Human herpesvirus-8 (Kaposi's sarcoma-associated virus) ORF50 increases in vitro cell susceptibility to human immunodeficiency virus type 1 infection

Application of the CDK9 inhibitor FIT-039 for the treatment of KSHV-associated malignancy

Chronic infection with Kaposi's sarcoma-associated herpes virus (KSHV) in B lymphocytes causes primary effusion lymphoma (PEL), the most aggressive form of KSHV-related cancer, which is resistant to conventional chemotherapy. In this study, we report that the BCBL-1 KSHV⁺ PEL cell line does not harbor oncogenic mutations responsible for its aggressive malignancy. Assuming that KSHV viral oncogenes play crucial roles in PEL proliferation, we examined the effect of cyclin-dependent kinase 9 (CDK9) inhibitor FIT-039 on KSHV viral gene expression and KSHV⁺ PEL proliferation. We found that FIT-039 treatment impaired the proliferation of KSHV⁺ PEL cells and the expression of KSHV viral genes in vitro. The effects of FIT-039 treatment on PEL cells were further evaluated in the PEL xenograft model that retains a more physiological environment for the growth of PEL growth and KSHV propagation, and we confirmed that FIT-039 administration drastically inhibited PEL growth in vivo. Our current study indicates that FIT-039 is a potential new anticancer drug targeting KSHV for PEL patients.

Molecular Mechanisms of Kaposi Sarcoma Development

Simple Summary

There are at least four forms of Kaposi’s sarcoma (KS) with the ‘HIV’-related form being the most aggressive and can involve mucosae or visceral organs. Kaposi’s sarcoma-associated herpes virus (KSHV) is the underlying cause of this disease. It can infect endothelial and/or mesenchymal cells and establish a latent phase in host cells in which latency proteins and various non-coding RNAs (ncRNAs) play a complex role in proliferation and angiogenesis. It also undergoes periods of sporadic lytic reactivation that are key for KS progression. Complex interactions with the microenvironment with production of inflammatory cytokines and paracrine signaling is a standout feature of KS development and maintenance. KSHV impairs the immune response by various mechanisms such as the degradation of a variety of proteins involved in immune response or binding to cellular chemokines. Treatment options include classical chemotherapy, but other novel therapies are being investigated.

Abstract

Kaposi’s sarcoma (KS) is a heterogeneous angioproliferative tumor that generally arises in the skin. At least four forms of this disease have been described, with the ‘HIV’-related form being the most aggressive and can involve mucosae or visceral organs. Three quarters of KS cases occur in sub-Saharan Africa (SSA) as geographic variation is explained by the disparate prevalence of KS-associated herpes virus (KSHV), which is the underlying cause of this disease. It can infect endothelial and/or mesenchymal cells that consequently transdifferentiate to an intermediate state. KSHV establishes a latent phase in host cells in which latency proteins and various non-coding RNAs (ncRNAs) play a complex role in proliferation and angiogenesis. It also undergoes periods of sporadic lytic reactivation triggered by various biological signals in which lytic stage proteins modulate host cell signaling pathways and are key in KS progression. Complex interactions with the microenvironment with production of inflammatory cytokines with paracrine signaling is a standout feature of KS development and maintenance. KSHV impairs the immune response by various mechanisms such as the degradation of a variety of proteins involved in immune response or binding to cellular chemokines. Treatment options include classical chemotherapy, but other novel therapies are being investigated.

Epidemiology of Kaposi's Sarcoma

Kaposi's sarcoma is an angioproliferative tumor caused by human herpesvirus 8 in the context of immunodeficiency, such as that induced by HIV infection or immunosuppressive therapy. Its incidence has dramatically fallen in patients living with HIV (PLHIV) since the introduction of potent antiretroviral combinations 25 years ago due to the restoration of immunity and better control of HIV replication. However, KS is still one of the most frequently occurring cancers in PLHIV, in particular in men who have sex with men and in sub-Saharan Africa, where it is still endemic. Even in the context of restored immunity, the risk of KS is still more than 30 times higher in PLHIV than in the general population. Recent evidence indicates that early initiation of antiretroviral treatment, which is recommended by current guidelines, may reduce the risk of KS but it needs to be accompanied by early access to care. This review mainly focuses on the recent epidemiological features of KS in the context of HIV infection.

Co-infections and Pathogenesis of KSHV-Associated Malignancies

Kaposi’s sarcoma-associated herpesvirus (KSHV), also known as human herpes virus 8 (HHV-8) is one of the several carcinogenic viruses that infect humans. KSHV infection has been implicated in the development of Kaposi’s sarcoma (KS), primary effusion lymphoma, and multicentric Castleman’s Disease. While KSHV infection is necessary for the development of KSHV associated malignancies, it is not sufficient to induce tumorigenesis. Evidently, other co-factors are essential for the progression of KSHV induced malignancies. One of the most important co-factors, necessary for the progression of KSHV induced tumors, is immune suppression that frequently arises during co-infection with HIV and also by other immune suppressants. In this mini-review, we discuss the roles of co-infection with HIV and other pathogens on KSHV infection and pathogenesis.

Human Herpesviruses as Copathogens of HIV Infection, Their Role in HIV Transmission, and Disease Progression

Of eight human herpesviruses (HHVs), often, only herpes simplex virus types 1 (HSV-1) and 2 (HSV-2) find mention in medical literature as both of these viruses are commonly associated with genital lesions and oral ulcers, commonly known as cold sores. However, role of human herpesviruses as copathogens and in aggravation and in the transmission of other human diseases, especially the Acquired immunodeficiency syndrome (HIV/AIDS) has only very recently been recognized. Therefore, screening and treating subclinical HHV infections may offer slowing of HIV infection, disease progression, and its transmission. Beside HSV-1 and HSV-2, HHV-3 a causative agent of herpes zoster remained one of the first manifestations of HIV disease before the era of highly active antiretroviral therapy (HAART). HHV-5 also known as human Cytomegalovirus infection remains a significant risk factor for HIV-associated mortality and morbidity even in HAART era. It is proposed that Cytomegalovirus viremia could be a better predictor of HIV disease progression than CD4+ T-lymphocyte count. The role of HHV-4 or Epstein-Burr virus and HHV-6, HHV-7, and HHV-8 is still being investigated in HIV disease progression. This review provides insight into the current understanding about these 8 HHVs, their co-pathogenesis, and role in HIV/AIDS disease progression. The review also covers recent literature in favor and against administering anti-HHV treatment along with HAART for slower AIDS progression and interrupted sexual transmission.

HIV and human herpesvirus 8 co-infection across the globe: Systematic review and meta-analysis

HIV-infection is an important risk factor for developing Kaposi sarcoma (KS), but it is unclear whether HIV-positive persons are also at increased risk of co-infection with human herpesvirus 8 (HHV-8), the infectious cause of KS. We systematically searched literature up to December 2012 and included studies reporting HHV-8 seroprevalence for HIV-positive and HIV-negative persons. We used random-effects meta-analysis to combine odds ratios (ORs) of the association between HIV and HHV-8 seropositivity and conducted random-effects meta-regression to identify sources of heterogeneity. We included 93 studies with 58,357 participants from 32 countries in sub-Saharan Africa, North and South America, Europe, Asia, and Australia. Overall, HIV-positive persons were more likely to be HHV-8 seropositive than HIV-negative persons (OR 1.99, 95% confidence interval [CI] 1.70-2.34) with considerable heterogeneity among studies (I(2) 84%). The association was strongest in men who have sex with men (MSM, OR 3.95, 95% CI 2.92-5.35), patients with hemophilia (OR 3.11, 95% CI 1.19-8.11), and children (OR 2.45, 95% CI 1.58-3.81), but weaker in heterosexuals who engage in low-risk (OR 1.42, 95% CI 1.16-1.74) or high-risk sexual behavior (OR 1.66, 95% CI 1.27-2.17), persons who inject drugs (OR 1.66, 95% CI 1.28-2.14), and pregnant women (OR 1.68, 95% CI 1.15-2.47), p value for interaction <0.001. In conclusion, HIV-infection was associated with an increased HHV-8 seroprevalence in all population groups examined. A better understanding of HHV-8 transmission in different age and behavioral groups is needed to develop strategies to prevent HHV-8 transmission.

Prevalence of Kaposi's sarcoma associated herpesvirus among men attending sexually transmitted infections clinics in Anhui, China

Kaposi's sarcoma-associated herpesvirus (KSHV) may be transmitted via sexual contacts, but limited information is available on KSHV infection status among sexually transmitted infection (STI) patients in China. The main objective of the present study was to determine the KSHV seroprevalence and its risk factors among male STI patients. A cross-sectional survey was conducted in three prefectures of Anhui province, China, between June and September 2013. A total of 1,600 male patients who visited an STI clinic were invited, and 1,372 participated in the study. Data were abstracted from the medical records for all the patients. Blood samples were collected and tested for antibodies to KSHV, HIV, HCV, and syphilis. Factors associated with KSHV seropositivity were examined using multivariable logistic regression analysis. The overall prevalence of KSHV, HIV, HCV, and syphilis was 13.3%, 0.7%, 0.6%, and 12.5%, respectively. After adjusting for potential confounders, KSHV infection was significantly associated with ever having anal sex with men (19 out of 30 males, OR: 8.64, 95%CI: 1.92-38.79) and HIV infection (six out of nine HIV-positive individuals, OR: 8.39, 95%CI: 1.80-39.04). There were no significant associations of KSHV infection with drug use, heterosexual sex behaviors, syphilis, and HCV. Our finding has shown that a relatively moderate prevalence of KSHV was found among male STI patients. While an increased risk for KSHV infection was observed among participants with homosexual contacts. Routine KSHV testing is recommended for male individuals attending STI clinics.

Short communication: activating transcription factor 4 (ATF4) promotes HIV type 1 activation

Activating transcription factor 4 (ATF4) is a central factor in the cellular response to multiple stresses, including altered metabolic conditions, anoxia and hypoxia, and redox stress. ATF4 is triggered by endoplasmic reticulum stress and consequent unfolded protein response. This report identifies for the first time ATF4 as a transcription factor upregulated by HIV-1 infection. Upregulation of ATF4 enhances HIV replication, by synergistic interactions with HIV Tat. Moreover, in specific cell lines ATF4 has a direct transactivating potential on the LTR, even in the absence of Tat. We also provide evidence that expression of ATF4 induces HIV reactivation in chronically infected cell lines. These results show for the first time that ATF4 induction might have an important role in HIV replication, and suggest that ATF4 might represent a convergent signaling molecule for different stressors important in regulating the HIV-1 cycle.

Activating transcription factor 4 (ATF4) is upregulated by human herpesvirus 8 infection, increases virus replication and promotes proangiogenic properties

Human herpesvirus 8 (HHV-8) triggers proangiogenic behaviour in endothelial cells by inducing monocyte chemoattractant protein 1 (MCP-1) through activation of Nuclear Factor κB (NF-κB). However, NF-κB inhibition still results in partial MCP-1 induction and consequent angiogenesis, suggesting the involvement of another transcriptional pathway. We analysed activating transcription factor 4 (ATF4), since it is central in the cellular response to stress and is involved in angiogenesis. The results show that HHV-8 upregulates ATF4 expression, which in turn promotes HHV-8 infection, and induces MCP-1 production and proangiogenic properties in endothelial cells. By contrast, ATF4 silencing decreases virus replication and inhibits virus-induced MCP-1 production and induction of tube-like structures. Therefore, ATF4 plays a role in HHV-8 replication and associated virus-induced angiogenesis. The elucidation of molecular pathways involved in this process will result in a better understanding of the virus-induced angiogenic process and might help in designing novel therapies to reduce tumour growth.

Mother-to-child HIV and HHV-8 transmission in neonates at Saint Camille Medical Centre in Burkina Faso

In Sub-Saharan Africa, many HIV infected people are co-infected with Human Herpes Virus 8 (HHV-8). Therefore, the present study aimed to: (1) identify the pregnant women co-infected by HIV and HHV-8 at Saint Camille Medical Centre; (2) use three molecules (Zidovudine, Nevirapine and Lamivudine) to interrupt the vertical transmission of HIV and (3) use the PCR technique to diagnose children, who were infected by these viruses, in order to offer them an early medical assistance. A total of 107 pregnant women, aged from 19 to 42 years were diagnosed to be HIV positive at Saint Camille Centre; among them 13 were co-infected with HHV-8. All included women received the HAART. Two to six months after childbirth their babies underwent PCR diagnosis for HIV and HHV-8. The results revealed that, among these mothers, 68.2% were housewives, 34.6% were illiterates and 60.7% did not have university degree. The prevalence of HHV-8 among these pregnant women was 12.15% and the rate of vertical transmission of both HIV and HHV-8, was 0.0%. The issue of this study revealed that the antiretroviral therapy increased the mother CD4 T-cells, prevented the transcription of the mRNA of HHV-8 and blocked HIV vertical transmission.

High human herpesvirus 8 (HHV-8) prevalence, clinical correlates and high incidence among recently HIV-1-infected subjects in Sao Paulo, Brazil

Background

Human herpesvirus 8 (HHV-8) is the etiological agent for Kaposi Sarcoma, which occurs especially in HIV-infected subjects. HHV-8 infection and its clinical correlates have not been well characterized in recently HIV-1-infected subjects, especially men who have sex with men (MSM).

Methodology/ Principal Findings

We assessed the HHV-8 seroprevalence, clinical correlates, and incidence after one year of follow-up in a cohort of 228 recently HIV-1-infected individuals, of whom 83.6% were MSM, using indirect immunofluorescence assay. The prevalence of HHV-8 infection at the time of cohort enrollment was 25.9% (59/228). In the univariate model, there were significant associations with male gender, black ethnicity, MSM practice, and previous hepatitis B virus and syphilis infections. In the multivariate model we could still demonstrate association with MSM, hepatitis B, and black ethnicity. No differences in mean CD4+ cell counts or HIV viral load according to HHV-8 status were found. In terms of incidence, there were 23/127 (18.1%) seroconversions in the cohort after 1 year.

Conclusions

HHV-8 is highly prevalent among recently HIV-1-infected subjects. Correlations with other sexually transmitted infections suggest common transmission routes.

Coinfecting viruses as determinants of HIV disease

The human body constitutes a balanced ecosystem of its own cells together with various microbes ("host-microbe ecosystem"). The transmission of HIV-1 and the progression of HIV disease in such an ecosystem are accompanied by de novo infection by other microbes or by activation of microbes that were present in the host in homeostatic equilibrium before HIV-1 infection. In recent years, data have accumulated on the interactions of these coinfecting microbes-viruses in particular-with HIV. Coinfecting viruses generate negative and positive signals that suppress or upregulate HIV-1. We suggest that the signals generated by these viruses may largely affect HIV transmission, pathogenesis, and evolution. The study of the mechanisms of HIV interaction with coinfecting viruses may indicate strategies to suppress positive signals, enhance negative signals, and lead to the development of new and original anti-HIV therapies.

Parotid localized Castleman’s disease and HHV-8 infection: a case report

Castleman's disease (CD) is an unusual massive proliferation of lymphoid tissue distinct in two clinical forms, localized and multicentric. The multicentric form has been related to human herpesvirus 8 (HHV-8), especially in HIV-infected patients, whereas the localized form of CD is still unrelated to viral pathogens. We report a case of a HIV-negative 16-year-old male referred to our hospital with a 12-month history of a painless swelling in his right parotid region. A parotidectomy was performed, and histological analysis evidenced a localized CD. The search for HHV-8 revealed an active virus infection. The patient was commenced on corticosteroid therapy and a follow-up was performed every 6 months. The patient was commenced on corticosteroid therapy and there has been no recurrence after 24 months. The authors report a case of localized parotid CD in a patient with evidence of an active HHV-8 infection. The results of this study does for the first time suggest an association between HHV-8 and localized CD in HIV-negative subjects.

Integration of HIV-1 caused STAT3-associated B cell lymphoma in an AIDS patient

Signal transducer and activator of transcription 3 (STAT3) is a DNA-binding transcription factor activated by multiple cytokines and interferons. High expression of STAT3 has also been implicated in cancer and lymphoma. Here, we show a case of B cell lymphoma in which a defective human immunodeficiency virus 1 (HIV-1) integrated upstream of the first STAT3 coding exon. The lymphoma cells with anaplastic large cell morphology formed multiple nodular lesions in the lung of an acquired immunodeficiency syndrome (AIDS) patient with Kaposi's sarcoma. The provirus had a 5' long terminal repeat (LTR) deletion, but the 3' LTR had stronger promoter activity than the STAT3 promoter in reporter assays. Immunohistochemistry showed increased expression of STAT3 in the nuclei of lymphoma cells. Transfection of STAT3 resulted in transient cell proliferation in primary B cells in vitro. Although this is a very rare case of HIV-1-integrated lymphoma, these data suggest that up-regulation of STAT3 caused by HIV-1 integration resulted in the development of B cell lymphoma in this special case.

Molecular biology of KSHV in relation to AIDS-associated oncogenesis

KSHV has been established as the causative agent of KS, PEL, and MCD, malignancies occurring more frequently in AIDS patients. The aggressive nature of KSHV in the context of HIV infection suggests that interactions between the two viruses enhance pathogenesis. KSHV latent infection and lytic reactivation are characterized by distinct gene expression profiles, and both latency and lytic reactivation seem to be required for malignant progression. As a sophisticated oncogenic virus, KSHV has evolved to possess a formidable repertoire of potent mechanisms that enable it to target and manipulate host cell pathways, leading to increased cell proliferation, increased cell survival, dysregulated angiogenesis, evasion of immunity, and malignant progression in the immunocompromised host. Worldwide, approximately 40.3 million people are currently living with HIV infection. Of these, a significant number are coinfected with KSHV. The complex interplay between the two viruses dramatically elevates the risk for development of KSHV-induced malignancies, KS, PEL, and MCD. Although HAART significantly reduces HIV viral load, the entire T-cell repertoire and immune function may not be completely restored. In fact, clinically significant immune deficiency is not necessary for the induction of KSHV-related malignancy. Because of variables such as lack of access to therapy noncompliance with prescribed treatment, failure to respond to treatment and the development of drug-resistant strains of HIV, KSHV-induced malignancies will continue to present as major health concerns.

Pregnancy and human herpesvirus 8 reactivation in human immunodeficiency virus type 1-infected women

To investigate the impact of pregnancy on human herpesvirus 8 (HHV-8) reactivation in human immunodeficiency virus type 1 (HIV-1)-infected women, the HHV-8 DNA presence and load were analyzed in peripheral blood mononuclear cells (PBMCs) and cervicovaginal secretions (CVSs) from 15 pregnant women coinfected with HIV-1 and HHV-8. HHV-8 detection was analyzed in relation to anti-HHV-8 antibodies and HIV-1-related parameters. Nucleotide sequence analysis of an ORFK1 hypervariable region of the HHV-8 strains was performed. HHV-8 was detected in maternal PBMCs (5/15 women) from the second trimester and in CVSs (5/15 women) mainly from the third trimester. The HHV-8 load significantly increased late in pregnancy in both maternal compartments and was associated with a significant increase in HIV-1 shedding in the genital tract. Antilytic antibodies were significantly more common in HHV-8 DNA-positive women. An elevated HHV-8 load was found in the PBMCs of an infant born to a mother with large amounts of HHV-8 in both compartments at delivery. Different ORFK1 subtypes were found in maternal samples, whereas the same subtype was identified in the mother-child pair. These data suggest that pregnancy may induce HHV-8 replication in HIV-1-infected women. An augmented HHV-8 load may, in turn, influence mother-to-child transmission, since one of the HIV-1-infected mothers with HHV-8 reactivation transmitted her ORFK1 subtype to the infant, who showed a high level of HHV-8 viremia indicative of a primary infection. This finding documents for the first time the perinatal transmission of a specific HHV-8 subtype. Vertical transmission may thus play a role in HHV-8 spread also in areas of subendemicity among HIV-1-infected women.

StpC-based gene therapy targeting latent reservoirs of HIV-1

The ability of HIV-1 to form latent reservoirs presents a major obstacle to eradication. One approach to elimination of the latent reservoir is induction therapy, whereby cells harboring latent virus are activated and therefore initiate virus replication. We have constructed a lentiviral vector encoding Herpesvirus saimiri subgroup C saimiri transformation-associated protein (StpC), which has been shown to modulate HIV-1 replication, under the control of a cytomegalovirus promoter in order to determine the ability of StpC to upregulate latent HIV-1. We have included a suicide gene, herpes simplex virus thymidine kinase (TK), under the control of the HIV-1 long terminal repeat (LTR) promoter. We hypothesized that upon StpC expression in latently infected cells induction of virus replication and subsequent production of viral transactivators of the LTR will activate expression of the tk gene, sensitizing the cells to the nucleoside analogue ganciclovir (GCV). Transduction of the latently infected cell line J1.1 resulted in increased virus replication. In the presence of GCV transduced cells exhibited decreased HIV-1 replication, inhibition of cell proliferation, and increased apoptosis. This prototype vector serves as a proof of concept of the utility of gene-based induction agents and suicide genes as a new method for targeting reservoirs of latent HIV-1.

Human herpesvirus 8 enhances human immunodeficiency virus replication in acutely infected cells and induces reactivation in latently infected cells

Human herpesvirus 8 (HHV-8) is etiologically associated with Kaposi sarcoma (KS), the most common AIDS-associated malignancy. Previous results indicate that the HHV-8 viral transactivator ORF50 interacts synergistically with Tat protein in the transactivation of human immunodeficiency virus (HIV) long terminal repeat (LTR), leading to increased cell susceptibility to HIV infection. Here, we analyze the effect of HHV-8 infection on HIV replication in monocyte-macrophage and endothelial cells, as potential targets of coinfection. Primary or transformed monocytic and endothelial cells were infected with a cell-free HHV-8 inoculum and subsequently infected with lymphotropic or monocytotropic strains of HIV. The results show that HHV-8 coinfection markedly increases HIV replication in both cell types. HHV-8 infection induces also HIV reactivation in chronically infected cell lines and in peripheral blood mononuclear cells (PBMCs) from patients with asymptomatic HIV, suggesting the possibility that similar interactions might take place also in vivo. Furthermore, coinfection is not an essential condition, since contiguity of differently infected cells is sufficient for HIV reactivation. The results suggest that HHV-8 might be a cofactor for HIV progression and that HHV-8-infected endothelial cells might play a relevant role in transendothelial HIV spread.