seronegative

Describes a laboratory test result that shows that a substance the test is supposed to find, such as an antibody, is not present at all or is present in very small amounts. Antibodies are proteins made by the body’s immune system in response to a foreign substance or microorganism, such as a virus. A seronegative test result usually means that a person has not been exposed to or infected with a virus or other infectious agent and has not made antibodies against that agent. Sometimes antibodies are made against the body’s own tissues. In that case, a seronegative test result means that a person does not have the antibodies or other markers for a certain disease, such as an autoimmune disease. More testing may be needed to make sure a seronegative test result is correct.