TRANSIENT EXPRESSION OF HEPATITIS-B VIRUS SURFACE-ANTIGEN (HBSAG) ANDHUMAN ERYTHROPOIETIN (HEPO) GENES IN MILK AFTER DIRECT INTRODUCTION INTO EWE

The ability to deliver nonviral DNA directly into animals would provid e major practical and economic benefits. To pursue this potential, as a preliminary approach, the expression in mammary epithelial cells wit h nonviral DNA encoding HBsAg and hEPO was investigated by in vivo, de livery directly into mammary gland. Either the bovine alpha s1-casein- HBsAg or the WAP-hEPO gene construct was introduced into mammary gland s of dose by mammary artery injection. A single injection of 10(11) co pies of DNA construct was implemented for a doe. Transient expression of the constructs in milk collected from milk letdown by induction up to 19 d after injection was measured with an hEPO ELISA kit from Boehr inger Mannheim (Cat. No. 1 693 417) for rhEPO, and a HBsAg-ELISA kit ( Abbott Lab, USA) for rHBsAg. The treated animals showed mean concentra tion oi recombinant molecules at 16 mu g/L for rHBsAg, and 2 mg/L for rhEPO in milk.