Chicken anaemia viruses of low pathogenicity
The present invention provides a new antigenic type of chicken anaemia viruses (CAV). The CAV according to this invention is isolatable from turkeys in the field and its virulence for chickens is significantly reduced. This property makes these viruses particularly suited for preparing a live vaccine for protecting poultry against disease conditions resulting from CAV infection.
1. A method for the preparation of CAV, comprising the steps of:
a. inoculating a susceptible substrate with the CAV,
b. propagating the virus, and
c. harvesting CAV containing material, wherein the CAV is an isolated chicken anaemia virus (CAV), wherein the virus is neutralized by a reference sample comprising monoclonal antibody R2 secreted by a hybridoma cell line, having the identifying characteristics of a sample deposited at the ECACC under accession no. 00020304 and the virus is not a chicken anemia agent (CAA) virus attenuated by passaging wild type CAA virus in embryonated chicken eggs, wherein the virus induces lesions in chicken embryos, and wherein the antibody titre of the reference sample is at least 5 (log 2) per 50 μl when examined against 300–1000 TCID 5 per 50 μl of the CAV.
2. A method for the preparation of a vaccine for protecting poultry against disease conditions resulting from a CAV infection, comprising the step of combining the harvested CAV containing material prepared according to the method of claim 1 with a pharmaceutically acceptable carrier or diluent.
3. The method according to claim 1 , wherein the titre of the reference sample against the CAV is at least 12 (log 2 ) per 50 μl when examined against 300–1000 TCID 50 per 50 μl of the CAV.
4. The method according to claim 1 , further comprising the step of inactivating the CAV.
5. The method according to claim 1 wherein the CAV has the identifying characteristics of the CAV strain 319, which is deposited at the ECACC under accession no. V00012608.
6. The method according to claim 1 wherein the CAV is CAV strain 319, which is deposited at the ECACC under accession no. V00012608.