title: Detection of human parvovirus 4 viremia in the follow-up blood samples from seropositive individuals suggests the existence of persistent viral replication or reactivation of latent viral infection.
abstract: BACKGROUND
  The transmission routes for human parvovirus 4 (PARV4) infections in areas with high seroprevalence are not known. In the work described here, persistent PARV4 viral replication was investigated by conducting a longitudinal study.
  
  
  METHODS
  Ten healthcare workers each provided a blood sample at the beginning of the study (first sample) and 12 months later (second sample). The paired samples were tested for PARV4-positivity by immunoblotting analysis and nested polymerase chain reactions.
  
  
  RESULTS
  IgG antibodies against PARV4 were detected in six participants, three of whom also had IgM antibodies against PARV4. The immunoblotting results did not vary over time. PARV4 DNA was detected in the first blood sample from one participant who had IgG antibodies against PARV4 and in the second blood samples from 2 participants who had IgG and IgM antibodies against PARV4.
  
  
  CONCLUSIONS
  Detection of PARV4 DNA in the second blood samples from two seropositive participants suggests the existence of persistent PARV4 replication or reactivation of inactive virus in the tissues. The finding of persistent or intermittent PARV4 replication in individuals with past infections provides an important clue toward unraveling the non-parenteral transmission routes of PARV4 infection in areas where the virus is endemic.
authors.affiliation: Department of Internal Medicine, National Taiwan University Hospital, No. 7, Chung Shan South Road, 1000, Taipei, Taiwan. maoyuanchen@ntu.edu.tw.
authors.forename: Mao-Yuan
authors.initials: MY
authors.lastname: Chen
authors.affiliation: Department of Internal Medicine, National Taiwan University Hospital, No. 7, Chung Shan South Road, 1000, Taipei, Taiwan. hcc0401@ntu.edu.tw.
authors.forename: Chien-Ching
authors.initials: CC
authors.lastname: Hung
authors.affiliation: Department of Internal Medicine, National Taiwan University Hospital, No. 7, Chung Shan South Road, 1000, Taipei, Taiwan. lkuanglun@ntu.edu.tw.
authors.forename: Kuang-Lun
authors.initials: KL
authors.lastname: Lee
mesh_terms: D000328:Adult; D000914:Antibodies, Viral / Q000097:blood; D001769:Blood / Q000821:virology*; D004279:DNA, Viral / Q000097:blood; D005260:Female; D006282:Health Personnel; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D007075:Immunoglobulin M / Q000097:blood; D008137:Longitudinal Studies; D008297:Male; D010322:Parvoviridae Infections / Q000821:virology*; D017992:Parvovirus / Q000302:isolation & purification* / Q000502:physiology*; D014766:Viremia / Q000821:virology*; D014775:Virus Activation; D014779:Virus Replication; D055815:Young Adult
chemical_list: D000914:Antibodies, Viral; D004279:DNA, Viral; D007074:Immunoglobulin G; D007075:Immunoglobulin M