TABLE CONTENTS

Human Hookworm Vaccines that Interrupt Blood-feeding
Loukas, A. (1), M. Pearson (2), N. Ranjit (1), D. Pickering (1), J. Bethony (2), M.E. Bottazzi
(2) & P. Hotez (2,3)
(1) Queensland Institute of Medical Research, Brisbane, Australia; (2) George Washington University,
Washington DC, USA; (3) Sabin Vaccine Institute, Washington DC, USA
Hookworms are gastrointestinal nematodes that infect almost one billion people in
developing countries. The main clinical symptom of human hookworm infections is irondeficiency
anemia, as a direct consequence of the intestinal blood loss resulting from the
parasite’s feeding behaviour. Although treatment is available and currently used for the
periodic removal of adult hookworms from patients, this approach has not effectively
controlled hookworm in areas of rural poverty. Moreover, treated individuals remain
susceptible to reinfection following exposure to third-stage infective hookworm larvae (L3)
in the soil as early as 4-12 months following drug treatment. Therefore, a prophylactic
vaccine against hookworm infection would provide an attractive additional tool for the public
health control of this disease. The feasibility of developing a vaccine is based on the prior
success of an attenuated larval vaccine against canine hookworm. Several laboratory and
field studies have explored the development of a human anti-hookworm vaccine, describing
potential protective mechanisms and identifying candidate antigens, one of which is now in
clinical trials. Antigen discovery has focused on two distinct developmental stages of the
parasite – (1) secreted proteins from the infective third stage larva (L3) and (2) intestinal
proteases that digest haemoglobin from the adult worm. This presentation will focus on the
biology of the blood-feeding process, and the selection and testing in pre-clinical efficacy
studies of the major enzymes involved in the haemoglobin digestion pathway.
5 th International Congress of Nematology, 2008 42