Submitted to: American Association of Avian Pathologists
Publication Type: Abstract Only
Publication Acceptance Date: 12/21/2012
Publication Date: 7/21/2013
Citation: Dunn, J.R., Auten, K.A., Heidari, M. 2013. Positive correlation between replication rate and pathotype of Marek’s disease virus strains in maternal antibody negative chickens [abstract]. American Association of Avian Pathologists, July 19-23, 2013, Chicago, Illinois. p. 34.
Technical Abstract: Pathotyping of new field strains of MDV requires both a long period of time and a large number of birds. Confirming a positive correlation of virus replication and pathotype may lead to faster and cheaper alternative pathotyping methods or as a screening assay for choosing isolates to be pathotyped. Past studies have found differences in replication rates between selected vMDV and vv+MDV, but this correlation has not been evaluated using a broad selection of virus strains. Our first trial evaluated replication rates of five virus strains from each virulent pathotype (v, vv & vv+) using maternal antibody positive chickens show very little difference in lymphoid atrophy between groups and mild differences between replication rates by pathotype. The current trial evaluated differences using maternal antibody negative chickens. We found a significant increase in viral load in brain, bursa and lung tissue at days 9 and 11 post challenge for vvMDV and vv+MDV strains compared to vMDV strains. No significant difference was seen between vvMDV and vv+MDV strains. Similar results were seen comparing lymphoid atrophy between pathotype groups. Using these results, it may be possible to determine a replication rate threshold as a preliminary screen to separate vMDV from vv/vv+MDV field strains.