Serologic evidence of human herpesvirus 8 transmission by homosexual but not heterosexual sex

Macrophages drive KSHV B cell latency

Kaposi's sarcoma herpesvirus (KSHV) establishes lifelong infection and persists in latently infected B cells. Paradoxically, in vitro B cell infection is inefficient, and cells rapidly die, suggesting the absence of necessary factor(s). KSHV epidemiology unexpectedly mirrors that of malaria and certain helminthic infections, while other herpesviruses are ubiquitous. Elevated circulating monocytes are common in these parasitic infections. Here, we show that KSHV infection of monocytes or M-CSF-differentiated (M2) macrophages is highly efficient. Proteomic analyses demonstrate that infection induces macrophage production of B cell chemoattractants and activating factor. We find that KSHV acts with monocytes or M2 macrophages to stimulate B cell survival, proliferation, and plasmablast differentiation. Further, macrophages drive infected plasma cell differentiation and long-term viral latency. In Kenya, where KSHV is endemic, we find elevated monocyte levels in children with malaria. These findings demonstrate a role for mononuclear phagocytes in KSHV B cell latency and suggest that mononuclear phagocyte abundance may underlie KSHV's geographic disparity.

Kaposi's Sarcoma-Associated Herpesvirus, the Etiological Agent of All Epidemiological Forms of Kaposi's Sarcoma

Simple Summary

Kaposi’s sarcoma-associated herpesvirus (KSHV) is one of the seven oncogenic viruses currently recognized by the International Agency for Research on Cancer. Its presence for Kaposi’s sarcoma development is essential and knowledge on the oncogenic process has increased since its discovery in 1994. However, some uncertainties remain to be clarified, in particular on the exact routes of transmission and disparities in KSHV seroprevalence and the prevalence of Kaposi’s sarcoma worldwide. Here, we summarized the current data on the KSHV viral particle’s structure, its genome, the replication, its seroprevalence, the viral diversity and the lytic and latent oncogenesis proteins involved in Kaposi’s sarcoma. Lastly, we reported the environmental, immunological and viral factors possibly associated with KSHV transmission that could also play a role in the development of Kaposi’s sarcoma.

Abstract

Kaposi’s sarcoma-associated herpesvirus (KSHV), also called human herpesvirus 8 (HHV-8), is an oncogenic virus belonging to the Herpesviridae family. The viral particle is composed of a double-stranded DNA harboring 90 open reading frames, incorporated in an icosahedral capsid and enveloped. The viral cycle is divided in the following two states: a short lytic phase, and a latency phase that leads to a persistent infection in target cells and the expression of a small number of genes, including LANA-1, v-FLIP and v-cyclin. The seroprevalence and risk factors of infection differ around the world, and saliva seems to play a major role in viral transmission. KSHV is found in all epidemiological forms of Kaposi’s sarcoma including classic, endemic, iatrogenic, epidemic and non-epidemic forms. In a Kaposi’s sarcoma lesion, KSHV is mainly in a latent state; however, a small proportion of viral particles (<5%) are in a replicative state and are reported to be potentially involved in the proliferation of neighboring cells, suggesting they have crucial roles in the process of tumorigenesis. KSHV encodes oncogenic proteins (LANA-1, v-FLIP, v-cyclin, v-GPCR, v-IL6, v-CCL, v-MIP, v-IRF, etc.) that can modulate cellular pathways in order to induce the characteristics found in all cancer, including the inhibition of apoptosis, cells’ proliferation stimulation, angiogenesis, inflammation and immune escape, and, therefore, are involved in the development of Kaposi’s sarcoma.

Poppers, by Inducing HHV-8 Virion Production, Can Act as a Promoter for HHV-8 Transmission in Men Who Have Sex With Men

Environmental factors were reported to increase the risk of human herpesvirus 8 (HHV-8) transmission. In a population of men who have sex with men (MSM), we found evidence that chemsex was associated with human herpesvirus 8 seropositivity in vivo and that poppers induced HHV-8 virion production in vitro. Our finding may explain the higher HHV-8 transmission in MSM.

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

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

AIDS-Associated Malignancies

Malignancies were one of the earliest recognized manifestations that led to the description of the acquired immune deficiency syndrome (AIDS). The majority of cancers in AIDS patients are associated with coinfection with oncogenic viruses, such as Epstein-Barr virus, human herpesvirus 8, and human papillomavirus, with resulting malignancies occurring secondary to diminished immune surveillance against viruses and virus-infected tumor cells. Over 50% of AIDS lymphomas are associated with Epstein-Barr virus (EBV) and/or HHV8 infection. HHV8-associated diseases include Kaposi sarcoma (KS), primary effusion lymphoma (PEL), and multicentric Castleman disease (MCD). EBV is associated with several malignancies, including Hodgkin lymphoma (HL) and non-Hodgkin lymphoma (NHL). Coinfection with HIV and HPV is associated with an increased risk of various squamous cell carcinomas of epithelial tissues. HAART has significantly impacted the incidence, management, and prognosis of AIDS-related malignancies. In addition to changing the natural history of HIV infection in regard to incidence and survival, HAART has dramatically decreased the incidence of certain virally mediated HIV-associated malignancies such as KS and primary CNS lymphoma. The beneficial effects of HAART on these tumors are attributed to drug-mediated HIV suppression and immune reconstitution. However, HAART has had a less favorable impact on EBV- and HPV-related malignancies. This chapter presents an overview of HIV-associated malignancies mediated by HHV-8, EBV, and HPV, and reviews the effect of HAART on the epidemiology, presentation, treatment, and outcomes of these cancers.

Disparities in Kaposi sarcoma incidence and survival in the United States: 2000-2013

OBJECTIVE

Geographic and racial disparities may contribute to variation in the incidence and outcomes of HIV-associated cancers in the United States.

METHOD

Using the Surveillance, Epidemiology, and End Results (SEER) database, we analyzed Kaposi sarcoma (KS) incidence and survival by race and geographic region during the combined antiretroviral therapy era. Reported cases of KS in men from 2000 to 2013 were obtained from 17 SEER cancer registries. Overall and age-standardized KS incidence rates were calculated and stratified by race and geographic region. We evaluated incidence trends using joinpoint analyses and calculated adjusted hazard ratios (aHR) for overall and KS-specific mortality using multivariable Cox proportional hazards models.

RESULTS

Of 4,455 KS cases identified in men younger than 55 years (median age 40 years), the annual percent change (APC) for KS incidence significantly decreased for white men between 2001 and 2013 (APC -4.52, p = 0.02). The APC for AA men demonstrated a non-significant decrease from 2000-2013 (APC -1.84, p = 0.09). Among AA men in the South, however, APC has significantly increased between 2000 and 2013 (+3.0, p = 0.03). In addition, compared with white men diagnosed with KS during the same time period, AA men were also more likely to die from all causes and KS cancer-specific causes (aHR 1.52, 95% CI 1.34-1.72, aHR 1.49, 95% CI 1.30-1.72 respectively).

CONCLUSION

Although overall KS incidence has decreased in the U.S., geographic and racial disparities in KS incidence and survival exist.

Seroprevalence of antibodies against Kaposi's sarcoma-associated herpesvirus among HIV-negative people in China

BACKGROUND

Little information on the prevalence of Kaposi's sarcoma associated herpesvirus (KSHV) among HIV-negative individuals is available from Asia.

METHODS

In the present study, we report findings from a new survey of KSHV in 983 HIV-negative male migrants from Shanghai and their combination with previous similar surveys of 600 female migrants, 600 female sex-workers (FSW), 1336 sexually transmitted infection (STI) clinic male patients, 439 intravenous drug-users (IVDU), and 226 men having sex with men (MSM) from China. KSHV-specific antibodies against latent and lytic antigens were assessed using Sf9 and BC3 monoclonal immunofluorescence assay. Age-adjusted prevalence ratios (PR) and 95% confidence interval (95% CI) for KSHV-positivity were estimated using Poisson regression.

RESULTS

In total, 4184 HIV-negative participants were included. KSHV prevalence ranged from 9.8% (95% CI: 7.9%-11.7%) in male migrants to 32.3% (95% CI: 24.1%-34.1%) in MSM. IVDU show intermediate level (17.5%, 95%CI: 14.1%-21.4%). KSHV was associated with syphilis (PR = 2.03, 95% CI: 1.38-2.98) in MSM but not in other groups. An association with human herpes virus 2 was also found among MSM (PR = 1. 83, 95%: 1.22-2.75) but not in migrant workers or FSW.

CONCLUSIONS

KSHV prevalence in HIV-negative heterosexuals, FSW, and STI male patients from China is approximately 10%, but 2- and 3-fold higher in IVDU and MSM, respectively. Associations of KSHV with STIs among MSM only suggest that sexual transmission of the virus is important in MSM but not in heterosexuals.

Infection and cancer: global distribution and burden of diseases

BACKGROUND

Infection is one of the main risk factors for cancer.

OBJECTIVES

Epidemiology, pathogenesis, and disease burden of infection-related cancers were reviewed by infectious agents.

FINDINGS

Chronic infection with Epstein-Barr virus, hepatitis B and C viruses, Kaposi sarcoma herpes virus, human immunodeficiency virus (HIV) type 1, human papillomavirus (HPV), human T-cell lymphotropic virus type 1, Helicobacter pylori, Clonorchis sinensis, Opisthorchis viverrini, and Schistosoma haematobium are associated with nasopharyngeal carcinoma; lymphoma and leukemia, including non-Hodgkin lymphoma, Hodgkin lymphoma, and Burkitt lymphoma; hepatocellular carcinoma; Kaposi sarcoma; oropharyngeal carcinoma; cervical carcinoma and carcinoma of other anogential sites; adult T-cell leukemia/lymphoma; gastric carcinoma; cholangiocarcinoma; and urinary bladder cancer. In 2008, approximately 2 million new cancer cases (16%) worldwide were attributable to infection. If these infections could be prevented and/or treated, it is estimated that there would be about 23% fewer cancers in less developed regions of the world, and about 7% fewer cancers in more developed regions.

CONCLUSION

Widespread application of existing public health methods for the prevention of infection, such as vaccination, safer injection practices, quality-assured screening of all donated blood and blood components, antimicrobial treatments, and safer sex practices, including minimizing one's lifetime number of sexual partners and condom use, could have a substantial effect on the future burden of cancer worldwide.

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

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

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.

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.

Kaposi`s sarcoma associated herpesvirus infection among female sex workers and general population women in Shanghai, China: a cross-sectional study

Background

Limited information on epidemiologic patterns of KSHV, with none focusing on heterosexual transmission, is available in mainland China. To clarify this, a cross-sectional study was conducted among a group of female sex workers (FSW) and general population women (GW) in Shanghai, China.

Methods

An anonymous questionnaire interview was administrated among 600 FSW and 600 GW. Blood samples were collected and tested for antibodies to KSHV, HSV-2, HIV, syphilis and HBsAg. Correlates of KSHV and HSV-2 were examined using multiple logistic regression analysis.

Results

None of the study participants were tested positive for HIV. The seroprevalence of KSHV, HSV-2 , HBV and syphilis was 10.0%, 52.2%, 12.3% and 10.5%, respectively for FSW, and was 11.0%, 15.3%, 9.8% and 2.8%, respectively for GW. KSHV seropositivity was not associated with syphilis and HSV-2 infection as well as sexual practices among either FSW or GW. Nevertheless, HSV-2 infection among FSW was independently associated with being ever married (OR = 1.59; 95%CI: 1.04-2.45), >5 years of prostitution (OR = 2.06; 95%CI: 1.16-3.68) and being syphilis positive (OR = 2.65; 95%CI: 1.43-4.93). HSV-2 infection among GW was independently associated with an age of >35 years (OR = 2.29; 95%CI: 1.07-4.93), having had more than 2 sex partners in the prior 12 months (OR = 6.44; 95%CI: 1.67-24.93) and being syphilis positive (OR = 3.94; 95%CI: 1.38-11.23). A gradual increase of prevalence with the prostitution time group was also detected for HSV-2 and syphilis, but not for KSHV.

Conclusions

KSHV is moderately and equivalently prevalent among FSW and GW. Heterosexual contact is not a predominant route for KSHV transmission among Chinese women.

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-.

Prevalence and correlates of Kaposi's sarcoma-associated herpesvirus infection in a sample of men who have sex with men in eastern China

This study aimed to determine the seroprevalence of Kaposi's sarcoma-associated herpesvirus (KSHV) and related factors in men who have sex with men (MSM) in China. A total of 208 subjects were recruited from eastern China from 2008 to 2009. Plasma samples were collected and screened for KSHV, HIV and syphilis. Overall, KSHV seroprevalence was 32·7% in the subjects. About 92·7% of subjects reported having ever had anal sex with a man, of whom 67·8% had receptive anal sex and 77·9% had insertive anal sex. About 93·1% of the study participants reported having had oral sex with a man, of whom 76·0% had receptive oral sex and 56·7% had insertive oral sex. KSHV seropositivity was independently associated with receptive anal sex [odds ratio (OR) 2·68, 95% confidence interval (CI) 1·15–6·23], syphilis (OR 3·25, 95% CI 1·56–6·76) and HSV-2 infection (OR 2·40, 95% CI 1·09–5·26). KSHV infection is highly prevalent and is probably sexually transmitted among MSM in eastern China.

Oral and genital human herpesvirus 8 and human papillomavirus in heterosexual partners

BACKGROUND

The purpose of this study was to verify a possible co-infection of human herpesvirus 8 (HHV-8) in commonly associated human papillomavirus (HPV) penile lesions and to determine the frequency of detection of these viruses in the oral mucosa of their female counterparts.

METHODS

Thirty-one male subjects underwent penile swabs from clinical HPV-related lesions. Their female counterparts underwent swabs of the vagina, uterine cervix, and oral mucosa. HPV and HHV-8 detection was performed by polymerase chain reaction using the consensus primers MY11/MY09 and KS1/KS2, respectively.

RESULTS

HPV DNA was detected in 31/31 penile lesions. HPV DNA was also detected in 18/31 (58%) female genital brushings and 17/31 (54%) female oral brushings. HHV-8 DNA was detected in 1/31 (3.2%) male genital brushings and 3/31 (9.6%) female oral mucosa brushings. None of the female genital brushings were HHV-8 DNA-infected.

CONCLUSIONS

Based upon the results of this study, co-infection between HPV and HHV-8 in malignant and pre-malignant penile lesions is an unlikely finding.

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.

[Epstein-Barr virus (EBV) and Kaposi's sarcoma-associated herpesvirus (KSHV, HHV-8)]

Epstein-Barr virus (EBV) and Kaposi's sarcoma-associated herpesvirus (KSHV or human herpesvirus 8, HHV-8) are members of gamma-herpes virus family. Both viruses infect to B cells and cause malignancies such as lymphoma. Since EBV and HHV-8 are so-called 'oncovirus', their oncogenecities have been focused in the researches on EBV and KSHV for a long time. EBV was discovered in 1964, whereas KSHV was identified in 1994. However, KSHV was analyzed rapidly in these fifteen years. One of the recent progresses in the research on EBV and KSHV is that virus-encoded small RNAs were identified in their genomes and characterized. EBV is the first human virus in whose genome microRNA was identified. The oncogenecity of EBV and KSHV remains unclear. Here, I discuss the pathogenesis by EBV and KSHV with special reference to recent progress in this field.

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.

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.

Human herpesvirus 8 infection in children and adults in a population-based study in rural Uganda

BACKGROUND

Human herpesvirus 8 (HHV-8) infection is endemic in sub-Saharan Africa. We examined sociodemographic, behavioral, and biological factors associated with HHV-8 infection in children and adults to determine HHV-8 seroprevalence and potential routes of transmission.

METHODS

Participants were 1383 children and 1477 adults from a population-based sample in a rural community in Uganda. Serum samples were tested for HHV-8 antibodies with use of an enzyme immunoassay against K8.1.

RESULTS

HHV-8 seroprevalence increased from 16% among children aged 1.5-2 years to 32% among children aged 10-13 years (P <.001) and from 37% among participants aged 14-19 years to 49% among adults aged ≥ 50 years (P <.05). HHV-8 seropositivity in children was independently associated with residing with a seropositive parent (P < .001) and residing with ≥ 1 other seropositive child aged <14 years (P < .001). History of sharing food and/or sauce plates was marginally associated with HHV-8 infection in children (P = .05). Among 1404 participants aged ≥ 15 years , there was no association between correlates of sexual behavior (eg, number of lifetime sex partners and HIV infection) and HHV-8 seropositivity (P > .10).

CONCLUSIONS

Our data suggest that HHV-8 is acquired primarily through horizontal transmission in childhood from intrafamilial contacts and that transmission continues into adulthood potentially through nonsexual routes.

Kaposi's Sarcoma Associated-Herpes Virus (KSHV) Seroprevalence in Pregnant Women in South Africa

Background

Factors previously associated with Kaposi's sarcoma-associated herpesvirus (KSHV) transmission in Africa include sexual, familial, and proximity to river water. We measured the seroprevalence of KSHV in relation to HIV, syphilis, and demographic factors among pregnant women attending public antenatal clinics in the Gauteng province of South Africa.

Methods

We tested for antibodies to KSHV lytic K8.1 and latent Orf73 antigens in 1740 pregnant women attending antenatal clinics who contributed blood to the "National HIV and Syphilis Sero-Prevalence Survey - South Africa, 2001". Information on HIV and syphilis serology, age, education, residential area, gravidity, and parity was anonymously linked to evaluate risk factors for KSHV seropositivity. Clinics were grouped by municipality regions and their proximity to the two main river catchments defined.

Results

KSHV seropositivity (reactive to either lytic K8.1 and latent Orf73) was nearly twice that of HIV (44.6% vs. 23.1%). HIV and syphilis seropositivity was 12.7% and 14.9% in women without KSHV, and 36.1% and 19.9% respectively in those with KSHV. Women who are KSHV seropositive were 4 times more likely to be HIV positive than those who were KSHV seronegative (AOR 4.1 95%CI: 3.4 - 5.7). Although, women with HIV infection were more likely to be syphilis seropositive (AOR 1.8 95%CI: 1.3 - 2.4), no association between KSHV and syphilis seropositivity was observed. Those with higher levels of education had lower levels of KSHV seropositivity compared to those with lower education levels. KSHV seropositivity showed a heterogeneous pattern of prevalence in some localities.

Conclusions

The association between KSHV and HIV seropositivity and a lack of common association with syphilis, suggests that KSHV transmission may involve geographical and cultural factors other than sexual transmission.

KSHV and the pathogenesis of Kaposi sarcoma: listening to human biology and medicine

The linkage of Kaposi sarcoma (KS) to infection by a novel human herpesvirus (Kaposi sarcoma-associated herpesvirus [KSHV]) is one of the great successes of contemporary biomedical research and was achieved by using advanced genomic technologies in a manner informed by a nuanced understanding of epidemiology and clinical investigation. Ongoing efforts to understand the molecular mechanisms by which KSHV infection predisposes to KS continue to be powerfully influenced by insights emanating from the clinic. Here, recent developments in KS pathogenesis are reviewed, with particular emphasis on clinical, pathologic, and molecular observations that highlight the many differences between this process and tumorigenesis by other oncogenic viruses.

Seroepidemiology of human herpesvirus 8 (HHV-8) infection in injecting drug users

A cross-sectional study was carried out in injecting drug users (IDUs) from Greece to assess the seroprevalence of human herpesvirus 8 (HHV-8) and to identify potentially associated risk factors. A total of 288 IDUs were tested for K8.1 antibodies to HHV-8 lytic antigen. Associations between HHV-8 serostatus and potential risk factors were examined using univariate and multivariate logistic regression analysis. Seroprevalence of HHV-8 was 24·3% (95% CI 19·5–29·7), increasing with age from 19·4% in those aged <30 years to 52·9% in those aged ⩾40 years (Pfor trend=0·003). No statistically significant associations between HHV-8-positive status and gender, educational level, age at first drug injection, needle sharing, number of imprisonments, complications from drug overdose, HIV and HCV were observed. In the multivariate logistic regression analysis, older age (⩾40vs. <40 years, OR 3·30, 95% CI 1·14–9·56) and report of septicaemia/abscess (yesvs. no, OR 1·80, 95% CI 1·01–3·18) were each independently associated with higher HHV-8 seroprevalence. HHV-8 is highly prevalent in the IDU population in Greece. The independent association between HHV-8 and reported abscess or septicaemia supports the hypothesis that poor hygiene conditions in the setting of drug injection may contribute to HHV-8 transmission.

Kaposi sarcoma-associated herpesvirus (KSHV) seroprevalence in population-based samples of African children: evidence for at least 2 patterns of KSHV transmission

BACKGROUND

Kaposi sarcoma-associated herpesvirus (KSHV) infection is endemic among adult populations in Africa. A prevailing view is that childhood transmission is primarily responsible for the high seroprevalence of KSHV among adults that is observed throughout the continent. However, few studies have directly examined children, particularly in locations where KS is not commonly endemic.

METHODS

Participants were children aged 1.5-8.9 years, including 427 children from a population-based sample in South Africa, 422 from a population-based sample in Uganda, and 567 from a clinic-based sample in Uganda. All serum specimens were tested by the same laboratory for KSHV antibodies with use of 2 enzyme immunoassays (against K8.1 and ORF65) and 1 immunofluorescence assay.

RESULTS

KSHV seroprevalence was 7.5%-9.0% among South African children and was not associated with age. In contrast, in the Ugandan population-based sample, KSHV seroprevalence increased from 10% among 2-year-old children to 30.6% among 8-year-old children (P(trend) < .001). In the Ugandan clinic-based sample, seroprevalence increased from 9.3% among 2-year-old children to 36.4% among 8-year-old children (P(trend) < .001).

CONCLUSION

Two distinct relationships between age and KSHV infection among children imply that KSHV transmission among children is not uniform throughout Africa and is therefore not always responsible for the high seroprevalence observed in adults. There are at least 2 patterns of KSHV transmission in Africa.

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.

Human herpesvirus 8 seroprevalence among Tobago women and the role of sexual lifestyle behavior

Human herpesvirus 8 (HHV-8) infection is present in 22.9% of Tobago men. However, seroprevalence and modes of transmission of HHV-8 among Tobago women are not known. HHV-8 seropositivity rates in Tobago women were examined and compared rates to Tobago men of similar ages. To assess possible modes of transmission, sexual behavior among Tobago women was examined to determine its association with HHV-8 seropositivity. A cross-sectional study was conducted in 213 Tobago women, ages 18-65 years, who participated in the Tobago Cervical and Oral Cancer Screening Study. HHV-8 seropositivity was determined by a monoclonal immunofluorescence assay. Age-specific rates were compared to those previously observed in men. Logistic regression analyses were performed to determine the association between HHV-8 seropositivity and sexual behavior among the women. HHV-8 seroprevalence among Tobago women was 14.1% (95% CI, 10-19%), with no significant difference with men of similar age (P-value = 0.741). Age <or=17 years at first sexual intercourse was found to have a minimal significant association with HHV-8 seropositivity (OR = 2.51, 95% CI = 1.09-5.78) in women. HHV-8 age-specific rates were similar between genders. Sexual activity may not be a major contributor to HHV-8 infection among Tobago women.

Four-antigen mixture containing v-cyclin for serological screening of human herpesvirus 8 infection

Improved diagnostic reagents and testing are currently needed for the serological detection of human herpesvirus 8 (HHV-8) infections. We evaluated the luciferase immunoprecipitation systems (LIPS) for profiling antibody responses to a panel of HHV-8 proteins for diagnosis of Kaposi sarcoma (KS)-infected individuals. Using a pilot serum set, LIPS detected robust antibody responses to several known antigens, and a screen of 14 additional HHV-8 proteins identified v-cyclin as a potentially new diagnostic antigen. In evaluating a training-serum set, a four-antigen panel (K8.1, v-cyclin, ORF65, and a LANA fragment) was found to provide sufficient information for diagnosis. Analysis of a validation serum set using the combined results from these four separate antigen tests showed 100% sensitivity and 100% specificity. Furthermore, a LIPS format using a mixture of the four antigens, which simplifies data collection and analysis, closely matched the diagnostic performance of the combined separate tests (R = 0.95). This four-antigen mixture format analyzed with the validation serum set also showed 100% sensitivity and 100% specificity but was not statistically different from two separate enzyme-linked immunosorbent assays (94% sensitivity and 100% specificity) using baculovirus-produced LANA and bacterially produced K8.1. Heat map analysis of KS patient antibody titers revealed marked heterogeneity in humoral responses to this four-antigen panel. Overall, the LIPS assay showed 97% sensitivity, and positive anti-v-cyclin antibodies were detected in approximately 75% of the KS sera. These results suggest that LIPS screening using an antigen mixture is a sensitive and high-throughput method for serological screening of HHV-8 infection in individuals with KS.

Use of saliva as a lubricant in anal sexual practices among homosexual men

OBJECTIVES

Compared with other sexually active adults, men who have sex with men (MSM) are more frequently infected with several pathogens including cytomegalovirus, hepatitis B virus, and Kaposi sarcoma-associated herpesvirus. Because one common element between these organisms is their presence in saliva, we evaluated saliva exposure among MSM in a heretofore relatively unrecognized route-via use of saliva as a lubricant in anal sex.

METHODS

MSM in a San Francisco population-based cohort were interviewed regarding use of saliva by the insertive partner as a lubricant in various anal sexual practices.

RESULTS

Among 283 MSM, 87% used saliva as a lubricant in insertive or receptive penile-anal intercourse or fingering/fisting at some point during their lifetime; 31%-47% did so, depending upon the act, in the prior 6 months. Saliva use as a lubricant was more common among younger men and among HIV-infected men when with HIV-infected partners. Even among MSM following safe sex guidelines by avoiding unprotected penile-anal intercourse, 26% had anal exposure to saliva via use as a lubricant.

CONCLUSIONS

Among MSM, use of saliva as a lubricant is a common, but not ubiquitous, practice in anal sex. The findings provide the rationale for formal investigation of whether saliva use in this way contributes to transmission of saliva-borne pathogens in MSM.

Awareness of Kaposi's sarcoma-associated herpesvirus among men who have sex with men

BACKGROUND

Despite burgeoning scientific knowledge about Kaposi's sarcoma-associated herpesvirus (KSHV), the etiologic agent of Kaposi's sarcoma (KS), little is known about awareness of this virus in the general community. This is particularly the case for men who have sex with men (MSM), the group at greatest risk for infection.

METHODS

The California Health Interview Survey was a random digit- dial survey of over 50,000 households. Men aged 18 to 64 years who self-identified as gay or bisexual were subsequently recontacted for a follow-up study of HIV-related knowledge and behavior in which they were asked if they had heard of KS and to describe the cause of KS.

RESULTS

Of 398 MSM interviewed, 73.0% (95% CI 65.0-79.7) had heard of KS. However, only 6.4% (95% CI 4.4-9.2) of participants correctly identified that KS is caused by KSHV or a virus other than HIV. Postgraduate education, urban residence, and concurrent HIV infection were all independently associated with greater awareness of the viral origin of KS.

CONCLUSION

Awareness of KSHV is very low, overall, among MSM and only somewhat higher, but still unacceptably low, among HIV-infected MSM. Significant efforts are needed to increase awareness of KSHV as a sexually transmitted infection in this population.

Kaposi's sarcoma in HIV-negative men having sex with men

BACKGROUND

Four epidemiologic forms of Kaposi's sarcoma have been described, all of which are associated with the human herpesvirus-8. In western countries, human herpesvirus-8 is more prevalent in homosexual men than in the general population, and anecdotal cases of Kaposi's sarcoma in HIV-negative homosexual men have been reported.

PATIENTS AND METHODS

We included HIV-negative homosexual and bisexual male patients with histologically proven Kaposi's sarcoma in a retrospective study. Clinical data were collected using a standardized form. Risk factors for human herpesvirus-8 infection and for the development of Kaposi's sarcoma were systematically recorded.

RESULTS

Between 1995 and 2007, 28 men met the defined inclusion criteria. Mean age at first symptoms of Kaposi's sarcoma was 53 years. Clinical presentation resembled classical Kaposi's sarcoma, with limited disease in most patients. No cellular or humoral immunodeficiency was observed. Serologic tests for human herpesvirus-8 (latent immunofluorescence assay) were positive in 88% of patients, and only two patients displayed human herpesvirus-8 viremia at the time of Kaposi's sarcoma diagnosis. Three patients developed lymphoproliferative disorders (Castleman disease, follicular lymphoma and Burkitt lymphoma). In this population, alpha-interferon was well tolerated and gave a complete response, but most patients require only local treatment, if any.

CONCLUSION

Kaposi's sarcoma may develop in homosexual or bisexual men without HIV infection. This type of Kaposi's sarcoma has clinical features in common with classical Kaposi's sarcoma but occurs in younger patients. Its prognosis is good, as Kaposi's sarcoma is generally limited, but clinicians should be aware of the association with lymphoproliferative diseases, which may affect prognosis.

No evidence of sexual transmission of Kaposi's sarcoma herpes virus in a heterosexual South African population

BACKGROUND

The transmission of Kaposi's sarcoma herpes virus (KSHV) in men who have sex with men is clearly associated with sexual risk factors, but evidence of heterosexual transmission of KSHV is conflicting.

METHODS

Sera were obtained from 2103 South African individuals (862 miners, 95 sex workers, 731 female and 415 male township residents; mean age 33.2 years; +/- 10.1). All sera were tested for antibodies to KSHV lytic K8.1 and latent Orf73, HIV, gonococcus, herpes simplex virus type 2 (HSV-2), syphilis and chlamydia. Information on social, demographic and high-risk sexual behavior was linked to laboratory data, to evaluate risk factors, expressed as odds ratios (95% confidence interval) for KSHV.

RESULTS

Overall KSHV and HIV prevalences were 47.5 and 40%, respectively (P = 0.43). The risk of HIV infection was highest in sex workers then female residents and miners, compared with male residents (P < 0.001). HSV-2 infection was highly prevalent (66%) and lower, but still substantial, prevalences (6-8%) were observed for other sexually transmitted infections (STI). No significant difference in KSHV infection was observed among the residential groups (P > 0.05). KSHV was not associated with any of the STI or any measures of sexual behavior (P > 0.05).

CONCLUSION

The pattern of HIV and STI in sex workers suggests high rates of high-risk sexual behavior in this population. The lack of association with high-risk sexual behavior, particularly in sex workers, and with any markers of STI strongly suggest that the sexual mode does not play a significant role in KSHV transmission in this South African population.

Incidence of human herpesvirus 8 (HHV-8) infection among HIV-uninfected individuals at high risk for sexually transmitted infections

Background

The occurrence of, and risk factors for, HHV-8 infection have yet to be definitively determined, particularly among heterosexual individuals with at-risk behavior for sexually transmitted infections (STI). The objective of this study was to estimate the incidence and determinants of HHV-8 infection among HIV-uninfected individuals repeatedly attending an urban STI clinic.

Methods

Sera from consecutive HIV-uninfected individuals repeatedly tested for HIV-1 antibodies were additionally tested for HHV-8 antibodies using an immunofluorescence assay. To identify determinants of HHV-8 infection, a nested case-control study and multivariate logistic regression analysis were performed.

Results

Sera from 456 HIV-uninfected individuals (224 multiple-partner heterosexuals and 232 men who have sex with men (MSM]) were identified for inclusion in the study. The HHV-8 seroprevalence at enrollment was 9.4% (21/224; 95% C.I.: 6.0–14.2%) among heterosexuals with multiple partners and 22.0% (51/232; 95% C.I.: 16.9–28.0%) among MSM. Among the 203 multiple-partner heterosexuals and 181 MSM who were initially HHV-8-negative, 17 (IR = 3.0/100 p-y, 95% C.I.: 1.9 – 4.8) and 21 (IR = 3.3/100 p-y, 95% C.I:.2.1 – 5.1) seroconversions occurred, respectively. HHV-8 seroconversion tended to be associated with a high number of sexual partners during the follow-up among MSM (> 10 partners: AOR = 3.32 95% CI:0.89–12.46) and among the multiple-partner heterosexuals (> 10 partner; AOR = 3.46, 95% CI:0.42–28.2). Moreover, among MSM, HHV-8 seroconversion tended to be associated with STI (AOR = 1.80 95%CI: 0.52–7.96).

During the study period the HIV-1 incidence was lower than that of HHV-8 among both groups (0.89/100 p-y among MSM and 0.95/100 p-y among multiple-partner heterosexuals).

Conclusion

The large difference between the incidence of HHV-8 and the incidence of HIV-1 and other STIs may suggest that the circulation of HHV-8 is sustained by practices other than classical at-risk sexual behavior.

Why is Kaposi’s sarcoma-associated herpesvirus not ubiquitous in the human population?

Kaposi's sarcoma-associated herpesvirus (KSHV), a γ-herpesvirus, is the causative agent of Kaposi's sarcoma. While the incidence of Kaposi's sarcoma may be explained by the differences in the prevalence of KSHV, there is currently no explanation for the variation of KSHV prevalence in different geographic locations and populations. This review summarizes the current understanding of KSHV transmission and aims to provide insight into how KHSV may be transmitted and maintained in the human population.

Risk factors for human Herpesvirus 8 infection and AIDS-associated Kaposi's sarcoma among men who have sex with men in a European multicentre study

We aimed to identify risk factors for Kaposi's sarcoma (KS) among HIV-positive patients and behaviors associated with human Herpesvirus 8 (HHV-8) infection, as well as to assess KS incidence and mortality rates longitudinally. To fulfill the first objective, a European case-control study was designed in the early 1990s (each KS case was matched to 2 controls with another AIDS indicative disease). After the discovery of HHV-8, serology testing enabled us to assess risk factors for KS development among HHV-8 and HIV-1 coinfected men who have sex with men (MSM), as well as risk factors for HHV-8 infection. HHV-8 seroprevalence was determined using a latent immunofluorescence assay. Relevant information was obtained by means of a questionnaire and medical charts review. Assessment of risk factors for KS development and HHV-8 infection was performed using conditional and unconditional logistic regression models, respectively. A low CD4 count was the only significant risk factor for KS. HHV-8 infection was most strongly linked to the number of life-time sex partners, and multiple body fluids such as saliva and semen are quite likely involved in sexual transmission. Longitudinal follow up showed a significant protective role for highly-active antiretroviral therapy (HAART) both on KS development and mortality of KS patients. Although more conclusive data from cohort studies are needed to better define specific transmission mechanisms for HHV-8, our results contribute to explain why KS incidence is higher among MSM, and the decreasing KS incidence trend observed in countries with universal access to HAART.

Reactivation of Kaposi's sarcoma-associated herpesvirus by natural products from Kaposi's sarcoma endemic regions

Kaposi's sarcoma (KS) and its causative agent, Kaposi's sarcoma associated herpesvirus (KSHV/HHV-8), a gamma2 herpesvirus, have distinctive geographical distributions that are largely unexplained. We propose the "oncoweed" hypothesis to explain these differences, namely that environmental cofactors present in KS endemic regions cause frequent reactivation of KSHV in infected subjects, leading to increased viral shedding and transmission leading to increased prevalence of KSHV infection as well as high viral load levels and antibody titers. Reactivation also plays a role in the pathogenesis of KSHV-associated malignancies. To test this hypothesis, we employed an in vitro KSHV reactivation assay that measured increases in KSHV viral load in KSHV infected primary effusion lymphoma (PEL) cells and screened aqueous natural product extracts from KS endemic regions. Of 4,842 extracts from 38 countries, 184 (5%) caused KSHV reactivation. Extracts that caused reactivation came from a wide variety of plant families, and extracts from Africa, where KSHV is highly prevalent, caused the greatest level of reactivation. Time course experiments were performed using 28 extracts that caused the highest levels of reactivation. The specificity of the effects on viral replication was examined using transcriptional profiling of all viral mRNAs. The array data indicated that the natural extracts caused an ordered cascade of lytic replication similar to that seen after induction with synthetic activators. These in vitro data provide support for the "oncoweed" hypothesis by demonstrating basic biological plausibility.

Activation of Kaposi's sarcoma-associated herpesvirus lytic gene expression during epithelial differentiation

The oral cavity has been identified as the major site for the shedding of infectious Kaposi's sarcoma-associated herpesvirus (KSHV). While KSHV DNA is frequently detected in the saliva of KSHV seropositive persons, it does not appear to replicate in salivary glands. Some viruses employ the process of epithelial differentiation for productive viral replication. To test if KSHV utilizes the differentiation of oral epithelium as a mechanism for the activation of lytic replication and virus production, we developed an organotypic raft culture model of epithelium using keratinocytes from human tonsils. This system produced a nonkeratinized stratified squamous oral epithelium in vitro, as demonstrated by the presence of nucleated cells at the apical surface; the expression of involucrin and keratins 6, 13, 14, and 19; and the absence of keratin 1. The activation of KSHV lytic-gene expression was examined in this system using rKSHV.219, a recombinant virus that expresses the green fluorescent protein during latency from the cellular EF-1alpha promoter and the red fluorescent protein (RFP) during lytic replication from the viral early PAN promoter. Infection of keratinocytes with rKSHV.219 resulted in latent infection; however, when these keratinocytes differentiated into a multilayered epithelium, lytic cycle activation of rKSHV.219 occurred, as evidenced by RFP expression, the expression of the late virion protein open reading frame K8.1, and the production of infectious rKSHV.219 at the epithelial surface. These findings demonstrate that KSHV lytic activation occurs as keratinocytes differentiate into a mature epithelium, and it may be responsible for the presence of infectious KSHV in saliva.

Kaposi's sarcoma-associated herpesvirus: clinical, diagnostic, and epidemiological aspects

Kaposi's sarcoma-associated herpesvirus (KSHI) is one of the few viruses proven to be associated with tumorigenesis in humans. Its causal association with all clinical and epidemiological variants of Kaposi's sarcoma (KS) is well established. KSHV is also involved in the pathogenesis of primary effusion lymphoma (PEL) and a subset of multicentric Castleman's disease (MCD). Possible associations of KSHV with other clinical settings have been extensively examined. The findings from several of these studies are contradictory and are yet to be resolved. Concentrated effort over the last decade, since the initial discovery of KSHV, led to the development of several experimental systems that resulted in a better comprehension of the biological characteristics of KSHV and set the stage for the understanding of mechainisms by which diseases are induced by the virus. The development of molecular, histological, and serological tools for KSHV diagnosis allowed researchers to track the transmission and to study the epidemiology of KSHV. These assays have been applied, in particular in ambiguous cases, in order to confirm clinically and pathologically based diagnoses. Here, we review the advances in the clinical, experimental, diagnostic, and epidemiological research of KSHV.

Therapy of other viral infections: herpes to hepatitis

Over the past several years, there has been an increase in knowledge pertaining to the diagnosis and management strategies for the herpes family (Types 1-8), the pox viruses, mumps, measles, rubella, and parvovirus B19 as well as the viral etiologies of hepatitis. Various antiviral treatments, such as nucleoside analogs and interferon therapy, have been available to reduce the signs and symptoms of these common viral infections. This article summarizes the preferred treatment strategies to be employed for each of the viruses for reducing severity, duration, recurrences (notably in the herpes family), transmission rates, as well as preventive alternatives. The majority of the therapeutic options attenuate the course of disease. Treatment decisions are driven by knowledge of the natural history and often are tailored to incorporate clinical circumstances for individual patients. Promotion of community awareness and the development of vaccines should be emphasized in the battle against these common viruses, particularly the herpes simplex viruses, the pox viruses, and hepatitis B.