Detection of Persistent Human Parvovirus 4 Infection in Patients with Antiphospholipid Syndrome

Parvovirus 4 (PARV4) is one of the emerging human parvoviruses discovered recently. PARV4 has long-lasting persistence in tissues after primary infection, but persistent PARV4 viremia has yet to be effectively detected in humans. In the present work, longitudinal serum samples from eleven patients with antiphospholipid syndrome were tested by nested polymerase chain reaction for the presence of PARV4 DNA. In one patient, PARV4 4 DNA was detected in all longitudinal serum samples collected over a period of 119 months. In addition, PARV4 DNA was present in two or more longitudinal serum samples from seven other patients. Two possible explanations are a persistent infection with intermittent low viral load below detection limit and a recurrent reactivation of latent infection. In conclusion, to our knowledge, this is the first direct evidence of detection of persistent PARV4 infection. Placental transmission may be one of the major routes of PARV4 infection in endemic areas if women of child-bearing age have continuous or intermittent circulating PARV4 DNA seen in our patients.