Kaposi's Sarcoma-Associated Herpesvirus Glycoproteins B and K8.1 Regulate Virion Egress and Synthesis of Vascular Endothelial Growth Factor and Viral Interleukin-6 in BCBL-1 Cells

Kaposi's sarcoma-associated herpesvirus (KSHV) is the etiological agent for Kaposi's sarcoma (KS). Both KSHV and KS are endemic in sub-Saharan Africa where approximately 84% of global KS cases occur. Nevertheless, whole-genome sequencing of KSHV has only been completed using isolates from Western countries-where KS is not endemic. The lack of whole-genome KSHV sequence data from the most clinically important geographical region, sub-Saharan Africa, represents an important gap since it remains unclear whether genomic diversity has a role on KSHV pathogenesis. We hypothesized that distinct KSHV genotypes might be present in sub-Saharan Africa compared to Western countries. Using a KSHV-targeted enrichment protocol followed by Illumina deep-sequencing, we generated and analyzed 16 unique Zambian, KS-derived, KSHV genomes. We enriched KSHV DNA over cellular DNA 1,851 to 18,235-fold. Enrichment provided coverage levels up to 24,740-fold; therefore, supporting highly confident polymorphism analysis. Multiple alignment of the 16 newly sequenced KSHV genomes showed low level variability across the entire central conserved region. This variability resulted in distinct phylogenetic clustering between Zambian KSHV genomic sequences and those derived from Western countries. Importantly, the phylogenetic segregation of Zambian from Western sequences occurred irrespective of inclusion of the highly variable genes K1 and K15. We also show that four genes within the more conserved region of the KSHV genome contained polymorphisms that partially, but not fully, contributed to the unique Zambian KSHV whole-genome phylogenetic structure. Taken together, our data suggest that the whole KSHV genome should be taken into consideration for accurate viral characterization. IMPORTANCEOur results represent the largest number of KSHV whole-genomic sequences published to date and the first time that multiple genomes have been sequenced from sub-Saharan Africa, a geographic area where KS is highly endemic. Based on our new sequence data, it is apparent that whole-genome KSHV diversity is greater than previously appreciated and differential phylogenetic clustering exists between viral genomes of Zambia and Western countries. Furthermore, individual genes may be insufficient for KSHV genetic characterization. Continued investigation of the KSHV genetic landscape is necessary in order to effectively understand the role of viral evolution and sequence diversity on KSHV gene functions and pathogenesis. K aposi's sarcoma-associated herpesvirus (KSHV), or human herpesvirus 8 (HHV-8), is the etiologic agent for all forms of Kaposi's sarcoma (KS) (1). KS manifests as an endothelial tumor primarily on the skin but can also involve mucosal membranes and visceral organs. Among the HIV-uninfected population, KS is rare worldwide; however, HIV infection and immunosuppression greatly increase the risk of developing KS (2). In sub-Saharan Africa, HIV is epidemic, and KSHV is endemic. Accordingly, KS is one of the most common cancers in sub-Saharan A...

Section: Discussionmentioning

confidence: 99%

Whole-Genome Sequencing of Kaposi's Sarcoma-Associated Herpesvirus from Zambian Kaposi's Sarcoma Biopsy Specimens Reveals Unique Viral Diversity

Olp

Jeanniard

Marimo

et al. 2015

“…The supernatant (cytoplasmic fraction) was carefully transferred to new 1.5-ml tubes and used for TaqMan real-time PCR as described previously (49,50).…”

Section: Cells and Antibodiesmentioning

confidence: 99%

“…Quantitative PCR (Q-PCR) was utilized to derive the number of viral genomes within cytoplasmic and extracellular samples that remained protected after DNase treatment, as described previously for Kaposi's sarcoma-associated herpesvirus (KSHV) (49,50). Specifically, the primers and probe (6-carboxytetramethylrhodamine [TAMRA]) for the real-time PCR were designed to detect HSV-1 US6 (gD).…”

Section: Cells and Antibodiesmentioning

confidence: 99%

Functional Hierarchy of Herpes Simplex Virus 1 Viral Glycoproteins in Cytoplasmic Virion Envelopment and Egress

Chouljenko

Kim

Chouljenko

et al. 2012

Herpes simplex virus 1 (HSV-1) viral glycoproteins gD (carboxyl terminus), gE, gK, and gM, the membrane protein UL20, and membrane-associated protein UL11 play important roles in cytoplasmic virion envelopment and egress from infected cells. We showed previously that a recombinant virus carrying a deletion of the carboxyl-terminal 29 amino acids of gD (gD⌬ct) and the entire gE gene ( Overall, comparisons of single, double, and triple mutant viruses generated in the same HSV-1(F) genetic background indicated that lack of either UL20 or gK expression caused the most severe defects in cytoplasmic envelopment, egress, and infectious virus production, followed by the double deletion of UL11 and gM.

“…Negative regulation of MAPK activation by DUSP1 reduces inflammation associated with a variety of infectious and inflammatory diseases (37)(38)(39)(40)(41). Proinflammatory and promigratory factors induced by activated MAPKs, including VEGF, IL-8, and IL-6, are secreted by KSHV-infected cells, and their presence within KS lesions and the peripheral circulation of KS patients is thought to facilitate KSHV-associated cellular pathogenesis and angiogenesis (34,(42)(43)(44)(45)(46)(47)(48)(49)(50). To first determine whether KSHV-induced secretion of promigratory factors is, at least in part, mediated through KSHV repression of DUSP1, we quantified the secretion of VEGF and IL-8 by KSHV-infected primary cells in the presence or absence of ectopic DUSP1 expression.…”

Section: Fig 4 Ectopic Expression Of Dusp1 Suppresses Erk-dependent Smentioning

confidence: 99%

Kaposi's Sarcoma-Associated Herpesvirus Suppression of DUSP1 Facilitates Cellular Pathogenesis following De Novo Infection

Qin

Dai

Defee

et al. 2013

Kaposi's sarcoma-associated herpesvirus (KSHV) is the causative agent of Kaposi's sarcoma (KS), and KSHV activation of mitogen-activated protein kinases (MAPKs) initiates a number of key pathogenic determinants of KS. Direct inhibition of signal transduction as a therapeutic approach presents several challenges, and a better understanding of KSHV-induced mechanisms regulating MAPK activation may facilitate the development of new treatment or prevention strategies for KS. MAPK phosphatases, including dual-specificity phosphatase-1 (DUSP1), negatively regulate signal transduction and cytokine activation through MAPK dephosphorylation or interference with effector molecule binding to MAPKs, including the extracellular signal-regulated kinase (ERK). We found that ERK-dependent latent viral gene expression, the induction of promigratory factors, and cell invasiveness following de novo infection of primary human endothelial cells are in part dependent on KSHV suppression of DUSP1 expression during de novo infection. KSHV-encoded miR-K12-11 upregulates the expression of xCT (an amino acid transporter and KSHV fusion/entry receptor), and existing data indicate a role for xCT in the regulation of 14-3-3␤, a transcriptional repressor of DUSP1. We found that miR-K12-11 induces endothelial cell secretion of promigratory factors and cell invasiveness through upregulation of xCT-dependent, 14-3-3␤-mediated suppression of DUSP1. Finally, proof-of-principle experiments revealed that pharmacologic upregulation of DUSP1 inhibits the induction of promigratory factors and cell invasiveness during de novo KSHV infection. These data reveal an indirect role for miR-K12-11 in the regulation of DUSP1 and downstream pathogenesis.