Yes, there are five primary classes of antibodies. Of those, IgG, IgM, and IgA are often used as part of infectious disease serology testing.

  • IgG antibodies are found in all body fluids. They account for 75 to 80 percent of all antibodies. IgG antibodies are essential in fighting bacterial and viral infections, and when present indicate that someone has previously been exposed to a particular antigen and has developed an immune response. In general, these antibodies usually appear 10-14 days after symptom onset.
  • IgM antibodies are found in blood and lymph fluid and are the first type of antibody made in response to an infection, usually detectable within 3-7 days from the start of the infection.
  • IgA antibodies play a crucial role in the immune function of mucous membranes, such as the respiratory epithelium, but is also found in the blood. These antibodies also appear early in the infection process (3-7 days).