A comparison of titration methods for live avian encephalomyelitis virus vaccines
Nicholas, R.A.; Hopkins, I.G.; Southern, S.J.; Thornton, D.H.
Developments in Biological Standardization 64: 207-212
1986
ISSN/ISBN: 0301-5149 PMID: 3025040 Document Number: 269768
Factors associated with the indirect fluorescent antibody test used for titrating avian encephalomyelitis virus (AEV) in chick-embryo brain cell cultures were examined for their influence on virus replication. Virus should be inoculated on to semi-confluent cell cultures and adsorbed for two hours at room temperature. The cells should then be examined for fluorescence after five days' incubation. With live commerical AEV vaccines, titres obtained by the chick assay were usually slightly higher than those obtained in the cell culture assay, although the reliability of the chick assay was, at times, questionable. In all cases titres obtained in the embryo assay were low. It is recommended that the cell culture assay be adopted for titrating AEV vaccines because it is rapid, reproducible, specific and greatly reduces the requirement for experimental animals.