Chemistry: molecular biology and microbiology – Micro-organism – tissue cell culture or enzyme using process... – Recombinant dna technique included in method of making a...
Patent
1993-03-08
1996-02-13
Jones, W. Gary
Chemistry: molecular biology and microbiology
Micro-organism, tissue cell culture or enzyme using process...
Recombinant dna technique included in method of making a...
435 5, 4351723, 4352401, 4352523, 435320, 536 2372, 536 2432, 935 9, 935 66, 935 77, C12P 2106, C07H 2102, C07H 2104, C12N 500
Patent
active
054910730
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention is in the fields of genetic engineering (gene manipulation) by means of the recombinant DNA (and RNA) technology, diagnostics and immunization/vaccination. More in particular, the invention relates to the detection, cloning and sequence analysis of the Chicken Anaemia Virus (CAV) DNA genome and applications thereby made possible.
BACKGROUND OF THE INVENTION
The CAV virus that has not been classified so far causes infectious anaemia in chicken. The virus was first isolated in Japan in 1979 and was given its name because of the serious anaemia caused by it in young chicks (Yuasa et al, 1979). The other symptoms of CAV infection are the atrophy of the bone marrow and destruction of lymphocytes in the thymus. Lesions occur in the spleen and liver.
Day-old chicks are most susceptible. In these animals lethargy, anorexia and a passing aneamia are observed from 4 to 7 days after inoculation with CAV and about half of the animals die between 2 and 3 weeks after infection. With increasing age the natural resistance also increases. Upon infection at the age of seven days the chicks only develop a passing anaemia after infection, and upon infection of 14 days old animals no anaemia follows.
Protection against CAV infection and CAV disease symptoms is highly based on humoral immunological defence mechanisms. Vielitz (1989) developed a practical, rather effective method of prevention by means of a "controlled exposure" with CAV-infected liver suspensions in layers, the offspring thus acquiring maternal immunity. In Germany this method of immunization is used in practice, but it does not seem to be quite risk-free.
Animal experiments conducted in isolated poultry houses with the Centraal Diergeneeskundig Instituut (CDI) at Letystad have confirmed the protective value of maternal antibodies. Here the "controlled exposure" was carried out with CAV multiplied in tissue culture. The presence of maternal antibodies against CAV fully prevented the CAV replication upon infection of day-old chicks from thus vaccinated mother animals. The CAV symptoms did not occur either. This passive protection was also obtained in offspring of immunized layers and also after injection of specifically pathogen-free (SPF) chicks with yolk extracts of eggs of the same immunized layers. The passive protection with respect to CAV infection by means of administration of CAV antibodies lasted until the age of 4 weeks. Then the passive protection was found to be incomplete. These experiments showed that maternal antibodies produced by vaccination of mother animals will play an important preventive role in the practical situation.
It has also been demonstrated by way of experiment that in chicks that survive the CAV infection a passing depletion of a specific population of thymus lymphocytes occurs (Jeurissen et al, 1989). The thymus atrophy is the possible cause of the immunodepression causing CAV, resulting in that specific vaccinations are less effective, e.g. against Newcastle Disease. CAV has been isolated several times in flocks with increased losses owing to Marek's disease, Gumboro's disease (Infectious Bursal Disease Virus, IBDV; Yuasa et al, 1980) and in animals with Blue Wing Disease in association with reoviruses (Engstrom, 1988a, Engstrom et al, 1988b). With experimental double infections the enhancing properties of CAV with respect to other chicken viruses (e.g. Marek's Disease Virus, MDV, De Boer et al, 1989a) have been demonstrated. Recently a sharply increased inoculation reaction was observed in our own experiments after aerosol vaccination with Newcastle Disease vaccine and simultaneous CAV infection. CAV therefore leads to immunosuppressive and enhancing effects on other virus infections. These properties of CAV probably cause an increased incidence of virulent disease outbreaks in practice.
CAV seems to be spread all over the world. A considerable time after the CAV research had started in Japan the first CAV isolations were conducted in Europe, namely in Germany by Von Bulow (1983) and la
REFERENCES:
D. Todd et al. J. Gen Virol 71, pp. 819-823 (1990) "Purification and biochemical characterization of chicken anaemica agent".
C. Woolston et al.--Plant Molec. Biol., 11, pp. 35-43 (1988) "Agroinfection and nucleotide sequence of cloned wheat dwarf virus DNA".
W. Rohde et al--Virology, 176, pp. 648-651 (1988) "Nucleotide Sequence of a Circular Single-Stranded DNA Associated with Coconut Foliar Decay Virus".
Claessens J of General Virology (Aug. 1991) 72:2003-2006.
D. Hanold et al. J. Gen. Virol., 69, pp. 1323-1329 (1988) "The Use of Cloned Sequences for the Identification of Coconut Foliar Decay Disease-Assocaited DNA".
Biological Abstracts, Abstract No. 68423, vol. 90, 15 Sep. 1990 McNulty et al.
Biological Abstracts, Abstract No. 68424, vol. 90, 15 Sep. 1990 Todd et al.
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Pallister et al. Veterinary Microbiology (1994) 39:167-178.
de Boer Gerben F.
Noteborn Matheus H. M.
Aesculaap B.V.
Jones W. Gary
Myers Carla
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