Protection of rainbow trout against infectious hematopoietic necrosis virus four days after specific or semi-specific DNA vaccination

A DNA vaccine against a fish rhabdovirus, infectious hematopoietic necrosis virus (IHNV), was shown to provide significant protection as soon as 4 d a fter intramuscular vaccination in 2 g rainbow trout (Oncorhynchus mykiss) h eld at 15 degreesC. Nearly complete protection was also observed at later t ime points (7, 14, and 28 d) using a standardized waterborne challenge mode l. In a test of the specificity of this early protection, immunization of r ainbow trout with a DNA vaccine against another fish rhabdovirus, viral hem orrhagic septicemia virus, provided a significant level of cross-protection against IHNV challenge for a transient period of time, whereas a rabies vi rus DNA vaccine was not protective. This indication of distinct early and l ate protective mechanisms was not dependent on DNA vaccine doses from 0.1 t o 2.5 mug. (C) 2001 Elsevier Science Ltd. All rights reserved.