Multicenter comparison of serologic assays and estimation of human herpesvirus 8 seroprevalence among US blood donors

Prevalence, Incidence, and Predictors of Kaposi Sarcoma-Associated Herpesvirus Infection Among Young Men Who Have Sex With Men in the Southern United States

Kaposi sarcoma (KS) continues to cause substantial morbidity and mortality in populations at risk in the southern United States. Utilizing biospecimens from the Houston site of the Young Men's Affiliate Project, 351 men who have sex with men had blood tested for KS-associated herpesvirus (KSHV) IgG. Seroprevalence, seroconversion between time points, and demographic and clinical correlates were measured. KSHV prevalence was 36.7% and incidence was 8.9 per 100 person-years. Furthermore, prevalence and incidence were higher among Black individuals, people living with HIV, and those with a history of syphilis. Further research on KSHV risk may improve health disparities in KS diagnosis and outcomes.

Chronic and Latent Viral Infections and Leukocyte Telomere Length across the Lifespan of Female and Male Individuals Living with or without HIV

BACKGROUND

Chronic/latent viral infections may accelerate immunological aging, particularly among people living with HIV (PLWH). We characterized chronic/latent virus infections across their lifespan and investigated their associations with leukocyte telomere length (LTL).

METHODS

Participants enrolled in the CARMA cohort study were randomly selected to include n = 15 for each decade of age between 0 and >60 y, for each sex, and each HIV status. Cytomegalovirus (CMV), Epstein-Barr virus (EBV), human herpesvirus 8 (HHV-8), herpes simplex virus 1 (HSV-1), and HSV-2 infection were determined serologically; HIV, hepatitis C (HCV), and hepatitis B (HBV) were self-reported. LTLs were measured using monochrome multiplex qPCR. Associations between the number of viruses, LTL, and sociodemographic factors were assessed using ordinal logistic and linear regression modeling.

RESULTS

The study included 187 PLWH (105 female/82 male) and 190 HIV-negative participants (105 female/84 male), ranging in age from 0.7 to 76.1 years. Living with HIV, being older, and being female were associated with harbouring a greater number of chronic/latent non-HIV viruses. Having more infections was in turn bivariately associated with a shorter LTL. In multivariable analyses, older age, living with HIV, and the female sex remained independently associated with having more infections, while having 3-4 viruses (vs. 0-2) was associated with a shorter LTL.

CONCLUSIONS

Our results suggest that persistent viral infections are more prevalent in PLWH and females, and that these may contribute to immunological aging. Whether this is associated with comorbidities later in life remains an important question.

Outcomes in Kaposi's sarcoma-associated herpesvirus -associated primary effusion lymphoma and multicentric Castleman's disease in patients with human immunodeficiency virus (HIV) in a safety-net hospital system

OBJECTIVE

To describe cases of Kaposi's sarcoma-associated herpesvirus (KSHV)-associated multicentric Castleman's disease (MCD) and primary effusion lymphoma (PEL) in patients with HIV from a large, safety-net hospital system in Dallas, Texas, USA.

METHODS

We conducted a retrospective review of patients with HIV-associated PEL and/or MCD.

RESULTS

Twelve patients with PEL and 10 patients with MCD were identified. All patients were male and 17 of 20 were men who have sex with men; 66.7% of PEL patients and 50% of MCD patients had concurrent KS at the time of diagnosis; 42% of patients with PEL and 20% of patients with MCD died during the follow-up period. We noted improved survival in our cohort compared to previous studies, particularly in our PEL patients with a median survival of 11.4 months compared to 3-6-month median survival historically. Median follow-up time for MCD patients was 17.5 months. This improved survival is despite suboptimal antiretroviral therapy (ART) adherence at diagnosis, with only 50% of patients on ART at the time of MCD/PEL diagnosis.

CONCLUSION

These data highlight the importance of early recognition of PEL and MCD, and the larger-scale efforts needed to better understand the pathogenetic drivers of clinical outcomes in patients affected by KSHV-related diseases.

High Seroprevalence of Kaposi Sarcoma-Associated Herpesvirus in Men Who Have Sex With Men With HIV in the Southern United States

Background

Disparities in mortality in human immunodeficiency virus (HIV)-associated Kaposi sarcoma have been described, particularly in Black men in the southern United States. It is unclear if there are racial/ethnic differences in the seroprevalence of Kaposi sarcoma-associated herpesvirus (KSHV) that may be contributing.

Methods

This is a cross-sectional study of men who have sex with men (MSM) and transgender women with HIV. Participants were recruited from an outpatient HIV clinic in Dallas, Texas, for a 1-time study visit and were excluded from analysis if they had any history of KSHV disease. Plasma was tested for antibodies to KSHV K8.1 or ORF73 antigens, and KSHV DNA was measured in oral fluids and blood by polymerase chain reaction. KSHV seroprevalence and viral shedding in blood and oral fluids were calculated. Additionally, independent risk factors for KSHV seropositivity were assessed by multivariable logistic regression analysis.

Results

Two hundred five participants were included in our analysis. Overall, KSHV seroprevalence was high (68%) with no significant difference between racial/ethnic groups. Among seropositive participants, KSHV DNA was detected in 28.6% of oral fluids and 10.9% of peripheral blood specimens, respectively. The factors most strongly associated with KSHV seropositivity were oral-anal sex (odds ratio [OR], 3.02), oral-penile sex (OR, 4.63), and methamphetamine use (OR, 4.67).

Conclusions

High local seroprevalence of KSHV is likely a key driver of the high burden of KSHV-associated diseases regionally, though it does not explain the observed disparities in KSHV-associated disease prevalence among racial/ethnic groups. Our findings support that KSHV is primarily transmitted via exchange of oral fluids.

KSHV (HHV8) vaccine: promises and potential pitfalls for a new anti-cancer vaccine

Seven viruses cause at least 15% of the total cancer burden. Viral cancers have been described as the "low-hanging fruit" that can be potentially prevented or treated by new vaccines that would alter the course of global human cancer. Kaposi sarcoma herpesvirus (KSHV or HHV8) is the sole cause of Kaposi sarcoma, which primarily afflicts resource-poor and socially marginalized populations. This review summarizes a recent NIH-sponsored workshop's findings on the epidemiology and biology of KSHV as an overlooked but potentially vaccine-preventable infection. The unique epidemiology of this virus provides opportunities to prevent its cancers if an effective, inexpensive, and well-tolerated vaccine can be developed and delivered.

Human herpesvirus 8 infection is associated with prostate cancer among IFNL4-ΔG carriers

Background

The dinucleotide germline variant, rs368234815-ΔG, in the IFNL4 gene (IFNL4-ΔG) has been associated with prostate cancer among men at increased risk of sexually transmitted infections and reported to impair viral clearance. Human herpesvirus 8 (HHV-8) seropositivity has been associated with prostate cancer in Tobago.

Methods

We examined whether the association of HHV-8 with prostate cancer is IFNL4-ΔG-dependent among 728 IFNL4-ΔG-genotyped cases and 813 genotyped population-based controls from the NCI-Maryland Prostate Cancer Case-Control study. Associations between HHV-8 and prostate cancer were assessed in multivariable unconditional logistic regression models. We calculated adjusted odds ratios (OR) and stratified the analysis into men harboring the IFNL4-ΔG-variant and non-carriers (ΔG/ΔG or ΔG/TT vs. TT/TT).

Results

HHV-8 seropositivity was higher in cases than controls (11% vs. 6%) and this association was restricted to carriers of the ΔG allele (OR 2.19: 95% CI:1.38–3.48) in both African American (OR 1.96; 95% CI:1.08–3.56) and European American men (OR 2.59; 95% CI:1.20–5.56).

Conclusions

HHV-8 seropositivity is associated with increased odds of prostate cancer in men harboring the IFNL4 rs368234815-ΔG variant. This study describes HHV-8 infection as a candidate prostate cancer risk factor in men with the IFNL4-ΔG genotype and supports the hypothesis that IFNL4-ΔG is a susceptibility factor that contributes to prostate cancer.

Optimal control application to a Kaposi’s sarcoma treatment model

Kaposi’s sarcoma (KS) is a malignant disorder of lymphatic endothelial origin that can have two main variants: AIDS-related KS (AKS) and non-AIDS related KS (NAKS) that all share a causal relationship with the human herpesvirus-8 (KSHV or HHV-8). We develop a mathematical model that accounts for B-cells latently and lytically infected with HHV-8 as well as the innate and adaptive arms of the immune system. As a sequel to numerous studies that have investigated the inhibition of HHV-8 endocytosis and reactivation of HHV-8 replication, we employ optimal control strategy to obtain treatment efficacies for these two therapeutic approaches. We have shown that when [Formula: see text] of the B-cell infections result in latency, administration of high efficacy drugs that inhibit entry and reactivation of latently infected B-cells leads to the clearance of KS as the population of infected cells cannot be sustained. Our results also reveal that at [Formula: see text] latency of B-cells, the therapy could produce similar results if the drug that targets viral entry is of moderate efficacy but the efficacy of the drug inhibiting reactivation is considerably more than [Formula: see text] Administration of the same drugs but both at moderate efficacy levels leads to the depletion of both uninfected B- and progenitor cells, a scenario which can lead to the growth of KS variants. When [Formula: see text] of the B-cell infections result in latency, administration with high efficacy drugs reduces the viral entry of HHV-8 but as [Formula: see text] of the infected B-cells are productive, this event leads to production of HHV-8 which ultimately results in more progenitor cells getting infected and the growth of KS. Our findings have the potential to offer more effective therapeutic approaches in the treatment of NAKS.

Infiltrating Kaposi sarcoma presenting as acute kidney injury: An unexpected consequence of deliberate hepatitis C-positive organ transplantation

Kaposi sarcoma (KS) following kidney transplantation can result from recipient reactivation of latent human herpesvirus 8 (HHV-8) infection or activation of donor-acquired HHV-8 infection. Post-transplant KS typically manifests with cutaneous pathology, but rare cases of renal allograft involvement have been reported. We describe two cases of donor-derived HHV-8 infection in two hepatitis C (HCV) viremia-negative transplant recipients who each received a kidney from a donor with HCV viremia. One recipient did not develop KS while the other presented with acute kidney injury caused by extensive KS infiltration of the renal parenchyma and metastatic disease. This report reviews the literature for cases of KS involving the renal allograft and highlights an unexpected consequence of deliberate HCV-positive organ transplantation.

Seroprevalence of human herpesvirus 8 in Ireland among blood donors, men who have sex with men, and heterosexual genitourinary medicine and infectious diseases clinic attendees

Human herpesvirus 8 (HHV-8) seroprevalence varies geographically and between subpopulations. High seroprevalence rates have been ascribed to men who have sex with men (MSM), African migrants, and HIV-infected individuals. The objective of this study was to determine the seroprevalence of HHV-8 in an Irish population, including specific risk groups. A cross-sectional study of 200 blood donors and 200 genitourinary medicine (GUM) and infectious diseases (ID) clinic patients was performed, with testing for Immunoglobulin G (IgG) antibodies to HHV-8 lytic antigens using a commercial indirect fluorescence assay (Scimedx Corp.). Verification was performed at the Centers for Disease Control and Prevention (CDC). All 200 blood donor samples were negative for HHV-8 IgG antibodies. 21% of GUM and ID patients were positive for HHV-8 IgG antibodies. One hundred of these patients were MSM, 35% of whom were HHV-8 seropositive (46% of HIV-positive MSM and 24% of HIV-negative MSM). Of 100 heterosexual patients, only 7% were HHV-8 seropositive. The absence of seropositivity in 200 Irish blood donors may suggest that Ireland has a low overall population HHV-8 seroprevalence. The proportion of HHV-8 seropositivity in the MSM population was significantly higher than in the heterosexual population and most marked in HIV-positive MSM.

Donor-derived human herpesvirus 8 and development of Kaposi sarcoma among 6 recipients of organs from donors with high-risk sexual and substance use behavior

Kaposi sarcoma (KS) can develop following organ transplantation through reactivation of recipient human herpesvirus 8 (HHV-8) infection or through donor-derived HHV-8 transmission. We describe 6 cases of donor-derived HHV-8 infection and KS investigated from July 2018 to January 2020. Organs from 6 donors, retrospectively identified as HHV-8-positive, with a history of drug use disorder, were transplanted into 22 recipients. Four of 6 donors had risk factors for HHV-8 infection reported in donor history questionnaires. Fourteen of 22 organ recipients (64%) had evidence of posttransplant HHV-8 infection. Lung recipients were particularly susceptible to KS. Four of the 6 recipients who developed KS died from KS or associated complications. The US opioid crisis has resulted in an increasing number and proportion of organ donors with substance use disorder, and particularly injection drug use history, which may increase the risk of HHV-8 transmission to recipients. Better awareness of the risk of posttransplant KS for recipients of organs from donors with HHV-8 infection risk could be useful for recipient management. Testing donors and recipients for HHV-8 is currently challenging with no validated commercial serology kits available. Limited HHV-8 antibody testing is available through some US reference laboratories and the Centers for Disease Control and Prevention.

Lymphotropic Viruses EBV, KSHV and HTLV in Latin America: Epidemiology and Associated Malignancies. A Literature-Based Study by the RIAL-CYTED

The Epstein-Barr virus (EBV), Kaposi sarcoma herpesvirus (KSHV) and human T-lymphotropic virus (HTLV-1) are lymphomagenic viruses with region-specific induced morbidity. The RIAL-CYTED aims to increase the knowledge of lymphoma in Latin America (LA), and, as such, we systematically analyzed the literature to better understand our risk for virus-induced lymphoma. We observed that high endemicity regions for certain lymphomas, e.g., Mexico and Peru, have a high incidence of EBV-positive lymphomas of T/NK cell origin. Peru also carries the highest frequency of EBV-positive classical Hodgkin lymphoma (HL) and EBV-positive diffuse large B cell lymphoma, not otherwise specified (NOS), than any other LA country. Adult T cell lymphoma is endemic to the North of Brazil and Chile. While only few cases of KSHV-positive lymphomas were found, in spite of the close correlation of Kaposi sarcoma and the prevalence of pathogenic types of KSHV. Both EBV-associated HL and Burkitt lymphoma mainly affect young children, unlike in developed countries, in which adolescents and young adults are the most affected, correlating with an early EBV seroconversion for LA population despite of lack of infectious mononucleosis symptoms. High endemicity of KSHV and HTLV infection was observed among Amerindian populations, with differences between Amazonian and Andean populations.

Donor-derived Kaposi's sarcoma in a liver-kidney transplant recipient

Human herpes virus 8 (HHV-8), also known as Kaposi's sarcoma associated herpesvirus (KSHV), is an oncogenic virus that can cause Kaposi's sarcoma (KS). KS can develop following organ transplantation through reactivation of the recipient's latent HHV-8 infection, or less commonly through donor-derived infection which has higher risk for severe illness and mortality. We describe a case of probable donor-derived KS in the recipient of a liver-kidney transplant. The donor had multiple risk factors for HHV-8 infection. The KS was successfully treated by switching immunosuppression from tacrolimus to sirolimus. With an increasing number of human immunodeficiency virus (HIV)-positive persons seeking organ transplantation and serving as organ donors for HIV-positive recipients, HHV-8 prevalence among donors and recipients will likely increase and with that the risk for post-transplant KS. Predetermination of HHV-8 status can be useful when considering organ donors and recipients with risk factors, although there are currently no validated commercial tests for HHV-8 antibody screening.

HIV-associated Kaposi sarcoma and related diseases

: The search for the etiologic agent for Kaposi sarcoma led to the discovery of Kaposi sarcoma-associated herpesvirus (KSHV) in 1994. KSHV, also called human herpesvirus-8, has since been shown to be the etiologic agent for several other tumors and diseases, including primary effusion lymphoma (PEL), an extracavitary variant of PEL, KSHV-associated diffuse large B-cell lymphoma, a form of multicentric Castleman disease, and KSHV inflammatory cytokine syndrome. KSHV encodes several genes that interfere with innate and specific immunity, thwart apoptosis, enhance cell proliferation and cytokine production, and promote angiogenesis, and these play important roles in disease pathogenesis. HIV is an important cofactor in Kaposi sarcoma pathogenesis, and widespread use of antiretroviral therapy has reduced Kaposi sarcoma incidence. However, Kaposi sarcoma remains the second most frequent tumor arising in HIV-infected patients in the United States and is particularly common in sub-Saharan Africa. KSHV prevalence varies substantially in different populations. KSHV is secreted in saliva, and public health measures to reduce its spread may help reduce the incidence of KSHV-associated diseases. Although there have been advances in the treatment of Kaposi sarcoma, KSHV-multicentric Castleman disease, and PEL, improved therapies are needed, especially those that are appropriate for Kaposi sarcoma in resource-poor regions.

Elevated Serum PSA is Associated With Human Herpesvirus 8 Infection and Increased Circulating Cytokine Levels in Men From Tobago

BACKGROUND

Serum-prostate specific antigen (PSA) levels have been used for many years as a biomarker for prostate cancer. This usage is under scrutiny due to the fact that elevated PSA levels can be caused by other conditions such as benign prostatic hyperplasia and infections of or injury to the prostate. As a result, the identification of specific pathogens capable of increasing serum levels of PSA is important. A potential candidate responsible for elevated PSA is human herpesvirus 8 (HHV-8). We have reported previously that HHV-8 is capable of infecting and establishing a latent infection in the prostate. In this current study we test the hypothesis that HHV-8 infection is associated with elevated PSA levels. Circulating cytokine levels between men with elevated PSA and controls are also compared.

METHODS

HHV-8 serostatus was determined among men with elevated serum PSA (≥4 ng/ml; n = 168, no prostate cancer on biopsy) and age-matched controls (PSA <4 ng/ml; n = 234), Circulating cytokine levels were determined among a subset of each group (116 with elevated PSA and 85 controls).

RESULTS

Men with an elevated serum PSA were significantly more likely to be HHV-8 seropositive (42.9%) than the age-matched cancer-free men (22.2%; OR 2.51; 95%CI 1.48-4.29, P = 00001). Comparison of circulating cytokine levels between men with elevated serum PSA and controls indicated that elevated serum PSA is associated with a pro-inflammatory response with a mixed Th1/Th2 response while HHV-8 infection was associated with significantly higher levels of IL12p70, IL-10, and IL-13 indicating a Th2 immune response.

CONCLUSIONS

We found a significant association between HHV-8 infection and increased levels of serum PSA. In an age of patient-centered medicine, men with an elevated serum PSA should be considered for HHV-8 serology testing to determine if HHV-8 is responsible for the elevated PSA. Prostate 77: 617-624, 2017. © 2017 Wiley Periodicals, Inc.

Rapid Multiplexed Immunoassay for Detection of Antibodies to Kaposi's Sarcoma-Associated Herpesvirus

Diagnosis of KSHV-infected individuals remains a challenge. KSHV prevalence is high in several populations with high prevalence of HIV, leading to increased risk of development of Kaposi’s sarcoma (KS). While current assays are reliable for detecting antibodies to KSHV, none are routinely utilized to identify individuals with KSHV infection and thus at increased risk for KS due to assay complexity, lack of access to testing, and cost, particularly in resource-limited settings. Here we describe the addition of KSHV proteins LANA and K8.1 to a previously evaluated HIV/co-infection multiplexed fluorescence immunoassay system. This study demonstrates assay performance by measuring antibody reactivity for KSHV and HIV-1 in a collection of clinical specimens from patients with biopsy-proven KS and sourced negative controls. The KSHV assay correctly identified 155 of 164 plasma samples from patients with biopsy-proven KS and 85 of 93 KSHV antibody (Ab)-negative samples for a sensitivity of 95.1% and specificity of 91.4%. Assay performance for HIV-1 detection was also assessed with 100% agreement with independently verified HIV-1 Ab-positive and Ab-negative samples. These results demonstrate good sensitivity and specificity for detection of antibody to KSHV antigens, and demonstrate the potential for multiplexed co-infection testing in resource-limited settings to identify those at increased risk for HIV-1-related complications.

Patterns of human herpesvirus-8 oral shedding among diverse cohorts of human herpesvirus-8 seropositive persons

Background

Human herpesvirus-8 (HHV-8), the etiologic agent of Kaposi sarcoma (KS), establishes lifelong latent infection with periodic lytic replication (“shedding”) at mucosal sites, especially the oropharynx. Patterns of HHV-8 shedding are not well understood, and require elucidation to better predict risk of HHV-8 related malignancies in those infected. We sought to characterize patterns of HHV-8 oropharyngeal shedding among diverse cohorts that enrolled HHV-8 seropositive persons.

Methods

We quantified HHV-8 oral shedding using PCR among HHV-8 seropositive persons who collected at least 14 days of oral swabs in 22 studies on 3 continents. We excluded persons taking antivirals during sampling or any prior use of antiretrovirals in those who were HIV-infected.

Results

248 participants were enrolled from the US, Peru, Cameroon, Uganda, and Kenya; 61 % were men, 58 % were HIV seropositive, and 16 % had KS. Overall, 3,123 of 10,557 samples (29.6 %) had HHV-8 detected. Quantity of virus shed was highly correlated with shedding rate, (ρ = 0.72, p < 0.0001). HHV-8 was detected in ≥1 sample in 55 % of participants with a median of 7 % of days in the US and Kenya, 0 % in Uganda and Peru, and 18 % in Cameroon. Median episode duration was three days, and episodes with high median quantity lasted longer (42 vs 3 days, p < 0.0001). In persons with multiple observations over time, 66 % of shedding rate variance was attributable to differences between individuals.

Conclusions

In HHV-8 infected individuals from diverse settings, oral mucosal shedding rate, quantity, and duration were correlated; individual shedding was highly variable. Studies are needed to determine factors accounting for between-person variation and the relationship of HHV-8 shedding to development of associated diseases.

Human herpesvirus 8 seroconversion in a population-based cohort of men in Tobago

Human herpesvirus 8 (HHV-8) is the causal agent of Kaposi's sarcoma (KS). In Tobago, KS is not common; however, HHV-8 seropositivity has been reported to be 39.9% in men with prostate cancer compared to <22.9% in healthier women and men. To understand HHV-8 transmission, we examined HHV-8 seroconversion and seroreversion, and risk factors for these changes in Tobago men. Serum specimens from a sub-cohort of Tobago Prostate Survey men, aged 40-81 years (n = 381/442), were collected at baseline and a subsequent visit between 3 and 9 years and tested for HHV-8 seropositivity using an immunofluorescence assay for antibodies against HHV-8 lytic antigens. Poisson distribution was used to calculate HHV-8 seroconversion and seroreversion rates and their 95% confidence intervals. Differences in baseline characteristics between HHV-seroconverters versus persistent HHV-8 seronegative men and HHV-8 seroreverters versus HHV-8 seropositive men were examined. HHV-8 seropositivity was 12.3% (N = 381) at baseline, with HHV-8 seropositivity significantly higher in increasing age groups, 40-49 (4.0%) to 70-81 (37.5%) years (P-value trend <0.0001). HHV-8 seroconversion and seroreversion rates were 0.23 per 100 person-years (95% C.I., 0.06-0.58) and 2.42 per 100 person-years (95% C.I., 0.89-5.26), respectively. There were significantly more HHV-8 seroconverters who reported "ever smoked cigarettes of >6 months" at baseline compared to HHV-8 persistent seronegative men (P-value = 0.03). Baseline characteristics of HHV-8 seroreverters did not differ from persistent seropositive men. Low HHV-8 seroconversion and seroreversion rates were found. Data suggest that HHV-8 transmission occurred at earlier ages, <40 years, in Tobago men.

Chromatinization of the KSHV Genome During the KSHV Life Cycle

Kaposi's sarcoma-associated herpesvirus (KSHV) belongs to the gamma herpesvirus family and is the causative agent of various lymphoproliferative diseases in humans. KSHV, like other herpesviruses, establishes life-long latent infection with the expression of a limited number of viral genes. Expression of these genes is tightly regulated by both the viral and cellular factors. Recent advancements in identifying the expression profiles of viral transcripts, using tilling arrays and next generation sequencing have identified additional coding and non-coding transcripts in the KSHV genome. Determining the functions of these transcripts will provide a better understanding of the mechanisms utilized by KSHV in altering cellular pathways involved in promoting cell growth and tumorigenesis. Replication of the viral genome is critical in maintaining the existing copies of the viral episomes during both latent and lytic phases of the viral life cycle. The replication of the viral episome is facilitated by viral components responsible for recruiting chromatin modifying enzymes and replication factors for altering the chromatin complexity and replication initiation functions, respectively. Importantly, chromatin modification of the viral genome plays a crucial role in determining whether the viral genome will persist as latent episome or undergo lytic reactivation. Additionally, chromatinization of the incoming virion DNA, which lacks chromatin structure, in the target cells during primary infection, helps in establishing latent infection. Here, we discuss the recent advancements on our understating of KSHV genome chromatinization and the consequences of chromatin modifications on viral life cycle.

Epidemiology and transmission of Kaposi's sarcoma-associated herpesvirus

This review summarizes the current knowledge pertaining to Kaposi sarcoma-associated herpesvirus (KSHV) epidemiology and transmission. Since the identification of KSHV twenty years ago, it is now known to be associated with Kaposi's sarcoma (KS), primary effusion lymphoma, and multicentric Castleman's disease. Many studies have been conducted to understand its epidemiology and pathogenesis and their results clearly show that the worldwide distribution of KSHV is uneven. Some geographical areas, such as sub-Saharan Africa, the Mediterranean region and the Xinjiang region of China, are endemic areas, but Western Europe and United States have a low prevalence in the general population. This makes it imperative to understand the risk factors associated with acquisition of infection. KSHV can be transmitted via sexual contact and non-sexual routes, such as transfusion of contaminated blood and tissues transplants, or via saliva contact. There is now a general consensus that salivary transmission is the main route of transmission, especially in children residing in endemic areas. Therefore, there is a need to better understand the sources of transmission to young children. Additionally, lack of animal models to study transmission, gold standard serological assay and the lack of emphasis on endemic KS research has hampered the efforts to further delineate KSHV transmission in order to design effective prevention strategies.

Prospective study of human herpesvirus type 8 serostatus and prostate cancer risk in the placebo arm of the Prostate Cancer Prevention Trial

BACKGROUND

Human herpesvirus type 8 (HHV-8), a gamma herpesvirus associated with Kaposi's sarcoma, has been proposed as a candidate risk factor for prostate cancer (PCa) because of its detection in benign and malignant prostate specimens, and its relation with histologic prostatic inflammation. We investigated the possible relation between pre-diagnostic HHV-8 infection and PCa risk in a case-control study sampled from the placebo arm of the Prostate Cancer Prevention Trial.

METHODS

We defined cases as men with a confirmed diagnosis of PCa after visit 2 (n = 315) and controls as men not diagnosed with PCa during the trial who also had a negative end-of-study prostate biopsy (n = 315). We tested sera from visit 2 for IgG antibodies against HHV-8 using a monoclonal antibody-enhanced immunofluorescence assay against multiple lytic HHV-8 antigens.

RESULTS

The adjusted seroprevalence of HHV-8 infection was 11.6 % for cases and 11.0 % for controls (p = 0.81). No association was observed between HHV-8 seropositivity and PCa risk (OR 1.06, 95 % CI 0.65-1.76).

CONCLUSION

Our findings of a null association between HHV-8 seropositivity and PCa risk do not support an association between HHV-8 infection and PCa development, consistent with the general tendency of the epidemiologic literature to date.

Epidemiology and genetic variability of HHV-8/KSHV in Pygmy and Bantu populations in Cameroon

Background

Kaposi's sarcoma associated herpesvirus (KSHV/HHV-8) is the causal agent of all forms of Kaposi sarcoma. Molecular epidemiology of the variable K1 region identified five major subtypes exhibiting a clear geographical clustering. The present study is designed to gain new insights into the KSHV epidemiology and genetic diversity in Cameroon.

Methodology/Principal Findings

Bantu and Pygmy populations from remote rural villages were studied. Antibodies directed against latent nuclear antigens (LANA) were detected by indirect immunofluorescence using BC3 cells. Peripheral blood cell DNAs were subjected to a nested PCR amplifying a 737 bp K1 gene fragment. Consensus sequences were phylogenetically analyzed. We studied 2,063 persons (967 females, 1,096 males, mean age 39 years), either Bantus (1,276) or Pygmies (787). The Bantu group was older (42 versus 35 years: P<10⁻⁴). KSHV anti-LANA seroprevalence was of 37.2% (768/2063), with a significant increase with age (P<10⁻⁴) but no difference according to sex. Seroprevalence, as well as the anti-LANA antibodies titres, were higher in Bantus (43.2%) than in Pygmies (27.6%) (P<10⁻⁴), independently of age. We generated 29 K1 sequences, comprising 24 Bantus and five Pygmies. These sequences belonged to A5 (24 cases) or B (five cases) subtypes. They exhibited neither geographical nor ethnic aggregation. A5 strains showed a wide genetic diversity while the B strains were more homogenous and belonged to the B1 subgroup.

Conclusion

These data demonstrate high KSHV seroprevalence in the two major populations living in Southern and Eastern Cameroon with presence of mostly genetically diverse A5 but also B K1 subtypes.

Kaposi's sarcoma associated herpesvirus (KSHV/HHV-8) is the causal agent of one of the most frequent skin tumors found endemically or epidemically associated to HIV in Central and Eastern Africa. This highly variable virus tends to cluster geographically according to specific major subtypes. Its prevalence is high in that area and increases with age. Despite its association to all forms of Kaposi sarcoma and high prevalence described in some low income populations in Cameroon, KSHV arouses limited interest, and only few focused previous studies have looked into prevalence and modes of transmission, especially in families. Extended molecular epidemiology is unknown both in healthy individuals and in Kaposi patients, which led to looking for new insights among Bantu and Pygmy populations from rural villages in three regions of Cameroon sharing a quite similar living environment but yet genetically, socially, and culturally different. The present study is designed to describe variations of molecular subtypes in each of these population groups regarding their geography in rural areas of southern, central, and eastern Cameroon.

Heterogeneity and breadth of host antibody response to KSHV infection demonstrated by systematic analysis of the KSHV proteome

The Kaposi sarcoma associated herpesvirus (KSHV) genome encodes more than 85 open reading frames (ORFs). Serological evaluation of KSHV infection now generally relies on reactivity to just one latent and/or one lytic protein (commonly ORF73 and K8.1). Most of the other polypeptides encoded by the virus have unknown antigenic profiles. We have systematically expressed and purified products from 72 KSHV ORFs in recombinant systems and analyzed seroreactivity in US patients with KSHV-associated malignancies, and US blood donors (low KSHV seroprevalence population). We identified several KSHV proteins (ORF38, ORF61, ORF59 and K5) that elicited significant responses in individuals with KSHV-associated diseases. In these patients, patterns of reactivity were heterogeneous; however, HIV infection appeared to be associated with breadth and intensity of serological responses. Improved antigenic characterization of additional ORFs may increase the sensitivity of serologic assays, lead to more rapid progresses in understanding immune responses to KSHV, and allow for better comprehension of the natural history of KSHV infection. To this end, we have developed a bead-based multiplex assay detecting antibodies to six KSHV antigens.

Seroprevalence of human herpesvirus-8 in HIV-1 infected and uninfected individuals in Cameroon

We evaluated the prevalence of HHV-8 antibodies in 516 plasma samples collected from HIV positive and negative patients from blood banks and urban areas of Cameroon. Among HIV-1 positive samples, HHV-8 seropositivity rate was 61% based on combined reactivity using both ELISA and IFA techniques. HIV negative samples showed 62% seropositivity rate for HHV-8 antibodies. Our results indicate a high HHV-8 prevalence rate in both HIV infected and uninfected individuals in Cameroon.

Blood donation clusters in Québec, Canada (2003-2008): spatial variations according to sex and age

BACKGROUND AND OBJECTIVES

The detection of spatial clusters of blood donation rate is an important issue, especially for targeting spatial units with significantly low rates, where it could be possible to increase the numbers of donors. The objective of this study is to detect spatial clusters of high or low blood donation rate in Québec according to sex and age of the donors.

MATERIALS AND METHODS

Blood donation data were obtained from Héma-Québec over a period of 5 years. We aggregated these data for each of 101 municipalités regionales de comté (i.e. counties) for men, women and four age groups. To detect spatial high/low donation rate areas, we used the Kulldorff's scan statistics. Kappa coefficient was used to assess discordance between clusters obtained for the different groups (18-29, 30-39, 40-49, 50-59, 60-69 years old). T-test analyses were conducted to identify significant associations between spatial clusters and socio-economic variables.

RESULTS

The results indicate the presence of several geographical areas with high or low blood donation rates for each group. The size, the location and the socio-demographic profiles of low/high clusters vary according to sex and age categories.

CONCLUSION

The Kulldorff's scan statistics are an efficient tool to assess the blood donation performance across a country or even a specific region over a period of several years. In terms of strategic planning and monitoring, it can be used as a fully operational tool to target areas with significantly low rates (for all donors or specific demographic groups) in future blood donation campaigns.

Immunosenescence is associated with presence of Kaposi's sarcoma in antiretroviral treated HIV infection

OBJECTIVE

Some antiretroviral treated HIV-infected patients develop Kaposi's sarcoma despite long-term suppression of HIV replication. These Kaposi's sarcoma lesions are consistent with Kaposi's sarcoma observed in the elderly uninfected population ('classical Kaposi's sarcoma'). We investigated potential mechanisms for this phenomenon, focusing on measures of immune activation and T-cell senescence.

DESIGN

We compared markers of immunosenescence, naive T cells, activation, and inflammation in CD4+ and CD8+ T cells from antiretroviral-treated participants with new-onset Kaposi's sarcoma (cases, n =  19) and from treated individuals without Kaposi's sarcoma (controls, n  = 47).

RESULTS

There was increased frequency of CD4+ and CD8+ T cells with an immunosenescence phenotype (CD57+ and CD28-) in cases vs. controls (CD4+ T cells: CD57+ 7.4 vs. 3.7%, P = 0.025; CD28- 9.1 vs. 4.8%, P  = 0.025; CD8+ T cells: CD57+ 41.5 vs. 27.7%, P  =  0.003; CD28- 60.5 vs. 51.3%, P  = 0.041). Cases had lower proportions of naïve T cells (CD27+ CD28+ CD45RA+) in CD4+ (23.0 vs. 32.2%, P = 0.023) and CD8+ (11.3 vs. 20.7%, P  <  0.001) T-cell compartments. CCR5 was more highly expressed in CD4+ (16.3 vs. 11.0%, P  = 0.025), and CD8+ (43.1 vs. 28.3%, P < 0.001) T-cell compartments in cases vs. controls. There was no difference in telomere length or telomerase activity in peripheral blood mononuclear cells, or in T-cell expression of activation markers (HLADRCD38).

CONCLUSION

Among antiretroviral-treated patients, increased frequencies of T cells with an immunosenescence phenotype and lower frequencies of naive T cells were associated with presence of Kaposi's sarcoma among effectively treated patients. These data suggest that certain immunologic perturbations--including those associated with aging--might be causally associated with development of Kaposi's sarcoma.

Measurements of human herpesvirus 8 viral load in blood before and after leukoreduction filtration

BACKGROUND

Human herpesvirus 8 (HHV-8) is likely transmitted through blood transfusion in high-prevalence areas. The efficacy of leukoreduction filtration for reducing HHV-8 in blood has not been reported.

STUDY DESIGN AND METHODS

Blood was drawn from 45 human immunodeficiency virus-positive men either with Kaposi's sarcoma (KS; n=21) or without KS (n=24) and subject to leukoreduction filtration. HHV-8 viral load was measured in plasma and in blood before and after filtration.

RESULTS

Twelve subjects, all with KS, had detectable HHV-8 viremia before filtration with viral loads of 10(2) to 10(5) copies/mL (mean, 3 × 10(4) copies/mL). After filtration, seven of 12 subjects no longer had detectable HHV-8 in their blood, and five of 12 subjects had detectable HHV-8 that was 90% reduced on average from prefiltration levels. The presence of HHV-8 in the blood after filtration was strongly associated with prefiltration viral loads greater than 1000 copies/mL and the presence of cell-free virus in plasma. None of the subjects without KS had detectable levels of HHV-8 virus in blood before or after filtration.

CONCLUSION

Cell-associated HHV-8 appeared to be effectively removed by leukoreduction filtration. Cell-free HHV-8 was present in 42% of subjects as 1% to 20% of the total virus which was not removed by filtration.

Development of whole-virus multiplex luminex-based serological assays for diagnosis of infections with kaposi's sarcoma-associated herpesvirus/human herpesvirus 8 homologs in macaques

Kaposi's sarcoma-associated herpesvirus (KSHV)/human herpesvirus 8 is a tumorigenic rhadinovirus that is associated with all forms of Kaposi's sarcoma. Current serological detection of KSHV is based on enzyme-linked immunosorbent or immunofluorescence assays that suffer from a variety of problems, including the lack of defined standards for test comparison. While KSHV is the only known human rhadinovirus, two lineages of KSHV-like rhadinoviruses are found in Old World primates: the RV1 lineage includes KSHV and retroperitoneal fibromatosis herpesvirus (RFHV) in macaques, and the RV2 lineage includes RRV and MneRV2 from different macaque species. To develop animal models of KSHV-associated diseases, we developed quantitative multiplex bead-based serological assays to detect antibodies against rhadinovirus antigens. Proteins from KSHV (RV1) and MneRV2 (RV2) virions were coupled to spectrally distinct fluorescent beads and used in Luminex flow cytometry-based assays to detect immune responses in macaques. Both assays showed large dynamic ranges with high levels of seroreactivity to both KSHV and MneRV2 proteins. A large set of macaque serum samples from the Washington National Primate Research Center was screened, and most of the samples (82%) were positive in both assays, consistent with the high level of RV1-RV2 coinfection detected by PCR. The macaque sera showed broad, variable, and unique serological responses to the different viral antigens, allowing an initial seroprevalence to be determined for the macaque viruses. The Luminex assays offer a novel multiplexed approach to assess rhadinovirus infection patterns in both humans and nonhuman primates. This will help advance our understanding of rhadinovirus biology and associated host immunological responses.

The National Heart, Lung, and Blood Institute retrovirus epidemiology donor studies (Retrovirus Epidemiology Donor Study and Retrovirus Epidemiology Donor Study-II): twenty years of research to advance blood product safety and availability

The Retrovirus Epidemiology Donor Study (REDS), conducted from 1989 to 2001, and the REDS-II, conducted from 2004 to 2012, were National Heart, Lung, and Blood Institute-funded, multicenter programs focused on improving blood safety and availability in the United States. The REDS-II also included international study sites in Brazil and China. The 3 major research domains of REDS/REDS-II have been infectious disease risk evaluation, blood donation availability, and blood donor characterization. Both programs have made significant contributions to transfusion medicine research methodology by the use of mathematical modeling, large-scale donor surveys, innovative methods of repository sample storage, and establishing an infrastructure that responded to potential emerging blood safety threats such as xenotropic murine leukemia virus-related virus. Blood safety studies have included protocols evaluating epidemiologic and/or laboratory aspects of human immunodeficiency virus, human T-lymphotropic virus 1/2, hepatitis C virus, hepatitis B virus, West Nile virus, cytomegalovirus, human herpesvirus 8, parvovirus B19, malaria, Creutzfeldt-Jakob disease, influenza, and Trypanosoma cruzi infections. Other analyses have characterized blood donor demographics, motivations to donate, factors influencing donor return, behavioral risk factors, donors' perception of the blood donation screening process, and aspects of donor deferral. In REDS-II, 2 large-scale blood donor protocols examined iron deficiency in donors and the prevalence of leukocyte antibodies. This review describes the major study results from over 150 peer-reviewed articles published by these 2 REDS programs. In 2011, a new 7-year program, the Recipient Epidemiology and Donor Evaluation Study-III, was launched. The Recipient Epidemiology and Donor Evaluation Study-III expands beyond donor-based research to include studies of blood transfusion recipients in the hospital setting and adds a third country, South Africa, to the international program.

Human herpesvirus 8 seroprevalence, China

To summarize the seroprevalence of human herpesvirus 8 (HHV-8) in mainland China, we conducted a systematic review and meta-analysis based on available literature. Data show that differences in HHV-8 prevalence vary considerably among different ethnic groups and geographic regions. Blood-borne transmission could be a potential route for HHV-8 infection in China.

A case-cohort study of human herpesvirus 8 seropositivity and incident prostate cancer in Tobago

Background

We previously reported a cross-sectional association between the presence of human herpesvirus 8 (HHV-8) serum antibodies and screen-detected prostate cancer in men living in Tobago. In the same study population, we examined the association between HHV-8 seropositivity and incident prostate cancer discovered at later screenings.

Methods

In 40-81 year-old men without prostate cancer discovered at initial digital rectal examination (DRE) and prostate-specific antigen (PSA) screening, a case-cohort design measured the association between baseline HHV-8 seropositivity (modified immunofluorescence assay for antibodies against HHV-8 lytic antigens) and incident prostate cancer detected at DRE and PSA screenings three or five years later.

Results

Analyses included 486 unique individuals, 96 incident prostate cancer cases, and 415 randomly selected subjects representing an at-risk cohort. By design, the random sub-cohort contained 25 incident prostate cancer cases. In the sub-cohort, the frequency of HHV-8 seropositivity increased across age groupings (40-49 years: 3.5%, 50-59 years: 13.6%, and ≥ 60 years: 22.9%). HHV-8 seropositivity was higher in men with elevated (≥ 4.0 ng/mL) than men with non-elevated PSA at initial screening (30.4% vs. 9.9% seropositive; crude odds ratio (OR) 3.96, 95% confidence interval (CI) 1.53-10.2; age-adjusted OR 2.42, 95% CI 0.91-6.47). HHV-8 seropositivity did not increase incident prostate cancer risk (age-adjusted hazard ratio (HR) 0.88, 95% CI 0.46-1.69).

Conclusions

Case-cohort analysis did not identify association between HHV-8 seropositivity and incident prostate cancer. However, analyses uncovered possible association between HHV-8 and PSA (a marker of prostate inflammation). Co-occurrence of HHV-8 seropositivity and PSA elevation may explain cross-sectional association between HHV-8 and PSA screen-detected prostate cancer.

Comparison of humoral immune responses to Epstein-Barr virus and Kaposi's sarcoma-associated herpesvirus using a viral proteome microarray

Background. Epstein-Barr virus (EBV) is a ubiquitous herpesvirus, and Kaposi’s sarcoma–associated herpesvirus (KSHV) has a restricted seroprevalence. Both viruses are associated with malignancies that have an increased frequency in individuals who are coinfected with human immunodeficiency virus type 1 (HIV-1).

Methods. To obtain an overview of humoral immune responses to these viruses, we generated a protein array that displayed 174 EBV and KSHV polypeptides purified from yeast. Antibody responses to EBV and KSHV were examined in plasma from healthy volunteers and patients with B cell lymphoma or with AIDS-related Kaposi’s sarcoma or lymphoma.

Results. In addition to the commonly studied antigens, IgG responses were frequently detected to the tegument proteins KSHV ORF38 and EBV BBRF and BGLF2 and BNRF1 and to the EBV early lytic proteins BRRF1 and BORF2. The EBV vIL-10 protein was particularly well recognized by plasma IgA. The most intense IgG responses to EBV antigens occurred in HIV-1–positive patients. No clear correlation was observed between viral DNA load in plasma and antibody profile.

Conclusions. The protein array provided a sensitive platform for global screening; identified new, frequently recognized viral antigens; and revealed a broader humoral response to EBV compared with KSHV in the same patients.

Antibodies against lytic and latent Kaposi's sarcoma-associated herpes virus antigens and lymphoma in the European EpiLymph case-control study

Background:

Kaposi's sarcoma-associated herpes virus is associated with primary effusion lymphoma and multicentric Castleman's disease.

Methods:

Seropositivity to lytic and latent Kaposi's sarcoma herpes virus (KSHV) antigens were examined in 2083 lymphomas and 2013 controls from six European countries.

Results:

Antibodies against KSHV latent and lytic antigens were detectable in 4.5% and 3.4% of controls, respectively, and 3.6% of cases (P>0.05). The KSHV seropositivity was associated with splenic marginal zone lymphoma (SMZL) (odds ratio (OR)=4.11, 95% confidence interval (CI)=1.57–10.83) and multiple myeloma (OR=0.31, 95% CI=0.11–0.85).

Conclusion:

The KSHV is unlikely to contribute importantly to lymphomagenesis among immunocompetent subjects. However, the observed association with SMZL may underline a chronic antigen mechanism in its aetiology.

Non-detection of human herpesvirus 8 (HHV-8) DNA in HHV-8-seropositive blood donors from three Brazilian regions

Human herpesvirus 8 (HHV-8), also known as Kaposi's sarcoma-associated herpesvirus (KSHV), is the etiologic agent of all forms of Kaposi's sarcoma, primary effusion lymphoma and the plasmablastic cell variant of multicentric Castleman disease. In endemic areas of sub-Saharan Africa, blood transfusions have been associated with a substantial risk of HHV-8 transmission. By contrast, several studies among healthy blood donors from North America have failed to detect HHV-8 DNA in samples of seropositive individuals. In this study, using a real-time PCR assay, we investigated the presence of HHV-8 DNA in whole-blood samples of 803 HHV-8 blood donors from three Brazilian states (São Paulo, Amazon, Bahia) who tested positive for HHV-8 antibodies, in a previous multicenter study. HHV-8 DNA was not detected in any sample. Our findings do not support the introduction of routine HHV-8 screening among healthy blood donors in Brazil. (WC = 140).

Prevalence of human herpesvirus 8 and hepatitis C virus in a rural community with a high risk for blood-borne infections in central China

Illegal blood donation in the past decade has caused human immunodeficiency virus (HIV) outbreaks in some rural areas in China. Other HIV-associated virus infections, such as those caused by human herpesvirus 8 (HHV8), in such areas are still not well defined. In order to explore HHV8 and hepatitis C virus (HCV) seroprevalence and potential risk factors in such areas, a cross-sectional study with 305 HIV-positive and 315 HIV-negative subjects recruited from a rural county in Shanxi province was conducted, in which illegal blood collection was reported. Interview questionnaires and serum testing were carried out with these participants. HCV and HHV8 seroprevalence were found to be higher in the HIV-positive than in the HIV-negative group (76.4% vs. 2.5% and 15.4% vs. 4.8%, respectively), whereas the difference in HBV seroprevalence was not significant. Co-infection with HCV and HHV8 was also more prevalent in the HIV-positive group. HIV status (OR 2.71; 95% CI 1.16-6.30) and HBV status (OR 2.56; 95% CI 1.14-5.75) were independently associated with HHV8 infection. HIV status (OR 23.03; 95% CI 9.95-53.27) and blood/plasma selling history (OR 14.57; 95% CI 7.49-28.23) were strongly associated with HCV infection. These findings demonstrate that both HHV8 and HCV infections are prevalent in this community. HIV infection is an important risk factor for both HHV8 and HCV infection. HBV infection is associated with HHV8 infection but not with HCV infection. It is possible that HHV8 and hepatitis B virus, but not HCV, have similar modes of transmission in this population.

[Emergent viral threats in blood transfusion]

Au cours des 20 dernières années, la sécurité en transfusion sanguine a fait de très grands progrès vis-à-vis du risque infectieux et notamment de celui représenté par les rétrovirus (HIV et HTLV) et les virus des hépatites B et C. L’objet de cette revue est de répertorier les risques viraux résiduels ou émergents qui seraient susceptibles d’entraîner de nouvelles contaminations chez les receveurs. À côté de nombreux autres virus (HHV-8, erythrovirus B19, virus des hépatites A et E…), une place toute particulière est faite aux arboviroses émergentes (infections à West Nile virus, dengue et chikungunya) qui menacent de toucher le territoire métropolitain suite à l’implantation en Europe du moustique Aedes albopictus, principal vecteur de la dengue et du chikungunya dans les régions tempérées. Un autre risque sanguin émergent, particulièrement au Royaume-Uni et en France, est constitué par le prion à l’origine de la forme variante de la maladie de Creutzfeldt-Jakob. La revue se termine par un rapide panorama des mesures qui sont susceptibles de contrôler ces émergences : exclusion des donneurs à risque, tests diagnostiques spécifiques de tel ou tel agent, déleucocytation des produits sanguins labiles et traitements physiques ou chimiques capables d’inactiver de façon non spécifique les agents infectieux potentiellement contaminants sans trop altérer les propriétés des composants sanguins. La capacité à maîtriser de façon prospective les nouveaux risques viraux au niveau transfusionnel représente un vrai défi pour préserver la confiance retrouvée des prescripteurs et des receveurs vis-à-vis des produits sanguins.

Update on KSHV epidemiology, Kaposi Sarcoma pathogenesis, and treatment of Kaposi Sarcoma

Much has been learned since the discovery of KSHV in 1994 about its epidemiology and pathology but much of what has been learned has yet to be translated into clinical practice. In this review, we survey the current state of knowledge on KSHV epidemiology and KS pathogenesis and highlight therapeutic opportunities in both the developed and developing world.

The T-Cell Immune Response against Kaposi's Sarcoma-Associated Herpesvirus

Kaposi's sarcoma-associated herpesvirus (KSHV) is the aetiological agent of Kaposi's sarcoma (KS), the most frequently arising malignancy in individuals with untreated HIV/AIDS. There are several lines of evidence to indicate that Kaposi's sarcoma oncogenesis is associated with loss of T-cell-mediated control of KSHV-infected cells. KSHV can establish life-long asymptomatic infection in immune-competent individuals. However, when T-cell immune control declines, for example, through AIDS or treatment with immunosuppressive drugs, both the prevalence of KSHV infection and the incidence of KS in KSHV carriers dramatically increase. Moreover, a dramatic and spontaneous improvement in KS is frequently seen when immunity is restored, for example, through antiretroviral therapy or the cessation of iatrogenic drugs. In this paper we describe the current state of knowledge on the T-cell immune responses against KSHV.

Intrafamiliar transmission of Kaposi's sarcoma-associated herpesvirus and seronegative infection in family members of classic Kaposi's sarcoma patients

The link between Kaposi's sarcoma-associated herpesvirus (KSHV or human herpesvirus 8) and Kaposi's sarcoma has been proven, but the transmission routes, especially in the heterosexual population, are not yet completely understood. To assess the intrafamilial patterns of transmission among first-degree relatives of Italian classic Kaposi's sarcoma (cKS) patients, KSHV seroprevalence and the presence of viral DNA in blood and saliva were evaluated in 18 families (32 cKS patients and 35 family members), comparing the results with those obtained in 200 elderly healthy controls without known exposure to KSHV. The KSHV genotype of variable region VR1 of the hypervariable ORF K1 gene was subsequently analysed in all KSHV-positive samples. The results showed that KSHV infection was significantly higher in relatives of cKS patients (11/35 cases) than in healthy controls (17/200 cases; P=0.001). The 11 infected relatives included spouses (n=3), siblings (n=2) and offspring (n=6) of the cKS patients; the same KSHV genotype was shared within the same family in the majority of cases (85%), indicating the presence of person-to-person transmission within families. Viral DNA was mostly observed in the saliva of infected relatives (45.4%); detection of DNA in blood was less frequent (27.3%). Notably, KSHV DNA was present in saliva and/or blood of three KSHV-infected relatives with indeterminate or negative serostatus. Thus, the risk of KSHV infection is greatly enhanced within families of cKS patients, where close contacts (horizontal and/or sexual) can contribute to the spread of KSHV.

Why do viruses cause cancer? Highlights of the first century of human tumour virology

The year 2011 marks the centenary of Francis Peyton Rous's landmark experiments on an avian cancer virus. Since then, seven human viruses have been found to cause 10-15% of human cancers worldwide. Viruses have been central to modern cancer research and provide profound insights into both infectious and non-infectious cancer causes. This diverse group of viruses reveals unexpected connections between innate immunity, immune sensors and tumour suppressor signalling that control both viral infection and cancer. This Timeline article describes common features of human tumour viruses and discusses how new technologies can be used to identify infectious causes of cancer.

Substantial regional differences in human herpesvirus 8 seroprevalence in sub-Saharan Africa: insights on the origin of the "Kaposi's sarcoma belt"

Equatorial Africa has among the highest incidences of Kaposi's sarcoma (KS) in the world, thus earning the name "KS Belt." This was the case even before the HIV epidemic. To date, there is no clear evidence that HHV-8 seroprevalence is higher in this region but interpretation of the available literature is tempered by differences in serologic assays used across studies. We examined representatively sampled ambulatory adults in Uganda, which is in the "KS Belt," and in Zimbabwe and South Africa which are outside the Belt, for HHV-8 antibodies. All serologic assays were uniformly performed in the same reference laboratory by the same personnel. In the base-case serologic algorithm, seropositivity was defined by reactivity in an immunofluorescence assay or in 2 enzyme immunoassays. A total of 2,375 participants were examined. In Uganda, HHV-8 seroprevalence was high early in adulthood (35.5% by age 21) without significant change thereafter. In contrast, HHV-8 seroprevalence early in adulthood was lower in Zimbabwe and South Africa (13.7 and 10.8%, respectively) but increased with age. After age adjustment, Ugandans had 3.24-fold greater odds of being HHV-8 infected than South Africans (p < 0.001) and 2.22-fold greater odds than Zimbabweans (p < 0.001). Inferences were unchanged using all other serologic algorithms evaluated. In conclusion, HHV-8 infection is substantially more common in Uganda than in Zimbabwe and South Africa. These findings help to explain the high KS incidence in the "KS Belt" and underscore the importance of a uniform approach to HHV-8 antibody testing.

Detection of HHV-8 (human herpesvirus-8) genomes in induced peripheral blood mononuclear cells (PBMCs) from US blood donors

BACKGROUND

Human herpesvirus-8 (HHV-8) causes Kaposi's sarcoma and can be detected and induced in peripheral blood mononuclear cells (PBMCs) from infected individuals. The prevalence of viral genomes in induced/cultured PBMCs from healthy blood donors has not been systematically studied.

MATERIALS AND METHODS

PBMCs from 164 donors were purified and stored as two equal aliquots in liquid nitrogen. One aliquot was used for CD19+ B-cell purification with a fraction reserved for DNA extraction. The second aliquot was cultured for 2 or 4 days in culture media containing n-butyrate and tetradecanoyl phorbol acetate. DNA was extracted from all four cell sources: PBMCs, purified B cells, induced PBMCs harvested at days 2 and 4 of culture. A sensitive real-time PCR with a DNA equivalent of 3×10(5) cells per reaction was run in duplicate for all samples along with a quantitative HHV-8 DNA standard ranging from 1.6 to 200 copies.

RESULTS

For all 164 donors, HHV-8 genomes were not detected in the DNA equivalent of 3-6×10(5) of PBMCs and induced/cultured PBMCs with a real-time PCR assay (95% CI: 0-3.5/164). HHV-8 DNA was not detected from DNA equivalent of 1.5 (0.5-5.6)×10(5) CD19+ B cells from 139/164 donors. HHV-8 antibodies were detected in 7 of the 164 donors (4.3%).

CONCLUSIONS

HHV-8 genomes were not detected from PBMCs, induced/cultured PBMCs and CD19+ B cells from 164 blood donors. The level of detectable HHV-8 genomes in blood donors seems to be extremely low, if they exist.

Detection of antibodies to Kaposi's sarcoma-associated herpesvirus: a new approach using K8.1 ELISA and a newly developed recombinant LANA ELISA

Detection of antibodies to Kaposi's sarcoma-associated herpesvirus (KSHV or Human herpesvirus 8) is a topic of ongoing controversy. KSHV expresses multiple antigens and host responses are highly variable. We have previously described an algorithm for determining KSHV infection based on K8.1 ELISA and LANA immunofluorescence assay (IFA). Here we describe the development of a recombinant ELISA for LANA and an improved testing strategy using ELISAs for LANA and K8.1. We assessed mammalian and baculovirus expression systems for the production of full-length recombinant LANA. We evaluated the performance of LANA ELISAs using human serum samples from several sources including blood donors and clinical patients diagnosed with Kaposi's sarcoma and compared them to LANA IFA. Both LANA ELISAs exhibited comparable sensitivity and specificity to LANA IFA but showed considerably greater reliability. The LANA ELISA can thus be used in conjunction with the previously described K8.1 ELISA to enable the highly sensitive and specific detection of antibodies to KSHV. Use of this testing strategy will provide a more accurate and reliable diagnostic assessment of KSHV status.