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.

Canine parvovirus empty capsids produced by expression in a baculovirus vector: use in analysis of viral properties and immunization of dogs.

The VP-2 genes of canine parvovirus (CPV) and a recombinant consisting of CPV and feline panleukopenia virus (FPV) sequences were cloned into baculovirus expression vectors, fused to the baculovirus polyhedrin promoter. Recombinant baculoviruses were prepared and the properties of the parvovirus proteins expressed in insect cells examined. The proteins produced were the same size as the authentic CPV VP-2 protein, and were produced late after infection; the quantity of proteins recovered from the insect cell cultures was similar to those produced in CPV infections. Parvovirus particles formed had the haemagglutination (HA), sedimentation and buoyant density properties of authentic CPV capsids. Both the CPV capsids and the CPV-FPV recombinant capsids from the baculovirus system expressed the same epitopes as those seen in the viable parvoviruses when tested with a panel of anti-parvovirus monoclonal antibodies. Lysates of recombinant baculovirus-infected cells were inoculated into dogs, giving rise to serum neutralizing and HA-inhibiting antibodies, and the immunized dogs were protected from clinical disease upon challenge with a virulent isolate of the most recent antigenic type of CPV.

Genotypic variation among wild isolates of Heliothis spp nuclear polyhedrosis viruses from different geographical regions.

Ten nuclear polyhedrosis viruses infecting insect hosts in the genus Heliothis and isolated in different geographical regions of the world were characterized using restriction endonuclease analysis. Digestion of the dsDNA genomes with BamHI, EcoRI, and HindIII resulted in fragmentation profiles which separated the wild-type isolates into two major genotypes, corresponding with the morphology of the virion (multiply embedded major genotypes, corresponding with the morphology of the virion (multiply embedded vs singly embedded). Isolates within each major genotype have similar fragmentation profiles, showing only slight differences in the number and size of several fragments, and thus represent variants of the major genotype. Submolar fragments present in a number of the digests suggests that these wild-type isolates might themselves consist of two or more genotypic variants. The significance of this genotypic heterogeneity is discussed.