Abstract The invention relates to a highly immunogenic virus preparation derived by attenuation employing serial passages in avian cell cultures and six plaque purification steps from a Marek's disease virus strain, belonging to Avian Herpesvirus serotype-1. The original virus strain MDV CVI-988 was recovered from a healthy chicken (Avian Diseases 16: 108-125, 1972). The live purified Marek's disease vaccine so obtained is innocuous for specific pathogen free Rhode Island Red chickens which are highly susceptible for development of Marek's disease tumors. The monovalent virus preparation, according to the invention, demonstrated in comparison with Marek's disease vaccines based on the same strain, currently in use at a lower cell passage level, an improved protective efficacy against challenge infection by two representatives of virulent Marek's disease virus. The monovalent virus preparation, according to the invention, provided significantly better protection than current MDV CVI-988 vaccine to challenge infection with a representative of the group of newly emerging very virulent strains of Marek's disease virus, MDV RB/1B. The monovalent virus preparation, according to the invention, provided significantly better protection than is HVT FC126 vaccine to challenge infection with another representative of the group of very virulent MD viruses, MDV Tun.
A virus preparation comprising a live viral clone of Marek's Disease virus, said clone being of the virus MDV CVI-988 CEF 65 clone C.
Claim 2
Dependent Claim
24 words
A virus preparation comprising a live viral clone of Marek's Disease virus, said clone being of the virus MDV CVI-988 CEF 65 clone C.
Claim 3
Dependent Claim
27 words
A virus preparation comprising a live viral clone of Marek's Disease Virus, said clone being selected from the group consisting of MDV CVI-988 CEF 65 clone C.
Claim 4
Dependent Claim
27 words
A virus preparation comprising a live viral clone of Marek's Disease Virus, said clone being selected from the group consisting of MDV CVI-988 CEF 65 clone C.
Claim 5
Dependent Claim
20 words
The preparation of claim 2, which does not comprise any Marek's disease virus belonging to Avian herpesvirus serotype-2 or serotype-3.
Claim 6
Dependent Claim
29 words
A method of immunizing chickens against Marek's disease caused by virus strains belonging to avian herpesvirus serotype-1, which comprises inoculating the chickens with a virus preparation of claim 2.
Claim 7
Dependent Claim
15 words
The method of claim 4 in which the virus preparation is administered intramuscularly or subcutaneously.