Detection and heterogeneity of herpesviruses causing Pacheco's disease in parrots

Pacheco's disease (PD) is a common, often fatal, disease of parrots. We clo ned a virus isolate from a parrot that had characteristic lesions of PD. Th ree viral clones were partially sequenced, demonstrating that this virus wa s an alphaherpesvirus most closely related to the gallid herpesvirus 1. Fiv e primer sets were developed from these sequences. The primer sets were use d with PCR to screen tissues or tissue culture media suspected to contain v iruses from 54 outbreaks of PD. The primer sets amplified DNA from all but one sample. Ten amplification patterns were detected, indicating that PD is caused by a genetically heterogeneous population of viruses. A single gene tic variant (psittacid herpesvirus variant 1) amplified with all primer set s and was the most common virus variant (62.7%). A single primer set (23F) amplified DNA from all of the positive samples, suggesting that PCR could b e used as a rapid postmortem assay for these viruses. PCR was found to be s ignificantly more sensitive than tissue culture for the detection of psitta cid herpesviruses.