| The surface antigen of Hepatitis B virus (HBV) contains three kinds of protein: large Hepatitis surface protein (L protein), middle Hepatitis surface protein (M protein) and small Hepatitis surface protein (S protein). The functions and the interaction with other HBV proteins of M protein are not clear. Because of the usefulness of transgenic model to identify the functions of genes, the transgenic mouse system of M protein may be an ideal experimental model to study the functions of M protein, which could provide new insight into it.In this study, the expression vector pcDNA3-S2-S, in which the CMV promoter controlled the expression of HBV pres2-s gene (ayw subtype), was microinjected into the male pronucleus of C57BL/6 mouse fertilized eggs. Fifty-eight effective microinjected fertilized eggs of the total 109 ones were implanted into 4 pseudopregnant recipients oviducts, of which 18 mice were borne with 14 survived. Four founders (F0 generation) were identified by PCR utilizing a set of specific primers for the target transgene. The integration frequency was 28.6%(4/14). In F07 founder, the 33kD M protein was detected by immunohistochemical staining and Western blot. Seven filial generation (F1 generation) mice were obtained by F07 copulated with normal mouse of the same linage, of which the target transgene were detected in six by PCR (85.6%). Four expressed M protein (66.7%) among the six F1 generation mice. Pathological changes were not observed in liver tissue of the transgenic mice expressed M protein, which indicated that the transgenic mice were immunotolerant to the M protein.These results suggest that pres2-s gene could be steadily inherited to the subsequent generations and express M protein. This transgenic mouse line is useful for studying the functions of the M protein and may be prospective to develop the therapeutic HBV DNA vaccine based on the pres2-s gene. |
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