Abstract
BackgroundHepatitis B and schistosomiasis are most prevalent in Africa and Asia, and co-infections of both are frequent in these areas. The immunomodulation reported to be induced by schistosome infections might restrict immune control of hepatitis B virus (HBV) leading to more severe viral infection. Vaccination is the most effective measure to control and prevent HBV infection, but there is evidence for a reduced immune response to the vaccine in patients with chronic schistosomiasis japonica.Methodology/Principal FindingsIn this paper, we demonstrate in a mouse model that a chronic Schistosoma japonicum infection can inhibit the immune response to hepatitis B vaccine (HBV vaccine) and lead to lower production of anti-HBs antibodies, interferon-γ (IFN-γ) and interleukin-2 (IL-2). After deworming with Praziquantel (PZQ), the level of anti-HBs antibodies gradually increased and the Th2-biased profile slowly tapered. At 16 weeks after deworming, the levels of anti-HBs antibodies and Th1/Th2 cytokines returned to the normal levels.Conclusions/SignificanceThe results suggest that the preexisting Th2-dominated immune profile in the host infected with the parasite may down–regulate levels of anti-HBs antibodies and Th1 cytokines. To improve the efficacy of HBV vaccination in schistosome infected humans it may be valuable to treat them with praziquantel (PZQ) some time prior to HBV vaccination.
Highlights
Poor immune responses after vaccination have been reported for both viral and bacterial vaccines [1,2,3,4]
The results show that the mean concentration of anti-HBsAg antibody in the mice with a chronic infection group was significantly lower than that in the un-infected control and acute infection group (P,0.05), and there was no significant difference between the acute infection and control groups (P.0.05)
It has been proved that chronic helminth infection is one of contributing causes for absent or weak response to some vaccines [9], [10]
Summary
Poor immune responses after vaccination have been reported for both viral and bacterial vaccines [1,2,3,4]. Epidemiological investigations in China found that the rates of absent or weak responses to the HBV vaccine are higher in rural than that in urban children The immunomodulation reported to be induced by schistosome infections might restrict immune control of hepatitis B virus (HBV) leading to more severe viral infection. Vaccination is the most effective measure to control and prevent HBV infection, but there is evidence for a reduced immune response to the vaccine in patients with chronic schistosomiasis japonica
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