Initial SEM observations of Herpes simplex virus infected chicken chorioallantoic membranes.

Chorioallantoic membranes (CAMs) of 10 day old embryonated chicken eggs were experimentally infected with types 1 and 2 Herpes simplex virus (HSV) and observed by scanning electron microscopy. This preliminary report examined CAMs at time periods ranging from 30 minutes to 24 hours post-infection. Samples also were taken for transmission electron microscopy to correlate topographic alterations with ultrastructural changes. Uninfected control CAMs, throughout the study, consisted of a homogeneous population of flattened chorionic ectodermal cells whose surface were covered with uniformly distributed microvilli of varying lengths and fairly constant diameter. At thirty minutes post infection, irrespective of infecting herpes type, microvilli were markedly decreased in numbers with those remaining showing noted blunting. Later stages of infection with type 1 HSV strains showed a cytopathic process consisting of a generalized rounding of individual cells and the presence of cells apparently containing multilobulated nuclei. CAMs infected with type 2 strains demonstrated a more focal spread of infection and the presence of intranuclear filamentous structures by transmission electron microscopy.