Kaposi's sarcoma-associated herpesvirus T cell responses in HIV seronegative individuals from rural Uganda.
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ABSTRACT:
SUBMITTER: Nalwoga A
PROVIDER: S-EPMC8677732 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:BackgroundDetectable Kaposi's sarcoma-associated herpesvirus (KSHV) DNA in blood and increased antibody titres may indicate KSHV reactivation, while the transmission of KSHV occurs via viral shedding in saliva.MethodsWe investigated the risk factors for KSHV DNA detection by real-time polymerase chain reaction in blood and by viral shedding in saliva, in 878 people aged 3 to 89 years of both sexes in a rural Ugandan population cohort. Helminths were detected using microscopy and the presence of malaria parasitaemia was identified using rapid diagnostic tests. Regression modelling was used for a statistical analysis.ResultsThe KSHV viral load in blood did not correlate with the viral load in saliva, suggesting separate immunological controls within each compartment. The proportions of individuals with a detectable virus in blood were 23% among children aged 3-5 years and 22% among those 6-12 years, thereafter reducing with increasing age. The proportions of individuals with a detectable virus in saliva increased from 30% in children aged 3-5 years to 45% in those aged 6-12 years, and decreased subsequently with increasing age. Overall, 29% of males shed in saliva, compared to 19% of females (P = .008).ConclusionsTogether, these data suggest that young males may be responsible for much of the onward transmission of KSHV. Individuals with a current malaria infection had higher levels of viral DNA in their blood (P = .031), compared to uninfected individuals. This suggests that malaria may lead to KSHV reactivation, thereby increasing the transmission and pathogenicity of the virus.
| S-EPMC7428384 | biostudies-literature
Project description:Kaposi's sarcoma-associated herpesvirus (KSHV) is a human pathogenic γ-herpesvirus strongly associated with the development of Kaposi's Sarcoma and B cell proliferative disorders, including primary effusion lymphoma (PEL). The identification and functional investigation of non-coding RNAs expressed by KSHV is a topic with rapidly emerging importance. KSHV miRNAs derived from 12 stem-loops located in the major latency locus have been the focus of particular attention. Recent studies describing the transcriptome-wide identification of mRNA targets of the KSHV miRNAs suggest that these miRNAs have evolved a highly complex network of interactions with the cellular and viral transcriptomes. Relatively few KSHV miRNA targets, however, have been characterized at a functional level. Here, our current understanding of KSHV miRNA expression, targets, and function will be reviewed.
| S-EPMC3342587 | biostudies-literature
Project description:BackgroundKaposi's sarcoma-associated herpesvirus (KSHV) is the causative agent of Kaposi sarcoma (KS), one of the leading cancers in human immunodeficiency virus (HIV)-infected patients in Zambia. KSHV was detected in the human central nervous system (CNS) by polymerase chain reaction (PCR) analysis, but tissue location and cell tropism for KSHV infection has not been established. Given the neurotropism exhibited by other herpesviruses and the frequent coinfection of HIV-positive individuals by KSHV, we sought to determine whether the central nervous system (CNS) can be infected by KSHV in HIV-positive Zambian individuals.MethodsPostmortem brain tissue specimens were collected from individuals coinfected with KSHV and HIV. PCR and Southern blots were performed on DNA extracted from the brain tissue specimens to verify KSHV infection. Immunohistochemical analysis and immunofluorescent microscopy were used to localize and identify KSHV-infected cells. Tropism was further established by in vitro infection of primary human neurons with rKSHV.219.ResultsKSHV DNA was detected in the CNS from 4 of 11 HIV-positive individuals. Immunohistochemical analysis and immunofluorescent microscopy demonstrated that KSHV infected neurons and oligodendrocytes in parenchymal brain tissues. KSHV infection of neurons was confirmed by in vitro infection of primary human neurons with rKSHV.219.ConclusionOur study showed that KSHV infects human CNS-resident cells, primarily neurons, in HIV-positive Zambian individuals.
| S-EPMC5853869 | biostudies-literature
Project description:BackgroundTo determine if variations exist in the KSHV host receptor EPHA2's coding region that affect KSHV infectivity and/or KS prevalence among South African HIV-infected patients.MethodsA retrospective candidate gene association study was performed on 150 patients which were randomly selected from a total of 756 HIV-infected patients and grouped according to their KS status and KSHV serodiagnosis; namely group 1: KS+/KSHV+; group 2: KS-/KSHV+; group 3: KS-/KSHV-. Peripheral blood DNA was used to extract DNA and PCR amplify and sequence the entire EPHA2 coding region, which was compared to the NCBI reference through multiple alignment.Results100% (95% CI 92.9-100%) of the KS positive patients, and 31.6% (95% CI 28.3-35.1%) of the KS negative patients were found to be KSHV seropositive. Aggregate variation across the entire EPHA2 coding region identified an association with KS (OR = 6.6 (95% CI 2.8, 15.9), p = 2.2 × 10-5). This was primarily driven by variation in the functionally important protein tyrosine kinase domain (Pkinase-Tyr; OR = 4.9 (95% CI 1.9, 12.4), p = 0.001) and the sterile-α-motif (SAM; OR = 13.8 (95% CI 1.7, 111.6), p = 0.014). Mutation analysis revealed two novel, non-synonymous heterozygous variants (c.2254 T > C: OR undefined, adj. p = 0.02; and c.2990 G > T: OR undefined, adj. p = 0.04) in Pkinase-Tyr and SAM, respectively, to be statistically associated with KS; and a novel heterozygous transition (c.2727C > T: OR = 6.4 (95% CI 1.4, 28.4), adj. p = 0.03) in Pkinase-Tyr to be statistically associated with KSHV.ConclusionsVariations in the KSHV entry receptor gene EPHA2 affected susceptibility to KSHV infection and KS development in a South African HIV-infected patient cohort.
| S-EPMC6206435 | biostudies-literature
Project description:Spontaneous lytic reactivation of Kaposi's sarcoma-associated herpesvirus (KSHV) occurs at a low rate in latently infected cells in disease and culture. This suggests imperfect epigenetic maintenance of viral transcription programs, perhaps due to variability in chromatin structure at specific loci across the population of KSHV episomal genomes. To characterize this locus-specific chromatin structural diversity, we used MAPit single-molecule footprinting, which simultaneously maps endogenous CG methylation and accessibility to M.CviPI at GC sites. Diverse chromatin structures were detected at the LANA, RTA and vIL6 promoters. At each locus, chromatin ranged from fully closed to fully open across the population. This diversity has not previously been reported in a virus. Phorbol ester and RTA transgene induction were used to identify chromatin conformations associated with reactivation of lytic transcription, which only a fraction of episomes had. Moreover, certain chromatin conformations correlated with CG methylation patterns at the RTA and vIL6 promoters. This indicated that some of the diverse chromatin conformations at these loci were epigenetically distinct. Finally, by comparing chromatin structures from a cell line infected with constitutively latent virus, we identified products of lytic replication. Our findings show that epigenetic drift can restrict viral propagation by chromatin compaction at latent and lytic promoters.
| S-EPMC3597696 | biostudies-literature
Project description:Kaposi's sarcoma-associated herpesvirus (KSHV) is etiologically related to Kaposi's sarcoma (KS), primary effusion lymphoma (PEL) and multicentric Castleman's disease (MCD). It typically displays two different phases in its life cycle, the default latency and occasional lytic replication. The epigenetic modifications are thought to determine the fate of KSHV infection. Previous studies elegantly depicted epigenetic landscape of latent viral genome in in vitro cell culture systems. However, the physiologically relevant scenario in clinical KS tissue samples is unclear. In the present study, we established a protocol of ChIP-Seq for clinical KS tissue samples and mapped out the epigenetic landscape of KSHV genome in classic KS tissues. We examined AcH3 and H3K27me3 histone modifications on KSHV genome, as well as the genome-wide binding sites of latency associated nuclear antigen (LANA). Our results demonstrated that the enriched AcH3 was mainly restricted at latent locus while H3K27me3 was widespread on KSHV genome in classic KS tissues. The epigenetic landscape at the region of vIRF3 gene confirmed its silenced state in KS tissues. Meanwhile, the abundant enrichment of LANA at the terminal repeat (TR) region was also validated in the classic KS tissues, however, different LANA binding sites were observed on the host genome. Furthermore, we verified the histone modifications by ChIP-qPCR and found the dominant repressive H3K27me3 at the promoter region of replication and transcription activator (RTA) in classic KS tissues. Intriguingly, we found that the TR region in classic KS tissues was lacking in AcH3 histone modifications. These data now established the epigenetic landscape of KSHV genome in classic KS tissues, which provides new insights for understanding KSHV epigenetics and pathogenesis.
| S-EPMC5291540 | biostudies-literature
Project description:Virus infection of a cell generally evokes an immune response by the host to defeat the intruder in its effort. Many viruses have developed an array of strategies to evade or antagonize host antiviral responses. Kaposi's sarcoma-associated herpesvirus (KSHV) is demonstrated in this report to be able to prevent activation of host antiviral defense mechanisms upon infection. Cells infected with wild-type KSHV were permissive for superinfection with vesicular stomatitis virus (VSV), suggesting that KSHV virions fail to induce host antiviral responses. We previously showed that ORF45, a KSHV immediate-early protein as well as a tegument protein of virions, interacts with IRF-7 and inhibits virus-mediated type I interferon induction by blocking IRF-7 phosphorylation and nuclear translocation (Zhu et al., Proc. Natl. Acad. Sci. USA. 99:5573-5578, 2002). Here, using an ORF45-null recombinant virus, we demonstrate a profound role of ORF45 in inhibiting host antiviral responses. Infection of cells with an ORF45-null mutant recombinant KSHV (BAC-stop45) triggered an immune response that resisted VSV super-infection, concomitantly associated with appreciable increases in transcription of type I IFN and downstream anti-viral effector genes. Gain-of-function analysis showed that ectopic expression of ORF45 in human fibroblast cells by a lentivirus vector decreased the antiviral responses of the cells. shRNA-mediated silencing of IRF-7, that predominantly regulates both the early and late phase induction of type I IFNs, clearly indicated its critical contribution to the innate antiviral responses generated against incoming KSHV particles. Thus ORF45 through its targeting of the crucial IRF-7 regulated type I IFN antiviral responses significantly contributes to the KSHV survival immediately following a primary infection allowing for progression onto subsequent stages in its life-cycle.
| S-EPMC2868026 | biostudies-literature
Project description:Kaposi's sarcoma-associated herpesvirus (KSHV) (also called human herpesvirus 8) is consistently found in Kaposi's sarcoma lesions and in body-cavity-based lymphomas. A 17-kb KSHV lambda clone was obtained directly from a Kaposi's sarcoma lesion. DNA sequence analysis of this clone identified an open reading frame which has 32% amino acid identity and 53% similarity to the virus-encoded cyclin (v-cyclin) of herpesvirus saimiri (HVS) and 31% identity and 53% similarity to human cellular cyclin D2. This KSHV open reading frame was shown to encode a 29- to 30-kDa protein with the properties of a v-cyclin. KSHV v-cyclin protein was found to associate predominantly with cdk6, a cellular cyclin-dependent kinase known to interact with cellular type D cyclins and HVS v-cyclin. The KSHV v-cyclin was also found to associate weakly with cdk4. KSHV v-cyclin-cdk6 complexes strongly phosphorylated glutathione S-transferase-Rb fusion protein and histone H1 as substrates in vitro. Thus, KSHV v-cyclin resembles the v-cyclin of the T-lymphocyte-transforming HVS in its specificity for association with cdk6 and in its ability to strongly activate cdk6 protein kinase activity.
| S-EPMC191282 | biostudies-other
Project description:Kaposi's sarcoma (KS) and its causative agent, Kaposi's sarcoma associated herpesvirus (KSHV/HHV-8), a gamma2 herpesvirus, have distinctive geographical distributions that are largely unexplained. We propose the "oncoweed" hypothesis to explain these differences, namely that environmental cofactors present in KS endemic regions cause frequent reactivation of KSHV in infected subjects, leading to increased viral shedding and transmission leading to increased prevalence of KSHV infection as well as high viral load levels and antibody titers. Reactivation also plays a role in the pathogenesis of KSHV-associated malignancies. To test this hypothesis, we employed an in vitro KSHV reactivation assay that measured increases in KSHV viral load in KSHV infected primary effusion lymphoma (PEL) cells and screened aqueous natural product extracts from KS endemic regions. Of 4,842 extracts from 38 countries, 184 (5%) caused KSHV reactivation. Extracts that caused reactivation came from a wide variety of plant families, and extracts from Africa, where KSHV is highly prevalent, caused the greatest level of reactivation. Time course experiments were performed using 28 extracts that caused the highest levels of reactivation. The specificity of the effects on viral replication was examined using transcriptional profiling of all viral mRNAs. The array data indicated that the natural extracts caused an ordered cascade of lytic replication similar to that seen after induction with synthetic activators. These in vitro data provide support for the "oncoweed" hypothesis by demonstrating basic biological plausibility.
| S-EPMC2857915 | biostudies-literature
Project description:Herpesvirus gene expression can be classified into four distinct kinetic stages: latent, immediate early, early, and late. Here we characterize the kinetic class of a group of 16 Kaposi's sarcoma-associated herpesvirus (KSHV)/human herpesvirus 8 genes in a cultured primary effusion cell line and examine the expression of a subset of these genes in KS biopsies. Expression of two latent genes, LANA and vFLIP, was constitutive and was not induced by chemicals that induce the lytic cycle in primary effusion lymphoma (PEL) cell lines. An immediate-early gene, Rta (open reading frame 50 [ORF50]), was induced within 4 h of the addition of n-butyrate, and its 3.6-kb mRNA was resistant to inhibition by cycloheximide. Early genes, including K3 and K5 that are homologues of the "immediate-early" gene of bovine herpesvirus 4, K8 that is a positional homologue of Epstein-Barr virus BZLF1, vMIP II, vIL-6, and polyadenylated nuclear (PAN) RNA, appeared 8 to 13 h after chemical induction. A second group of early genes that were slightly delayed in their appearance included viral DHFR, thymidylate synthase, vMIP I, G protein-coupled receptor, K12, vBcl2, and a lytic transcript that overlapped LANA. The transcript of sVCA (ORF65), a late gene whose expression was abolished by Phosphonoacetic acid, an inhibitor of KSHV DNA replication, did not appear until 30 h after induction. Single-cell assays indicated that the induction of lytic cycle transcripts resulted from the recruitment of additional cells into the lytic cycle. In situ hybridization of KS biopsies showed that about 3% of spindle-shaped tumor cells expressed Rta, ORF K8, vIL-6, vMIP I, vBcl-2, PAN RNA, and sVCA. Our study shows that several KSHV-encoded homologues of cellular cytokines, chemokines, and antiapoptotic factors are expressed during the viral lytic cycle in PEL cell lines and in KS biopsies. The lytic cycle of KSHV, probably under the initial control of the KSHV/Rta gene, may directly contribute to tumor pathogenesis.
| S-EPMC104468 | biostudies-literature