Herpesviruses of birds--a review.

The family of herpesviridae is divided into the subfamilies alpha-, beta- and gammaherpesvirinae. Members of the alphaherpesvirinae (infectious laryngo-tracheitis in gallinaceous birds and duck viral enteritis in waterfowl) may cause substantial economic and ecological losses. Marek's disease and turkey herpesviruses are the only members of the gammaherpesvirinae. Most herpesviruses from free-living and pet birds are tentatively classified as bctaherpesvirinae. These may induce diseases, with variably non-specific clinical signs but including respiratory distress, ocular lesions, enteritis and liver involvement. Prominent pathological lesions consist either of haemorrhages on respiratory or intestinal epithelium or of multi-focal necrotic lesions in livers, spleen and bone marrow. At least four different plaque types of betaherpersvirinae can be differentiated in infected chick embryo fibroblasts or chick kidney cell cultures. Infectivity may be cell-associated or detectable in supernatant fluids and transformed cultured cells. All avian herpesviruses are presently grouped on the basis of results of cross neutralisation tests into 11 different serotypes.