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

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.

Evidence linking APOBEC3B genesis and evolution of innate immune antagonism by gamma-herpesvirus ribonucleotide reductases

Viruses have evolved diverse mechanisms to antagonize host immunity such as direct inhibition and relocalization of cellular APOBEC3B (A3B) by the ribonucleotide reductase (RNR) of Epstein-Barr virus. Here, we investigate the mechanistic conservation and evolutionary origin of this innate immune counteraction strategy. First, we find that human gamma-herpesvirus RNRs engage A3B via largely distinct surfaces. Second, we show that RNR-mediated enzymatic inhibition and relocalization of A3B depend upon binding to different regions of the catalytic domain. Third, we show that the capability of viral RNRs to antagonize A3B is conserved among gamma-herpesviruses that infect humans and Old World monkeys that encode this enzyme but absent in homologous viruses that infect New World monkeys that naturally lack the A3B gene. Finally, we reconstruct the ancestral primate A3B protein and demonstrate that it is active and similarly engaged by the RNRs from viruses that infect humans and Old World monkeys but not by the RNRs from viruses that infect New World monkeys. These results combine to indicate that the birth of A3B at a critical branchpoint in primate evolution may have been a driving force in selecting for an ancestral gamma-herpesvirus with an expanded RNR functionality through counteraction of this antiviral enzyme.

Potential Association between Kaposi Sarcoma and Gout: An Exploratory Observational Study

Background

Kaposi sarcoma is a rare vascular mesenchymal neoplasm, associated with Human Herpes Virus 8 (HHV8). Gout is a condition clinically characterized by recurrent flares of arthritis and hyperuricemia. Following our clinical impression that patients with classical Kaposi sarcoma (CKS) have a high rate of gout, we explored this in a retrospective manner.

Methods

All consecutive patients diagnosed with sarcoma or carcinosarcoma within a single tertiary center between 1/2012–12/2017 were identified through the pathology department database. A cohort of CKS patients was compared with the non-Kaposi sarcoma and carcinosarcoma cohort. Data were extracted from patients' electronic medical records. Patients younger than 18 and patients without clinical data available were excluded. Association between diagnosis of gout and CKS was assessed and adjusted for risk factors.

Results

Three hundred and sixty-one patients were eligible for this analysis, 61 were diagnosed with CKS and 300 with other types of sarcoma. We found a higher incidence of gout in CKS patients, 11/61 (18%) patients, compared with 8/300 (2.6%) with other types of sarcoma, odds ratio (OR) 8.0 (P < 0.00001). This association persisted when adjusted for age >39 years (OR = 6.7, P < 0.00001), age and male sex (OR = 4.97, P < 0.0001), and when adjusting for multiple confounding factors and medical comorbidities.

Conclusions

We have demonstrated a statistically significant association between gout and CKS. As risk factors for gout were accounted for, this association may be explained by HHV8 immune-related effects. This should be further explored in vitro and in population-based studies.

HIV-1 Persistence and Chronic Induction of Innate Immune Responses in Macrophages

A hallmark of HIV-1 infection is chronic inflammation, which plays a significant role in disease pathogenesis. Acute HIV infection induces robust inflammatory responses, which are insufficient to prevent or eliminate virus in mucosal tissues. While establishment of viral set-point is coincident with downregulation of acute innate responses, systemic inflammatory responses persist during the course of chronic HIV infection. Since the introduction of combination antiviral therapy (cART), most HIV-1⁺ individuals can suppress viremia under detection levels for decades. However, chronic immune activation persists and has been postulated to cause HIV associated non-AIDS complications (HANA). Importantly, inflammatory cytokines and activation markers associated with macrophages are strongly and selectively correlated with the incidence of HIV-associated neurocognitive disorder (HAND), cardiovascular dysfunctions (CVD) and other HANA conditions. In this review, we discuss the roles of macrophages in facilitating viral persistence and contributing to generation of persistent inflammatory responses.

Kaposi's Sarcoma-Associated Herpesvirus Increases PD-L1 and Proinflammatory Cytokine Expression in Human Monocytes

Kaposi’s sarcoma-associated herpesvirus (KSHV) is associated with the human malignancy Kaposi’s sarcoma and the lymphoproliferative disorders primary effusion lymphoma and multicentric Castleman’s disease. KSHV establishes lytic infection of monocytes in vivo, which may represent an important cellular reservoir during KS disease progression. KS tumors consist of latently infected endothelial cells; however, lytic phase gene products are important for KS onset. Early KS lesion progression is driven by proinflammatory cytokines supplied by immune cell infiltrates including T cells and monocytes. KSHV-infected monocytes may supply the lytic viral products and the inflammatory milieu conducive to KS tumor progression. To establish successful infection, KSHV extensively modulates the host immune system. KSHV antigens activate both innate and adaptive immune responses including KSHV-specific T cells, but lifelong infection is still established. Programmed death ligand 1 (PD-L1) is a prosurvival cell surface protein that suppresses T-cell-mediated killing. PD-L1 is variably present on various tumor cells and is a targetable marker for cancer treatment. We show that KSHV infection of human monocytes increases PD-L1 expression and transcription in a dose-dependent manner. We also saw evidence of lytic gene expression in the KSHV-infected monocytes. Intact KSHV is needed for full PD-L1 response in human monocytes. KSHV induces a general proinflammatory cytokine milieu including interleukins 1α, 1β, and 6, which have been implicated in early KS lesion progression. KSHV-mediated PD-L1 increase may represent a novel mechanism of KSHV-mediated immune modulation to allow for virus survival and eventually malignant progression.

KSHV is the etiologic agent of Kaposi’s sarcoma and the lymphoproliferative disorders primary effusion lymphoma and multicentric Castleman’s disease. Programmed death ligand 1 (PD-L1) is an immunosuppressive cell surface marker that inhibits T cell activation. We report that KSHV infection of primary human monocytes upregulates PD-L1 transcription and protein expression. Analysis of the cytokine and chemokine milieu following KSHV infection of monocytes revealed that KSHV induces interleukins 1α, 1β, and 6, all of which have been implicated in KS development. Our work has identified another potential immune evasion strategy for KSHV and a potential target for immunotherapy of KSHV-derived disease.

Infection of KSHV and Interaction with HIV: The Bad Romance

Kaposi's sarcoma-associated herpesvirus (KSHV), namely, human herpesvirus 8 (HHV-8), is considered as the pathogen of Kaposi's sarcoma (KS), the most frequent cancer in untreated HIV-infected individuals. Patients infected with HIV have a much higher possibility developing KS than average individual. Researchers have found that HIV, which functions as a cofactor of KS, contributes a lot to the development of KS. In this article, we will give a brief introduction of KS and KSHV and how the interaction between KSHV and HIV contributes to the development of KS. Also we will take a glance at the development of treatment in KS, especially AIDS-KS.

Changing Incidence and Risk Factors for Kaposi Sarcoma by Time Since Starting Antiretroviral Therapy: Collaborative Analysis of 21 European Cohort Studies

BACKGROUND

 Kaposi sarcoma (KS) remains a frequent cancer in human immunodeficiency virus (HIV)-positive patients starting combination antiretroviral therapy (cART). We examined incidence rates and risk factors for developing KS in different periods after starting cART in patients from European observational HIV cohorts.

METHODS

 We included HIV-positive adults starting cART after 1 January 1996. We analyzed incidence rates and risk factors for developing KS up to 90 and 180 days and 1, 2, 5, and 8 years after cART start and fitted univariable and multivariable Cox regression models.

RESULTS

 We included 109 461 patients from 21 prospective clinical cohorts in Europe with 916 incident KS cases. The incidence rate per 100 000 person-years was highest 6 months after starting cART, at 953 (95% confidence interval, 866-1048), declining to 82 (68-100) after 5-8 years. In multivariable analyses adjusted for exposure group, origin, age, type of first-line regimen, and calendar year, low current CD4 cell counts increased the risk of developing KS throughout all observation periods after cART initiation. Lack of viral control was not associated with the hazard of developing KS in the first year after cART initiation, but was over time since starting cART increasingly positively associated (P < .001 for interaction).

CONCLUSION

 In patients initiating cART, both incidence and risk factors for KS change with time since starting cART. Whereas soon after starting cART low CD4 cell count is the dominant risk factor, detectable HIV-1 RNA viral load becomes an increasingly important risk factor in patients who started cART several years earlier, independently of immunodeficiency.

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.

Multitarget, quantitative nanoplasmonic electrical field-enhanced resonating device (NE2RD) for diagnostics

Recent advances in biosensing technologies present great potential for medical diagnostics, thus improving clinical decisions. However, creating a label-free general sensing platform capable of detecting multiple biotargets in various clinical specimens over a wide dynamic range, without lengthy sample-processing steps, remains a considerable challenge. In practice, these barriers prevent broad applications in clinics and at patients' homes. Here, we demonstrate the nanoplasmonic electrical field-enhanced resonating device (NE(2)RD), which addresses all these impediments on a single platform. The NE(2)RD employs an immunodetection assay to capture biotargets, and precisely measures spectral color changes by their wavelength and extinction intensity shifts in nanoparticles without prior sample labeling or preprocessing. We present through multiple examples, a label-free, quantitative, portable, multitarget platform by rapidly detecting various protein biomarkers, drugs, protein allergens, bacteria, eukaryotic cells, and distinct viruses. The linear dynamic range of NE(2)RD is five orders of magnitude broader than ELISA, with a sensitivity down to 400 fg/mL This range and sensitivity are achieved by self-assembling gold nanoparticles to generate hot spots on a 3D-oriented substrate for ultrasensitive measurements. We demonstrate that this precise platform handles multiple clinical samples such as whole blood, serum, and saliva without sample preprocessing under diverse conditions of temperature, pH, and ionic strength. The NE(2)RD's broad dynamic range, detection limit, and portability integrated with a disposable fluidic chip have broad applications, potentially enabling the transition toward precision medicine at the point-of-care or primary care settings and at patients' homes.

Eradication of HIV-1 from the macrophage reservoir: an uncertain goal?

Human immunodeficiency virus type 1 (HIV-1) establishes latency in resting memory CD4+ T cells and cells of myeloid lineage. In contrast to the T cells, cells of myeloid lineage are resistant to the HIV-1 induced cytopathic effect. Cells of myeloid lineage including macrophages are present in anatomical sanctuaries making them a difficult drug target. In addition, the long life span of macrophages as compared to the CD4+ T cells make them important viral reservoirs in infected individuals especially in the late stage of viral infection where CD4+ T cells are largely depleted. In the past decade, HIV-1 persistence in resting CD4+ T cells has gained considerable attention. It is currently believed that rebound viremia following cessation of combination anti-retroviral therapy (cART) originates from this source. However, the clinical relevance of this reservoir has been questioned. It is suggested that the resting CD4+ T cells are only one source of residual viremia and other viral reservoirs such as tissue macrophages should be seriously considered. In the present review we will discuss how macrophages contribute to the development of long-lived latent reservoirs and how macrophages can be used as a therapeutic target in eradicating latent reservoir.

Molecular phenotypes of human parvovirus B19 in patients with myocarditis

AIM: To investigate molecular phenotypes of myocardial B19V-infection to determine the role of B19V in myocarditis and dilated cardiomyopathy (DCM).

METHODS: Endomyocardial biopsies (EMBs) from 498 B19V-positive patients with myocarditis and DCM were analyzed using molecular methods and functional experiments. EMBs were obtained from the University Hospitals of Greifswald and Tuebingen and additionally from 36 German cardiology centers. Control tissues were obtained at autopsy from 34 victims of accidents, crime or suicide. Identification of mononuclear cell infiltrates in EMBs was performed using immunohistological staining. Anti-B19V-IgM and anti-B19V-IgG were analyzed by enzyme-linked immunosorbent assay (ELISA). B19V viral loads were determined using in-house quantitative real-time polymerase chain reaction (PCR). For B19V-genotyping a new B19V-genotype-specific restriction fragment length polymorphism (RFLP)-PCR was established. B19V-genotyping was verified by direct DNA-sequencing and sequences were aligned using BLAST and BioEdit software. B19V P6-promoter and HHV6-U94-transactivator constructs were generated for cell culture experiments. Transfection experiments were conducted using human endothelial cells 1. Luciferase reporter assays were performed to determine B19V-replication activity. Statistical analysis and graphical representation were calculated using SPSS and Prism5 software.

RESULTS: The prevalence of B19V was significantly more likely to be associated with inflammatory cardiomyopathy (iCMP) compared to uninflamed DCM (59.6% vs 35.3%) (P < 0.0001). The detection of B19V-mRNA replication intermediates proved that replication of B19V was present. RFLP-PCR assays showed that B19V-genotype 1 (57.4%) and B19V-genotype 2 (36.7%) were the most prevalent viral genotypes. B19V-genotype 2 was observed more frequently in EMBs with iCMP (65.0%) compared to DCM (35%) (P = 0.049). Although there was no significant difference in gender-specific B19V-loads, women were more frequently infected with B19V-genotype 2 (44.6%) than men (36.0%) (P = 0.0448). Coinfection with B19V and other cardiotropic viruses was found in 19.2% of tissue samples and was associated with higher B19V viral load compared to B19V-monoinfected tissue (P = 0.0012). The most frequent coinfecting virus was human herpes virus 6 (HHV6, 16.5%). B19V-coinfection with HHV6 showed higher B19V-loads compared to B19V-monoinfected EMBs (P = 0.0033), suggesting that HHV6 had transactivated B19V. In vitro experiments confirmed a 2.4-fold increased B19V P6-promoter activity by the HHV6 U94-transactivator.

CONCLUSION: The finding of significantly increased B19V loads in patients with histologically proven cardiac inflammation suggests a crucial role of B19V-genotypes and reactivation of B19V-infection by HHV6-coinfection in B19V-associated iCMP. Our findings suggest that B19V-infection of the human heart can be a causative event for the development of an endothelial cell-mediated inflammatory disease and that this is related to both viral load and genotype.

HIV-1 latency in monocytes/macrophages

Human immunodeficiency virus type 1 (HIV-1) targets CD4⁺ T cells and cells of the monocyte/macrophage lineage. HIV pathogenesis is characterized by the depletion of T lymphocytes and by the presence of a population of cells in which latency has been established called the HIV-1 reservoir. Highly active antiretroviral therapy (HAART) has significantly improved the life of HIV-1 infected patients. However, complete eradication of HIV-1 from infected individuals is not possible without targeting latent sources of infection. HIV-1 establishes latent infection in resting CD4⁺ T cells and findings indicate that latency can also be established in the cells of monocyte/macrophage lineage. Monocyte/macrophage lineage includes among others, monocytes, macrophages and brain resident macrophages. These cells are relatively more resistant to apoptosis induced by HIV-1, thus are important stable hideouts of the virus. Much effort has been made in the direction of eliminating HIV-1 resting CD4⁺ T-cell reservoirs. However, it is impossible to achieve a cure for HIV-1 without considering these neglected latent reservoirs, the cells of monocyte/macrophage lineage. In this review we will describe our current understanding of the mechanism of latency in monocyte/macrophage lineage and how such cells can be specifically eliminated from the infected host.

Kaposi's sarcoma-associated herpesvirus ORF45 mediates transcriptional activation of the HIV-1 long terminal repeat via RSK2

Robust activation of human immunodeficiency virus type 1 (HIV-1) gene expression occurs upon superinfection with Kaposi's sarcoma-associated herpesvirus (KSHV), a common AIDS-associated pathogen. Though the mechanisms underlying this phenotype remain unknown, several KSHV-encoded factors have been reported to stimulate HIV-1 long terminal repeat (LTR) activity. Here, we systematically evaluated the ability of KSHV tegument proteins to modulate the activation of an integrated HIV-1 LTR and revealed that the most potent individual activator is ORF45. ORF45 directs an increase in RNA polymerase II recruitment to the HIV-1 LTR, leading to enhanced transcriptional output. ORF45 is a robust activator of the p90 ribosomal S6 kinases (RSK), and we found that this activity is necessary but not sufficient to increase transcription from the LTR. Of the three widely expressed RSK isoforms, RSK2 appears to be selectively involved in LTR stimulation by both KSHV ORF45 and HIV-1 Tat. However, constitutively active RSK2 is unable to stimulate the LTR, suggesting that ORF45 may preferentially direct this kinase to a specific set of targets. Collectively, our findings reveal a novel transcriptional activation function for KSHV ORF45 and highlight the importance of RSK2 in shaping the transcriptional environment during infection.

IMPORTANCE

Kaposi's sarcoma-associated herpesvirus (KSHV) is a prominent AIDS-associated pathogen. Previous studies have shown that infection of cells containing human immunodeficiency virus type 1 (HIV-1) with KSHV leads to potent stimulation of HIV-1 gene expression by activating the HIV-1 promoter, termed the long terminal repeat (LTR). Here, we compared the abilities of various KSHV proteins to activate gene expression from the HIV-1 LTR and found that KSHV ORF45 is the most potent activator. ORF45 is known to induce cell signaling through ribosomal S6 kinase (RSK) and enhance protein translation. However, we revealed that the activation of a specific isoform of RSK by ORF45 also leads to increased mRNA synthesis from the LTR by the host RNA polymerase. Collectively, our findings provide new insight into the interviral interactions between KSHV and HIV that may ultimately impact disease.

The macrophage: a therapeutic target in HIV-1 infection

Human immunodeficiency virus (HIV) is still a serious global health concern responsible for more than 25 million deaths in last three decades. More than 34 million people are living with HIV infection. Macrophages and CD4+ T cells are the principal targets of HIV-1. The pathogenesis of HIV-1 takes different routes in macrophages and CD4+ T cells. Macrophages are resistant to the cytopathic effect of HIV-1 and produce virus for longer periods of time. In addition, macrophages being present in every organ system thus can disseminate virus to the different anatomical sites leading to the formation of viral sanctuaries. Complete cure of HIV-1 needs better understanding of viral pathogenesis in these reservoirs and implementation of knowledge into robust therapeutic products. In this review we will focus on the unique relationship between HIV-1 and macrophages. Furthermore, we will describe how successful antiretroviral therapy (ART) is in suppressing HIV and novel molecular and cellular strategies against HIV-1 in macrophages.

Susceptibility of human placenta derived mesenchymal stromal/stem cells to human herpesviruses infection

Fetal membranes (FM) derived mesenchymal stromal/stem cells (MSCs) are higher in number, expansion and differentiation abilities compared with those obtained from adult tissues, including bone marrow. Upon systemic administration, ex vivo expanded FM-MSCs preferentially home to damaged tissues promoting regenerative processes through their unique biological properties. These characteristics together with their immune-privileged nature and immune suppressive activity, a low infection rate and young age of placenta compared to other sources of SCs make FM-MSCs an attractive target for cell-based therapy and a valuable tool in regenerative medicine, currently being evaluated in clinical trials. In the present study we investigated the permissivity of FM-MSCs to all members of the human Herpesviridae family, an issue which is relevant to their purification, propagation, conservation and therapeutic use, as well as to their potential role in the vertical transmission of viral agents to the fetus and to their potential viral vector-mediated genetic modification. We present here evidence that FM-MSCs are fully permissive to infection with Herpes simplex virus 1 and 2 (HSV-1 and HSV-2), Varicella zoster virus (VZV), and Human Cytomegalovirus (HCMV), but not with Epstein-Barr virus (EBV), Human Herpesvirus-6, 7 and 8 (HHV-6, 7, 8) although these viruses are capable of entering FM-MSCs and transient, limited viral gene expression occurs. Our findings therefore strongly suggest that FM-MSCs should be screened for the presence of herpesviruses before xenotransplantation. In addition, they suggest that herpesviruses may be indicated as viral vectors for gene expression in MSCs both in gene therapy applications and in the selective induction of differentiation.

Kaposi sarcoma-associated herpes virus and response to antiretroviral therapy: a prospective study of HIV-infected adults

BACKGROUND

The possible impact of coinfection with the Kaposi sarcoma-associated herpes virus (KSHV) on the response to antiretroviral therapy (ART) is unknown. Prospective studies are rare, particularly in Africa.

METHODS

We enrolled a prospective cohort of HIV-infected adults initiating ART in Johannesburg, South Africa. The subjects were defined as seropositive to KSHV if they were reactive to either KSHV lytic K8.1 or latent Orf73 antigen or to both. The subjects were followed from ART initiation until 18 months of treatment. HIV viral load and CD4 counts were tested 6 monthly. Linear generalized estimating and log-binomial regression models were used to estimate the effect of KSHV infection on immunologic recovery and response and HIV viral load suppression within 18 months after ART initiation.

RESULTS

Three hundred eighty-five subjects initiating ART from November 2008 to March 2009 were considered to be eligible including 184 (48%) KSHV+. The KSHV+ group was similar to the KSHV- in terms of age, gender, initiating CD4 count, body mass index, tuberculosis, and hemoglobin levels. The KSHV+ group gained a similar number of cells at 6 [difference of 10 cells per cubic millimeter, 95% confidence interval (CI): -11 to 31], 12 (3 cells per cubic millimeter, 95% CI: -19 to 25), and 18 months (24 cells per cubic millimeter, 95% CI: -13 to 61) compared with that gained by the KSHV- group. Adjusted relative risk of failure to suppress viral load to <400 copies per milliliter (1.03; 95% CI: 0.90 to 1.17) were similar for KSHV+ and KSHV- by 6 months on treatment.

CONCLUSIONS

In a population with a high KSHV prevalence, HIV-positive adults coinfected with KSHV achieved similar immunologic and virologic responses to ART early after treatment initiation compared with those with KSHV-.

Anti-infective periodontal therapy promoting improvement in systemic markers of HIV infection

Research supports the theory that the chronic infectious response occurring in periodontal disease may have a role as a risk modifier of systemic diseases. This study assessed the impact of HIV-associated chronic periodontitis treatment on systemic HIV-related markers (CD4 T lymphocytes cell counts and HIV viral load). Fifteen HIV patients presenting chronic periodontitis [at least eight sites presenting a probing depth (PD) >4 mm and bleeding] were included in this study. Patients received full mouth periodontal treatment with an ultrasonic device and supragingival plaque control. Medical (CD4 cell counts and HIV load) as well as periodontal clinical parameters [probing pocket depth (PPD), clinical attachment level (CAL)] were assessed at baseline and 3 and 6 months after treatment. ANOVA/Tukey and Pearson's correlation tests were used for statistical analysis (α=5%). The results showed that PPD reduction and CAL gain were statistically significant at 3 and 6 months after periodontal therapy (p<0.05). At 6 months, CAL gain was 0.6±0.5 mm and PPD reduction was 0.7±0.5 mm. At the same time, a statistically significant increase in CD4 cell counts could be seen after the third month (p<0.05) and sixth month (p<0.05). Moreover, at 6 months, the relationship between the improvement in clinical parameters, i.e., PPD reduction, and the number of TCD4 lymphocytes could be highlighted. This was shown as the greater the PPD reduction, the greater the increase in TCD4 cells (r=0.68, p=0.02). These data suggest that periodontitis treatment could be associated with an improvement in medical conditions in HIV subjects.

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.

Latent Kaposi's sarcoma-associated herpesvirus infection of monocytes downregulates expression of adaptive immune response costimulatory receptors and proinflammatory cytokines

Kaposi's sarcoma-associated herpesvirus (KSHV) infection is associated with the development of Kaposi's sarcoma, primary effusion lymphoma, and multicentric Castleman's disease. We report the establishment of a monocytic cell line latently infected with KSHV (KSHV-THP-1). We profiled viral and cytokine gene expression in the KSHV-THP-1 cells compared to that in uninfected THP-1 cells and found that several genes involved in the host immune response were downregulated during latent infection, including genes for CD80, CD86, and the cytokines tumor necrosis factor alpha (TNF-α) and interleukin-1β (IL-1β). Thus, KSHV minimizes its immunological signature by suppressing key immune response factors, enabling persistent infection and evasion from host detection.

Prevalence and predictors of kaposi sarcoma herpes virus seropositivity: a cross-sectional analysis of HIV-infected adults initiating ART in Johannesburg, South Africa

Background

Kaposi sarcoma (KS) is the most common AIDS-defining tumour in HIV-infected individuals in Africa. Kaposi sarcoma herpes virus (KSHV) infection precedes development of KS. KSHV co-infection may be associated with worse outcomes in HIV disease and elevated KSHV viral load may be an early marker for advanced HIV disease among untreated patients. We examined the prevalence of KSHV among adults initiating antiretroviral therapy (ART) and compared immunological, demographic and clinical factors between patients seropositive and seronegative for KSHV.

Results

We analyzed cross-sectional data collected from 404 HIV-infected treatment-naïve adults initiating ART at the Themba Lethu Clinic, Johannesburg, South Africa between November 2008 and March 2009. Subjects were screened at ART initiation for antibodies to KSHV lytic K8.1 and latent Orf73 antigens. Seropositivity to KSHV was defined as positive to either lytic KSHV K8.1 or latent KSHV Orf73 antibodies. KSHV viremia was determined by quantitative PCR and CD3, 4 and 8 lymphocyte counts were determined with flow cytometry. Of the 404 participants, 193 (48%) tested positive for KSHV at ART initiation; with 76 (39%) reactive to lytic K8.1, 35 (18%) to latent Orf73 and 82 (42%) to both. One individual presented with clinical KS at ART initiation. The KSHV infected group was similar to those without KSHV in terms of age, race, gender, ethnicity, smoking and alcohol use. KSHV infected individuals presented with slightly higher median CD3 (817 vs. 726 cells/mm³) and CD4 (90 vs. 80 cells/mm³) counts than KSHV negative subjects. We found no associations between KSHV seropositivity and body mass index, tuberculosis status, WHO stage, HIV RNA levels, full blood count or liver function tests at initiation. Those with detectable KSHV viremia (n = 19), however, appeared to present with signs of more advanced HIV disease including anemia and WHO stage 3 or 4 defining conditions compared to those in whom the virus was undetectable.

Conclusions

We demonstrate a high prevalence of KSHV among HIV-infected adults initiating ART in a large urban public-sector HIV clinic. KSHV viremia but not KSHV seropositivity may be associated with markers of advanced HIV disease.

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.

Lack of association of herpes simplex virus type 2 seropositivity with the progression of HIV infection in the HERS cohort

Many studies have chronicled the "epidemiologic synergy" between human immunodeficiency virus (HIV) and herpes simplex virus type 2 (HSV-2). HIV adversely affects the natural history of HSV-2 and results in more frequent and severe HSV-2 reactivation. Few longitudinal studies, however, have examined whether HSV-2 is associated with increased HIV plasma viral loads or decreased CD4 counts. The authors estimated the effect of HSV-2 seropositivity on HIV RNA viral load and on CD4 count over time among 777 HIV-seropositive US women not receiving suppressive HSV-2 therapy in the HIV Epidemiology Research Study (1993-2000). Linear mixed models were used to assess the effect of HSV-2 on log HIV viral load and CD4 count/mm(3) prior to widespread initiation of highly active antiretroviral therapy. Coinfection with HSV-2 was not associated with HIV RNA plasma viral loads during study follow-up. There was a statistically significant association between HSV-2 seropositivity and CD4 count over time, but this difference was small and counterintuitive at an increase of 8 cells/mm(3) (95% confidence interval: 2, 14) per year among HSV-2-seropositive women compared with HSV-2-seronegative women. These data do not support a clinically meaningful effect of baseline HSV-2 seropositivity on the trajectories of HIV plasma viral loads or CD4 counts.

X-box binding protein 1 induces the expression of the lytic cycle transactivator of Kaposi's sarcoma-associated herpesvirus but not Epstein-Barr virus in co-infected primary effusion lymphoma

Cells of primary effusion lymphoma (PEL), a B-cell non-Hodgkin's lymphoma, are latently infected by Kaposi's sarcoma-associated herpesvirus (KSHV), with about 80 % of PEL also co-infected with Epstein–Barr virus (EBV). Both viruses can be reactivated into their lytic replication cycle in PEL by chemical inducers. However, simultaneous activation of both lytic cascades leads to mutual lytic cycle co-repression. The plasma cell-differentiation factor X-box binding protein 1 (XBP-1) transactivates the KSHV immediate–early promoter leading to the production of the replication and transcription activator protein (RTA), and reactivation of KSHV from latency. XBP-1 has been reported to act similarly on the EBV immediate–early promoter Zp, leading to the production of the lytic-cycle transactivator protein BZLF1. Here we show that activated B-cell terminal-differentiation transcription factor X-box binding protein 1 (XBP-1s) does not induce EBV BZLF1 and BRLF1 expression in PEL and BL cell lines, despite inducing lytic reactivation of KSHV in PEL. We show that XBP-1s transactivates the KSHV RTA promoter but does not transactivate the EBV BZLF1 promoter in non-B-cells by using a luciferase assay. Co-expression of activated protein kinase D, which can phosphorylate and inactivate class II histone deacetylases (HDACs), does not rescue XBP-1 activity on Zp nor does it induce BZLF1 and BRLF1 expression in PEL. Finally, chemical inducers of KSHV and EBV lytic replication in PEL, including HDAC inhibitors, do not lead to XBP-1 activation. We conclude that XBP-1 specifically reactivates the KSHV lytic cycle in dually infected PELs.

Antagonism of host antiviral responses by Kaposi's sarcoma-associated herpesvirus tegument protein ORF45

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.

Molecular mechanisms of HIV-1 persistence in the monocyte-macrophage lineage

The introduction of the highly active antiretroviral therapy (HAART) has greatly improved survival. However, these treatments fail to definitively cure the patients and unveil the presence of quiescent HIV-1 reservoirs like cells from monocyte-macrophage lineage. A purge, or at least a significant reduction of these long lived HIV-1 reservoirs will be needed to raise the hope of the viral eradication. This review focuses on the molecular mechanisms responsible for viral persistence in cells of the monocyte-macrophage lineage. Controversy on latency and/or cryptic chronic replication will be specifically evoked. In addition, since HIV-1 infected monocyte-macrophage cells appear to be more resistant to apoptosis, this obstacle to the viral eradication will be discussed. Understanding the intimate mechanisms of HIV-1 persistence is a prerequisite to devise new and original therapies aiming to achieve viral eradication.

The virion host shut-off (vhs) protein blocks a TLR-independent pathway of herpes simplex virus type 1 recognition in human and mouse dendritic cells

Molecular pathways underlying the activation of dendritic cells (DCs) in response to Herpes Simplex Virus type 1 (HSV-1) are poorly understood. Removal of the HSV virion host shut-off (vhs) protein relieves a block to DC activation observed during wild-type infection. In this study, we utilized a potent DC stimulatory HSV-1 recombinant virus lacking vhs as a tool to investigate the mechanisms involved in the activation of DCs by HSV-1. We report that the release of pro-inflammatory cytokines by conventional DC (cDC) during HSV-1 infection is triggered by both virus replication-dependent and replication-independent pathways. Interestingly, while vhs is capable of inhibiting the release of cytokines during infection of human and mouse cDCs, the secretion of cytokines by plasmacytoid DC (pDC) is not affected by vhs. These data prompted us to postulate that infection of cDCs by HSV triggers a TLR independent pathway for cDC activation that is susceptible to blockage by the vhs protein. Using cDCs isolated from mice deficient in both the TLR adaptor protein MyD88 and TLR3, we show that HSV-1 and the vhs-deleted virus can activate cDCs independently of TLR signaling. In addition, virion-associated vhs fails to block cDC activation in response to treatment with TLR agonists, but it efficiently blocked cDC activation triggered by the paramyxoviruses Sendai Virus (SeV) and Newcastle Disease Virus (NDV). This block to SeV- and NDV-induced activation of cDC resulted in elevated SeV and NDV viral gene expression indicating that infection with HSV-1 enhances the cell's susceptibility to other pathogens through the action of vhs. Our results demonstrate for the first time that a viral protein contained in the tegument of HSV-1 can block the induction of DC activation by TLR-independent pathways of viral recognition.

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.

HIV-1 regulation of latency in the monocyte-macrophage lineage and in CD4+ T lymphocytes

The introduction in 1996 of the HAART raised hopes for the eradication of HIV-1. Unfortunately, the discovery of latent HIV-1 reservoirs in CD4+ T cells and in the monocyte-macrophage lineage proved the optimism to be premature. The long-lived HIV-1 reservoirs constitute a major obstacle to the eradication of HIV-1. In this review, we focus on the establishment and maintenance of HIV-1 latency in the two major targets for HIV-1: the CD4+ T cells and the monocyte-macrophage lineage. Understanding the cell-type molecular mechanisms of establishment, maintenance, and reactivation of HIV-1 latency in these reservoirs is crucial for efficient therapeutic intervention. A complete viral eradication, the holy graal for clinicians, might be achieved by strategic interventions targeting latently and productively infected cells. We suggest that new approaches, such as the combination of different kinds of proviral activators, may help to reduce dramatically the size of latent HIV-1 reservoirs in patients on HAART.

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.

Oral infectious diseases: a potential risk factor for HIV virus recrudescence?

As the highly active antiretroviral therapy (HAART) has transitioned human immunodeficiency virus (HIV) infection into a 'chronic disease' management strategy, there is growing evidence that infection with non-HIV pathogens in HIV+ patients may have important public health implications in undermining HAART success and acquired immunodeficiency syndrome progression. Several bacterial and host cell products during infections with non-HIV pathogens have shown the capacity to regulate HIV replication in latently infected cells. A high prevalence of oral infections caused by bacteria, viruses and fungi has been described in HIV+ patients, including periodontal disease. The oral cavity appears to be a site of HIV pathogenesis and potential reservoir for the disease as HIV RNA and DNA forms are present in saliva as well as in gingival crevicular fluid, and oral epithelial cells are susceptible to either cell free or cell-associated HIV infection. The clinical and biological bases of potential associations between chronic oral inflammatory disorders, such as periodontal disease, and exacerbation of HIV viraemia have received little attention. This review attempts to evaluate the current understanding of HIV reactivation as a result of co-infection and/or inflammation induced by non-HIV pathogens in HIV-infected patients, and presents a hypothetic model about the potential role of periodontitis as a global oral infection that potentially contributes to HIV recrudescence.

Cellular reservoirs of HIV-1 and their role in viral persistence

A major obstacle in human immunodeficiency virus type 1 (HIV-1) eradication is the ability of the virus to remain latent in a subpopulation of the cells it infects. Latently infected cells can escape the viral immune response and persist for long periods of time, despite the presence of successful highly active antiretroviral therapy (HAART). Given the appropriate stimulus, latently infected cells can reactivate and start producing infectious virions. The susceptibility of these cell populations to HIV-1, their life span, their proliferative capacity, and their ability to periodically produce infectious virus subsequent to alterations in cellular physiology and/or immunologic controls are critical issues which determine the contribution of these cells to viral persistence. Memory CD4+ T cells due to the long life span, which may be several years, and their ability to reactivate upon encounter with their cognate antigen or other stimulation, are considered a critical reservoir for maintenance of latent HIV-1 proviral DNA. Cells of the monocyte-macrophage lineage, which originate in the bone marrow (BM), are of particular importance in HIV-1 persistence due to their ability to cross the blood-brain barrier (BBB) and spread HIV-1 infection in the immunoprivileged central nervous system (CNS). Hematopoietic progenitor cells (HPCs) are also a potential HIV-1 reservoir, as several studies have shown that CD34+ HPCs carrying proviral DNA can be found in vivo in a subpopulation of HIV-1-infected patients. The ability of HPCs to proliferate and potentially generate clonal populations of infected cells of the monocyte-macrophage lineage may be crucial in HIV-1 dissemination. The contribution of these and other cell populations in HIV-1 persistence, as well as the possible strategies to eliminate latently infected cells are critically examined in this review.

HIV/AIDS: epidemiology, pathophysiology, and treatment of Kaposi sarcoma-associated herpesvirus disease: Kaposi sarcoma, primary effusion lymphoma, and multicentric Castleman disease

Kaposi sarcoma-associated herpesvirus infection is associated with the development of 3 proliferative diseases: Kaposi sarcoma, primary effusion lymphoma, and multicentric Castleman disease. These conditions are also intimately associated with human immunodeficiency virus infection, and important synergistic interactions between these 2 viruses have been described. Despite differences in viral gene expression patterns in each condition, Kaposi sarcoma-associated herpesvirus encodes similar oncogenic proteins that promote the activation of sequential and parallel signaling pathways. Therapeutic strategies have been implemented to target these unique signaling pathways, and this sort of molecular targeting is the focus of many current research efforts. The scope of this review is to present contemporary knowledge about the epidemiology, virology, and immunology of Kaposi sarcoma-associated herpesvirus and to highlight several key oncogene products that may be targets for chemotherapy.

Enhanced adaptation of vesicular stomatitis virus in cells infected with vaccinia virus

Infections involving different viruses (multiple infections) are common in nature and can take place between different strains of the same virus or between different virus species, including DNA and RNA viruses. The influence of multiple infections on viral evolution has been previously studied using different populations of the same virus. Here, we took a step forward by studying the evolution of an RNA virus (vesicular stomatitis virus, VSV) in the presence of a resident DNA virus (vaccinia virus, VV). Cell cultures were infected with a constant amount of VV, and VSV was added at four different post-VV-inoculation times and four different population sizes. The results showed that the presence of VV accelerates the adaptation of VSV to a cellular environment, especially at high population sizes. The effect of VV on VSV evolution was stronger when cells were incubated for longer times with VV prior to the addition of VSV. Our results suggest that cooperation between the two viruses rather than competition might be responsible for the enhanced rate of adaptation of VSV. Further studies are needed to discern whether infections involving different viruses could have an increased ability to escape antiviral strategies.

Upregulation of the TLR3 pathway by Kaposi's sarcoma-associated herpesvirus during primary infection

Kaposi's sarcoma-associated herpesvirus (KSHV) is associated with several different human malignancies, including Kaposi's sarcoma, primary effusion lymphoma, and multicentric Castleman's disease. KSHV establishes lifelong latency in the host and modulates the host immune response. Innate immunity is critical for controlling de novo viral infection. Toll-like receptors (TLRs) are key components of the innate immune system, and they serve as pathogen recognition receptors that stimulate the host antiviral response. In particular, TLR3 has been implicated in RNA virus recognition. Currently, there is no information regarding how KSHV infection modulates any TLR pathway. We report the first evidence that KSHV upregulates TLR3 expression in human monocytes during primary infection. This is also the first demonstration of a human DNA tumor virus upregulating TLR3, a TLR that thus far has been associated with the recognition of RNA viruses. We found that KSHV upregulates the TLR3 pathway and induces TLR3-specific cytokines and chemokines, including beta 1 interferon (IFN-beta1) and CXCL10 (IP-10). Small interfering RNAs directed against TLR3 greatly reduced the ability of KSHV to upregulate IFN-beta1 and CXCL10 upon infection.

Retinoic Acid Analogues Inhibit Human Herpesvirus 8 Replication

Background

Retinoids have a pronounced antiviral effect against several viruses. In this study we aimed to investigate the effect of retinoids on human herpesvirus 8 (HHV-8).

Methods

A panel of retinoic acid compounds were tested for their antiviral activity against HHV-8 in human umbilical vascular endothelial cells (HUVECs) and in a human epithelial cell line. The presence, transcription and antigen expression of HHV-8 in infected cells – in the presence or absence of retinoic acid compounds – were evaluated by PCR, reverse transcriptase PCR and immunofluorescence assays; HHV-8 viral load was determined by real-time quantitative PCR. Angiogenesis induced by HHV-8 was also assessed using Cultrex® basement membrane extract.

Results

The compounds tested specifically inhibited viral promoters, during the early and late phases of infection in both cell systems tested, and resulted in up to 100fold reduction of viral titre and release of progeny virus. The inhibition of viral replication induced by retinoids in endothelial cells, the primary target of HHV-8-driven transformation in Kaposi's Sarcoma, prevented endothelial cells from developing spindle morphology and in vitro tube formation, characteristic changes associated with HHV-8 infection and transformation.

Conclusions

We show that retinoids inhibit HHV-8 replication and identify new retinoid compounds with a strong antiviral effect. Selective retinoids, particularly those with retinoic acid receptor agonist activity, may be good candidates for the development of antiviral drugs.

PAX2 expression by HHV-8-infected endothelial cells induced a proangiogenic and proinvasive phenotype

In the present study, we evaluated whether infection of microvascular endothelial cells (HMECs) with HHV-8 can trigger the expression of PAX2 oncogene and whether PAX2 protein is involved in HHV-8-induced transformation of HMECs. We found that HHV-8 infection induced the expression of both the PAX2 gene and PAX2 protein in HMECs but failed to induce PAX2 protein in HMECs stably transfected with PAX2 antisense (HMEC-AS). HHV-8-infected HMECs but not HMEC-AS acquired proinvasive proadhesive properties, enhanced survival and in vitro angiogenesis, suggesting a correlation between PAX2 expression and the effects triggered by HHV-8 infection. When HMEC-expressing PAX2 by stable transfection with PAX2 sense gene or by HHV-8 infection were implanted in vivo in severe combined immunodeficient (SCID) mice, enhanced angiogenesis and proliferative lesions resembling KS were observed. HHV-8-infected HMEC-AS failed to induce angiogenesis and KS-like lesions. These results suggest that the expression of PAX2 is required for the proangiogenic and proinvasive changes induced by HHV-8 infection in HMECs. In conclusion, HHV-8 infection may activate an embryonic angiogenic program in HMECs by inducing the expression of PAX2 oncogene.

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.

Human herpesvirus 8 acute infection of endothelial cells induces monocyte chemoattractant protein 1-dependent capillary-like structure formation: role of the IKK/NF-kappaB pathway

Human herpesvirus 8 (HHV-8) is considered the causative agent of Kaposi sarcoma, a highly vascularized neoplasm characterized by spindle-shaped cells of endothelial origin and inflammatory cell infiltration. The cell transforming ability of HHV-8 has been associated with the activation of NF-kappaB, a nuclear factor playing a pivotal role in promoting inflammation and cell proliferation; however, little is known about NF-kappaB activation during acute HHV-8 infection. In the present study, we used a recently established in vitro model of HHV-8 acute productive infection in endothelial cells to investigate the effect of HHV-8 on NF-kappaB activity and function. HHV-8 rapidly and potently induced NF-kappaB activity in endothelial cells via stimulation of the IkappaB kinase (IKK). Following IKK activation, HHV-8 selectively triggered the production of high levels of monocyte chemoattractant protein 1 (MCP-1), whereas it did not affect the expression of other NF-kappaB-dependent proinflammatory proteins, including TNF-alpha, IL-8, and RANTES. Deletion of NF-kappaB-binding sites in the MCP-1 enhancer resulted in significant inhibition of HHV-8-induced transcription. Furthermore, MCP-1 production was accompanied by virus-induced capillary-like structure formation at early stages of infection. The results suggest that HHV-8-induced MCP-1 may play an important role in promoting inflammation and pathogenic angiogenesis typical of HHV-8-associated lesions.

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.

HIV-associated Kaposi's sarcoma

Kaposi's sarcoma (KS) is a multifocal vascular tumor that occurs most commonly in patients who have immunosuppression caused by HIV. KS-associated herpes virus (human herpes virus 8, KSHV) has been identified as the causative agent. There are marked geographic differences in the prevalence of both KS and seropositivity to KSHV. The incidence of the tumor has shown a marked decline in first-world countries with the widespread use of effective antiretroviral therapy. The most effective anthracycline is pegylated liposomal doxorubicin; however, few developing countries, where KS prevalence is highest, can afford to use these agents.

H. saimiri tyrosine-kinase interacting protein inhibits Tat function: A prototypic strategy for restricting HIV-1-induced cytopathic effects in immune cells

Herpesvirus saimiri (HVS)-transformed human T cells become permissive for X4 and R5 strains of human immunodeficiency virus type 1 (HIV-1), evidence that HVS-encoded proteins associated with T cell transformation enhance HIV-1 replication. Analyzing the contribution of transformation-associated bicistronic HVS open reading frames (ORF) to HIV-1 replication revealed expression of the second ORF saimiri transformation-associated protein type C (StpC) conferred the permissive phenotype to T cells. In contrast, expression of the first HVS ORF tyrosine-kinase interacting protein (Tip) in the absence of StpC enhanced restriction of HIV-1 replication in T cell lines and peripheral blood mononuclear cells. Understanding the mechanism whereby Tip enhanced restriction of HIV-1 replication may uncover unique pathways that could be targeted therapeutically. Here we report that Tip restricts HIV-1 replication in a monocyte-derived cell line and restricts reactivation of replication of HIV-1 in a T cell line harboring provirus. In this report, we begin to unravel the molecular underpinnings of Tip-mediated restriction. Tip mediates both lymphocyte-cell-specific kinase (Lck)-dependent and -independent effects on HIV-1 replication. We also provide evidence that Tip-mediated restriction is in part due to inhibition of Tat transactivation of the HIV-1 long terminal repeat (LTR). Expression of Tip in T cells increased activation of Stat1 and Stat3, as well as activation of protein kinase RNA-dependent (PKR/p68) and interferon-gamma production. Taken together, these results provide evidence that Tip restricts HIV-1 replication and reactivation by inhibiting HIV-1 transcription while inducing an intercellular antiviral state. We propose that genetically engineered vectors driving Tip expression could provide a prototypic strategy for restricting HIV-1 replication and reactivation in diverse cell lineages.

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.