Clone, Purification And Expression Of Variant HBV S Gene

Hepatitis B (HB) an serious infectious disease posed a great threaten to human health is caused by hepatitis virus , which is a kind of Hepadnaviridae, not only can cause acute and chronic viral hepatitis, but also has a close relationship with liver cirrhosis(LC) and the development of hepatoma.. The domestic incidence is higher about 50-70% of the population.has been exposed to the infection of HBV, and approximately 8-12% people are HBsAg carrier, the total population of them amount to as much as one hundred million .So the HBV prevention and control is of significance in public health of our country. However, available vaccines have been used to prevent HBV infection, in fact, the incidence and mortality have been decreased efficiently by inocula-tion in the epidemic area of the world. With the increase inoculating of Hepatitis B vaccines and the appearance of some HBV variants, we should be alert to the S gene variant which can escape the HBV neutralization antibody.At present, the variants with HBsAg'a'epitope mutation has been discovered in the inoculated and patient with HBV liver graft who had received the HB immune globulin(IG)therapy as repor-ted in some research reports. .Studies indicated that the neutralization antibody produced by common vaccine was inefficient to these variants. The further sequence analysis reveals that the DNA region which code the HBsAg'a'epitope with the single nucleotide mutation (G587A), and this results in the point ami-no acid mutation (G145R) of HBV S gene. The mutation region may well be an important epitope that combine with the antibody induced by vaccine, so the variants can't be identified by neutralization antibody. Even Five years later the variants can still be detected in patients, this indicates that this mutation is replicable and the inheritance of these variants was stable. One study about intra-family infection reveals that such mutation has the ability to transmit to wild type HBV carrier or others via vertical transmission and horizontal transm-ission. This results in the inapparent infection by variant and combined infecti-on with wild type and mutat. Although as a common index to HBV infection HBsAg has been confirmed, HBsAg can't be detected in the variant HBV car-rier by common immunological methods, that's what we are worried. This variant carrier may exist in blood donors, so it's urgent to identify promptly and correctly such variants with HBsAg'A'epitope mutation infection.