title: Shift in the buoyant density of hepatitis C virus particles in infants infected by mother-to-infant transmission.
abstract: BACKGROUND
  Hepatitis C virus (HCV) particles in sera can be divided into two classes: low-density free particles and high-density immune complex particles. Previous studies have revealed that the clinical progression of HCV infection is closely associated with the occurrence of the former class, rather than the latter, in an experimental chimpanzee model and in HCV-infected adult cases.
  
  
  METHODS
  To verify this concept in infantile cases, we prospectively analysed HCV particle populations, fractionated according to buoyant density, in serum samples from five infants infected by mother-to-infant transmission.
  
  
  RESULTS
  In all five cases, HCV particles were predominantly high density at the age of one month. In four of five cases, low-density HCV particles became predominant in association with a decrease in maternally transmitted antibody levels. In one case, in which high serum levels of alanine aminotransferase persisted, low-density particles were predominant between the ages of 3 and 9 months, in three consecutive samples. In other cases, in which infants were asymptomatic or had transient hepatitis, low-density HCV particles were predominant at only one sampling point or not at all throughout the follow-up period.
  
  
  CONCLUSIONS
  Maternal antibody transmitted via the placenta reacts with the HCV particles in infants infected through vertical transmission. A decrease in maternal antibody levels results in an increase in low-density free virions. It is suggested that low-density particles play an important role in liver inflammation.
authors.affiliation: Department of Pediatrics, Faculty of Medicine, Tottori University, Yonago, Japan. okamoto@ibm.net
authors.forename: M
authors.initials: M
authors.lastname: Okamoto
authors.forename: I
authors.initials: I
authors.lastname: Nagata
authors.forename: J
authors.initials: J
authors.lastname: Murakami
authors.forename: S
authors.initials: S
authors.lastname: Hino
authors.forename: K
authors.initials: K
authors.lastname: Shiraki
mesh_terms: D002499:Centrifugation, Density Gradient; D016174:Hepacivirus / Q000235:genetics; D006526:Hepatitis C / Q000635:transmission*; D006801:Humans; D007223:Infant; D018445:Infectious Disease Transmission, Vertical; D011446:Prospective Studies; D012367:RNA, Viral / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D012367:RNA, Viral