Inefficient establishment of KSHV latency suggests an additional role for continued lytic replication in Kaposi sarcoma pathogenesis
Adam Grundhoff, Don Ganem
Adam Grundhoff, Don Ganem
Published January 1, 2004
Citation Information: J Clin Invest. 2004;113(1):124-136. https://doi.org/10.1172/JCI17803.
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Article Infectious disease

Inefficient establishment of KSHV latency suggests an additional role for continued lytic replication in Kaposi sarcoma pathogenesis

Abstract

Kaposi sarcoma–associated (KS-associated) herpesvirus (KSHV) infection is linked to the development of both KS and several lymphoproliferative diseases. In all cases, the resulting tumor cells predominantly display latent viral infection. KS tumorigenesis requires ongoing lytic viral replication as well, however, for reasons that are unclear but have been suggested to involve the production of angiogenic or mitogenic factors by lytically infected cells. Here we demonstrate that proliferating cells infected with KSHV in vitro display a marked propensity to segregate latent viral genomes, with only a variable but small subpopulation being capable of stable episome maintenance. Stable maintenance is not due to the enhanced production of viral or host trans-acting factors, but is associated with cis-acting, epigenetic changes in the viral chromosome. These results indicate that acquisition of stable KSHV latency is a multistep process that proceeds with varying degrees of efficiency in different cell types. They also suggest an additional role for lytic replication in sustaining KS tumorigenesis: namely, the recruitment of new cells to latency to replace those that have segregated the viral episome.

Authors

Adam Grundhoff, Don Ganem

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Figure 7

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Analysis of SLKP and SLKN cells. (a) SLKN cells were infected with viral...
Analysis of SLKP and SLKN cells. (a) SLKN cells were infected with viral supernatants from lytically induced BCBL-1 cells. The percentage of LANA-positive cells was evaluated over a period of 40 days by IFA (solid line). The curve obtained from the initial infection of the parental SLK mass cultures (see Figure 4) is shown for comparison (dashed line). (b) SLKN (open circles) or SLKP cells (filled squares) were infected with recombinant KSHV-GFP supernatants, and the percentage of GFP-positive cells was analyzed by FACS over a period of 3 weeks. Shown are normalized percentages relative to the initial infection level (absolute infection efficiencies were 2.9% and 4.2% for SLKN and SLKP cells, respectively). (c) SLKN cells (solid lines, filled symbols) or uninfected SLK cells (dashed lines, open symbols) were transfected with the reporter constructs pGFP (circles), pGTR4 (squares), or pGTR4:73 (triangles). The percentage of GFP-expressing cells was monitored over a period of 17 days after transfection by FACS. (d) SLKP cells were transfected with pGFP (circles) or pGTR4 (squares) and analyzed by FACS over a period of 17 days. (e) PCR analysis of the transfected SLK, SLKN, and SLKP cultures described above. Episomal DNA was isolated at the time points indicated (in days) above the lanes by Hirt extraction and subjected to PCR amplification of the GFP cassette as described in Methods.