Drug – bio-affecting and body treating compositions – Antigen – epitope – or other immunospecific immunoeffector – Recombinant virus encoding one or more heterologous proteins...
Reexamination Certificate
1999-03-18
2001-10-02
Salimi, Ali R. (Department: 1648)
Drug, bio-affecting and body treating compositions
Antigen, epitope, or other immunospecific immunoeffector
Recombinant virus encoding one or more heterologous proteins...
C424S233100, C424S185100, C424S184100, C424S186100, C424S001210, C424S204100, C435S320100, C435S235100, C536S023720, C536S023100
Reexamination Certificate
active
06296852
ABSTRACT:
FIELD OF INVENTION
This invention relates to delivery vectors for antigen producing genes (heterologous gene sequences) used to generate immune responses in commercial poultry flocks susceptible to decimation by disease. Such vectors are especially useful for the preparation of vaccines which can be easily administered on a large scale to protect poultry flocks against disease. This invention also relates to a method of production of suitable delivery vectors, to methods of preparation of vaccines based on the vectors, to administration strategies and to a method of protecting poultry from disease.
BACKGROUND OF THE INVENTION
The productivity of the intensive poultry industry depends on the control of infectious diseases. In Australia the cost of disease to industry is conservatively estimated at $50 million annually. Whilst diseases can be controlled in part by good hygiene and quarantine measures, the industry must still rely on vaccination to protect flocks. In a commercial situation the difficulty and cost in the administration of suitable preventative or curative agents or adjuvants is caused by the sheer number of poultry to be treated. Thus, vaccines must be cheap, effective and easy to deliver.
Conventionally, vaccines constituting live viral particles have been prepared by virus passage and selection of attenuated forms. Alternatively, killed vaccines were prepared from virulent viruses.
One recent attempt to vaccinate commercial bird flocks against a common viral infection is that described in AU-A-34353/93 (VIROGENETICS CORPORATION). This application describes a recombinant poxvirus such as vaccinia virus or fowlpox virus containing heterologous DNA from the Marek's disease virus which is used as a vaccine to induce an immunological response in a host animal. However, the use of poxviruses has the disadvantage that the immune response of poultry is not sustained sufficiently long enough to generate adequate protection. Particularly, the immunoprotection generated may not be sufficient to protect a bird once maternal antibody has ceased to play a role in antibody mediated immunity.
A different approach has been taken by a group at Medisorb Technologies, Inc., in the U.S. as reported in the journal
Genetic Engineering News
September 1993. This approach used a conventional Salmonella vaccine encapsulated in a biodegradable microsphere based on polylactic-colycolic acid. The approach requires, however that the microsphere be injected into the bird. This approach is not necessarily commercially feasible for large flocks.
It is thus an aim of this invention to provide a delivery vehicle for heterologous sequences of genetic material that is particularly suited to administration on a large scale.
In particular, it is an aim of this invention to provide or enhance means for the generation and/or optimization of antibodies and/or cell-mediated immunity so as to provide protection against infection with common avian diseases, which means is quickly and effectively administered, particularly to large flocks of poultry, that is, to provide or enhance means for the induction of an antibody response and/or cell mediated response in a recipient which affords the recipient protection against infection with common avian diseases. It is an additional aim to provide a process for preparation of a suitable means for the induction of an antibody response and/or cell mediated immune response so as to protect birds against infection with common avian diseases. It is a further aim to provide a protection strategy.
SUMMARY OF INVENTION
The invention provides, in one embodiment, a recombinant avian adenovirus capable of expressing DNA of interest, said DNA of interest being stably integrated into an appropriate site of said recombinant avian adenovirus genome.
In another embodiment the invention provides a recombinant vector comprising a recombinant avian adenovirus which incorporates at least one heterologous nucleotide sequence. Preferably the heterologous nucleotide sequence is capable of expression as an antigenic polypeptide and/or an immunopotentiating molecule.
In another embodiment the invention provides an immunogenic composition comprising at least one recombinant avian adenovirus vector incorporating and expressing at least one heterologous coding sequence and suitable carriers and/or excipients.
It is to be understood that an immunogenic composition includes a vaccine, and it is capable of inducing an antibody response and/or a cell mediated response affording immune protection to the recipient. It is also understood that an immunogenic composition can provide long term protection.
The antigenic polypeptide encoded by the at least one nucleotide sequence is preferably foreign to the host vector.
The recombinant vector may comprise an infectious live recombinant avian adenovirus in which the virion structural proteins are unchanged from those in the native avian adenovirus from which the recombinant avian adenovirus is produced.
The invention is predicated upon the discovery that certain regions of the Fowl Adenovirus genome has unique properties. In particular, the major late promoter and leader sequences are quite dissimilar to equivalent regions in Adenoviruses previously characterized. It has surprisingly been discovered that the leader sequence is a dipartite leader sequence. It is also surprising, based on knowledge of human adenoviruses that there are nonessential regions in the fowl Adenovirus genome which do not correspond to those characterized previously in other Adenoviruses thus making this virus particularly suited to delivery of heterologous sequences.
This invention is further predicated on the discovery that the Avian adenovirus generates a prolonged response in poultry thus making it well suited as a vaccine vehicle. Furthermore, the existence of a number of serotypes of varying virulence allows the selection of a vaccine vehicle suited to the level of immune response required.
Adenoviruses are a large and diverse family, having been isolated from many living species, including man and other mammals, as well as a variety of birds, particularly chickens [Wigand, R., Gelderblom, H. and Ozell, M. (1977) Biological and biophysical characteristics of mouse adenovirus, strain FL. Arch,
Virol.
54:131-142]. As a result, adenoviruses have been separated into two different genera, one group has a mammalian host range (Mastadenoviradae) and the other an avian host range (Aviadenoviradae). Because the avian adenovirus serotypes are only very distantly related to mammalian adenoviruses a knowledge of the latter is only partially instructive in relation to the former. The avian adenoviruses show only very limited DNA homology with human adenoviruses [Alestrom, P., Stenlund, A., Li, P., Bellet, A. J. D. and Pettersson, U. (1982) Sequence homology between avian and human adenoviruses.
J. Virol.
42:306-310] with fowl adenovirus (“FAV”) genomes being some 10 kilobases larger than the human adenovirus genome. The classification of these viruses as adenoviruses is based solely on morphological and structural similarities.
The genus Aviadenovirus is currently divided into five species groups: fowl, turkey, goose, pheasant and duck adenoviruses. Fowl adenoviruses were first recognized in the 1950s when they were isolated as a consequence of using embryonated eggs and cell cultures with FAV [Van Den Ende, M., Don, P. A. and Kipps, A. (1949) The isolation in eggs of a new filterable agent which may be the cause of bovine lumpy skin disease.
J. Gen. Micro.
3:174-182; Yates, V. J. and Fry, D. E. (1957) Observations on a chicken embryo lethal orphan (CELO) virus (serotype 1).
Am. J. Vet. Res.
18:657-660]. However, the only fowl adenovirus upon which some molecular study has been undertaken is the oncogenic FAV, chicken embryo lethal orphan (CELO). The CELO virus genome is almost 30% longer than that of human adenoviruses (HAV) [Laver, W. G., Bandfield-Younghusband, H. and Wrigley, N. G. (1971) Purification and properties of chick embryo le
Johnson Michael A.
Lowenthal John W.
McCoy Richard J.
Prideaux Christopher T.
Commonwealth Scientific and Industrial Research Organisation
Greenlee Winner and Sullivan P.C.
Salimi Ali R.
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