The Biology of Kaposi’s Sarcoma-Associated Herpesvirus and the Infection of Human Immunodeficiency Virus

Kaposi sarcoma-associated herpesvirus (KSHV),also known as human herpesvirus 8 (HHV-8),is discovered in 1994 from Kaposi's sarcoma (KS) lesion of an acquired immunodeficiency syndrome (AIDS) patient. In addition to its association with KS,KSHV has also been implicated as the causative agent of two other AIDS-associated malignancies: primary effusion lymphoma (PEL) and multicentric Castleman’s disease (MCD). KSHV is a complex DNA virus that not only has the ability to promote cellular growth and survival for tumor development,but also can provoke deregulated angiogenesis,inflammation,and modulate the patient’s immune system in favor of tumor growth. As KSHV is a necessary but not sufficient etiological factor for KS,human immunodeficiency virus (HIV) is a very important cofactor. Here we review the basic information about the biology of KSHV,development of pathogenesis and interaction between KSHV and HIV.

Allicin and Glycyrrhizic Acid Display Antiviral Activity Against Latent and Lytic Kaposi Sarcoma-associated Herpesvirus

Kaposi sarcoma-associated herpesvirus(KSHV)triggers the development of Kaposi sarcoma,a skin malignancy that is one of the most widespread defining symptoms in acquired immunodeficiency syndrome patients.KSHV manifests in two distinct cycles,a chronic latent cycle and an acute lytic cycle.Current clinical anti-herpesvirus therapeutic agents are predominantly composed of nucleoside analogues that target viral replication in the lytic cycle only,while KSHV latent genes are at the basis tumorigenesis.Currently,there are no effective therapies targeting latent KSHV infections.Therefore,the aim of this study was to identify putative therapeutic compounds with inhibitory activity against latent KSHV.The KSHV-infected primary effusion lymphoma cell line BC-3 was used to study antiviral activity of glycyrrhizic acid(GA),Allicin,and epigallocatechin-3-gallate(EGCG)against latent and lytic KSHV.Activity of GA,Allicin,EGCG,and the established anti-lytic cycle control compound ganciclovir was quantified by real-time polymerase chain reaction of nuclear and virion KSHV DNA yields after treatment compared with the untreated control.GA and Allicin showed antiviral activity against both latent and lytic KSHV,while EGCG displayed activity against lytic KSHV only.Therefore,GA and Allicin are interesting compounds for further development of anti-KSHV therapy against latent cycle infections.

Establishment of an ELISA to Detect Kaposi's Sarcoma-associated Herpesvirus Using Recombinant ORF73

Kaposi's sarcoma-associated herpesvirus (KSHV) is causally related to Kaposi's sarcoma (KS), primary effusion lymphoma (PEL) and a proportion of cases of multicentric Castleman's disease (MCD). The ORF73 protein was cloned into pQE80L-orf73 and expressed in E.coli and purified. The expressed recombinant ORF73 was identified by sodium dodecyl sulfatepolyacrylamide gel electrophoresis (SDS-PAGE). A protein of about 27 kDa was expressed as expected. Western Blotting showed that the purified recombinant ORF73 reacted with KSHV positive serum. The immunogenicity of the recombinant ORF73 was further analysed by ELISA and the optimal conditions were determined. The ORF73 ELISA was used to compare the KSHV seroprevalence between Hubei and Xinjiang Han people. The Han people in Xinjiang have significantly higher KSHV seroprevalence than their counterparts in Hubei (6.7% vs 2.9%, P = 0.005).

Expression of Kaposi's Sarcoma-associated Herpesvirus ORFK8.1 and Its Preliminary Diagnostic Application

The ORFK8.1 of Kaposi＇s sarcoma associated-herpesvirus （KSHV） was expressed in a prokaryotic expression system. The expression of recombinant E.coli containing pQE-80L-orf KS.1 was induced by isopropyl-b-D-thiogalactopyranoside （IPTG）. The fusion protein was purified by chromatyography. The expressed protein and its purified product were identified by sodium dodecyl sulfate-polyacrylamide gel eletrophoresis （SDS-PAGE）. SDS-PAGE showed that a protein of 26 kDa was visualized as expected. A western blot assay was established to analyze the immunogenicity of purified recombinant ORFKS. 1 protein. The optimal condition of the recombinant ORFKS. 1 ELISA assay was confirmed： the concentration of antigen was 5 μg/mL, the dilution of serum was 1：200. We used the ELISA method to investigate the recombinant ORF KS. 1 protein＇s specificity, the data showed that the specificity of ORF KS.1 to detect KSHV was 100%. At the same time, 560 sera samples from Hubei province were detected by using ORFKS. 1 ELISA to investigate KSHV seroprevalence in this region. The KSHV seroprevalence in Hubei province is shown to be 6.80%.

Pathogenesis and Associated Diseases of Kaposi's Sarcoma-associated Herpesvirus

Kaposi's sarcoma-associated herpesvirus(KSHV)is the primary etiological agent of Kaposi's sarcoma,primary effusion lymphoma and muticentric Castleman's disease.In common with the other herpesviruses,KSHV exhibits both latent and lytic life cycles,both of which are characterized by distinct gene expression profiles and programs.KSHV encodes proteins which play essential roles in the inhibition of host adaptive and innate immunity,the inhibition of apoptosis,and the regulation of the cell cycle.KSHV also encodes several proteins which have transforming and intrcellular signalling activity.

Angiogenesis,Kaposi’s Sarcoma and Kaposi’s Sarcoma-associated Herpesvirus

Tumor angiogenesis is the uncontrolled growth of blood vessels in tumors,serving to supply nutrients and oxygen,and remove metabolic wastes. Kaposi’s sarcoma (KS),a multifocal angioproliferative disorder characterized by spindle cell proliferation,neo-angiogenesis,inflammation,and edema,is associated with infection by Kaposi's sarcoma-associated herpesvirus (KSHV). Recent studies indicate that KSHV infection directly promotes angiogenesis and inflammation through an autocrine and paracrine mechanism by inducing pro-angiogenic and pro-inflammatory cytokines. Many of these cytokines are also expressed in KS lesions,implicating a direct role of KSHV in the pathogenesis of this malignancy. Several KSHV genes are involved in KSHV-induced angiogenesis. These studies have provided insights into the pathogenesis of KS,and identified potential therapeutic targets for this malignancy.

Genotypic analysis on the ORF-K1 gene of human herpesvirus 8 from patients with Kaposi's sarcoma in Xinjiang,China

Human herpesvirus 8 （HHV-8） is thought to be essential for the development of all forms of Kaposi＇s sarcoma （KS）. HHV-8 DNA is present virtually in all KS tumor biopsy samples. Genes at both ends of the HHV-8 genome have been shown to vary considerably. Seven major molecular subtypes of HHV-8 were defined based on the amino acid sequence of the open reading frame K1 （ORF-K1）, generally known as A, B, C, D, E, F, and Z. Most strains collected worldwide were clustered into two subtypes （A and C）. Here, the K1/VRI region of HHV-8 was amplified by nested PCR in 22 （81.48%） of 27 cases from Xinjiang Uygur Autonomous Region, a province in northwestern China. Phylogenetic analysis on the basis of the K1/VR1 amino acid sequence indicated that the majority of these KS patients were infected by subtype C HHV-8 （n = 18, including 15 belonging to the C2 group）, and several by subtype A （n = 4, including 3 being the A1 group）. This is the first report of subtype A HHV-8 in China. Furthermore, the correlations between different forms and lesions of KS and different subtypes of HHV-8 were analyzed. The findings showed that subtype A HHV-8 resulted in significantly more frequent mucosal KS lesions than subtype C. However, there was no obvious correlation between different forms of KS and different subtypes of HHV-8.

Immunogenicity Analysis of Prokaryotic Expression Products of Kaposi's Sarcoma Associated Herpesvirus orf65

To purify the protein encoding the small capsid protein （SCP） of KSHV and analyze its immunogenicity, the carboxyl terminus of orf65 of Kaposi＇s sarcoma associated-herpesvirus （KSHV） was expressed in a prokaryotic expression system. The expression of recombinant E.coli containing pQE-80L-orf65 was induced by isopropyl-13-D-thiogalactopyranoside （IPTG） and the fusion protein was purified by chromatography. The expressed protein and its purified product were identified by sodium dodecyl sulfate- polyacrylamide gel electrophoresis （SDS-PAGE） and showed that 9 kDa was the expected size of the purified orf65 protein. The antiserum was produced in rabbit which was immunized by purified orf65 protein. An ELISA assay was established to analyze the immunogenicity of the purified orf65 protein. The ELISA analysis demonstrated that orf65 protein has strong immune activity, and the immune activity of polyclonal antibody against orf65 was more than 4 fold higher than that in the serum of the non-immunized rabbit. These results demonstrate that purified orf65 protein has very strong immunogenicity and can be used in screening KSHV infection in the general population using ELISA.

Human herpesvirus-8 positive iatrogenic Kaposi's sarcoma in the setting of refractory ulcerative colitis

Although Kaposi sarcoma(KS) has been more traditionally considered an AIDS-defining illness,it may also be seen in individuals on immunosuppresive therapy.We report a case of a patient who presented to the hospital in the setting of increasingly refractory ulcerative colitis.Computed tomography scan of the abdomen was consistent with sigmoid diverticulititis and blood cultures were positive for Klebsiella.After a course of antibiotics with resolution of infection,a colonoscopy was performed to evaluate his diverticulitis and incidentally revealed a new rectal tumor.Immunohistochemistry showed the tumor was consistent with KS,with cells staining strongly positive for human herpesvirus-8.This case not only illustrates a rare case of KS found in an HIV-negative individual,but it also highlights the importance of considering an alternative diagnosis in a patient refractory to medical treatment.We discuss the management and care of an ulcerative colitis patient diagnosed with KS on immunosuppressive therapy.

Regulation of Wnt/β-catenin signaling by herpesviruses

The Wnt/β-catenin signaling pathway is instrumental in successful differentiation and proliferation of mammalian cells. It is therefore not surprising that the herpesvirus family has developed mechanisms to interact with and manipulate this pathway. Successful coexistence with the host requires that herpesviruses establish a lifelong infection that includes periods of latency and reactivation or persistence. Many herpesviruses establish latency in progenitor cells and viral reactivation is linked to host-cell proliferation and differentiation status. Importantly, Wnt/β-catenin is tightly connected to stem/progenitor cell maintenance and differentiation. Numerous studies have linked Wnt/β-catenin signaling to a variety of cancers, emphasizing the importance of Wnt/β-catenin pathways in development, tissue homeostasis and disease. This review details how the alpha-, beta-, and gammaherpesviruses interact and manipulate the Wnt/β-catenin pathway to promote a virus-centric agenda.

The Role of Human Herpesvirus 8 Molecular Characterization in the Management of HIV Infected Patients Diagnosed with Malignancies Associated with Its Infection

Despite the progress has been reached with Human herpesvirus 8 (HHV-8) research, there are gaps in the knowledge of viral induced oncogenesis. The aim of the present study was to identify possible associations between HHV-8 subtypes, HHV-8 loads and clinical manifestations of HIV infected patients diagnosed with different malignancies associated with HHV-8 infection. Forty six HIV-1 infected individuals diagnosed with different HHV-8 associated diseases were studied [37 epidemic Kaposi’s sarcoma (KS), 3 pleural effusion lymphoma (PEL);5 peripheral lymphadenopathies (PL);1 Hodgkin’s lymphoma (HL);1 non Hodgkin’s lymphoma (NHL)]. HHV-8 loads were determined by quantitative real time PCR (qRT-PCR) whilst HHV-8 subtypes were determined by open-reading frame (ORF)-K1 gen genotyping. HHV-8 subtypes B, A, C, A5 and E were exhibited by 31.8%, 23.4%, 19.1%, 17% and 8.5% of the studied patients, respectively. The median HHV-8 viral load did not differ between subtypes (p > 0.05) but HHV-8 viral loads were significantly higher in PEL than in epidemic KS lesion or lymph nodes (p = 0.04). Subtype B was detected in 60% of patients with B cell lymphoma (NHL, PEL and HL) whereas subtype E was only detected in patients with epidemic KS diagnosis. Our data suggest that HHV-8 DNA quantification instead of subtype identification could be used as a surrogate marker for monitoring its infection, not only in epidemic KS patients but also in HIV infected individuals with lymphoproliferative disorders.

Recent advances in the study of Kaposi's sarcoma-associated herpesvirus replication and pathogenesis

It has now been over twenty years since a novel herpesviral genome was identified in Kaposi's sarcoma biopsies. Since then, the cumulative research effort by molecular biologists, virologists, clinicians, and epidemiologists alike has led to the extensive characterization of this tumor virus, Kaposi's sarcoma-associated herpesvirus(KSHV; also known as human herpesvirus 8(HHV-8)), and its associated diseases. Here we review the current knowledge of KSHV biology and pathogenesis, with a particular emphasis on new and exciting advances in the field of epigenetics. We also discuss the development and practicality of various cell culture and animal model systems to study KSHV replication and pathogenesis.

Prevalence of Kaposi's sarcoma-associated herpesvirus in Uygur and Han populations from the Urumqi and Kashgar regions of Xinjiang, China

Kaposi's sarcoma-associated herpesvirus(KSHV) is the infectious etiologic agent associated with Kaposi's sarcoma(KS), primary effusion lymphoma, and multicentric Castleman disease. It has been shown that high KSHV prevalence and high incidence of both classic KS and AIDSassociated KS are found mostly among people of Uygur ethnicity in Xinjiang, while people of Han ethnicity in Xinjiang have a higher KSHV seroprevalence than those of other Han populations in China's Mainland. However, it is still unclear why there is such geographical and population variation in KSHV distribution in China. In this work, we focused on the populations in the Kashgar region and Urumqi area, where a total of 1294 research subjects were randomly selected to investigate the potential correlation between KSHV prevalence and different ethnicities in endemic areas of Xinjiang, and to determine risk factors that may affect KSHV infection rates or KS incidence. We identified a high seroprevalence of KSHV and high peripheral blood DNA infection in the general Uygur and Han populations in both Urumqi and Kashgar regions of Xinjiang, and determined that advancing age, low education level, and stationary population status affect KSHV infection rates. Further, KSHV-positive Uygur participants were shown to have higher prevalence of neutralizing antibodies and neutralizing antibody titers than KSHV-positive Han participants.

Lipids, lipid metabolism and Kaposi's sarcoma-associated herpesvirus pathogenesis

Lipids are essential for mammalian cells to maintain many physiological functions. Emerging evidence has shown that cancer cells can develop specific alterations in lipid biosynthesis and metabolism to facilitate their survival and various malignant behaviors. To date, the precise role of cellular lipids and lipid metabolism in viral oncogenesis is still largely unclear with only a handful of literature covering this topic to implicate lipid metabolism in oncogenic virus associated pathogenesis. In this review, we focus on the role of lipid biosynthesis and metabolism in the pathogenesis of the Kaposi's sarcoma-associated herpesvirus, a common causative factor for cancers arising in the immunocompromised settings.

Prevalence of Kaposi's sarcoma-associated herpesvirus among intravenous drug users： a systematic review and meta-analysis

Intravenous drug users(IDUs) have been demonstrated to be highly vulnerable to HIV/AIDS.Nevertheless, the prevalence of Kaposi's sarcoma associated herpesvirus(KSHV), an important co-infected agent with HIV, among this population remained obscure. We conducted a systematic review on the epidemiological features of KSHV among IDUs worldwide. Eligible studies were retrieved from 6 electronic databases(Pub Med, EMBASE, Web of Science, CBM, CNKI and Wanfang).We calculated the pooled prevalence and 95% confidence interval(CI) overall and among subgroups using either random-effects model or fixed-effects model depending on between-study heterogeneity. The potential publication bias was assessed by the Egger's test. A meta-regression analysis was performed to explore the sources of heterogeneity. Finally, twenty-two studies with a total sample of 7881 IDUs were included in the analysis. The pooled prevalence of KSHV was14.71%(95% CI 11.12%–19.46%) among IDUs. Specifically, KSHV prevalence was 10.86%(95% CI6.95%–16.96%) in HIV-negative IDUs, and 13.56%(95% CI 10.57%–17.38%) in HIV-positive IDUs.Moreover, prevalence among IDUs from the three continents involved in the current study was similar:16.10%(95%CI 7.73%–33.54%) in Asia; 14.22%(95%CI 8.96%–22.57%) in Europe and 14.06%(95%CI11.38%–17.37%) in America. Globally, IDUs are at higher risk of the KSHV infection when compared with the general population, regardless of geographical region or HIV-infection status.

The replication and transcription activator (RTA) of Kaposi's sarcoma-associated herpesvirus/human herpesvirus-8

Kaposi’s sarcoma-associated herpesvirus(KSHV)is γ-2 herpesvirus with latency and lytic replication stages in its life-cycle.The viral replication and transcription activator(RTA)is the key protein for triggering KSHV lytic gene expression and replication from latency.In this review,we will discuss the gene expression program in KSHV lytic replication and latency,the regulation of the RTA expression,the RTA protein and the mechanisms that RTA utilizes to transactivate its target genes.We will focus on the RTA-mediated transactivation mechanisms,including DNA-binding,interacting with cellular co-factors and promoting repressor degradation.

Amino acids essential for the interaction between cellular heat shock protein 90 and a Kaposi's sarcoma-associated herpesvirus-encoded protein kinase ORF36

Dear Editor,Protein-protein interactions（PPIs）often play important roles in biological processes（Zhang et al.,2016）.The split Renilla luciferase complementation assay（SRLCA）is one of the methods in studying PPIs.SRLCA is based on the complementation of the N-terminal domains of Renilla luciferase（LN）and C-terminal domains of Renilla luciferase （LC） non-functional halves of Renilla luciferase fused to possibly interacting proteins and emit luminescence （Deng et al., 2011; Jiang et al., 2010） （Supplementary Figure S1A）.

新疆Kaposi肉瘤组织内EBV、HHV-8双重感染的调查

应用PCR方法，对20例新疆Kaposi肉瘤病理组织进行了EBV和HHV－8双重感染的调查。结果：20例Kaposi肉瘤病理组织中14例检出HHV－8DNA（70％），EBV均为阴性。正常皮肤对照：10例这两种疱疹类病毒均为阴性。作者认为新疆Kaposi肉瘤的发生与EBV的相关性很小，但明显与HHV－8感染有关，但是否HHV－8感染就是新疆Kaposi肉瘤发生的决定因素，仍需进一步研究。

维吾尔族Kaposi’s肉瘤患者组织中KSHV-vFLIP表达水平与患者临床特征相关性

目的探讨维吾尔族卡波西肉瘤(Kaposi’s sarcoma,KS)患者皮损组织内KSHV-vFLIP基因表达水平与临床特征的相关性。方法选取29例维吾尔族卡波西肉瘤患者和12例血管瘤(hemangioma)患者、11例健康对照患者皮损石蜡包埋组织,反转录-聚合酶链反应(RT-PCR)分析KSHV-vFLIP基因mRNA表达水平。结果 KS患者KSHV-vFLIP基因表达水平(4.436±0.508)显著高于健康对照组(1.145±0.112,P<0.05),其中斑块型组KSHV-vFLIP基因表达水平(8.104±2.225)显著高于结节型组(3.971±0.371,P<0.05)和斑片组(2.774±0.867,P<0.05)。而KS组(4.436±0.507)与血管瘤组(6.343±0.949)差异无统计学意义(P>0.05),且HIV携带组(3.739±0.816)与非HIV携带组(4.618±0.604)差异无统计学意义(P>0.05)。结论在维吾尔族卡波西肉瘤患者组织中,KSHV-vFLIP基因表达水平与瘤体体积正相关。

人类疱疹病毒8型k12/T0.7基因亚型与Kaposi肉瘤的相关性研究

目的:了解Kaposi肉瘤患者所感染的疱疹病毒8型(HHV-8)k12/T0.7基因亚型分类,初步探索k12/T0.7基因亚型与Kaposi肉瘤不同临床分型的相关性。方法:对30例病理诊断明确的Kaposi肉瘤石蜡包埋组织进行HHV-8 DNA提取、k12/T0.7基因扩增、双向测序。使用DNAMAN软件、ClustalW软件和PHYLIP软件包对测序结果进行系统发生学分析,确定HHV-8 k12/T0.7基因亚型。最后用Fisher确切概率法对结果进行统计学分析。结果:30例Kaposi肉瘤中有22例HHV-8阳性,阳性率为73.33%,其中7例艾滋病相关型患者HHV-8均阳性。30例HHV-8阳性患者中,10例为HHV-8 k12 A亚型,12例为A/C亚型。Kaposi肉瘤患者不同亚型间有无黏膜损害及临床分型的分布差异均无统计学意义(P>0.05)。结论:Kaposi肉瘤患者感染HHV-8 k12亚型以A亚型和A/C亚型为主,不同亚型与临床分型无关。