Division II.2.5 Haemadsorption

As replication of ISAV in cell cultures does not always result in a CPE, every well shall be subject to an RT-PCR test or a haemadsorption test in accordance with this point, or an IF test in accordance with point II.2.6.

Cell culture medium shall be removed from each well, including those of positive and negative controls, and placed in labelled sterile tubes. 500 μl of a 0,2 % (vol:vol) suspension of washed rabbit or horse red blood cells, or a 0,05 % (vol:vol) suspension of washed rainbow trout or Atlantic salmon red blood cells, shall be added to each well and incubated at room temperature for 45 minutes. The red blood cells shall be removed and each well shall be washed twice with L-15 medium. Each well shall be examined using a microscope.

The presence of clusters of red blood cells attaching to the surface of ASK cells shall be indicative of presumptive infection with an orthomyxovirus. If a haemadsorption test is positive, a virus identification test shall be performed immediately in accordance with point II.2.4.