Drug – bio-affecting and body treating compositions – Antigen – epitope – or other immunospecific immunoeffector
Reexamination Certificate
1997-10-24
2001-08-07
Stucker, Jeffrey (Department: 1648)
Drug, bio-affecting and body treating compositions
Antigen, epitope, or other immunospecific immunoeffector
C424S201100, C424S202100, C424S204100, C424S816000, C435S235100, C435S236000, C435S237000, C435S238000, C435S239000
Reexamination Certificate
active
06270770
ABSTRACT:
This application is a 371 of PCT/EP96/00122 filed Jan. 6, 1996.
The present invention is concerned with a live attenuated CAA vaccine.
Chicken anaemia agent (CAA) is the causative agent of a disease known as avian infectious anaemia, anaemia dermatitis syndrome or blue-wing disease and was first described by Yuasa et al. in 1979 (Avian Diseases 23, 366-385, 1979).
Most outbreaks of naturally occurring CAA-induced disease have been reported in broilers. The disease is acute and the first signs usually occur at 10-14 days of age. This clinical disease is characterized by a sudden increase in mortality, usually around 5-10%, but up to 60% has been reported. Peak mortality occurs within 5 to 6 days of onset of disease. Further clinical signs include depression and anorexia. Moreover, severe anaemia, hemorrhages throughout the body, atrophy of the thymus and bursa of Fabricius and yellowish bone marrow is seen in affected chickens McNulty, M. S., Avian Pathol. 20, 187-203, 1991).
The clinical syndrome in broilers occurs in commercial flocks when in-lay breeders with no previous exposure to the virus, i.e. seronegative breeders, become infected. CAA is transmitted vertically to the progeny, which develop the disease at 10 to 14 days. No clinical signs have been reported in the infected breeders, and there is no apparent effect on egg production, hatchability or fertility, because chicks develop an age resistance to CAA-induced disease.
The anaemia dermatitis syndrome in chickens caused by the vertical spread of CAA from the breeder through the egg to the progeny can be prevented by ensuring that the parent flocks develop antibodies to CAA before the onset of lay. This can occur through natural exposure of the flocks to the virus. However, due to the significant economical losses resulting from clinical CAA it is preferable to vaccinate the parent stock in order to induce a sero-conversion in breeder flocks during the rearing period. Older birds inoculated with the virus develop significant titers of neutralising antibodies at about 3 weeks after infection. These virus neutralizing antibodies are passed from the breeder to the progeny via the egg such that the chickens obtain a titer of maternal antibody which protects the young chickens against CAA infection during the first weeks after hatching.
Yuasa, N. et al. (Avian Diseases 24, 197-201, 1980) disclose that commercial chickens are generally refractory to CAA field infection and that this was closely related to the presence of maternal antibodies in the chick. Otaki, Y. et al. (Avian Pathology 21, 147-151, 1992) showed that even a very low level of maternal antibody is effective for preventing CAA-infection. Maternal antibodies could be detected up to 3 to 5 weeks of age. In a study using chickens with maternal derived antibodies (MDA) against CAA Yuasa, N. (Poultry Diseases, Proc. 2nd Asian/Pacific Poultry Health Conference, 385-406, 1988) has shown that the antibody-positive rate starts decreasing at about 3 weeks of age.
Vielitz et al. (J. Vet. Medicine 34, 553-557, 1987) describes a CAA vaccine comprising the not-attenuated Cux-1 anaemia pathogen suitable for vaccinating parent stock at the age of 13-15 weeks. Although chickens vaccinated intramuscularly with this vaccine developed antibodies 2 weeks after vaccination, in chickens vaccinated via drinking water antibodies were observed only from 4 weeks after administration of the vaccine.
Recently, the first live attenuated vaccine for administration to older birds has been disclosed in European patent application No. 0533294 (Akzo Nobel N. V.). Although this vaccine was able to elicit a sufficient amount of CAA neutralizing antibodies in these birds when administered parentally, vaccination with the live attenuated vaccine via the drinking water or spray route did not induce an adequate immune response (Steenhuisen, W. et al., International symposium on infectious bursal disease and chicken infectious anaemia, Rauischholzhausen, Germany, 1994).
In addition to the vertically spreading of CAA in chickens the virus also spreads horizontally. Horizontal spread in broilers probably occurs through ingestion of faecally contaminated material or contaminated fomites. Horizontal acquired infections in broiler progeny of immune breeder flocks also occur when MDA against CAA are declining. However, the effect of horizontal CAA infection in broilers is not clear.
McNulty et al. (Avian Diseases 35, 263-268, 1991) compared production and performance parameters of clinically normal broiler flocks which had antibody to CAA at slaughter with clinically normal broiler flocks which had no antibody to CAA at slaughter and reported that subclinical CAA in broilers of about 6 weeks of age was associated with significant economic losses. It was suggested to devise a live attenuated vaccine for broilers to decrease the losses associated with subclinical CAA. Contrary to this Goodwin, M. A. et al. (Avian Diseases 37, 542-545, 1993) found no differences in weight gain or production performance among healthy CAA-antibody positive and negative SPF chicks and broiler chicks.
The existence of a new type of health problems in broilers and its solution is for the first time disclosed herein. This type of problem can be observed in broilers from about 3 weeks of age and is characterized by the following symptoms:
an arrest of growth during the third or fourth week of age
a decrease of the feed-conversion
increased leg problems and lameness
slight increase of mortality towards the end of the growing period
pale appearance
undigested feed in the feaces. These problems resulted in successive production rounds with disappointing performance results in broiler farms with previous good performance records.
An object of the present invention is to provide a vaccine which is able to prevent this performance drop syndrome affecting broiler flocks during the growth period, taking into account that the vaccine must have a beneficial effect in the face of maternal antibodies.
A further object of the present invention is to provide a vaccine which is able to induce a beneficial response within a very short time after administration in order to prevent the early performance drop in broilers.
The present invention provides a vaccine for mucosal administration for the protection of broilers against production drop and comprising a live attenuated CAA virus and a pharmaceutically acceptable carrier.
It is surprising, that a live attenuated CAA vaccine for mucosal administration is able to stimulate the broiler's immune system within a very short time after administration, which is a prerequisite for an effective prevention of the production drop syndrome which affects the broilers already from about 3 weeks of age, because a CAA vaccine for parent stock derived from a virulent CAA, administered via the mucosal route, i.e. via drinking water developed an immune response only from 4 weeks onwards after administration (Vielitz et al., supra). In addition, with respect to the live attenuated CAA vaccine disclosed in EPA 0533294, it was demonstrated that such a vaccine in a form suitable for spray or drinking water administration did not induce an adequate immune response (Steenhuisen, W. et al., supra) in older birds.
The term broiler refers to a young, tender chicken, specially produced for the table. These fast growing chicks specially reared for the slaughter are the progeny of special types (heavy) breeder hens and cocks. For example, female broiler breeders are usually derived of the White Plymouth Rock-Sussex or New Hampshire breeds. Broiler breeder males are usually derived from the Cornish breed, such as Cornish Indian game.
The vaccine according to the present invention is in a form suitable for mucosal administration. This means that the vaccine is administered such that it is brought into contact with the broiler's mucosal membranes, for example of the respiratory tract, intestinal tract or the eye. Therefore, the vaccine can be applied intranasally, orally, intraocularly or intracloacal.
In a preferred em
Schrier Carla Christina
Van Dijk Pieter Matthijs
Akzo Nobel N.V.
Blackstone William M.
Nelson Brett
Stucker Jeffrey
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