Expression and characterization of the multiplied, recombinant preS1 antigen of hepatitis B virus

A flexible peptide linker enhances the immunoreactivity of two copies HBsAg preS1 (21-47) fusion protein

PreS1 (21-47) region of HBV large surface protein is hepatocyte receptor binding site and the anti-preS1 (21-47) antibody possesses the virus-neutralizing activity and protective effect. It is important to obtain the peptide with higher immunoreactivity on a large scale for detecting the anti-preS1 (21-47) antibody in the sera from HBV infected patients and future vaccine recipients. The expression vector pGEX SLS, which expressed two copies of the preS1 (21-47) peptide connected by a flexible linker (Gly4Ser3) fused to glutathione S-transferase (GST), was constructed. The fusion protein, named GST-SLS, was highly expressed in E. coli and purified by affinity chromatography. Ninety milligrams purified protein can be obtained from 1l of culture. The data in ELISA analysis showed that the immunoreactivity of GST-SLS was enhanced significantly in comparison with GST-S II, a GST fusion protein with two copies preS1 (21-47) linked directly; GST-S I, another GST fusion protein with one copy preS1 (21-47) and preS1 (21-47) synthesized peptide. In addition, GST-SLS has been tried to use in detecting anti-preS1 (21-47) antibody in the sera from HBV infected patients and a satisfied result was gained. Therefore, GST-SLS may have potential to be developed into a new kit for diagnosis and prognosis of hepatitis B (HB) patients.

Oxidative burst response of neutrophils primed with PreS1 antigen of hepatitis B virus in patients with chronic hepatitis B and convalescents

The pathogenesis of liver damage in the course of hepatitis B virus (HBV) infection depends on the host's specific and non-specific immune response to various viral antigens. The role of polymorphonuclear neutrophils (PMN) in the natural immune reaction and during secondary microbial infections is well documented. Increased free radical production is associated with many pathological conditions such as shock, ischaemia or chronic inflammatory diseases. We studied the oxidative metabolism of neutrophils in patients with chronic HBV and after recovery (convalescents). The effect of the PreS1 fragment of HBV antigen on some neutrophil functions in vitro was also examined. There were significant differences in the values of spontaneous and stimulated oxidative burst of neutrophils, measured using luminol-chemiluminescence, in patients with HBV when compared with the convalescents. PreS1 antigen did not by itself induce the respiratory burst in human neutrophils but it potentiated their response to a second stimulus. Hence we observed a priming of neutrophils, for an enhanced respiratory burst, by PreS1 antigen.

Effect of pre-S1 antigen on human lymphocyte proliferative responses

The peripheral blood mononuclear cells (PBMCs) from patients acutely infected with HBV and recovered completely (n = 20), patients with chronic hepatitis B infection (CHB)- (n = 10) and HBsAg-positive carriers (n = 9) and healthy individuals (n = 8) were studied for their in vitro proliferative response to a synthetic pre-S1(20-49)x4 antigen. PBMCs from convalescents showed significant proliferative response in the presence of synthetic pre-S1 antigen. PBMCs from CHB- and HBsAg-positive exhibited reduced proliferative response not only to Pre-S1 antigen but also to nonspecific mitogens. This study suggests that the immune recognition of pre-S1 antigen and response of PBMCs to the pre-S1 antigen may be an important part of the normal human response to HBV infection. Failure to clear the HBV infection with development of the chronic carrier state may be caused by the lack of an efficient pre-S1 antigen-specific response.