<i>Clonorchis sinensis</i> Co-infection Could Affect the Disease State and Treatment Response of HBV Patients LiWenfang DongHuimin HuangYan ChenTingjin KongXiangzhan SunHengchang YuXinbing XuJin 2016 <div><p>Background</p><p><i>Clonorchis sinensis</i> (<i>C</i>. <i>sinensis</i>) is considered to be an important parasitic zoonosis because it infects approximately 35 million people, while approximately 15 million were distributed in China. Hepatitis B virus (HBV) infection is a major public health issue. Two types of pathogens have the potential to cause human liver disease and eventually hepatocellular carcinoma. Concurrent infection with HBV and <i>C</i>. <i>sinensis</i> is often observed in some areas where <i>C</i>. <i>sinensis</i> is endemic. However, whether <i>C</i>. <i>sinensis</i> could impact HBV infection or vice versa remains unknown.</p><p>Principal Findings</p><p>Co-infection with <i>C</i>. <i>sinensis</i> and HBV develops predominantly in males. Co-infected <i>C</i>. <i>sinensis</i> and HBV patients presented weaker liver function and higher HBV DNA titers. Combination treatment with antiviral and anti-<i>C</i>. <i>sinensis</i> drugs in co-infected patients could contribute to a reduction in viral load and help with liver function recovery. Excretory-secretory products (ESPs) may, in some ways, increase HBV viral replication <i>in vitro</i>. A mixture of ESP and HBV positive sera could induce peripheral blood mononuclear cells (PBMCs) to produce higher level of Th2 cytokines including IL-4, IL-6 and IL-10 compared to HBV alone, it seems that due to presence of ESP, the cytokine production shift towards Th2. <i>C</i>. <i>sinensis</i>/HBV co-infected patients showed higher serum IL-6 and IL-10 levels and lower serum IFN-γ levels.</p><p>Conclusions/Significance</p><p>Patients with concomitant <i>C</i>. <i>sinensis</i> and HBV infection presented weaker liver function and higher HBV DNA copies. In co-infected patients, the efficacy of anti-viral treatment was better in patients who were prescribed with entecavir and praziquantel than entecavir alone. One possible reason for the weaker response to antiviral therapies in co-infected patients was the shift in cytokine production from Th1 to Th2 that may inhibit viral clearance. <i>C</i>. <i>sinensis</i>/HBV co-infection could exacerbate the imbalance of Th1/Th2 cytokine.</p></div>