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%.

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.

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.

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.

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.

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.

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.

Manipulation of the host cell membrane by humanγ-herpesviruses EBV and KSHV for pathogenesis

The cell membrane regulates many physiological processes including cellular communication,homing and metabolism. It is therefore not surprising that the composition of the host cell membrane is manipulated by intracellular pathogens. Among these, the human oncogenic herpesviruses Epstein–Barr virus(EBV) and Kaposi's sarcoma-associated herpesvirus(KSHV)exploit the host cell membrane to avoid immune surveillance and promote viral replication.Accumulating evidence has shown that both EBV and KSHV directly encode several similar membrane-associated proteins, including receptors and receptor-specific ligands(cytokines and chemokines), to increase virus fitness in spite of host antiviral immune responses. These proteins are expressed individually at different phases of the EBV/KSHV life cycle and employ various mechanisms to manipulate the host cell membrane. In recent decades, much effort has been made to address how these membrane-based signals contribute to viral tumorigenesis. In this review, we summarize and highlight the recent understanding of how EBV and KSHV similarly manipulate host cell membrane signals, particularly how remodeling of the cell membrane allows EBV and KSHV to avoid host antiviral immune responses and favors their latent and lytic infection.

Prevention and Treatment of KSHV-associated Diseases with Antiviral Drugs

Kaposi’s sarcoma-associated herpesvirus (KSHV) was first identified as the etiologic agent of Kaposi’s sarcoma (KS) in 1994. KSHV infection is necessary,but not sufficient for the development of Kaposi sarcoma (KS),primary effusion lymphoma (PEL),and multicentric Castleman disease (MCD). Advances in the prevention and treatment of KSHV-associated Diseases have been achieved,even though current treatment options are ineffective,or toxic to many affected persons. The identification of new targets for potential future therapies and the randomized trial to evaluate the efficacy of new antivirals are required.

Preparation and application of polyclonal antibodies against KSHV v-cyclin

We prepared rabbit polyclonal antibodies against Kaposi＇s sarcoma-associated herpesvirus （KSHV）-encoded v- cyclin （ORF 72） and detected the natural viral protein using these polyclonal antibodies. Three antigenic polypep- tides of v-cyclin were designed and synthesized. A fragment of the v-cyclin gene was cloned into a eukaryotic expression vector pEF-MCS-Flag-IRES/Puro to construct a recombinant vector, pEF v-cyclin. Then, pEF v-cyclin was transfected into 293T and EA.hy926 cells to obtain v-cyclin-Flag fusion proteins. Six New Zealand white rabbits were immunized with KLH-conjugated peptides to generate polyclonal antibodies against v-cyclin. The polyclonal antibodies were then characterized by ELISA and Western blotting assays. Finally, the polyclonal anti- bodies against v-cyclin were used to detect natural viral protein expressed in BCBL-1, BC-3, and JSC-1 cells. The results showed that using the Flag antibody, v-cyclin-Flag fusion protein was detected in 293T and EA.hy926 cells transfected with pEF-v-cyclin. Furthermore, ELISA showed that the titer of the induced polyclonal rabbit anti-v- cyclin antibodies was higher than 1：8,000. In Western blotting assays, the antibodies reacted specifically with the v-cyclin-Flag fusion protein as well as the natural viral protein. The recombinant expression vector pEF-v-cyclin was constructed successfully, and the polyclonal antibodies prepared can be used for various biological tests in- cluding ELISA and Western blotting assays.

The regulatory role of protein phosphorylation in human gammaherpesvirus associated cancers

Activation of specific sets of protein kinases by intracellular signal molecules has become more and more apparent in the past decade. Phosphorylation, one of key posttranslational modification events, is activated by kinase or regulatory protein and is vital for controlling many physiological functions of eukaryotic cells such as cell proliferation, differentiation, malignant transformation,and signal transduction mediated by external stimuli. Moreovers, the reversible modification of phosphorylation and dephosphorylation can result in different features of the target substrate molecules including DNA binding, protein-protein interaction, subcellular location and enzymatic activity, and is often hijacked by viral infection. Epstein-Barr virus(EBV) and Kaposi's sarcomaassociated herpesvirus(KSHV), two human oncogenic gamma-herpesviruses, are shown to tightly associate with many malignancies. In this review, we summarize the recent progresses on understanding of molecular properties and regulatory modes of cellular and viral proteins phosphorylation influenced by these two tumor viruses, and highlight the potential therapeutic targets and strategies against their related cancers.

Towards Better Understanding of KSHV Life Cycle: from Transcription and Posttranscriptional Regulations to Pathogenesis

Kaposi’s sarcoma-associated herpesvirus(KSHV), also known as human herpesvirus-8(HHV-8), is etiologically linked to the development of Kaposi’s sarcoma, primary effusion lymphoma, and multicentric Castleman’s disease. These malignancies often occur in immunosuppressed individuals, making KSHV infection-associated diseases an increasing global health concern with persistence of the AIDS epidemic. KSHV exhibits biphasic life cycles between latent and lytic infection and extensive transcriptional and posttranscriptional regulation of gene expression. As a member of the herpesvirus family, KSHV has evolved many strategies to evade the host immune response, which help the virus establish a successful lifelong infection. In this review, we summarize the current research status on the biology of latent and lytic viral infection, the regulation of viral life cycles and the related pathogenesis.