Efficacy of a recombinant fowl pox-based Newcastle disease virus vaccine candidate against velogenic and respiratory challenge.

A fowl pox-based recombinant virus TROVAC-NDV (vFP96.5) was developed expressing the fusion and hemagglutinin-neuraminidase glycoproteins from a velogenic strain of Newcastle disease virus (NDV). Studies in specific-pathogen-free birds indicated that inoculation of a single dose of the recombinant led to the induction of significant levels of hemagglutination-inhibiting antibody that were maintained to 8 wk postinoculation. Further, the recombinant induced protective immunity against a combined intramuscular velogenic NDV challenge and respiratory NDV challenge. In commercial broiler chickens that were inoculated in the presence of maternally derived NDV immunity, the level of the NDV-specific humoral response was dampened, but significant levels of protection against both a lethal intramuscular NDV challenge and a fowl poxvirus challenge were obtained.

Herpesvirus of turkey recombinant viruses expressing infectious bursal disease virus (IBDV) VP2 immunogen induce protection against an IBDV virulent challenge in chickens.

Two recombinant herpesviruses of turkey (HVT) expressing the VP2 protein of infectious bursal disease virus (IBDV or Gumboro disease virus) have been constructed: vHVT001 and vHVT002. The VP2 open reading frame was inserted at the locus of the small subunit of ribonucleotide reductase gene (HSV-1 UL40 homolog) without any exogenous promoter in vHVT001 and at the locus of gl gene (HSV-1 US7 homolog) under the control of the human cytomegalovirus immediate-early promoter in vHVT002. The isolation of these recombinant viruses indicated that the deleted genes were not required for replication of HVT in chicken embryo fibroblasts. Efficacy of these recombinant viruses against IBDV strain 52/70 and Marek's disease virus (MDV strain RB1B) virulent challenges was evaluated in chickens vaccinated at 1 day of age. In the IBDV challenge, a good protection against mortality and bursal gross lesion was observed in vHVT002-vaccinated chickens: 100% with 10(5) PFU dose and 60% with 10(4) PFU dose; in contrast, only a weak level of protection was achieved after vaccination with vHVT001. Protection levels against MDV challenge obtained with vHVT001 and vHVT002 were low (around 10%) compared to that induced by the parental HVT (84%). In spite of the low protection level against MDV, this is the first report which describes induction of full protection against IBDV with a single inoculation of a recombinant virus.

Newcastle disease virus (NDV) vaccine based on immunization with avian cells expressing the NDV hemagglutinin-neuraminidase glycoprotein.

Newcastle disease virus (NDV) is a paramyxovirus that bears two envelope glycoproteins at the virion surface. These proteins, fusion and hemagglutinin-neuraminidase (HN), are involved in the immune response against NDV infection. Recombinant cells constitutively expressing at their surface the HN protein from the velogenic Texas strain were generated by introducing the HN gene with a helper-free AEV-based vector. These recombinant cells were used to immunize chickens by various protocols, and birds were subsequently challenged with a lethal NDV injection. Both NDV protection and serologic response were observed.

Protection of chickens with a recombinant fowlpox virus expressing the Newcastle disease virus hemagglutinin-neuraminidase gene.

A recombinant fowlpox virus expressing the hemagglutinin-neuraminidase (HN) protein of Newcastle disease virus (NDV) strain Texas was generated. Immunoprecipitation with chicken anti-NDV serum confirmed authentic expression of the HN protein. Protection of chickens from infection with NDV was observed when birds were immunized with the recombinant HN fowlpox virus by the intramuscular route after one or two inoculations. Vaccination by the ocular route with a mixture of fowlpox recombinants expressing the fusion and HN proteins did not show added protection over that seen with the individual viruses.

Newcastle disease virus fusion protein expressed in a fowlpox virus recombinant confers protection in chickens.

A cDNA copy of the RNA encoding the fusion (F) protein of Newcastle disease virus (NDV) strain Texas, a velogenic strain of NDV, was obtained and the sequence was determined. The 1,792-base-pair sequence encodes a protein of 553 amino acids which has essential features previously established for the F protein of virulent NDV strains. These include the presence of three strongly hydrophobic regions and pairs of dibasic amino acids in the pentapeptide Arg-Arg-Gln-Arg-Arg preceding the putative cleavage site. When inserted into a fowlpox virus vector, a glycosylated protein was expressed and presented on the surface of infected chicken embryo fibroblast cells. The F protein expressed by the recombinant fowlpox virus was cleaved into two polypeptides. When inoculated into susceptible birds by a variety of routes, an immunological response was induced. Ocular or oral administration of the recombinant fowlpox virus gave partial protection, whereas both intramuscular and wing-web routes of inoculation gave complete protection after a single inoculation.

Isolation and characterisation of an adenovirus isolated from Muscovy ducks.

A virus isolated from Muscovy ducks can be classified as an adenovirus on chemical and morphological grounds. It shares the avian group antigen and is not related to 12 fowl, two turkey and one duck prototype strains of adenovirus. The virus grows well in cells of duck and fowl origin, and is probably a new duck adenovirus serotype.

Vaccination of one-day-old chicks against newcastle disease using inactivated oil adjuvant vaccine and/or live vaccine.

One-day-old chicks, with or without maternal antibodies against Newcastle disease, were vaccinated by different methods: one group received a live vaccine (Hitchner B1 strain), the second group an oil-adjuvant vaccine, and the third group both vaccines simultaneously. The serological response and the protection of the chicks against challenge were evaluated regularly up to 80 days of age. The best results were obtained when using both vaccines, which induced a good level of protection against the challenge virus strain.