title: Human herpesvirus-6 infection in neonates: Not protected by only humoral immunity.
abstract: BACKGROUND
  Infants are usually protected from various viral infections, including human herpesvirus-6 (HHV-6) and human herpesvirus-7 (HHV-7) infections, during the early infantile period by antibodies transferred from their mothers. However, rare cases of exanthem subitum (ES) in neonates have been described in published reports.
  
  
  METHODS
  From the infantile patients of febrile illness, HHV-6 and HHV-7 DNA were examined by the polymerase chain reaction method. Antibodies to HHV-6 and HHV-7 were detected by indirect immuno-fluorescence assay and neutralization test. Viral isolation was attempted from the patient's peripheral blood mononuclear cells (PBMC) during the acute phase of febrile illness.
  
  
  RESULTS
  Human herpesvirus-6 was verified virologically in two neonates who were clinically diagnosed as ES within the first month of life. Although high copies of HHV-6 DNA were detected in their PBMC during the acute phase, the isolation of HHV-6 from their PBMC was not successful. Neutralizing antibodies to HHV-6 were detected in sera of the acute phase, and those antibodies were considered to be transferred from their mothers. Antibody titers showed fourfold elevation in sera of the convalescent phase. The HHV-6 infection occurred despite the presence of pre-existing maternal antibody. Human herpesvirus-7 and HHV-7 DNA were not detected from their clinical samples.
  
  
  CONCLUSIONS
  This observation suggests that HHV-6 infection could not be protected by only humoral immunity.
authors: Division of Pediatrics,Toyonaka Municipal Hospital, Toyonaka, Osaka, Japan.
authors: Tomoko
authors: T
authors: Sugimoto
authors: Keiko
authors: K
authors: Tanaka-Taya
authors: Jiro
authors: J
authors: Ono
authors: Hiroko
authors: H
authors: Miyoshi
authors: Shintaro
authors: S
authors: Okada
authors: Koichi
authors: K
authors: Yamanishi
mesh_terms: D000914:Antibodies, Viral / Q000032:analysis; D000917:Antibody Formation; D005077:Exanthema Subitum / Q000276:immunology*; D015654:Herpesvirus 6, Human / Q000276:immunology*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn
chemical_list: D000914:Antibodies, Viral