IgM-class antibodies to TT virus (TTV) in patients with acute TTV infection

TT virus (TTV) is a human circovirus with a single-stranded, circular DNA genome of 3.8 kb. A method was developed to detect IgM antibodies to TTV as a serological marker for the diagnosis of acute TTV infection. IgM antibodies in test sera were captured by a monoclonal antibody against IgM/µ on a solid support followed by binding of IgM with TTV derived from fecal extract of a TTV carrier. The presence of IgM-specific TTV particles was determined by polymerase chain reaction (PCR) using nucleic acids extracted from the solid support. Anti-TTV IgM was detected in sera from two patients with non-A to G post-transfusion hepatitis, who were positive for TTV DNA during weeks 10-21 and 12-17, respectively, following transfusion. The anti-TTV IgM was detectable after alanine transaminase levels were elevated and TTV DNA was detectable in the patients. The duration of the anti-TTV IgM was short-lived compared with anti-TTV IgG. Anti-TTV IgM was not detected in sera from any of 36 healthy individuals, with no detectable anti-TTV IgG or TTV DNA in their serum. These results indicate that anti-TTV IgM antibodies would be a useful marker to detect acute TTV infection.