Which testing method is primarily used for virus isolation in diagnosing ASF?

The HAD test, which stands for Hemadsorption Test, is a crucial method used for virus isolation in diagnosing African Swine Fever (ASF). This technique is particularly effective because it allows for the detection of ASF virus by observing the adsorption of red blood cells to infected cells. When the ASF virus infects certain types of cells, such as macrophages, these cells begin to express viral proteins on their surfaces, which can then bind to red blood cells, indicating the presence of the virus.

Other testing methods listed do not serve the primary purpose of isolating viruses. Bacterial culture tests are primarily used to grow and identify bacteria rather than viruses. Blood antigen tests typically detect specific proteins or antigens produced by the pathogen, which may be useful for diagnosis but do not focus on virus isolation. Similarly, biochemical analysis involves assessing biochemical compounds and reactions in samples, which would not provide the specific information needed for virus isolation related to ASF diagnosis. Thus, the HAD test is favored for its specificity and effectiveness in isolating the virus responsible for ASF.