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.
Department of Pathology, National Institute of Infectious Diseases, University of Tokyo, Tokyo, Japan.
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H
Katano
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Sato
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Kurata
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Mori
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Sata
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)