug administration (MDA) to school-aged children and other control measures, helminth infections are spreading into new areas. Thus, there is a strong rationale for developing anthelminthic vaccines as cost-effective, long-term immunological control strategies, which, unlike MDA, are not haunted by the threat of emerging drug-resistant helminths nor limited by reinfection risk. Advances in vaccinology, immunology, and immunomics include the development of new tools that improve the safety, immunogenicity, and efficacy of vaccines; and some of these tools have been used in the development of helminth vaccines. The development of anthelminthic vaccines is fraught with difficulty. Multiple lifecycle stages exist each presenting stage-specific antigens. Further, helminth parasites are notorious for their ability to dampen down and regulate host immunity. One of the first significant challenges in developing any vaccine is identifying suitable candidate protective antigens. This review explores our current knowledge in lead antigen identification and reports on recent pre-clinical and clinical trials in the context of the soil-transmitted helminths Trichuris , the hookworms and Ascaris . Ultimately, a multivalent anthelminthic vaccine could become an essential tool for achieving the medium-to long-term goal of controlling, or even eliminating helminth infections.

Transgenesis in parasitic helminths: a brief history and prospects for the future

“…For example, anthelmintic drugs do not protect against reinfection, and treatment failure because of repeated use of these drugs has drawn attention to the development of drug resistance [ 6 ]. In addition, despite the promise of attenuated larvae, the use of which has shown promising results in vaccine studies, recombinant and epitope-based vaccine candidates show variable efficacy [ 2 , 7 , 8 ]. For example, a phase 1 clinical trial using ultraviolet-attenuated Necator americanus larvae elicited an antigen-specific humoral and cellular immune response that resulted in reduced larval output in vaccinated participants [ 8 ].…”

Current Finding of Helminth Morphology Cause Infectious Disease

“…Microscopically, the morphology of microfilariae species can be distinguished based on: the size of the head space and the color of the sheath in Giemsa staining, the composition of the body nucleus, the number and location of the nucleus at the tip of the tail. [9] Fasciola hepatica This worm belongs to the leaf worm group because its body shape resembles a leaf measuring 20-30 mm x 8-13 mm. Hermaphrodite is where in one individual tiger has 2 different sex organs.…”

Mucosal Vaccination With Recombinant Tm-WAP49 Protein Induces Protective Humoral and Cellular Immunity Against Experimental Trichuriasis in AKR Mice

“…More than 360 million people are chronically infected, resulting in 236,000 disabilityadjusted life years (DALYs) lost based on Global Burden of Disease 2019 estimates (1). T. trichiura commonly infects people in rural subtropical and tropical areas where poverty is widespread and sanitation facilities are inadequate (2,3). The infection causes malnutrition, diarrhea, anemia, and even rectal prolapse (4)(5)(6).…”