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Humoral Immune Response Survey in a Schistosoma Japonicum (Sjap) Endemic Chinese Population
Sunday, March 6, 2016
South Exhibit Hall H (Convention Center)
Jianping Zhao, MD, Qian Chen, M.D. PHD, Xing Long, M.D. PHD., Jingjing Wang, M.D., Huifang Liang, PHD, Bixiang Zhang, M.D. PHD, Kathleen C Barnes, PHD, Robert G. Hamilton, PhD D.ABMLI FAAAAI, Xiaoping Chen, M.D. PHD
Rationale: Schistosomasis is a neglected parasitic fluke-borne disease that infects over 500,000 along the Yangtze River in China and induces life-threatening hepatosplenic and neurologic disease.  To investigate disease control and therapeutic strategies, we initiated a population based humoral immune response and genome-focused survey of Sjap disease susceptibility (IgG4-anti-Sjap-positivity) and resistance (IgE-anti-Sjap-positivity) in China.

 Methods: In the humoral immune response phase of the study, the prevalence of IgG/IgG4 and IgE antibody specific for Soluble Sjap Adult Worm extracted antigenic Protein (SWAP) was determined by indirect hemagglutination and monoclonal antibody-based ELISA in sera from Sjap-infected (fecal egg positive-n=100) and non-infected (fecal egg negative-n=100) Chinese living in the Sjapendemic Hubei province. To reduce interference, >95% of IgG was removed by Protein-G-Agarose preabsorption prior to IgE anti-SWAP analysis.

Results: Sjap exposure as evidenced by IgG anti-SWAP immune response positivity (>0.5kU/ml) occurred in 88% of egg-positive and 25% of egg-negative individuals.  IgG1 and IgG4 were the predominant IgG-anti-Sjap subclasses detected.  IgG4 anti-SWAP was detected (>0.4 kU/ml) in 66.3% of infected and 19% of uninfected subjects.  This contrasted with only 15% IgE anti-SWAP positivity in the infected (egg positive) and 0% in the non-infected groups.

Conclusions: IgG4 anti-SWAP is believed to attenuate protective effects of IgE anti-SWAP. In this study, SWAP-specific total IgG and IgG4 were both good surrogate markers for exposure to an Sjapinfection. The surprisingly low prevalence of IgE and high prevalence of IgG4 anti-SWAP positivity among egg-positive infected individuals, indicates a higher risk in this population for re-infection.