Quantitative analysis of Kaposi sarcoma-associated herpesvirus (KSHV) in KSHV-associated diseases.
BACKGROUND
Accurate numbers of copies of Kaposi sarcoma-associated herpesvirus (KSHV) and numbers of virus-infected cells in lesions caused by KSHV-associated diseases are unknown.


METHODS
Quantitative polymerase chain reaction (PCR) and computerized imaging of immunohistochemical analysis were performed on pathologic sections of samples from persons with KSHV-associated diseases.


RESULTS
Real-time PCR and semiquantitative PCR-Southern blotting demonstrated that DNA extracted from biopsy samples of KS lesions contained approximately 1-2 viral copies/cell. KSHV-associated lymphoma contained 10-50 viral copies/cell. Computerized-image analysis demonstrated that approximately 49% of cells expressed KSHV-encoded latency-associated nuclear antigen in KS biopsy samples. On the basis of results of real-time PCR and computerized-image analysis, the predicted number of viral copies was 3.2 viral copies/cell in KS lesions. Computerized-image analysis also revealed that the expression of open-reading frame (ORF)-50 protein, an immediate early protein of KSHV, was very rare in KS lesions, which implies that they were mainly composed of proliferating cells latently infected with KSHV. In multicentric Castleman disease lesions, 25% of virus-infected cells expressed ORF50 protein, which suggests the frequent lytic replication of KSHV.


CONCLUSIONS
Numbers of viral copies and of virus-positive cells vary among KSHV-associated diseases, which suggests different mechanisms of viral pathogenesis. The combination of real-time PCR and computerized-image analysis provides a useful tool for the assessment of the number of viral copies in KSHV-associated diseases.
Department of Pathology, National Institute of Infectious Diseases, Shinjuku, Tokyo, Japan.
Yasuko
Y
Asahi-Ozaki
Yuko
Y
Sato
Takayuki
T
Kanno
Tetsutaro
T
Sata
Harutaka
H
Katano
D006566:Herpesviridae Infections / Q000276:immunology / Q000821:virology*; D019288:Herpesvirus 8, Human / Q000235:genetics / Q000302:isolation & purification*; D007150:Immunohistochemistry; D016366:Open Reading Frames; D016133:Polymerase Chain Reaction; D012514:Sarcoma, Kaposi / Q000209:etiology / Q000821:virology*; D019562:Viral Load