Previous work has been done to develop L3 vaccines that can be used in canines, therefore there is existent research of larval antigens that induce a primary immune response. The development of hookworm vaccines depends on the eradication of both the larval and adult stages of the hookworm. An antigen discovery program has been established to isolate macromolecules that are used by adult hookworms to feed on human blood and ensure their survival. 

Antigen Discovery and Selection

The hookworm larval antigen (ASP-3) was identified as a protective antigen linked to recent larval vaccines. Additionally, there is a positive correlation between human anti-ASP-2 antibodies and the reduction of heavy-intensity hookworm infection in populations endemic to hookworm. Data has confirmed that recombinant ASP-2 can partially protect animals against larval hookworm infections. 

Tulane University

The Human Hookworm Vaccine Initiative (HHVI) is in the process of developing a functional and safe vaccine. HHVI is a non-profit collaboration at the George Washington University, London School of Hygiene and Tropical Medicine and the Oswaldo Cruz Foundation (vaccine development has been sponsored by the Sabin Vaccine Institute). Hookworm vaccine development involves research, process development, vaccine manufacturing and control and pre-clinical/clinical testing. 

Na-ASP-2 Hookworm Vaccine

Hookworm: “The Great Infection of Mankind”
Hotez PJ, Bethony J, Bottazzi ME, Brooker S, Buss P (2005) Hookworm: “The Great Infection of Mankind”. PLOS Medicine 2(3): e67. https://doi.org/10.1371/journal.pmed.0020067

Hookworm: "The Great Infection of Mankind"

Vaccine Construction

Pre-clinical testing and manufacture of Na-ASP-2 from N. americanus were finalized in 2004. Clinical testing was expected to take place in 2005 following approval from the FDA. This vaccine will be developed in the nonprofit sector and distribution will be targeted to populations of susceptible individuals in moderately and/or heavily impacted regions. 

Vaccine Development Process

Immunization would affect the transmission of hookworm larvae and not adult parasites living within the gastrointestinal tract of infected individuals. Therefore, the first dose would need to be administered after deworming. Vaccination administration would rely on established infrastructure, such as school wide deworming programs. Given that hookworm infections impact impoverished populations, there is a small commercial market available. Investment for manufacturing and industrial scale-up is still necessary to provide the vaccine to marginalized communities. 

Distribution of the Vaccine

Hookworm vaccines will primarily affect the larval stage of the parasitic worm by inducing the production of IgG antibodies. These antibodies will prevent larval development, reducing the population of larvae that develop into adult worms. This will lower mortality rates by preventing the adult hookworms from entering the host’s gastrointestinal tract and producing intestinal blood loss. 

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