Polyvalent recombinant Marek's disease virus vaccine against poultry diseases.

Abstract

In 1982, ) and constructed a recombinant vaccinia virus expressing a foreign gene, the thymidine kinase (TK) gene of herpes simplex virus (HSV), which was inserted into the nonessential regions of the virus genome by homologous recombination. Since then, a variety of foreign genes were inserted into large DNA viruses such as poxviruses and herpesviruses, and many attempts have been made to use recombinant viruses as polyvalent vaccines against human and animal diseases. Why are recombinant viruses expected to produce better vaccines against infectious disease? Firstly,polyvalent recombinant viruses may save labor for vaccination and cost for production. Secondly, a live vaccine is required for effective vaccination. It is especially important for pathogens which cannot grow in culture. In this case, the subunit vaccine and recombinant proteins have been developed against hepatitis B and malaria for human use. Insertion of the gene for protection against these diseases into virus vectors may produce better protective efficacy. In addition, care is taken to use the attenuated strain of pathogens for safety, especially for retroviruses, because of the increased virulency due to spontaneous mutation or the induction of cellular transformation by retroviral transduction of cellular oncogenes. RNA viruses generally produce much higher rates of spontaneous mutation than DNA viruses. In that respect, DNA viruses are preferable to use as virus vectors for recombinant vaccines. The rabies-recombinant vaccine using vaccinia virus as a virus vector is the most successful case in the veterinary field which has been used in Europe and North America (). This is mainly because it can be used as an oral vaccination and os heat-stable.