Jm. Orenstein et al., VISUALIZATION OF HUMAN HERPESVIRUS TYPE-8 IN KAPOSIS-SARCOMA BY LIGHTAND TRANSMISSION ELECTRON-MICROSCOPY, AIDS, 11(5), 1997, pp. 35-45
Background: Human herpesvirus type 8 (HHV-8) has been associated with
Kaposi's sarcoma, body cavity-based lymphoma (BCBL), and multicentric
Castleman's disease through DNA, in situ hybridization, and serologic
studies. HHV-8 has been visualized only in HHV-8-positive/Epstein-Barr
virus (EBV)-negative/ cytomegalovirus (CMV)-negative BCBL cell lines,
but not in HHV-8-positive/EBV-negative/CMV-negative Kaposi's sarcoma
lesions. Design: Kaposi's sarcoma of the skin, lymph node, and spleen
from three patients with AIDS were analysed for HHV-8, EBV and CMV DNA
by polymerase chain reaction (PCR), for HHV-8 RNA (T1.1 riboprobe) by
in situ hybridization (ISH), for viral inclusions by light microscopy
, and for herpesviruses by transmission electron microscopy (TEM). Sec
tions were also labeled with T1.1 counterstained with CD34, an endothe
lial cell marker. Results: The skin lesion was DNA PCR-positive for HH
V-8 and CMV (nested, but not single PCR), the lymph node was positive
for HHV-8 and EBV, and the spleen was positive for only HHV-8. TEM rev
ealed infection by a virus displaying the typical morphology and cytop
athicity of herpesviruses. Hexagonal nucleocapsids and mature envelope
d virions were present in vasoformative spindle cells and mononuclear
cells, often resembling lymphocytes. Extrapolating from TEM to standar
d light microscopy on hematoxylin and eosin-stained paraffin sections,
eosinophilic, targetoid intranuclear inclusions were identified withi
n spindle cells which often lined vascular lumina. The T1.1-riboprobe
labeled CD34+ spindle cells containing intranuclear inclusions, as wel
l as mononuclear cells within Kaposi's sarcoma and residual lymphoid t
issue. Conclusion: The herpesvirus visualized in Kaposi's sarcoma lesi
ons has morphologic and cytopathic features typical of human herpesvir
uses, productively infects vasoformative spindle cells and mononuclear
cells, and is consistent with HHV-8. It can also form intranuclear in
clusions that are identifiable by light microscopy in hematoxylin and
eosin sections and by ISH.