Induction of interferon synthesis in rainbow trout leucocytes by various homeotherm viruses

Interferon synthesis by leucocytes from rainbow trout kidney was induced in vitro by contact with various viruses. The best inducer found was Newcastle disease virus (NDV), followed by two coronaviruses (porcine TGEV and a bovine coronavirus). Interferon was also produced by leucocytes stimulated with viral haemorrhagic septicaemia virus-infected and glutaraldehyde-fixed cells, but the titre was much lower. The secretion of interferon stimulated by NDV was detectable 24 h after induction. The interferon so obtained protected young trout against VHSV when injected at the time of infection.