title: Evidence for lytic infection by Epstein-Barr virus in mucosal lymphocytes instead of nasopharyngeal epithelial cells in normal individuals.
abstract: Normal nasopharyngeal tissues from 23 individuals who died of causes unrelated to the upper respiratory system and had no evidence of Epstein-Barr virus (EBV)-related diseases were studied using in situ hybridisation (ISH) and immunohistochemistry for the detection of EBV RNA and expression of EBV proteins, respectively. ISH using 35S-labelled riboprobe for EBV EBER RNA showed occasional to a few EBER+ lymphocytes in the stroma of nasopharyngeal mucosa in 14/16 cases with available paraffin-embedded tissues. In addition, very rare intraepithelial EBER+ lymphocytes were also detected in 3/16 cases. However, in none of these cases was EBER detected in the epithelial cells. Similar results were obtained using a nonradioactive ISH method for EBER (Dako). In 3/23 cases, immunostaining using monoclonal antibodies for EBV proteins on cryostat sections showed occasional cells in the stroma expressing EBV nuclear antigen 2 (EBNA2), latent membrane protein-1 (LMP), and switch protein encoded by BZLF1 gene (ZEBRA) in two cases and only very rare LMP+ and ZEBRA+ cells in one other case. Double immunostaining combining alkaline phosphatase anti-alkaline phosphatase (APAAP) for CD markers and indirect immunofluorescence for LMP showed that the LMP+ cells were either CD19+ or less frequently CD3+, but none were CD68+. These results show that both B and T lymphocytes harbouring EBV can be found in the normal nasopharyngeal tissues. Interestingly, EBV proteins associated with lytic viral replication--diffuse early antigen (EA-D), viral capsid antigen (VCA), or membrane antigen (MA)--were also detected in rare cells in the stroma in one case, and in another case only one MA+ cell was detected.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Pathology, Queen Mary Hospital Compound, University of Hong Kong.
authors.forename: Q
authors.initials: Q
authors.lastname: Tao
authors.forename: G
authors.initials: G
authors.lastname: Srivastava
authors.forename: A C
authors.initials: AC
authors.lastname: Chan
authors.forename: L P
authors.initials: LP
authors.lastname: Chung
authors.forename: S L
authors.initials: SL
authors.lastname: Loke
authors.forename: F C
authors.initials: FC
authors.lastname: Ho
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004847:Epithelial Cells; D004848:Epithelium / Q000821:virology; D005260:Female; D006566:Herpesviridae Infections / Q000821:virology*; D004854:Herpesvirus 4, Human / Q000302:isolation & purification* / Q000502:physiology*; D006801:Humans; D008214:Lymphocytes / Q000821:virology*; D008297:Male; D008875:Middle Aged; D009297:Nasal Mucosa / Q000821:virology*; D009305:Nasopharynx / Q000821:virology; D012367:RNA, Viral / Q000032:analysis; D014764:Viral Proteins / Q000032:analysis; D017735:Virus Latency; D014779:Virus Replication
chemical_list: D012367:RNA, Viral; D014764:Viral Proteins