High expression of HHV-8-encoded ORF73 protein in spindle-shaped cells of Kaposi's sarcoma.
Human herpesvirus 8 (HHV-8) has been demonstrated previously in Kaposi's sarcoma (KS) tissues by immunohistochemistry, in situ polymerase chain reaction, and in situ hybridization. The HHV-8-encoded protein ORF73 is a 222- or 234-kd protein named latent nuclear antigen (LNA) or latency-associated nuclear antigen (LANA) that is identified in HHV-8-infected cell lines by immunofluorescence assay. In the present study, a rabbit antibody against a recombinant ORF73 protein was developed. Immunofluorescent staining of a HHV-8-infected cell line, TY-1, showed that the staining pattern of the anti-ORF73 antibody overlapped completely the LANA staining pattern obtained using KS patients' sera. Immunoblotting analysis showed that the anti-ORF73 antibody reacted specifically with 222- and 234-kd proteins that were present in TY-1 and BCBL-1 cell lysates. Immunohistochemistry using a catalyzed signal amplification system demonstrated that the anti-ORF73 antibody reacted exclusively with the majority of KS spindle-shaped cells, showing a nuclear dot-like staining pattern. Some of the ORF73 protein-positive cells also expressed CD34 and vimentin but not CD68 or factor-VIII-related antigen. These data indicate that the anti-ORF73 antibody recognizes LANA and that most KS cells are infected with HHV-8 in the latent phase. Our findings also suggest that ORF73 protein plays an important role in the pathogenesis of KS.
Katano
H
H
Department of Pathology, National Institute of Infectious Diseases, University of Tokyo, Tokyo, Japan.
Sato
Y
Y
Kurata
T
T
Mori
S
S
Sata
T
T
D000818:Animals; D015153:Blotting, Western; D002460:Cell Line / Q000378:metabolism / Q000821:virology; D005455:Fluorescent Antibody Technique; D006566:Herpesviridae Infections / Q000378:metabolism; D019288:Herpesvirus 8, Human; D006801:Humans; D007150:Immunohistochemistry; D009687:Nuclear Proteins / Q000378:metabolism*; D010750:Phosphoproteins; D011817:Rabbits; D012514:Sarcoma, Kaposi / Q000378:metabolism* / Q000473:pathology
D009687:Nuclear Proteins; D010750:Phosphoproteins; C118485:latent nuclear antigen (LNA)