FIG 1.

Relative changes in CMV IgM, IgG, and IgG avidity levels over time following primary CMV infection. IgM pattern A represents the typical IgM response pattern, whereas IgM pattern B represents long-term IgM persistence. In a CMV IgG-positive individual, an IgM-positive result of 20 indicates infection around 3 months previously if the individual exhibits IgM pattern A but around 6 months previously if the individual exhibits IgM pattern B. By employing CMV IgG avidity testing, the correct time since infection can be determined; a low-avidity result (expected to be about 30 based on this figure) indicates primary infection about 3 months previously, whereas a high-avidity result (expected to be about 70) indicates primary infection more than 6 months previously.