Characterization of transgenic mice lineages. II. Transgenic mice expressing HBsAg particles and showing female sterility

The tissue specificity of the expression of the hepatitis B surface antigen (HBsAg) in transgenic mice was studied. Northern blot hybridization and electron microscopy of various tissues revealed the higher HBsAg transcription levels confined to the liver and kidney, and to a lesser extent to the spleen and intestines. In electron microscopic studies we found HBsAg particles in the serum of transgenic animals to be positive by ELISA to HBsAg. The expression of the transgene was localized in situ in the ovary, liver, kidney, and spleen of transgenic mice, employing a polyclonal antiserum directed against the HBsAg and conjugated with protein A-gold. Surprisingly, F1 transgenic females from the CB-104 line, expressing HBsAg in the serum, showed impaired fertility, although the ovarian function was not diminished. Normal off-spring were obtained after cross embryo transfer between transgenic (Tg) females to non-transgenic (Ntg) recipients or from Ntg embryos transferred to Tg recipients. We speculate that this phenomenon could be related to a disruption on a gene(s) somehow involved in the reproductive performance of the transgenic females.