Immuno-epidemiology of human Schistosoma haematobium infection: preferential IgG3 antibody responsiveness to a recombinant antigen dependent on age and parasite burden.

Mutapi, Francisca; Mduluza, Takafira; Gomez-Escobar, Natalia; Gregory, William F.; Fernandez, Cecilia; Midzi, Nicholas; Maizels, Rick M.

Background: Schistosomiasis is a major parasitic disease affecting over 200 million people in the developing world with a further 400 million people at risk of infection. The aim of this study was to identify a single antigen from adult Schistosoma haematobium worms and subsequently use this antigen to study the development of schistosome-acquired immunity in a human population. Methods: The full-length cDNA sequence of a S. haematobium protein, a putative orthologue of the S. mansoni tegumental antigen Sm13, was obtained from a cDNA library of adult S. haematobium worms and named Sh13 following a small-scale expressed sequence tags (EST) project. The recombinant Sh13 protein expressed in E. coli, was used to investigate immuno-epidemiological patterns in 147 Zimbabweans (7-18 years old) exposed to S. haematobium. Results: Sequence analysis of the full-length cDNA sequence of the S. haematobium protein Sh13, indicated that the protein has an N-terminal signal peptide and encodes an 85-amino acid mature protein with a highly conserved predicted transmembrane domain (86 % identity with the S. mansoni tegumental antigen Sm13). The recombinant Sh13 protein was used in ELISA assays to determine the reactivity of sera from the study participants. Antibody responses against Sh13 were predominantly IgG3 isotype compared to responses against crude worm antigens which were predominantly IgG1 and IgG4. The relationship between anti-Sh13 IgG3 levels and infection intensity varied significantly with host age. The youngest children (7-10 years old) had relatively low levels of both infection and anti-Sh13 IgG3. In older children (11-12 years old) rising infection levels were accompanied by a significant increase in anti-Sh13 IgG3 levels. Subsequently, infection intensity declined significantly in 13-18 year olds but levels of the antibody continued to rise. The changing relationship between infection intensity and anti-Sh13 IgG3 levels with host age is consistent with the profile of a protective immune response predicted from theoretical work.

SCHISTOSOMA haematobium; INFECTION; RECOMBINANT antibodies; SCHISTOSOMIASIS; PARASITIC diseases

BMC Infectious Diseases, 2006, Vol 6, Issue 1, p1

1471-2334

Academic Journal

10.1186/1471-2334-6-96