Defining serologic correlates of human hookworm infection

PROJECT SUMMARY
Hookworm infection is a leading cause of anemia, malnutrition and growth delay in poor countries, especially
in sub-Saharan Africa, where millions of people are infected. Current strategies to control hookworm rely on
Mass Drug Administration of anthelminthic drugs, although evidence calls into question the long-term
effectiveness of this approach to sustainably control or eliminate hookworm in populations at risk. Since 2007,
Yale University and the Noguchi Memorial Institute for Medical Research at the University of Ghana have
collaborated to characterize the epidemiology of hookworm in endemic communities. These studies have
identified factors associated with hookworm infection status and response to deworming treatment. Preliminary
data using human samples from Kintampo North, Ghana, suggests that host antibody (IgG) levels directed at
hookworm adult worm excretory/secretory (ES) proteins are closely correlated with active infection. However,
to date little is known about the targets of these antibody responses to hookworm antigens, which is a major
gap in understanding of host-parasite interactions and pathogenesis. We hypothesize that host antibodies to
specific hookworm proteins are predictive of infection status, and that a particular class of proteins, namely
allergens, are the drivers of this response. Studies in Specific Aim 1 will validate the correlation between IgG
antibody levels and infection status using 1,002 human serum samples and demographic data collected
between 2007-2020 in Ghana field studies. Antibody levels will be measured by ELISA and analyzed for
associations with hookworm infection status as determined by fecal microscopy. Data from human studies will
be compared to results from controlled infection and treatment studies using the hamster model of Necator
americanus. Studies in Aim 2 will focus on identifying the specific protein targets of host antibody responses
using recombinant protein expression and Label Free Quantitative proteomics. Candidate hookworm allergen
proteins will be expressed and purified, followed by screening for immunoreactivity using the human and
hamster serum samples described in Aim 1. In addition, N. americanus adult worm ES proteins will be
immunoprecipitated using highly reactive serum pools, followed by LC-MS/MS isolation and peptide mapping
against hookworm/helminth genome sequence databases. These experiments will test the hypothesis that
hookworm allergens are antigenic drivers of the host immune response that is associated with active infection.
The overarching goals of the proposed research are to (1) correlate antibody responses with infection status
and (2) characterize the role of hookworm allergens and novel antigenic proteins in host immune responses.
These studies leverage a longstanding, productive collaboration between the University of Ghana and Yale
that led to generation of novel preliminary data and adaptation of the first African hookworm strain in a
laboratory model. These studies will enhance our understanding of hookworm pathogenesis and inform
development of innovative tools to monitor deworming programs in endemic communities.

Grant Number: 5R21AI171842-02
NIH Institute/Center: NIH
Principal Investigator: MICHAEL CAPPELLO