One hundred and three isolates of aquatic birnaviruses (ABV) belonging to all 9 serotypes of serogroup A were tested for their ability to grow in 4 continuous cell lines derived from salmonids and non-salmonids. All 103 isolates replicated and produced rapid and extensive cytopathogenic effects (CPE) in the salmonid cell lines derived from chinook salmon (CHSE-214) and rainbow trout (RTG-2), whereas only half produced visible CPE in two non-salmonid cell lines tested (from carp (EPC) and minnows (FHM)) in 7 days. There was a significant positive correlation between the level of CPE and the virus titer produced in the infected cells. In addition, it was found that 19/46 isolates that failed to produce CPE in EPC and FHM cells at 7 days post-infection, had replicated to titers up to 10(5) TCID50/mL, and that 27/46 isolates produced no evidence of virus replication. The ability to produce CPE in non-salmonid cells was strongly correlated with the virus serotype. Isolates belonging to serotypes A(1) (subtypes WB and VR-299), A(2) (Sp), A(4) (He), and A(9) (Jasper), produced high levels of CPE in both EPC and FHM cells. By contrast, isolates belonging to serotype A(1) (Buhl subtype only), A(3) (Ab), A(5) (Tellina), A(6) (Canada 1), A(7) (Canada 2), and A(8) (Canada 3) serotypes did not produce CPE on EPC or FHM cells. This ability to cause CPE in non-salmonid cells was highly correlated with the presence of the W4 epitope on the virus, with those isolates possessing the epitope 50-100 times more likely to produce CPE in these cells than those isolates lacking this epitope (P < 0.001).