Differentiation of psittacine herpesvirus field isolates by restriction endonuclease analysis.

Thirty-one viruses were isolated from 15 different psittacine species. They were all identified as herpesviruses on the basis of chloroform sensitivity, inhibition of replication in cell cultures by 5-iodo-2'-deoxyuridine and morphology by electron microscopy. DNA from all 31 field isolates of psittacine herpesviruses (PsHV) was analysed by cleavage with restriction endonucleases EcoRI, PstI, and BglII. Using this technique, 12 different restriction patterns were recognizable. In previous work, we have differentiated PsHV strains according to their serological interrelationships. Restriction endonuclease profiles confirmed the results of conventional serogrouping but additional differences were observed among the five established serological subtypes. Using this method, it was possible to demonstrate a spontaneous reinfection of parrots in an aviary with a serologically and genetically different PsHV strain 4 years after the first outbreak of Pacheco's parrot disease (PPD). The results of this study reaffirm that antigenetically and genetically different PsHV exist and can cause PPD.