RESUMEN
<p><b>AIM</b>To detect the expression of hepatitis B virus (HBV) genes (HB S and C genes) in early embryonic cells after introducing motile human sperm carrying HBV DNA into zona-free hamster oocytes via the in vitro fertilization (IVF) technique.</p><p><b>METHODS</b>Human sperm-mediated HBV genes were delivered into zona-free hamster oocytes by the IVF method. Polymerase chain reaction (PCR) was used to detect HB S and pre-Core/Core (pre-C/C) coding genes both in one- and two-cell embryos. Reverse transcription-PCR (RT-PCR) analysis was used to study the expression of the two genes. Fluorescence in situ hybridization (FISH) analysis using the full-length HBV DNA as the hybridization probe was performed to confirm the integration of viral DNA in the host embryonic genome.</p><p><b>RESULTS</b>Both HB S and pre-C/C coding genes are present and transcribed in one- and two-cell embryos originated from hamster ova IVF with human spermatozoa carrying HBV DNA sequences.</p><p><b>CONCLUSION</b>Sperm-mediated HBV genes are able to replicate and express themselves in early embryonic cells. These results provide direct evidence that HBV DNA could transmit vertically to the next generation via the male germ line.</p>