Abstract: BACKGROUND ＆ AIM：Hepatitis B is a public health problem of worldwide importance. To explore feasibility of Hepatitis B virus(HBV) vertically transmitting via oocytes, the transfection of mouse oocytes with recombinant plasmid, pBR322-HBV was studied. MATERIAL AND METHODS： Genomic DNA was isolated and the metaphases were prepared, respectively from mouse oocytes co-cultured with pBR322-HBV DNA plasmids. PCR, Southern blot, Dot hybridization and FISH were performed to demonstrate if the mouse oocytes were transfected by pBR322-HBV plasmid. RESULTS: PCR detected positive bands in the tested samples, and then Southern blot revealed clear hybridization signal in above PCR products. Final washing solutions were collected for Dot hybridization and no signal for HBV DNA was observed, which excluded the possibility that contamination of washing solutions gave rise to positive results of PCR and Southern blot. FISH demonstrated that 36 of 1 000 metaphases presented positive signals. CONCLUSION: HBV DNA sequences were able to pass through the zona and oolemma to enter into oocytes and integrate into their chromosomes. It suggested that HBV DNA sequences might be brought into embryo via oocytes as vectors when they were fertilized with normal spermatozoa.

Key words: HBV DNA, transmission, mouse, oocyte, integration, chromosomes