Introduction of the human lactoferrin gene into grass carp (Ctenopharyngodon idellus) to increase resistance against GCH virus

Haemorrhage can be an epidemic and fatal condition in grass carp. It is known now that the Grass Carp Haemorrhage Virus (GCHV) triggers haemorrhage. Human lactoferrin (hLF) plays an important role in the non-specific immune system, making some organisms more resistant to some viruses. Sperm of grass carp was mixed with linearized pCAhLFc, which is a DNA construct containing an hLF cDNA and the promoter of common carp beta-actin gene, and then electroporated. Then, mature eggs were fertilized in vitro with the treated sperm cells. The fry were sampled and analyzed by polymerase chain reaction (PCR). Results indicated that the foreign gene had been transferred successfully into the cells of some fry. Under optimal electroporation conditions, the efficiency of gene transfer was as high as 46.8%. About 35.7% of treated 5-month-old grass carp contained foreign genes. Most transgenic fry demonstrated significant delays in onset of symptoms of haemerrhage after injection of GCHV, suggesting a significant positive relationship between hLF cDNA and levels of disease resistance (P < 0.01). Results suggest that transgenic grass carp could be bred for increased resistance to haemorrhage. (C) 2002 Elsevier Science B.V. All rights reserved.