Comparison of cultural methods for primary isolation of infectious laryngotracheitis virus from field material

Primary isolation of infectious laryngotracheitis virus (ILT) from tracheal samples from 11 suspected field outbreaks was attempted using a variety of avian cell cultures, Vero cells and embryonated chicken eggs. Tracheal smears of each field sample were also examined by electron microscopy (EM) for the presence of herpesvirus particles. Chick embryo liver cells (CELi) appeared to be the most rapid and sensitive isolation system of those examined with chick kidney (CK) a satisfactory alternative, both demonstrating virus in all 11 samples on first passage. Chick embryo kidney, chick embryo lung and the dropped chorioallantoic membrane of eggs were all less sensitive. Chick embryo fibroblasts and Vero cells were of no particular value for the primary isolation of ILT virus. EM was a useful method of rapid virus identification and confirmation but at least 3.51og10/0.1ml of infectious virus was required to be detected by this method.