Oral Transfer of Adult Ancylostoma ceylanicum Hookworms into Permissive and Nonpermissive Host Species

Abstract

Syrian hamsters become anemic and exhibit delayed growth following oral infection with third-stage Ancylostoma ceylanicum hookworm larvae. Here we describe experiments designed to determine the feasibility of adult worm transfer (AWT) between hosts, a technique that would facilitate the specific study of bloodfeeding hookworms in vivo without prior exposure of the host to larva-specific antigens, permit the ex vivo manipulation of adult parasites prior to reimplantation, and also allow for cross-species transfer of worms. Weanling hamsters given an oral AWT of 40 or 60 mixed-sex A. ceylanicum worms rapidly developed anemia; in the higher-dose group, hemoglobin levels declined from prechallenge levels by 44% within 4 days following AWT. Long-term survival of transferred worms was demonstrated by recovery of parasites from the intestines 42 days after AWT. AWT hamsters acquired humoral immune responses against soluble adult hookworm extracts and excretory-secretory products that were comparable in magnitude to those of animals given a typical infection with larvae. In AWT experiments employing the nonpermissive murine model, C57BL/6 mice given adult worms rapidly became anemic and lost weight in a manner similar to AWT hamsters. Infection of additional mouse strains demonstrated that while C57BL/10 and CD-1 mice also developed anemia following AWT, BALB/c mice were resistant. The technique of AWT to mice may further our understanding of hookworm pathogenesis by allowing the study of adult hookworm infections in a species with well-characterized genetics and an abundance of available reagents.Hundreds of millions of persons worldwide suffer from disease caused by bloodfeeding hookworms (12, 13), with children and pregnant women bearing a particularly heavy pathological burden (14,(34)(35)(36)(37)40). Effective anthelmintic agents for hookworm are available (1); however, reinfection typically occurs quickly following treatment (2, 28), and drug resistance has been documented in human isolates (16,33). Accordingly, novel strategies to control hookworm disease, such as vaccines, may offer a welcome addition to currently available treatment and control options.Over the past 30 years, the Syrian golden hamster (Mesocricetus auratus) has been utilized as a rodent model for studies of hookworm pathology, immunology, and vaccination. Unlike mice, which do not generally permit the development of adult Ancylostoma sp. hookworms upon larval infection (9, 30), immunocompetent hamsters are fully permissive hosts for the human hookworm Ancylostoma ceylanicum (29,31,38). Our group (5) and others (17, 25) have found that, when infected with A. ceylanicum larvae, hamsters exhibit the major clinical features observed in children, namely, anemia and delayed growth. It has been demonstrated that immunization with soluble extracts or secretory products from adult A. ceylanicum worms leads to reduced worm burdens (20) or reduced pathology (5) in hamsters following challenge infection, establishing the utility of this model for vaccine d...

Molecular Characterization ofAncylostoma ceylanicumKunitz-Type Serine Protease Inhibitor: Evidence for a Role in Hookworm-Associated Growth Delay

“…5, animals that were immunized with rAceKI in alum exhibited improved growth following infection with 100 L3 compared with the growth of animals that received alum alone. Although these animals did not grow as well as uninfected animals, the beneficial effect of rAceKI immunization on growth was similar to the effect obtained with soluble extracts of A. ceylanicum adults, which have previously been shown to protect animals in this vaccine model (6,9). Consistent with our hypothesis, AceKI immunization had no effect on hookworm-associated anemia, as measured by blood hemoglobin levels following infection.…”

“…Weights and hemoglobin concentrations were determined throughout the course of the study. For hemoglobin studies, blood samples were collected from the orbital plexus in heparinized capillary tubes (Fisher Scientific) and were assayed by using reagents from a hemoglobin assay kit (Sigma Diagnostics) as previously described (6,7). Data are presented below as means Ϯ standard errors.…”

“…Immunoblots were prepared by subjecting rAceKI or pooled A. ceylanicum ES products to sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), followed by transfer to nitrocellulose. The blots were incubated with purified anti-rAceKI IgG, and the bound antibody was detected by using horseradish peroxidase-labeled anti-rabbit IgG and chemiluminescence as previously described (5,6,25). For immunohistochemistry studies, live A. ceylanicum adults were fixed in 10% formalin.…”

Dietary Iron Content Mediates Hookworm Pathogenesis In Vivo

“…The capacity of adult hookworms to cause significant losses of blood and iron during feeding has been well established using in vivo models (4,5,21). Hookworm infection has long been associated with iron deficiency anemia, and data from human studies generally confirm an inverse correlation between intensity of infection, as estimated by fecal egg counts, and blood hemoglobin levels (9,22,(33)(34)(35).…”

The Impact of Concurrent and TreatedAncylostoma ceylanicumHookworm Infections on the Immunogenicity of a Recombinant Hookworm Vaccine in Hamsters

“…Ancylostoma ceylanicum infection in the Golden Syrian hamster (Mesocricetus auratus) has been used as an experimental hookworm infection model [14][15][16][17][18][19][20][21][22]. Infective larvae administered orally develop in the small intestine to the adult stage without embarking on tissue migration.…”