Author ORCID Identifier
https://orcid.org/0000-0002-5583-7057
Date of Graduation
8-2018
Document Type
Dissertation (PhD)
Program Affiliation
Immunology
Degree Name
Doctor of Philosophy (PhD)
Advisor/Committee Chair
Jagannadha Sastry, Ph.D.
Committee Member
Peter Hotez, M.D., Ph.D.
Committee Member
Maria Elena Bottazzi, Ph.D.
Committee Member
Dorothy Lewis, Ph.D.
Committee Member
Kimberly Schluns, Ph.D.
Committee Member
Dianna Milewicz, M.D., Ph.D.
Abstract
Human whipworm (Trichuris trichiura) infects approximately 1 in 15 people worldwide, representing the leading infectious cause of colitis and subsequent, inflammatory bowel disease (IBD). Current control measures focused on mass deworming have had limited success due to low drug efficacies. Vaccination would be an ideal, cost-effective strategy to induce protective immunity, leading to control of infection and transmission. Here we report the identification of whey acidic protein, a whipworm secretory protein, as a strong immunogen for inducing protective efficacy in a surrogate mouse T. muris infection model. The near full-length recombinant WAP protein (rTm-WAP49), as well as a single, highly conserved repeat within WAP (fragment 8) expressed as an Na-GST-1 fusion protein (rTm-WAP-F8+Na-GST-1), generate a strong T helper type 2 (TH2) immune response when delivered as subcutaneous immunization formulated with Montanide ISA 720. Oral challenge with T. muris infective eggs following vaccination led to a significant reduction in worm burden of 48% by rTm-WAP49 and 33% by rTm-WAP-F8+Na-GST-1. The cellular immune correlates of protection included significant antigen-specific production of TH2 cytokines IL-4, IL-9, and IL-13 by cells isolated from the vaccine-draining inguinal lymph nodes, parasite-draining mesenteric lymph nodes, and spleen in mice vaccinated with either rTm-WAP49 or rTm-WAP-F8+Na-GST-1. The humoral immune correlates included a high antigen-specific ratio of IgG1 to IgG2a, without eliciting an IgE-mediated allergic response. Immunofluorescent staining of adult T. muris with WAP antisera identified the worm’s pathogenic stichosome organ as the site of secretion of native Tm-WAP protein into the colonic mucosa. While both rTm-WAP49 or rTm-WAP-F8+Na-GST-1 have high purity and stability properties by analytical analysis, rTm-WAP49 has a more complex biophysical profile, with oligomerization to dimers and trimers through intermolecular disulfide bond formation. Recognition of rTm-WAP49 by endemic patient serum samples suggests that conserved epitopes may exist between T. muris and T. trichiura (or possibly non-Trichuris nematodes) derived WAPs. To our knowledge, this is the first study identifying a promising immunogen for further investigation of its vaccine potential against T. muris and eventually against T. trichiura.
Keywords
Trichuris trichiura, whipworm, vaccine development, helminth