The isolation of <answer>enzymes</answer> from infected tissue can also provide the basis of a biochemical diagnosis of an infectious disease. For example, humans can make neither RNA replicases nor reverse transcriptase, and the presence of these <answer>enzymes</answer> are characteristic of specific types of viral infections. The ability of the viral protein hemagglutinin to bind red blood cells together into a detectable matrix may also be characterized as a biochemical test for viral infection, although strictly speaking hemagglutinin is not an enzyme and has no metabolic function.
What needs to be isolated from infected tissue to provide a biochemical diagnosis of an infectious disease?
enzymes