Drug – bio-affecting and body treating compositions – Antigen – epitope – or other immunospecific immunoeffector
Reexamination Certificate
1998-04-09
2001-04-17
Schwartzman, Robert A. (Department: 1636)
Drug, bio-affecting and body treating compositions
Antigen, epitope, or other immunospecific immunoeffector
C424S209100, C435S320100, C435S348000, C435S349000, C536S023720, C536S024100, C536S024320
Reexamination Certificate
active
06217870
ABSTRACT:
INTRODUCTION
1. Technical Field
The present invention relates to novel proteins and/or polypeptides of the Chicken Anemia Virus (CAV) together with vaccines and compositions for preventing or treating virus infections in poultry, in particular infections with CAV.
2. Background
Day-old chicks are most susceptible to CAV infections. In these animals lethargy, anorexia and anemia are observed from 10 days after inoculation with CAV. After infection mortality may increase to a maximum of 50%. With increasing age the resistance also increases. Jeurissen et al. (1992) J. Virology 66:7383-7388 have reported that only the hematocrit values of chicks that had been infected with CAV at an age of 1-3 days are decreased. CAV infections of 1-21 days old chicks result in a depletion of in particular the thymus cortex. However, in older chickens CAV can subclinically multiply. CAV infection in older chickens can be determined by the occurrence of serum conversion (McIlroy et al., (1992) Avian Diseases 36:566-574).
The spread of CAV within a flock of chickens substantially occurs via contact infection. Most probable is ingestion of feces or other material contaminated with feces from CAV infected animals. Infection via the air, however, cannot be ruled out. Transmission of viruses to offspring via the egg is suggested by Yuasa et al., (1979)
Avian Diseases
23:366-385 but by way of experimental vertical transmission of CAV from mother animals to chicks could not be demonstrated by us.
Immune deficiency resulting from the CAV induced deletion of the thymus cortex is considered to be the cause of disease symptoms occurring after secondary infections of normally non-pathogenic agents (De Boer et al., (1992) In: Proceedings World's Poultry Congress Symposium, Amsterdam, The Netherlands, 1:262-271); Avian Diseases 33:707-713; Engström, (1988) Avian Pathology 17:23-32; Rosenberger and Cloud, (1989); Von Bülow et al., (1986) J. Vet. Med. B 33:717-726; Yuasa et al., (1980) Avian Diseases 24:202-209). Thus CAV is isolated in animals with Newcastle disease, Marek's disease, infectious bursitis (Gumboro) and in animals with ‘blue wing disease’ in association with retroviruses. CAV infections lead to increased inoculation reactions, e.g. against Newcastle disease virus.
Maternal antibodies have been found to give an important protection against CAV infection. A recent study under laboratory conditions has shown that maternal immune day-old chicks develop no CAV infection. Day-old chicks can also be protected passively by intravenous injection of antibodies from egg yolks of immune mother animals.
CAV can be multiplied in tissue culture, however, in general the titers so obtained are low. At present MDCC-MSB1 cells (Yuasa, (1983) National Institute of Animal Health Quarterly 23:13-20; Yuasa et al., (1983) ibid, 78-81) are used therefor, in which CAV induces a cytopathogenic effect 48-72 hours after infection. MDCC-MSB1 cells are also used to determine neutralizing antibodies and antibodies directed against CAV by means of immunofluorescence (Von Bülow et al., (1985) J. Vet. Medicine B 32:679-693; Chettle et al., (1991) The Veterinary Record 128:304-306). It has not been found possible so far to attenuate the virulence of CAV by serial passage in MDCC-MSB1 cells.
Older animals do not develop disease symptoms after CAV infection and chicks with maternal antibodies are protected. These data were used in Germany in a vaccination program based on controlled exposure to CAV of 14-16 weeks old mother animals. In the Netherlands this vaccination method is not allowed except at an experimental level because of the attendant risks. As mentioned above, it is quite possible that CAV can be transmitted to offspring via the fertilized egg. McNulty et al. (1991) Avian Diseases 35:263-268 have recently shown that flocks that are CAV seropositive have production numbers inferior to those of CAV seronegative flocks. Moreover, immune deficiency in chickens having a subclinical CAV infection has been shown. The possible vertical virus spread and the immune deficiency caused by CAV with (sub)clinical infections renders a control program based on an innocuous vaccine very desirable.
The Chicken Anemia Virus (CAV) is a recently characterized DNA virus (Noteborn and De Boer, (1990) Dutch Patent No. 9002008). It belongs to a new virus family. In young chickens CAV causes anemia by destruction of erythroblastoid precursor cells and immune deficiency by depletion of thymocytes. Lesions occur in the spleen and liver (Jeurissen et al.,, (1989) Thymus 14:115-123). A recent study has shown that the depletion of thymocytes is caused via apoptosis induced by CAV ((Jeurissen et al., (1992) J. Virology 66:7383-7388).
Gelderblom et al. (1989) Archives of Virology 109:115-120 and Todd et al. (1990) J. Gen. Virology 71:819-823 have shown by means of electron microscopic studies that CAV particles have a T3 icosahedron symmetry and a diameter of 23-25 nm. The CAV particles concentrate after equilibrium sedimentation at a density of 1.33-1.34 g/ml in CsCl.
Todd et al., (1990) supra have shown that isolated virus particles contain only one protein having a molecular weight of 50 kDa. The single-stranded DNA in the CAV particles is in the form of a circular minus strand (Gelderblom et al., (1989, supra; Todd et al., (1990) supra; Noteborn et al., (1991) J. Virology 65:3131-3139). The replicative DNA intermediary was cloned and fully sequenced. The CAV genome is 2319 nucleotides long. On the basis of the genome structure and the DNA sequence the virus cannot be placed into one of the known virus families (Noteborn et al.,, (1991) supra; Todd et al., (1991) Archives Virology 71:819-823). The CAV genome contains three large, partially or completely overlapping reading frames coding for possible proteins having molecular weights of 51.6, 24.0 and 13.3 kDa. The CAV genome moreover contains one evident promoter/enhancer region and only one polyadenylation signal. Transcription of the replicative DNA intermediary produces a polyadenylated polycistronic RNA molecule of approximately 2100 nucleotides (Noteborn et al., (1992) supra).
SUMMARY
Provided are methods and compositions derived from the Chicken Anemia Virus (CAV) for use in vaccines and other therapeutics, for example. The method of vaccinating host animals against CAV includes induction of neutralized antibodies by way of providing recombinantly produced VP1/VP2 compositions.
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Koch Guus
Noteborn Mathieu Hubertus Maria
Leadd BV
Rae-Venter Barbara
Rae-Venter Law Group
Sandals William
Schwartzman Robert A.
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