Replication of infectious laryngotracheitis virus in a quail cell line, QT-35

The relative resistance of the quail fibroblastic cell line QT-35 to infection by infectious laryngotracheitis virus (ILTV) was circumvented by the continual passaging of infected cells in the presence of uninfected monolayers. Such virus-containing cells were used to extend the infection to an otherwise refractory quail liver cell line IQ1A, as well as to a normally permissive chicken liver cell line LMH, with nearly equal efficiency. In contrast, extracellular virus that had been derived from either QT-35 or IQ1A cells could not readily infect either quail cell line, although LMH cells were still susceptible. Therefore, the block to ILTV replication in quail cells is probably at the adsorption/penetration stage.