Human herpesvirus 8 primary infection occurs during childhood in Cameroon, Central Africa

Clinical and Demographic Factors Associated With Kaposi Sarcoma-Associated Herpesvirus Shedding in Saliva or Cervical Secretions in a Cohort of Tanzanian Women

Background

Reasons for the high prevalence of Kaposi sarcoma-associated herpesvirus (KSHV) in sub-Saharan Africa, and risk factors leading to viral reactivation and shedding, remain largely undefined. Preliminary studies have suggested that schistosome infection, which has been associated with impaired viral control, is associated with KSHV. In this study we sought to determine the relationship between active Schistosoma mansoni or Schistosoma haematobium infection and KSHV shedding.

Methods

We quantified KSHV DNA in saliva and cervical swabs from 2 cohorts of women living in northwestern Tanzanian communities endemic for S mansoni or S haematobium by real-time polymerase chain reaction. χ2 and Fisher exact tests were used to determine differences in clinical and demographic factors between those who were and were not shedding KSHV.

Results

Among 139 total women, 44.6% were KSHV seropositive. Six percent of those with S mansoni and 17.1% of those with S haematobium were actively shedding KSHV in saliva and none in cervical samples. Women from the S mansoni cohort who were shedding virus reported infertility more frequently (80% vs 19.5%, P = .009). There was no difference in frequency of KSHV salivary shedding between schistosome-infected and -uninfected women.

Conclusions

In an area with high KSHV seroprevalence and endemic schistosome infections, we provide the first report with data demonstrating no association between schistosome infection and salivary or cervical herpesvirus shedding. KSHV salivary shedding was associated with infertility, a known effect of another herpesvirus, human herpesvirus 6.

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.

Epidemiology and Genetic Variability of HHV-8/KSHV among Rural Populations and Kaposi's Sarcoma Patients in Gabon, Central Africa. Review of the Geographical Distribution of HHV-8 K1 Genotypes in Africa

Human herpesvirus 8 (HHV-8) is the etiological agent of all forms of Kaposi's sarcoma (KS). K1 gene studies have identified five major molecular genotypes with geographical clustering. This study described the epidemiology of HHV-8 and its molecular diversity in Gabon among Bantu and Pygmy adult rural populations and KS patients. Plasma antibodies against latency-associated nuclear antigens (LANA) were searched by indirect immunofluorescence. Buffy coat DNA samples were subjected to polymerase chain reaction (PCR) to obtain a K1 gene fragment. We studied 1020 persons; 91% were Bantus and 9% Pygmies. HHV-8 seroprevalence was 48.3% and 36.5% at the 1:40 and 1:160 dilution thresholds, respectively, although the seroprevalence of HHV-8 is probably higher in Gabon. These seroprevalences did not differ by sex, age, ethnicity or province. The detection rate of HHV-8 K1 sequence was 2.6% by PCR. Most of the 31 HHV-8 strains belonged to the B genotype (24), while the remaining clustered within the A5 subgroup (6) and one belonged to the F genotype. Additionally, we reviewed the K1 molecular diversity of published HHV-8 strains in Africa. This study demonstrated a high seroprevalence of HHV-8 in rural adult populations in Gabon and the presence of genetically diverse strains with B, A and also F genotypes.

Seroepidemiology of the human herpesvirus 8 infection among people living with HIV in Taiwan, 2014-2018

BACKGROUND

Human herpesvirus type 8 (HHV-8) can be transmitted through unprotected sex as HIV. We aimed to investigate the seroincidence of HHV-8 and associated factors among people living with HIV (PLWH).

METHODS

From 2014 to 2018, blood samples of PLWH on the first date of HIV care were determined for antibodies against HHV-8. Individuals testing HHV-8-seronegative at baseline were followed for at least four months to estimate the annual seroconversion rate. To identify the factors associated with HHV-8 seroconversion, we compared the clinical characteristics between seroconverters and non-seroconverters who were matched for observation duration.

RESULTS

The HHV-8 seroprevalence increased from 8.1% in 2014 to 20.0% in 2018. HHV-8 seroconversion occurred in 154 (14.7%) PLWH after a total of 2652.16 person-years of follow-up (PYFU), resulting in an overall incidence rate of 5.62 per 100 PYFU, which increased from 3.20 to 6.84 per 100 PYFU during the study period. HHV-8 seroconverters were less likely to have chronic hepatitis B virus (HBV) infection (1.9% vs 10.6%) and more likely to be antiretroviral-naïve on entry into care (87.7% vs 75.4%) (both p < 0.05). In multivariate logistic analysis, men who have sex with men (MSM) (adjusted odds ratio [aOR], 2.22; 95% CI, 1.01-4.86), being antiretroviral-naïve (aOR, 2.91; 95% CI, 1.27-6.67), and chronic HBV infection (aOR, 0.13; 95% CI, 0.03-0.61) at baseline were associated with HHV-8 seroconversion.

CONCLUSIONS

An increasing trend of HHV-8 infection was observed among PLWH in Taiwan between 2014 and 2018. MSM and being antiretroviral-naïve were associated with higher risk for HHV-8 seroconversion.

Mutual detection of Kaposi's sarcoma-associated herpesvirus and Epstein-Barr virus in blood and saliva of Cameroonians with and without Kaposi's sarcoma

Kaposi's sarcoma-associated herpesvirus (KSHV) and Epstein-Barr virus (EBV) are prevalent in sub-Saharan Africa, together with HIV; the consequent burden of disease is grave. The cofactors driving transmission of the two viruses and pathogenesis of associated malignancies are not well understood. We measured KSHV and EBV DNA in whole blood and saliva as well as serum antibodies levels in 175 Cameroonians with Kaposi's sarcoma and 1,002 age- and sex-matched controls with and without HIV. KSHV seroprevalence was very high (81%) in controls, while EBV seroprevalence was 100% overall. KSHV DNA was detectable in the blood of 36-46% of cases and 6-12% of controls; EBV DNA was detected in most participants (72-89%). In saliva, more cases (50-58%) than controls (25-28%) shed KSHV, regardless of HIV infection. EBV shedding was common (75-100%); more HIV+ than HIV- controls shed EBV. Cases had higher KSHV and EBV VL in blood and saliva then controls, only among HIV+ participants. KSHV and EBV VL were also higher in HIV+ than in HIV- controls. Cases (but not controls) were more likely to have detectable KSHV in blood if they also had EBV, whereas shedding of each virus in saliva was independent. While EBV VL in saliva and blood were modestly correlated, no correlation existed for KSHV. Numerous factors, several related to parasitic coinfections, were associated with detection of either virus or with VL. These findings may help better understand the interplay between the two gammaherpesviruses and generally among copathogens contributing to cancer burden in sub-Saharan Africa.

HHV-8 Seroprevalence and Genotype Distribution in Africa, 1998⁻2017: A Systematic Review

Human herpes virus type 8 (HHV-8) is the causative agent of Kaposi's sarcoma (KS). We systematically reviewed literature published between 1998 and 2017, according to the PRISMA guidelines, to understand the distribution of HHV-8 infection in Africa. More than two-thirds (64%) of studies reported on seroprevalence and 29.3% on genotypes; 9.5% were on both seroprevalence and genotypes. About 45% of African countries had data on HHV-8 seroprevalence exclusively, and more than half (53%) had data on either seroprevalence or genotypes. Almost half (47%) of the countries had no data on HHV-8 infection. There was high heterogeneity in the types of tests and interpretation algorithms used in determining HHV-8 seropositivity across the different studies. Generally, seroprevalence ranged from 2.0% in a group of young children in Eritrea to 100% in a small group of individuals with KS in Central African Republic, and in a larger group of individuals with KS in Morocco. Approximately 16% of studies reported on children. Difference in seroprevalence across the African regions was not significant (95% CI, χ² = 0.86; p = 0.35), although specifically a relatively significant level of infection was observed in HIV-infected children. About 38% of the countries had data on K1 genotypes. K1 genotypes A, A5, B, C, F and Z occurred at frequencies of 5.3%, 26.3%, 42.1%, 18.4%, 5.3% and 2.6%, respectively. Twenty-three percent of the countries had data for K15 genotypes, and genotypes P, M and N occurred at frequencies of 52.2%, 39.1%, and 8.7%, respectively. Data on HHV-8 inter-genotype recombinants in Africa are scanty. HHV-8 may be endemic in the entire Africa continent but there is need for a harmonized testing protocol for a better understanding of HHV-8 seropositivity. K1 genotypes A5 and B, and K15 genotypes P and M, from Africa, should be considered in vaccine design efforts.

Epidemiology of Castleman Disease

Castleman disease is a rare entity, including unicentric Castleman disease (UCD), human herpesvirus-8 plus Castleman disease (HHV-8+MCD), and idiopathic multicentric Castleman disease (iMCD). UCD is the most common at 16 per million person years and occurs at every age. HHV-8+MCD incidence varies widely, mostly affecting human immunodeficiency virus-positive men. iMCD is likely a more heterogeneous disease with an estimated incidence of 5 per million person years. Improved definitions should improve understanding of the epidemiology of Castleman disease and its subtypes.

Association of Household Food- and Drink-Sharing Practices With Human Herpesvirus 8 Seroconversion in a Cohort of Zambian Children

Background

Human herpesvirus 8 (HHV-8) infection occurs in early childhood and is associated with human immunodeficiency virus type 1 (HIV-1) infection and risk for Kaposi sarcoma, but behaviors associated with HHV-8 transmission are not well described.

Methods

We enrolled and followed a prospective cohort of 270 children and their household members to investigate risk factors for HHV-8 transmission in Lusaka, Zambia.

Results

We report an incidence of 30.07 seroconversions per 100 child-years. Independent risk factors for HHV-8 incident infection included having a child who shared utensils with a primary caregiver (hazards ratio [HR], 2.33; 95% confidence interval [CI], 1.49-7.14), having an increasing number of HHV-8-infected household members (HR, 1.27; 95% CI, 1.09-2.79), and having ≥5 siblings/children in the household (HR, 2.24; 95% CI, 1.03-4.88). Playing with >5 children a day was protective against infection (HR, 0.54; 95% CI, .33-0.89), as was increasing child age (HR, 0.96; 95% CI, .93-.99).

Conclusions

This is the first study to find a temporal association between limited child feeding behaviors and risk for HHV-8 infection. Child food- and drink-sharing behaviors should be included in efforts to minimize HHV-8 transmission, and households with a large number of siblings should receive additional counseling as childhood infections occur in the home context.

Kaposi's disease in an HIV positive child, with probable contamination from his grandmother

Kaposi's disease in children with HIV is rarely reported in everyday practice. This is a case study of cutaneous Kaposi's disease revealing HIV in a 5-year-old child with polymorphic eruption of papules and nodules on the face, trunk, back, and limbs. Histopathological examination confirmed the diagnosis of Kaposi's disease. The child's HIV serology was positive with a CD4 count of 240/mm³, normochromic and normocytic anemia, and a hemoglobin level at 8.5 g/dl. It was found that the child, after early weaning from his HIV-negative mother, had repeatedly suckled his healthy grandmother, who had no skin lesions but was HIV1 positive. Both grandmother and child were referred for treatment in their locality. The case is noteworthy for the way in which the HIV1 virus infected the child during weaning and then being suckled by his grandmother. The child already had an initial dental flare that could have injured his grandmother. Thus, in our case, there is a contamination by HIV1 virus most likely from the grandmother and contamination by the HHV8 virus, source unidentified as a technical plateau was reached.

Conceptual Emergence of Human Herpesvirus 8 (Kaposi’s Sarcoma-associated Herpesvirus) as an Oral Herpesvirus

Recognition of the various clinico-epidemiologic forms of Kaposi’s sarcoma, a disease putatively caused by an infectious agent, did not provide ready clues as to how that agent might be transmitted, although fecal and sexual routes were implicated. Application of serologic and genome-detection assays, and cell-culture studies following the identification of human herpesvirus 8 as the causative agent now implicate that virus as one that is orally shed. While oral transmission of the virus might account for the viral endemicity in Africa and Mediterranean countries, why it is particularly prevalent among male homosexuals in the West remains more difficult to explain. Such explanation may be sought from behavioral studies into the role saliva plays in sexual interactions.

Kaposi Sarcoma of Childhood: Inborn or Acquired Immunodeficiency to Oncogenic HHV-8

Kaposi sarcoma (KS) is an endothelial malignancy caused by human herpes virus-8 (HHV-8) infection. The epidemic and iatrogenic forms of childhood KS result from a profound and acquired T cell deficiency. Recent studies have shown that classic KS of childhood can result from rare single-gene inborn errors of immunity, with mutations in WAS, IFNGR1, STIM1, and TNFRSF4. The pathogenesis of the endemic form of childhood KS has remained elusive. We review childhood KS pathogenesis and its relationship to inherited and acquired immunodeficiency to oncogenic HHV-8.

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.

Oral HHV-8 replication among women in Mombasa, Kenya

Human herpesvirus-8 (HHV-8) replication in the oropharynx may play an important role in HHV-8 transmission and contribute to the development of Kaposi sarcoma (KS) in some individuals. Studies in the United States and Europe report high rates of HHV-8 DNA detection in saliva of HHV-8 infected men, but little is known about the natural history of HHV-8 among persons in sub-Saharan Africa, where prevalence of HHV-8 infection and KS is greatest. To address this gap, this study evaluated oral HHV-8 replication in a cohort of 40 HHV-8 seropositive Kenyan women. Study clinicians collected daily oral swabs from participants for up to 30 consecutive days, and swab samples were tested for HHV-8 DNA using quantitative, real-time polymerase chain reaction. HHV-8 was detected at least once in 27 (68%) participants, and the overall shedding rate was 23%. On days with HHV-8 detection, mean HHV-8 quantity was 4.5 log10  copies/ml. Among HIV-infected women, CD4 count ≥500 cells/mm(3) versus <500 cells/mm(3) was associated with higher HHV-8 copy number (4.8 log10  copies/ml vs. 3.4 log10  copies/ml; coef 1.2 [95% CI, 0.5-1.9]; P = 0.001) and a higher HHV-8 shedding rate (49% vs.12%; RR, 4.2 [95% CI, 0.8-21.4]; P = 0.08). No other factors were associated with HHV-8 shedding rate or copy number. The study demonstrates high rates and quantity of HHV-8 in the oropharynx of HHV-8 seropositive African women. These findings support the observation that oral replication is an essential feature of HHV-8 infection, with likely implications for HHV-8 transmission and KS pathogenesis.

Risk factors for Kaposi's sarcoma among HIV-positive individuals in a case control study in Cameroon

BACKGROUND

Individuals co-infected with Kaposi's sarcoma herpesvirus (KSHV) and Human Immunodeficiency Virus (HIV) are at greatly increased risk of developing Kaposi's sarcoma (KS). The objective of the current analysis is to identify risk cofactors for KS among HIV-positive individuals.

METHODS

We conducted a case-control study of KS in Cameroon on 161 HIV-positive and 14 HIV-negative cases and 680 HIV-positive and 322 HIV-negative controls. Participants answered a physician-administered questionnaire and provided blood and saliva specimens. Antibodies against KSHV lytic, K8.1, and latent, ORF73, antigens were measured by ELISA to determine KSHV serostatus. Conditional logistic regression was performed to determine multivariate odds ratios (OR) and 95% confidence intervals (CI) for risk factors associated with KS among HIV-positive cases and controls.

RESULTS

Overall, 98% (158) of HIV-positive cases, 100% (14) of HIV-negative cases, 81% (550) of HIV-positive controls, and 80% (257) of HIV-negative controls were KSHV seropositive. Risk factors for KS among HIV-positive individuals included KSHV seropositivity (OR=9.6; 95% CI 2.9, 31.5), non-use of a mosquito bed net (OR 1.9; 95% CI 1.2, 2.9), minority ethnicity (OR=3.1; 95% CI 1.1, 9.3), treatment from a traditional healer (OR=2.3; 95% CI 1.5, 3.7), history of transfusion (OR=2.4; 95% CI 1.5, 3.9), and family history of cancer (OR=1.9; 95% CI 1.1, 3.1).

CONCLUSION

KSHV seroprevalence of ≥80% indicates a high prevalence in the general population in Cameroon. Among HIV-positive individuals, the strong association of KS with non-use of mosquito nets and treatment from traditional healers are compelling findings, consistent with recently reported data from East Africa.

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.

Inherited human OX40 deficiency underlying classic Kaposi sarcoma of childhood

Human OX40 is necessary for robust CD4⁺ T cell memory and confers selective protective immunity against HHV-8 infection in endothelial cells.

Kaposi sarcoma (KS), a human herpes virus 8 (HHV-8; also called KSHV)–induced endothelial tumor, develops only in a small fraction of individuals infected with HHV-8. We hypothesized that inborn errors of immunity to HHV-8 might underlie the exceedingly rare development of classic KS in childhood. We report here autosomal recessive OX40 deficiency in an otherwise healthy adult with childhood-onset classic KS. OX40 is a co-stimulatory receptor expressed on activated T cells. Its ligand, OX40L, is expressed on various cell types, including endothelial cells. We found OX40L was abundantly expressed in KS lesions. The mutant OX40 protein was poorly expressed on the cell surface and failed to bind OX40L, resulting in complete functional OX40 deficiency. The patient had a low proportion of effector memory CD4⁺ T cells in the peripheral blood, consistent with impaired CD4⁺ T cell responses to recall antigens in vitro. The proportion of effector memory CD8⁺ T cells was less diminished. The proportion of circulating memory B cells was low, but the antibody response in vivo was intact, including the response to a vaccine boost. Together, these findings suggest that human OX40 is necessary for robust CD4⁺ T cell memory and confers apparently selective protective immunity against HHV-8 infection in endothelial cells.

Merkel cell polyomavirus infection occurs during early childhood and is transmitted between siblings

Merkel cell polyomavirus (MCPyV) is thought to be the etiological agent of Merkel cell carcinoma, but little is known about its distribution and modes of transmission. We conducted seroepidemiological surveys in more than 1000 individuals, from two populations from Cameroon. Overall MCPyV seroprevalence was high in both populations (>75% in adults). Data from the first population, comprising mainly children, indicated that MCPyV infections mostly occurred during early childhood, after the disappearance of specific maternal antibodies. Results from the second family-based population provided evidence for familial aggregation of MCPyV infection status. We observed significant sib-sib correlation (odds ratio=3.42 [95% CI 1.27-9.19], p=0.014), particularly for siblings close together in age, and a trend for mother-child correlation (OR=2.71 [0.86-8.44], p=0.08). Overall, our results suggest that MCPyV infection is acquired through close contact, possibly involving saliva and/or the skin, especially between young siblings and between mothers and their children.

[Seroprevalence and risk factors of human herpes virus 8 infection in Central-East Tunisia]

OBJECTIVE

Epidemiology of human herpesvirus 8 (HHV8) is still unknown in Tunisia. We aimed to assess the prevalence of HHV8 infection in adults and children from Central-East Tunisia and in patients with high risk of parenteral or sexual infection.

METHODS

We enrolled 553 subjects: 116 blood donors, 100 pregnant women, 100 children, 50 subjects with sexually transmitted infections with positive HIV serology and 50 other without HIV infection, 107 multitransfused patients and 30 kidney transplant patients. Antibodies against HHV8 were tested using a sensitive indirect immunofluorescence assay.

RESULTS

The seroprevalence of HHV8 was found to be 13.8% in blood donors, 13% in pregnant women and 12% in children. In healthy adult population, no association was found between HHV8 seropositivity and sex, sociodemographic characteristics, parenteral risk factors or serological markers of hepatitis B. Rates of HHV8 infection were significantly higher in patients having high-risk sexual behavior with or without HIV infection (P<10(-4)), in polytransfused patients (P<10(-4)) and in patients with kidney transplantation (P=0.001).

CONCLUSION

Our findings suggest that HHV8 infection is widespread in Central-East Tunisia such as in the Mediterranean area. HHV8 infection appears to be acquired early in life, probably through saliva. HHV8 transmission by blood transfusion, subject of controversy in literature, is well established in our study. Early screening of this infection should be considered in populations with high risk of Kaposi's sarcoma in our areas.

The Zambia Children's KS-HHV8 Study: rationale, study design, and study methods

The epidemic of human immunodeficiency virus in Zambia has led to a dramatic rise in the incidence of human herpesvirus-8 (HHV-8)-associated Kaposi's sarcoma in both adults and children. However, there is a paucity of knowledge about the routes of HHV-8 transmission to young children. The Zambia Children's KS-HHV8 Study, a large, prospective cohort study in Lusaka, Zambia, was launched in 2004 to investigate the role of household members as a source of HHV-8 infection in young children and social behaviors that may modify the risk of HHV-8 acquisition. This cohort is distinct from other epidemiologic studies designed to investigate HHV-8 incidence and transmission because it recruited and followed complete households in the urban central African context. Between July 2004 and March 2007, 1,600 households were screened; 368 households comprising 464 children and 1,335 caregivers and household members were enrolled. Follow-up of this population continued for 48 months postrecruitment, affording a unique opportunity to study horizontal transmission of HHV-8 and understand the routes and sources of transmission to young children in Zambia. The authors describe the study rationale, design, execution, and characteristics of this cohort, which provides critical data on the epidemiology and transmission of HHV-8 to young children in Zambia.

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.

A population-based study of how children are exposed to saliva in KwaZulu-Natal Province, South Africa: implications for the spread of saliva-borne pathogens to children

OBJECTIVES

In sub-Saharan Africa, many viral infections, including Epstein-Barr virus, cytomegalovirus, Kaposi's sarcoma-associated herpesvirus and hepatitis B are acquired in childhood. While saliva is an important transmission conduit for these viruses, little is known about how saliva is passed to African children. We endeavoured to identify the range and determinants of acts by which African children are exposed to saliva.

METHODS

To identify the range of acts by which African children are exposed to saliva, we conducted focus groups, semi-structured interviews and participant observations in an urban and a rural community in South Africa. To measure the prevalence and determinants of the identified acts, we administered a questionnaire to a population-based sample of caregivers.

RESULTS

We identified 12 caregiving practices that expose a child's oral-respiratory mucosa, cutaneous surfaces or anal-rectal mucosa to saliva. Several acts were heretofore not described in the contemporary literature (e.g., caregiver inserting finger lubricated with saliva into child's rectum to relieve constipation). Among 896 participants in the population-based survey, many of the acts were commonly practised by all respondent types (mothers, fathers, grandmothers and siblings). The most common were premastication of food, sharing sweets and premastication of medicinal plants that are spit onto a child's body.

CONCLUSIONS

African children are exposed to saliva through a variety of acts, practised by a variety of caregivers, with no single predominant practice. This diversity poses challenges for epidemiologic work seeking to identify specific saliva-passing practices that transmit viruses. Most acts could be replaced by other actions and are theoretically preventable.

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

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

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.

Seroprevalence of HHV-8, CMV, and EBV among the general population in Ghana, West Africa

Background

Human herpesvirus 8 (HHV-8), cytomegalovirus (CMV) and Epstein-Barr virus (EBV) are prevalent in Africa, but less common elsewhere and the modes of transmission are still subject to debate. Generally, they rarely cause disease in the immunocompetent host but are highly oncogenic when associated with immunosuppression. Although the high prevalence of HHV-8, CMV and EBV has been well documented in Africa, such data are sparse from Ghana.

Methods

Serum samples from 3275 HIV-seronegative healthy blood donors and 250 HIV-AIDS patients were tested for antibodies specific for HHV-8, CMV and EBV by IgG ELISA assays. Differences in seropositivity rates by gender and age were evaluated using the Chi-square test with Yates correction.

Results

Of the 3275 HIV-seronegative healthy blood donors tested, 2573 (78.6%) were males and 702 (21.4%) were females, with ages ranging from 18 to 65 years (median 32.6; mean 31.2; mode 30). Of the 250 HIV-AIDS patients tested, 140 (56%) were males and 110 (44%) were females, with ages ranging from 17 to 64 years (median 30.8; mean 30.3; mode 28). Among the HIV-seronegative healthy blood donors, overall seroprevalence of HHV-8, CMV and EBV was 23.7%, 77.6% and 20.0%, respectively. Among the HIV-AIDS patients, overall seroprevalence of HHV-8, CMV and EBV was 65.6%, 59.2% and 87.2%, respectively. The seroprevalence of HHV-8 (p < 0.005) and EBV (p < 0.001) was statistically significantly higher in HIV-AIDS patients compared to HIV-seronegative healthy blood donors. There was no statistically significant difference (p = 0.24) between CMV seroprevalence in HIV-AIDS patients and HIV-seronegative healthy blood donors. Age and gender were not independent determinants (p > 0.05) for all three infections among HIV-seronegative healthy blood donors and HIV-AIDS patients in Ghana.

Conclusion

The results presented herein indicate that HHV-8, CMV and EBV infections are hyperendemic in both HIV-seronegative and HIV-seropositive Ghanaians, and suggest primarily a horizontal route of transmission of these three viral infections in Ghana.

Early childhood infection by human herpesvirus 8 in Zambia and the role of human immunodeficiency virus type 1 coinfection in a highly endemic area

Kaposi's sarcoma occurs at high incidence among Zambian adults and children, but there is a paucity of data on human herpesvirus 8 (HHV-8) incidence and routes of infection, especially in children. Between 1998 and 2004, the authors conducted a prospective study of viral transmission in a cohort of 684 children in Lusaka, Zambia, to estimate the annual incidence of HHV-8 from birth through 48 months of age. Maternal and pediatric human immunodeficiency virus type 1 (HIV-1) infection status was also determined. The results, based on 1,532 child-years of follow-up, showed that HHV-8 seroconversion occurs early in life. The incidence rate of HHV-8 seroconversion was 13.8 infections per 100 child-years by 48 months of age. HIV-1-infected children were at substantially higher risk for HHV-8 seroconversion (adjusted hazard ratio = 4.60, 95% confidence interval: 2.93, 7.22). Maternal HIV-1 and HHV-8 infection status were not independently associated with risk of HHV-8 seroconversion in the child. HHV-8 antibody titers in children followed at all consecutive time points revealed sero-reversion of HHV-8 antibodies, with undetectable titers in some children at one or more time points after seroconversion. These results demonstrate that cross-sectional serologic screening probably underestimates true HHV-8 seroprevalence in young Zambian children because of fluctuations in detectable antibody titers.

Development of an immunofluorescence assay using recombinant proteins expressed in insect cells to screen and confirm presence of human herpesvirus 8-specific antibodies

Human herpesvirus 8 (HHV-8), or Kaposi's sarcoma (KS)-associated herpesvirus, has been linked to all forms of KS. The results of most current serological assays for the detection of HHV-8-specific antibodies have low levels of concordance among themselves. To establish a sensitive and specific testing strategy that can be used to screen for HHV-8-specific antibodies, three HHV-8 proteins, ORF65, ORF73, and K8.1A, were expressed by using baculoviral vectors in insect cells and incorporated into a monoclonal antibody-enhanced immunofluorescence assay (mIFA) termed the Sf9 three-antigen mIFA. The results obtained by this mIFA were compared to those obtained by a standard mIFA with an HHV-8-infected B-cell line (BC3 mIFA). Test sera were obtained from patients diagnosed with KS, human immunodeficiency virus type 1-infected patients at high risk for HHV-8 infection, and healthy controls from a local blood bank. The combined use of both assays had a sensitivity of 94% and a specificity of 96%. The performance of these two assays when they were used together indicates that they may be useful for the reliable detection of HHV-8-specific immunoglobulin G antibodies in a population.

High diversity of HHV-8 molecular subtypes in the Amazon region of Brazil: evidence of an ancient human infection

The present study describes the molecular epidemiology of Human herpesvirus 8 (HHV-8) among four Indian tribes (Kararao, Arara Laranjal, Tiriyo, and Zo'e) of the Amazon region of Brazil and a group of HIV-1-infected subjects from the urban population of Belem, Para. Infection was characterized by the presence of antibodies using ELISA (measuring antibodies to ORF59, ORF65, K8.1A, K8.1B, and ORF73), and molecular assays (gene amplification of the regions ORF26 and the variable region VR1). Antibodies to HHV-8 were detected in 66 samples of the 221 Brazilian Amerindians, namely, 6 (25%) in the Kararao, 18 (19.6%) in the Arara Laranjal, 24 (42.9%) in the Tiriyo, and 18 (36.7%) in the Zo'e. Among the 477 HIV-1-infected subjects, antibodies to HHV-8 were present in 74 (15.5%) persons. The ORF26 region was amplified in seven samples, one of the Arara Laranjal, one of the Tiriyo, two of the Zo'e, and three of the HIV-1-infected group. Subtyping of HHV-8 described a high multiplicity of molecular subtypes, including C (Zo'e), E (Tiriyo), and B (HIV-1 infected). Serological results confirm the high prevalence of HHV-8 among Amerindians and the presence of three subtypes in the Amazon region of Brazil, including a unique subtype, which favors the idea of HHV-8 as an ancient human infection within this particular geographical region.

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.

Transmission of human herpesvirus 8: an update

PURPOSE OF REVIEW

Human herpesvirus 8 is associated with neoplastic diseases in the immunocompromised host, including Kaposi's sarcoma, multicentric Castleman disease and primary effusion lymphoma. Acquisition and control of human herpesvirus 8 infection have not yet been fully elucidated. This review focuses on the most recent findings on human herpesvirus 8 transmission.

RECENT FINDINGS

Horizontal transmission by saliva appears the most common route not only in families in endemic regions, but also among high-risk groups in Western countries. Vertical, sexual, and blood and transplant-related transmission, however, remain of significant concern worldwide. Novel approaches to standardize and optimize the assessment of human herpesvirus 8 infection have been reported. New insights on the host immune cell mechanisms devoted to the control of human herpesvirus 8 infection have also been presented.

SUMMARY

The increasing knowledge about the routes of human herpesvirus 8 transmission, which appear now more similar to those of other more ubiquitous human herpesviruses (i.e. Epstein-Barr virus and cytomegalovirus), the growing efforts in improving laboratory diagnosis and the caution in the research of new biological associations are the major recent findings. They constitute a fundamental background for directing more appropriate future research and achieving more stringent evidence useful for the control of human herpesvirus 8 spread and for the management of human herpesvirus 8-related diseases.

Traditional practices and exposure to bodily fluids in Lusaka, Zambia

OBJECTIVES

To ascertain if there are specific sociocultural and behavioural practices associated with the exposure to saliva, semen and vaginal fluids, particularly through child-rearing practices and the use of traditional medicine in Lusaka, Zambia.

METHODS

We conducted 11 focus group discussions with men and women from diverse ethnic and socioeconomic backgrounds (n = 105) in Lusaka, Zambia in March 2004. We also conducted a brief sociodemographic survey of all focus group participants.

RESULTS

Discussions indicated that saliva was used while engaging in home health care practices associated with childcare and the use of traditional medicine. Additionally, semen and vaginal fluids may be used in rituals associated with childcare and health care for children. Our survey indicated that the use of traditional medicine is associated with lower socioeconomic status.

CONCLUSIONS

Population-based studies are needed to evaluate the relationship between traditional behavioural and sociocultural practices, which involve exchange of saliva and other bodily fluids and risk of infectious disease.

Human herpesvirus 8 and human herpesvirus 2 infections in prison population

Incarcerated persons have high rates of infectious diseases. Few data on the prevalence of sexually transmitted diseases in prisoners are available. This multi-center cross-sectional study enrolled 973 inmates from eight Italian prisons. Demographic and behavioral data were collected using an anonymous standardized questionnaire and antibodies to HIV, HCV, HBV, HSV-2, and HHV-8 were detected in a blood sample obtained from each person at the time of the enrollment in the study. Two hundred and two out of the 973 subjects (20.7%) had antibodies against HHV-8. HHV-8-seropositive subjects were more likely to be older than 30 years with a higher educational level. HHV-8 infection was associated significantly with HBV (P < 0.001) and HSV-2 (P = 0.004) seropositivity and with previous imprisonments. Multivariate analysis showed that HHV-8 infection in Italian inmates was associated with HBV (P < 0.001) and HSV-2 (P = 0.002) seropositivity otherwise among foreigners inmates HHV-8 was significantly associated with HBV infection (P = 0.05). One hundred and eighty-six (21.2%) prisoners had anti-HSV-2 antibodies. At multivariate analysis HSV-2-positivity was significantly associated with HIV (P < 0.001) and HHV-8 infections (P = 0.003), whereas it was inversely associated with HCV infection (0.004). A relatively high seroprevalence of HHV-8 and HSV-2 among Italian prison inmates was found. The association of HHV-8 and HSV-2 infections suggest sexual transmission of these viruses among Italian prison inmates.

HIV-associated Kaposi's sarcoma

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

Seroprevalence of HHV-8 infection in the pediatric population of two university hospitals in Rio de Janeiro, Brazil

BACKGROUND

The authors present a serologic survey of the prevalence of herpesvirus-8 (HHV-8) among 171 children from 0 to 12 years old in Rio de Janeiro, Brazil.

MATERIALS AND METHODS

Sera were tested for latent nuclear and lytic antigens using indirect immunofluorescence and Western blotting.

RESULTS

Serology for HHV-8 was positive in 16 of 171 patients (9.35%). Among 13 HIV-positive patients, four (31%) were also positive for HHV-8. The seropositivity among healthy children was 7.6%, and females were significantly (P<0.002) more associated with HHV-8 seropositivity (16%) than males (1.1%).

CONCLUSIONS

We detected a higher HHV-8 seroprevalence among the pediatric population in Rio de Janeiro, Brazil, when compared with similar studies performed in other countries. Nonsexual routes of transmission are a possible explanation for this pattern. The unusual finding of a higher seroprevalence among female children could be explained by a specific route of exposition or even an epidemiological bias.

Molecular epidemiology of the HHV-8 K1 gene from Moroccan patients with Kaposi's sarcoma

The genetic variability of the human herpesvirus 8 (HHV-8) strains circulating in the populations living in the Maghreb region, an endemic area for HHV-8 and associated Kaposi's sarcoma, remains largely unknown. We have thus analyzed the genetic variation of the complete K1 gene of HHV-8 in a series of 35 viral strains, originating from 28 Moroccan patients with classic, AIDS-associated or iatrogenic Kaposi's sarcoma lesions. All but one of the 35 strains belonged to the large C molecular subtype. Furthermore, high genetic diversity within the C subtype was observed in the 35 sequenced HHV-8 K1 genes, with strains belonging to several and distinct subgroups highly supported from a phylogenetically viewpoint (e.g., C3, C7, C'' and C5). Considering these newly identified Moroccan viral strains in the context of 189 complete K1 genes, we were able to characterized, using the Simplot program, two main groups of recombinant chimeric K1 genes, either intertypic (C5) or intratypic (C7). In addition, the genetic characterization of the host maternal gene pool, through the analyses of mtDNA variation, did not provide evidence for any association between a particular human ethno-geographic background (i.e., North African vs. sub-Saharan African vs. West Eurasian linages) and any HHV-8 strain because both C' and C'' strains were randomly distributed among the different patients' population backgrounds.

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

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

Seroprevalence of six different viruses among pregnant women and blood donors in rural and urban Burkina Faso: A comparative analysis

A seroprevalence study was carried out of six different human pathogenic viruses, namely human immunodeficiency virus (HIV), hepatitis B virus (HBV), hepatitis C virus (HCV), human T-cell leukemia virus (HTLV), human herpesvirus type 8 (HHV-8), and dengue virus among pregnant women and blood donors from rural (Nouna) and urban (Ouagadougou) Burkina Faso, West Africa. A total of 683 samples from blood donors (n = 191) and pregnant women (n = 492) were collected from both sites and screened for the different virus infection markers resulting in the following prevalence values for Nouna or Ouagadougou, respectively: HIV 3.6/4.6, anti-HBV core (anti-HBc) 69.6/76.4, HBV surface antigen (HBsAg)14.3/17.3, HCV 2.2/1.5, HTLV 1.4/0.5, HHV-8 11.5/13.5, dengue virus 26.3/36.5. Individuals aged > or =25 years were more likely to be infected with HIV than those below 24 years (P < 0.05). Infection with HIV increased the likelihood of co-infection with other viruses, such as HHV-8, HBV and HTLV. Co-infection studies involving five viruses (HBV-HBsAg, HHV-8, HIV, HCV, and HTLV) showed that 4.8% (33/683) of the studied population were dually infected, with HBsAg+ HHV-8 (13/33), HBsAg+HIV (8/33) and HIV+HHV-8 (8/33) being the most common co-infections. Of the population studied 0.6% (4/683) was triply infected, the most common infection being with HBV+HIV+HHV-8 (3/4). There was no difference in the prevalence of HIV, anti-HBc, HBsAg, HCV, HTLV, and HHV-8 either among blood donors or pregnant women in urban or rural setting, while dengue virus prevalence was relatively lower in rural (26.3%) than in urban (36.5%) Burkina Faso.

Cell signaling pathways engaged by KSHV

Kaposi's sarcoma herpesvirus (KSHV) is the eighth human herpesvirus discovered in 1994 from Kaposi's sarcoma lesion of an AIDS patient. The strong molecular and epidemiological links associating KSHV with Kaposi's sarcoma and certain lymphoproliferative disorders indicate that KSHV is required for the development of these malignancies. Although KSHV is equipped to manipulate and deregulate several cellular signaling pathways, it is not yet understood how this leads to cell transformation. Profound understanding of the interplay of viral and cellular factors in KSHV-infected cells will provide valuable information on the mechanisms of viral tumorigenesis and enable development of efficient targeted therapies for virus-induced cancers. This review focuses on the cellular signaling pathways that KSHV gene products impinge on and discusses their putative contribution to tumorigenesis.

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.

Human herpesvirus 8 serological markers and viral load in patients with AIDS-associated Kaposi's sarcoma in Central African Republic

Epidemic Kaposi's sarcoma (KS) is one of the most frequent types of cancer in several African countries; however, very few data are available on human herpesvirus 8 (HHV-8) markers in KS patients from Central Africa. In a series of 36 AIDS-KS cases from Central African Republic, we showed, using a real-time PCR quantitative assay, the high frequency (82%) of detectable HHV-8 DNA in peripheral blood mononuclear cells (PBMCs). We also found that the level of antibodies directed against lytic or latent HHV-8 antigens is not correlated to the amount of HHV-8 viral load in the PBMCs, and finally, we demonstrated a much higher viral load in tumoral skin lesions (6.07 log copies/mug DNA) than in unaffected skin (2.93 log copies/mug DNA) or in PBMCs (2.55 log copies/mug DNA).

Human herpesvirus 8--a novel human pathogen

In 1994, Chang and Moore reported on the latest of the gammaherpesviruses to infect humans, human herpesvirus 8 (HHV-8) [1]. This novel herpesvirus has and continues to present challenges to define its scope of involvement in human disease. In this review, aspects of HHV-8 infection are discussed, such as, the human immune response, viral pathogenesis and transmission, viral disease entities, and the virus's epidemiology with an emphasis on HHV-8 diagnostics.

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.

Water, socioeconomic factors, and human herpesvirus 8 infection in Ugandan children and their mothers

BACKGROUND

Human herpesvirus 8 (HHV-8) infection is common in sub-Saharan Africa, but its distribution is uneven. Transmission occurs during childhood within families by unclear routes.

METHODS

We evaluated 600 Ugandan children with sickle cell disease and their mothers for factors associated with HHV-8 seropositivity in a cross-sectional study. HHV-8 serostatus was determined using an HHV-8 K8.1 glycoprotein enzyme immunoassay. Odds ratios for seropositivity were estimated using logistic regression, and factor analysis was used to identify clustering among socioeconomic variables.

RESULTS

One hundred seventeen (21%) of 561 children and 166 (34%) of 485 mothers with definite HHV-8 serostatus were seropositive. For children, seropositivity was associated with age, mother's HHV-8 serostatus (especially for children aged 6 years or younger), lower maternal education level, mother's income, and low-status father's occupation (P < 0.05 for all). Using communal standpipe or using surface water sources were both associated with seropositivity (OR 2.70, 95% CI 0.80-9.06 and 4.02, 95% CI 1.18-13.7, respectively) as compared to using private tap water. These associations remained, albeit attenuated, after adjusting for maternal education and child's age (P = 0.08). In factor analysis, low scores on environmental and family factors, which captured household and parental characteristics, respectively, were positively associated with seropositivity (P(trend) < 0.05 for both). For mothers, HHV-8 seropositivity was significantly associated with water source and maternal income.

CONCLUSIONS

HHV-8 infection in Ugandan children was associated with lower socioeconomic status and using surface water. Households with limited access to water may have less hygienic practices that increase risk for HHV-8 infection.

Aspects épidémiologiques de l'herpèsvirus humain 8 (HHV-8) et du sarcome de Kaposi

HHV-8 belongs to the herpesviridae family, to the gammaherpesvirinae subfamily, and to the rhadinovirus genus. Whereas several viral homologues exist in non human primates, HHV-8 is the only rhadinovirus known in human. HHV-8 is mainly the etiological agent of the four clinico-epidemiological forms of Kaposi's sarcoma (classic, endemic, post-transplant, and epidemic/HIV associated). HHV-8 is not an ubiquitous virus. It is mainly endemic in areas of high endemicity for classic or endemic Kaposi's sarcoma including the Mediterranean area and most of East and Central Africa. Its prevalence varies in the adult population, from less than 5% in the USA and Northern Europe to more than 50% in some regions of the African continent and around 10 to 20% in Italy and Greece. One can estimate that several hundred million people are HHV-8 infected worldwide with at least 150 million on the African continent. Modes of infection seem different in low and highly endemic areas. In low endemic areas, HHV-8 is mainly present in the male homosexual population, where this herpesvirus is transmitted during sexual contacts. In contrast, in highly endemic areas, as Central Africa, HHV-8 transmission occurs mainly from mother to child and between siblings. Heterosexual transmission remains low as well as transmission through blood products. Saliva seems to play a major role in the viral transmission, and may be a reservoir for HHV-8.

Respective roles of serological status and blood specific antihuman herpesvirus 8 antibody levels in human herpesvirus 8 intrafamilial transmission in a highly endemic area

Transmission of human herpesvirus 8 (HHV-8), the etiological agent of Kaposi's sarcoma, occurs mainly during childhood in endemic countries and, to a large extent, through intrafamilial contacts. To additionally investigate this familial transmission, and especially the role of plasma anti-HHV-8 antibody titers, we conducted a large survey in a village from Cameroon, Central Africa, including 92 families (608 individuals). Plasma samples were tested for specific IgG directed against HHV-8 lytic antigens by immunofluorescence assay, and titers were determined by 2-fold dilutions. Global HHV-8 seroprevalence was 60%, raising from 32% under 9 years up to a plateau of around 62% between 15 and 40 years. The familial correlation patterns in HHV-8 seropositive/seronegative status showed strong dependence from mother to child and between siblings. In contrast, no familial correlation in anti-HHV-8 antibody levels was observed among infected subjects. In particular, no relationship was observed between the anti-HHV-8 antibody titer of HHV-8 seropositive mothers and the proportion of their HHV-8 seropositive children. Furthermore, a random permutation study of the anti-HHV-8 antibody titers among HHV-8 infected subjects showed that the main risk factor for infection was the HHV-8 serologic status and not the antibody level. In addition, no correlation was found between anti-HHV-8 antibody levels and buffy coat HHV-8 viral loads in a subsample of 95 infected subjects. Overall, these results strongly suggest that, in this highly endemic population from Central Africa, HHV-8 transmission mainly occurs from mother to child and between siblings, and it is independent of plasma antibody levels of HHV-8 infected relatives.