[Comparison of three strains of herpesvirus isolated from psittacine birds with the pigeon herpesvirus].

Two strains of herpesvirus isolated from psittacine birds in Belgium (PsiHV/B/Cu; Vindevogel et al., 1978) (PsiHV/B/U; Meulemans et al., 1978) and a third one isolated in Switzerland (PsiHV/S/1355; Ehrsam et al., 1978) were compared with the pigeon herpesvirus (strain PHV/B/Cu1; Vindevogel et al., 1975). On chick embryo fibroblasts, the cytopathic effect of strain PsiHV/B/Cu was focal whereas strains PsiHV/B/U and PsiHV/S/1355 showed a diffuse cytopathic effect. Also, under agarose overlay, the plaques of strain PsiHV/B/Cu and of pigeon herpesvirus were the same while those of PsiHV/B/U and PsiHV/S/1355 were significantly larger. Strain PsiHV/B/Cu is antigenically identical to pigeon herpesvirus but differs totally from strains PsiHV/B/U and PsiHV/S/1355. Conversely, the latter are antigenically identical but differ from strain PsiHV/B/Cu and from pigeon herpesvirus. The pigeon is susceptible to strain PsiHV/B/Cu but not to strains PsiHV/B/U and PsiHV/S/1355. According to our results, strain PsiHV/B/Cu is probably a strain of pigeon herpesvirus affecting also budgerigars and the strains PsiHV/B/U and PsiHV/S/1355 belong to the group of viruses inducing Pacheco's disease. The virus of Pacheco's disease and the pigeon herpesvirus would then belong to two separate groups of viruses with different biological and antigenic characteristics. Both can be isolated from sick psittacine birds but the pigeon is susceptible only to its own virus.