Evidence of inability of human cytomegalovirus to reactivate Kaposi's sarcoma-associated herpesvirus from latency in body cavity-based lymphocytes

BackgroundKaposi's sarcoma-associated herpesvirus (KSHV; also known as human herpesvirus 8 (HHV-8)) has been determined to be the most frequent cause of malignancies in AIDS patients. It is associated primarily with Kaposi's sarcoma (KS) and primary effusion lymphoma (PEL), as well as with multicentric Castleman's disease (MCD).² The switch from the latent to the lytic stage is important in the maintenance of malignancy and viral infection. So far, the mechanism of its reactivation has not been fully understood.ObjectivesHuman cytomegalovirus (HCMV) and KSHV might infect the same cells, and it was found by other groups that several viruses could reactivate KSHV from latency. We investigate whether HCMV infection could reactivate KSHV from latency in body cavity-based lymphocyte (BCBL-1) cells.Study design and resultsLaboratory strains of HCMV cannot infect B cells. In this article, we demonstrate that the UL131-repaired HCMV (vDW215-BADrUL131) derived from AD169 strain is able to infect B lymphocytes. We directly infected KSHV latent cells including BCBL-1 with vDW215-BADrUL131 to evaluate the ability of HCMV to reactivate KSHV. Inconsistent with previous reports in human fibroblast cells, our results provide direct evidence that HCMV is unable to reactivate KSHV from latency-to-lytic infection in BCBL-1 cell lines. As a control, herpes simplex virus type 1 (HSV-1) was shown to be able to reactivate KSHV.ConclusionsOur observations, different from others, suggest that reactivation mechanisms for KSHV might vary in different cells.     

Consistent polymerse chain reaction–single-strand conformation polymorphism pattern of human herpesvirus-8 in the course of classical Kaposi's sarcoma assumes its clonal origin

There is emerging evidence that Kaposi's sarcoma–associated herpesvirus (KSHV or HHV-8) has a central role in the pathogenesis of Kaposi's sarcoma (KS). The occurrence of HHV-8 in classical KS biopsies is reported irrespective of its clinical stage (patch, plaque, nodular). HHV-8 was detected in 25 of 28 formalin-fixed paraffin-embedded classical KS samples by nested polymerase chain reaction. In addition, in six patients multiple tumors were available (n = 21). Single-strand conformation polymorphism (SSCP) analysis of the amplicons showed uniform SSCP pattern of samples belonging to the same patient regardless of whether the KS was multiplex or developed again years after the first excision. Most of the SSCP patterns were confirmed by further sequence analysis. The presence of the same sequence variant of HHV-8 in various samples of the same patient supports the clonal origin of classical Kaposi's sarcoma. J. Med. Virol. 54:300–304, 1998. © 1998 Wiley-Liss, Inc.     

HHV8 a subtype is associated with rapidly evolving classic Kaposi's sarcoma

The link between human herpesvirus 8 (KSHV) and Kaposi's sarcoma (KS) has been proven, but many important aspects including risk factors, genetic predisposition to tumor development, transmission of KSHV, and the pathogenic potential of different genotypes remain to be elucidated. Possible associations between clinical parameters and antibody levels, viral load fluctuations, and viral genotype were analyzed by quantitative real‐time PCR, an in‐house developed IFA assay, and sequence analysis of ORF K1‐VR1 in blood, serum and saliva of 38 subjects with classic KS (cKS). KSHV lytic antibodies were significantly increased in stage IV compared to stage I and II patients (p = 0.006 and p = 0.041, respectively). KSHV blood, serum, and saliva viral load was comparable in all stages. The highest viral loads were detected in saliva, and they decreased in stages III–IV compared to stages I–II patients. Higher concentrations of lytic antibodies and higher viral loads were observed in fast progressing cKS patients, in whom KSHV detection from blood was also more frequent. Type A KSHV strain was almost exclusively present in rapid progressors (12/17 cases), while C type was mainly present in slow progressing patients (6/7 cases). Finally, detection of type A KSHV strain associated with higher blood viral loads. KSHV lytic antibody levels and viral load can be used to monitor clinical evolution of cKS. Infection supported by KSHV A subtype is associated with more rapid progressive disease. Careful monitoring and aggressive therapeutic protocols should be considered in patients with KSHV A‐supported infection. J. Med. Virol. 80:2153–2160, 2008. © 2008 Wiley‐Liss, Inc.     

Porphyromonas gingivalis coinfects with KSHV in oral cavities of HIV+ patients and induces viral lytic reactivation

Kaposi's sarcoma-associated herpesvirus (KSHV) infection causes several human cancers, including Kaposi's sarcoma (KS), one of the most common AIDS-associated tumors. The involvement of the oral cavity represents one common clinical manifestation of AIDS-KS individuals with periodontal diseases and an oral carriage of a variety of pathogenic bacteria, including Porphyromonas gingivalis. In the current study, we report the clinical relevance of P. gingivalis and KSHV coinfection in the oral cavity of a cohort of HIV+ patients. Furthermore, we found that P. gingivalis conditioned medium or derived lipopolysaccharide effectively induced KSHV lytic reactivation from infected oral cells. This reactivation requires TLR4 as well as the activities of p38 and Jun N-terminal kinase- mitogen-activated protein kinase signaling pathways. Our findings reveal the mechanisms through which coinfected periodontal pathogens potentially promote oncogenic virus pathogenesis in the unique niche of immunocompromised patients.     

Seroprevalence of Kaposi's sarcoma‐associated herpesvirus and risk factors in Xinjiang,China

Xinjiang, China is an endemic area for Kaposi's sarcoma (KS) but the seroprevalence of Kaposi's sarcoma‐associated herpesvirus (KSHV) and risk factors remain undefined. In this study, antibodies to one KSHV latent protein (ORF73) and two KSHV lytic proteins (ORF65 and ORF‐K8.1) were examined in 2,228 subjects from the general population and 37 subjects infected with HIV‐1 in Xinjiang, and 560 subjects from the general population in Hubei, a low KS incidence region. The serostatus of a serum sample was defined based on positive results in any one of the three serologic assays. The seroprevalence of KSHV in the general population was higher in Xinjiang than in Hubei (19.2% vs. 9.5%; odds ratios [OR], 2.28; 95% confidence interval [CI], 1.68–3.08; P < 0.001). Among the ethnic groups in Xinjiang, 68 (15.8%) Han, 182 (20.7%) Uygur, 140 (19.9%) Hazakh, 9 (33.3%) Xibo, and 29 (16.8%) Hui were KSHV‐seropositive, respectively. Compared to the Han, the latter groups had an increase in the risk of KSHV of 62.2%, 63.8%, 180.1%, and 30.2% (P = 0.003, 0.004, 0.018, and 0.286, respectively). Subjects aged <20, 20–50, and >50 had a seroprevalence of KSHV of 11.8%, 17.9%, and 24.6%, respectively. Compared to subjects aged <20, the latter groups had an increase in the risk of KSHV of 63.3% and 144.5% (P = 0.009 and <0.001, respectively). Subjects infected with HIV‐1 in Xinjiang had a seroprevalence of KSHV of 43.2%, and a 220% increase in the risk of KSHV compared to the general population (P < 0.001). Similar results were obtained when the seroprevalence of KSHV was analyzed with any single or two of the three serologic assays alone. Genotyping identified three unique sequences clustered in the A clade. This study indicates that Xinjiang has a high seroprevalence of KSHV. Geographic location, ethnicity, age and HIV‐1 infection are risk factors. Serologic and genotyping results suggest the introduction of KSHV into Xinjiang by specific ethnic groups. J. Med. Virol. 81:1422–1431, 2009. © 2009 Wiley‐Liss, Inc.     

Profound reduction of CD4+ lymphocytes without HIV infection: two cases from the horn of Africa

Idiopathic CD4+ lymphocytopenia is a disorder associated with low CD4+ T cell count and opportunistic infections resembling AIDS. Most cases are described in developed countries. We report two HIV-negative patients with idiopathic CD4+ lymphocytopenia and AIDS-defining events diagnosed in Djibouti. The first patient developed lesions of Kaposi''s sarcoma and the second one presented with pulmonary tuberculosis. Both patients died with severe immunodepression. In poor resource-areas where HIV testing may not be available it is important to bear in mind that severe immunodepression and a clinical presentation compatible with AIDS do not necessary carry the diagnosis of AIDS.     

Human herpesvirus 8: Biology and role in the pathogenesis of Kaposi’s sarcoma and other aids-related malignancies

Human herpesvirus type 8, or Kaposi’s sarcoma-associated herpesvirus (KSHV), is the only known human γ ₂ herpesvirus (rhadinovirus) and the most recently discovered tumor virus. KSHV is associated with Kaposi’s sarcoma and two other lymphoproliferative disorders in the AIDS setting: primary effusion lymphoma and the plasma cell variant of multicentric Castleman’s disease. This review offers an update on the epidemiology and the role of KSHV genes in the development of disease.     

Ultrastructural characterization of human herpesvirus 8 (Kaposi's sarcoma- associated herpesvirus) in Kaposi's sarcoma lesions: electron microscopy permits distinction from cytomegalovirus (CMV)

Kaposi's sarcoma (KS) has been shown by molecular techniques to be associated with infection with human herpesvirus 8 (HHV8/KSHV), but specific ultrastructural characterization of the virus has been impaired by the frequent presence in these lesions of other herpesviruses, particularly cytomegalovirus (CMV). Since the ultrastructural appearance of HHV8/KSHV has been studied in the cell line KS-1 uninfected with other viruses including CMV, it was possible to undertake a comparative study of CMV and HHV8/KSHV in KS lesions. HHV8/KSHV was sparsely present and lytic infection was restricted to endothelial cells. The following specific ultrastructural features allowed distinction between HHV8/KSHV and CMV: the viral particles were more delicate and less numerous in cases of HHV8/KSHV infection; the viral tegument was more electron-dense in CMV than in HHV8/KSHV; dense bodies characteristic of CMV were absent in HHV/KSHV; complete CMV viral particles were more variable in size and generally larger (150–200 nm) than HHV8/KSHV (120–150 nm); and finally, the viral envelope was more pleomorphic in CMV than in KSHV/HHV8. Similarities between CMV and HHV8/KSHV included the basic structure of the nucleocapsids and the presence of capsids lacking central DNA cores (so-called non-infectious enveloped particles). These observations show that electron microscopy can be used to identify HHV8/KSHV and confirm the relationship between HHV8/KSHV and KS. © 1997 John Wiley & Sons, Ltd.     

Treatment for Kaposi sarcoma herpesvirus: great challenges with promising accomplishments

Kaposi sarcoma-associated herpesvirus (KSHV) is associated with three distinct malignancies: Kaposi sarcoma (KS), primary effusion lymphoma, and multicentric Castleman disease. Treatment modalities for KSHV have largely been developed based on understanding its molecular pathogenesis. The KSHV genome has been fully sequenced and contains numerous genes with homology to human regulatory genes that are potentially important in KS development. Therapeutic strategies have been developed to target signaling pathways that are activated by KSHV. This review describes multiple classes of pharmacological compounds that have been studied in patients with KS, including antivirals, chemotherapeutics, and novel agents related to KSHV pathogenesis.     

Seroprevalence of Kaposi's sarcoma‐associated herpesvirus among men who have sex with men in Japan

Kaposi's sarcoma‐associated herpesvirus (KSHV), the etiologic agent of Kaposi's sarcoma, causes malignancies frequently in patients with acquired immunodeficiency syndrome. In the United States and Europe, KSHV infection is common among men who have sex with men. However, the seroprevalence of KSHV among men who have sex with men in Japan is unknown. In the present study, the seroprevalence of KSHV was investigated among 230 men who have sex with men and 400 age‐ and area of residence‐matched men (controls) using a mixed‐antigen (KSHV‐encoded K8.1, open reading frame 59, 65, and 73 proteins) enzyme‐linked immunosorbent assay and an immunofluorescence assay. Among the Japanese men who have sex with men, serological assays revealed that 27 (11.7%) were seropositive for KSHV; 20 (5%) of the men in the control group were also KSHV seropositive. The seroprevalence of KSHV among men who have sex with men was significantly higher than in the control group (odds ratio = 2.52, 95% confidence intervals = 1.38–4.62, P = 0.0019, Chi‐square test). Infection with the human immunodeficiency virus, Treponema pallidum, or hepatitis B and C virus did not correlate with KSHV infection. Furthermore, the association of KSHV seropositivity with specific sexual activities was not statistically significant. In conclusion, a higher KSHV seroprevalence was found among Japanese men who have sex with men than among the controls, suggesting that the circulation of KSHV infection is more efficient among men who have sex with men in Japan than among men who do not engage in such sexual activities. J. Med. Virol. 85: 1046–1052, 2013. © 2013 Wiley Periodicals, Inc.     

Detection of Kaposi's sarcoma-associated herpesvirus-like DNA sequence in angiosarcoma.

The partial DNA sequence of a putative new herpesvirus has recently been isolated from almost all cases of Kaposi''s sarcoma (KS), from a small subset of AIDS-related lymphomas, and from a high proportion of multicentric Castleman''s disease. The presence of this KS-associated herpesvirus, which is also known as human herpes virus 8 (KSHV/ HHV8), has not been reported in vascular tumors other than KS. We therefore examined a series of vascular neoplasms of both endothelial and pericyte derivation using polymerase chain reaction to detect a 233-hp segment of the viral DNA. KSHV/HHV8 sequences were found in 7 of 24 (29%) angiosarcomas and 1 of 20 (5%) hemangiomas but not in any hemangiopericytomas (0 of 6). The presence of the virus in angiosarcoma was confirmed by direct sequencing of the polymerase chain reaction product and Southern blotting in one case each. Only one of the affected patients was known to be immunocompromised. By detecting its presence in a significant proportion of angiosarcomas, this study extends the number of tumors associated with KSHV/HHV8, further tightens its association with malignancy, and suggests a tropism of the virus for endothelial cells. The presence of KSHV/HHV8 in angiosarcomas in addition to classical KS also indicates that immunosuppression is not a requisite for viral infection.     

Human leukocyte antigen polymorphisms and Kaposi's sarcoma-associated herpesvirus infection outcomes: A call for deeper exploration

Host genetic background may influence the immunity to resist viral infection. As the most polymorphic loci in the entire human genome, the human leukocyte antigen (HLA) system plays an important role in innate and adaptive immune responses to many invading pathogens. Studies have shown that an association might exist between HLA polymorphisms and susceptibility to Kaposi's sarcoma-associated herpesvirus (KSHV) infection and associated diseases. However, discrepant conclusions were reached among different subjects with different detection methods. Therefore, it is now urgent to summarize current results and figure out the achievements and deficiencies of the existing research for the reference to future studies. A better understanding about the role of HLA polymorphisms in KSHV infection outcome would enable us to elucidate the pathways through which the virus evades the host defense system and improve strategies for the prevention and treatment of KSHV infection.     

Detection of Merkel cell polyomavirus in Merkel cell carcinoma and Kaposi's sarcoma

Merkel cell carcinoma is a rare malignancy that sometimes occurs in the skin of elderly people. Recently, a new human polyomavirus, Merkel cell polyomavirus (MCPyV) was identified in Merkel cell carcinoma. In the present study, MCPyV‐DNA was detected in 6 of 11 (55%) cases of Merkel cell carcinoma by nested PCR and real‐time PCR. Histologically, MCPyV‐positive cases showed round and vesicular nuclei with a fine granular chromatin and small nucleoli, whereas MCPyV‐negative cases showed polygonal nuclei with diffusely distributed chromatin. Real‐time PCR analysis to detect the MCPyV gene revealed that viral copy numbers ranged 0.04–0.43 per cell in cases of Merkel cell carcinoma. MCPyV was also detected in 3 of 49 (6.1%) cases of Kaposi's sarcoma (KS), but not in 192 DNA samples of other diseases including 142 autopsy samples from 20 immunodeficient patients. The MCPyV copy number in KS was lower than that in Merkel cell carcinoma. PCR successfully amplified a full‐length MCPyV genome from a case of KS. Sequence analysis revealed that the MCPyV isolated from KS had 98% homology to the previously reported MCPyV genomes. These data suggest that the prevalence of MCPyV is low in Japan, and is at least partly associated with the pathogenesis of Merkel cell carcinoma. J. Med. Virol. 81:1951–1958, 2009. © 2009 Wiley‐Liss, Inc.     

Detection rate and intratumoral virus load of human herpesvirus-8 in immunodeficiency-related B-cell lymphoid malignancies

Human herpesvirus-8 (HHV-8), associated with Kaposi's sarcoma, primary effusion lymphoma, and Castleman's disease, has been found in circulating B-cells and might have a causative role in B-cell malignancies associated with immunodeficiency syndromes. We determined the rate of detection and intratumoral virus load of HHV-8 by means of a semiquantitative approach in post-transplant lymphoproliferative diseases (PTLDs), AIDS-related non-Hodgkin's lymphomas (NHLs), including both Burkitt's lymphomas (BLs) and large cell lymphomas (LCLs), as well as in control groups consisting of follicular hyperplasias (FHs) and HIV-negative LCLs. HHV-8 sequences were detected at a similar rate in HIV-negative PTLDs (24%), HIV-negative LCLs (22%) and HIV-negative FHs (17%). The detection rate was significantly higher in HIV-positive BLs (73%), HIV-positive LCLs (67%), and HIV-positive FHs (65%) supporting the view of an epidemiological link between HHV-8 and HIV infections. The viral load was 10² genome copies per cell in the single case of primary effusion lymphoma included in the LCL group while it was 10⁻³ copy per cell (median value; range: 10⁻⁴–10⁻¹) in all the other HHV-8-positive samples. No significant difference of viral load was found according to HIV status. The virus loads of PTLDs and HIV-positive LCLs were significantly higher than those observed in HIV-positive BLs and FHs, suggesting, to some extent, that the degree of immunodeficiency may influence HHV-8 replication. However, with the exception of the single case of primary effusion lymphoma studied, the low intratumoral load of HHV-8 strongly argues against a direct causative agent of the virus in the occurrence of PTLDs and AIDS-related NHLs. J. Med. Virol. 53:277–281, 1997. © 1997 Wiley-Liss, Inc.     

Kaposi sarcoma-associated herpesvirus in non-Hodgkin lymphoma and reactive lymphadenopathy in Uganda

Kaposi sarcoma-associated herpesvirus (KSHV) causes Kaposi sarcoma and is also associated with primary effusion lymphoma, a subset of diffuse large B-cell lymphomas, and multicentric Castleman disease. Because KSHV infection is endemic in sub-Saharan Africa, we sought to identify cases of KSHV-positive non-Hodgkin lymphomas (NHLs) and reactive lymphadenopathy in this region. One hundred forty-four cases (80 NHLs, 64 reactive lymph nodes) from the major pathology laboratory in Uganda were reviewed. One NHL was KSHV-positive, as indicated by staining for the viral latent nuclear antigen. This NHL was a diffuse large B-cell lymphoma in a 5-year-old boy. The tumor was also Epstein-Barr virus-positive. In addition, 2 reactive lymph nodes, both classified histologically as follicular involution, stained KSHV latent nuclear antigen-positive and thus most likely represent multicentric Castleman disease. In all 3 KSHV-positive cases, a minority of cells expressed KSHV viral interleukin 6, a biologically active cytokine homolog. In conclusion, we show that KSHV is rarely associated with lymphoproliferative disorders in sub-Saharan Africa. We describe the first case of a KSHV-positive NHL from this region; this case is also the first reported pediatric lymphoma associated with KSHV infection.     

Human herpes virus 8: a new virus discloses its face

The human herpes virus 8 (HHV8) or Kaposi’s sarcoma-associated herpes virus (KSHV) is present in all Kaposi’s sarcoma, and the detection of the virus using polymerase chain reaction or in situ hybridization is a highly sensitive and specific diagnostic test for the diagnosis of this neoplasm. HHV8 is furthermore invariably present in primary effusion lymphoma (PEL) and has also been detected in patients with acquired immunodeficiency syndrome (AIDS)-associated multicentric Castleman’s disease (MCD) as well as, to a lesser extent, in non-AIDS MCD. In contrast to Kaposi’s sarcoma, in which the tumor cells show primarily latent HHV8 infection, a higher rate of lytically infected cells can be observed in MCD. Epidemiological surveys indicate that the seroprevalence for HHV8 parallels the risk of developing Kaposi’s sarcoma – 5–10% in the general population of the Western world but ranging up to 20–70% in homosexual human immunodeficiency virus (HIV)-infected patients, and the infection precedes the development of Kaposis’s sarcoma. Finally, HHV8 has been reported in a number of other diseases, especially in multiple myeloma. However, the highly controversial role of HHV8 in these lesions has to be clarified. Based on the data available today, HHV8 can be assigned as a new human virus, associated with tumors. Received: 23 August 1999 / Accepted: 27 October 1999     

Molecular analysis of clonality in Kaposi's sarcoma.

BACKGROUND: Kaposi''s sarcoma is considered to be an angioproliferative disease associated with a novel herpesvirus (KSHV/HHV8), but the precise pathophysiology of the lesion remains unclear. The study of clonality in Kaposi''s sarcoma using X linked DNA polymorphism has been difficult so far, because of a very strong prevalence of the disease in males. AIMS: To study the clonality of Kaposi''s sarcoma lesions. METHODS: An assay based on a methyl sensitive restriction digest followed by polymerase chain reaction (PCR) amplification of the highly polymorphic human androgen receptor (HUMARA) gene was used. Tissues from Kaposi''s sarcoma lesions and control tissues from the same patients were obtained from seven females, four with classic Kaposi''s sarcoma and three with AIDS associated Kaposi''s sarcoma. A cutaneous angiosarcoma was also analysed, for comparative purposes, and showed evidence of clonality after HpaII digestion. RESULTS: All patients were heterozygous for the HUMARA polymorphism and informative for analysis. In all patients, including four with a nodular form of Kaposi''s sarcoma and more than 70% spindle cells in the lesion, a polyclonal pattern of inactivation could be demonstrated. CONCLUSIONS: The Kaposi''s sarcoma lesion is first of all a polyclonal cell proliferation.