Geographic heterogeneity of prevalence of the human herpesvirus 8 in sub-Saharan Africa: clues about etiology.

PURPOSE: Human herpesvirus 8 (HHV-8, or Kaposi sarcoma [KS]-associated herpesvirus, KSHV) is a necessary but insufficient cause of KS, as KS develops in few HHV-8-infected persons. In sub-Saharan Africa, marked differences in the geographic distribution of HHV-8 and KS suggest that environmental cofactors influence HHV-8 transmission, control, and progression to KS. However, a direct comparison of HHV-8 prevalence estimates is complicated because studies used different serologic assays and analytic methods. We assessed HHV-8 seropositivity in several African countries with heterogeneous environments and varying KS incidence using a unified approach. METHODS: HHV-8 antibodies were measured among 3196 adults (aged 20+ years) and 2404 children (aged <20 years) from five studies in four sub-Saharan countries in Africa. Serum samples were tested by the same laboratory using K8.1 and orf73 enzyme immunoassays. RESULTS: Children's HHV-8-seropositivity ranged from 18.1% in Kampala, Uganda, to 33.8% in North Mara, Tanzania, increasing steeply with age in all populations. Among adults, HHV-8-seropositivity ranged from 23.5% in Nigeria to 70.6% in rural West Nile, Uganda. It was higher in males and rural areas. CONCLUSIONS: Our data indicate that geographical exposures, gender, age, and factors correlated with rural residence impact HHV-8 seropositivity in sub-Saharan Africa.

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.

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

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

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.

Geographic variation in the prevalence of Kaposi sarcoma-associated herpesvirus and risk factors for transmission.

BACKGROUND: The aim of the present study was to estimate the prevalence of Kaposi sarcoma-associated herpesvirus (KSHV) in the female general population, to define geographic variation in and heterosexual transmission of the virus. METHODS: The study included 10,963 women from 9 countries for whom information on sociodemographic characteristics and reproductive, sexual, and smoking behaviors were available. Antibodies against KSHV that encoded lytic antigen K8.1 and latent antigen ORF73 were determined. RESULTS: The range of prevalence of KSHV (defined as detection of any antigen) was 3.81%-46.02%, with significant geographic variation noted. In Nigeria, the prevalence was 46.02%; in Colombia, 13.32%; in Costa Rica, 9.81%; in Argentina, 6.40%; in Ho Chi Minh City, Vietnam, 15.50%; in Hanoi, Vietnam, 11.26%; in Songkla, Thailand, 10%; in Lampang, Thailand, 8.63%; in Korea, 4.93%; and in Spain, 3.65%. The prevalence of KSHV slightly increased with increasing age among subjects in geographic areas where the prevalence of KSHV was high, such as Nigeria and Colombia, and it significantly decreased with increases in the educational level attained by subjects in those areas. KSHV was not statistically associated with age at first sexual intercourse, number of sex partners, number of children, patterns of oral contraceptive use, presence of cervical human papillomavirus DNA, or smoking status. CONCLUSIONS: The study provides comparable estimates of KSHV prevalence in diverse cultural settings across 4 continents and provides evidence that sexual transmission of KSHV is not a major source of infection in the general population.

Human herpesvirus 8 seroprevalence among children and adolescents in the United States.

We measured human herpesvirus-8 antibodies (K8.1 and orf73 enzyme immunoassays) in 4166 children, aged 6-17 years, in a U.S. cross-sectional survey. Forty-six were K8.1 seropositive (weighted seroprevalence: 1.1%) and 20 were orf73 seropositive (weighted seroprevalence 0.4%). K8.1 seropositivity was associated with asthma (odds ratio: 6.3; 95% confidence interval: 2.4-16.9) and hay fever (3.5; 1.1-11.0), and there were borderline associations with measures of crowding and low socioeconomic status.

Human herpesvirus 8 load and progression of AIDS-related Kaposi sarcoma lesions.

INTRODUCTION: Human herpesvirus 8 (HHV8) is necessary for Kaposi sarcoma (KS) to develop, but whether peripheral blood viral load is a marker of KS burden (total number of KS lesions), KS progression (the rate of eruption of new KS lesions), or both is unclear. We investigated these relationships in persons with AIDS. METHODS: Newly diagnosed patients with AIDS-related KS attending Mulago Hospital, in Kampala, Uganda, were assessed for KS burden and progression by questionnaire and medical examination. Venous blood samples were taken for HHV8 load measurements by PCR. Associations were examined with odds ratio (OR) and 95% confidence intervals (CI) from logistic regression models and with t-tests. RESULTS: Among 74 patients (59% men), median age was 34.5 years (interquartile range [IQR], 28.5-41). HHV8 DNA was detected in 93% and quantified in 77% patients. Median virus load was 3.8 logs10/10(6) peripheral blood cells (IQR 3.4-5.0) and was higher in men than women (4.4 vs. 3.8 logs; p=0.04), in patients with faster (>20 lesions per year) than slower rate of KS lesion eruption (4.5 vs. 3.6 logs; p<0.001), and higher, but not significantly, among patients with more (>median 20 KS lesions) than fewer KS lesions (4.4 vs. 4.0 logs; p=0.16). HHV8 load was unrelated to CD4 lymphocyte count (p=0.23). CONCLUSIONS: We show significant association of HHV8 load in peripheral blood with rate of eruption of KS lesions, but not with total lesion count. Our results suggest that viral load increases concurrently with development of new KS lesions.

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.

Risk factors for human herpesvirus 8 infection among adults in the United States and evidence for sexual transmission.

BACKGROUND: Human herpesvirus 8 (HHV-8) causes Kaposi sarcoma. In the United States, transmission routes for HHV-8 are uncertain. METHODS: The National Health and Nutrition Examination Survey III sampled individuals from the US general population (1988-1994). We used enzyme immunoassays (EIAs) to measure HHV-8 antibodies (K8.1 and open reading frame [ORF] 73 antigens) in 13,894 surveyed adults. HHV-8 seroprevalence was examined according to sexual history and viral coinfection markers. RESULTS: Overall, seroprevalence was low when a highly specific cutoff was used (K8.1, 1.6%; ORF73, 1.5%) but was higher when a less-specific cutoff was used (K8.1, 7.1%; ORF73, 7.4%). When the more-specific approach was used, K8.1 seroprevalence was similar in men and women. Men who have sex with men (MSM) had a higher K8.1 seroprevalence (8.2%). Among other men, K8.1 seroprevalence was marginally associated with duration of heterosexual activity (P=.1) and was positively associated with the lifetime number of sex partners (P=.04) and with coinfections with hepatitis B virus (6.1% vs. 1.2% without coinfection; P<.001) and herpes simplex virus 2 (2.7% vs. 1.0%; P=.003). Among women, K8.1 seroprevalence was not significantly related to duration of sexual activity, the lifetime number of sex partners, or viral coinfections. The ORF73 EIA revealed similar but less clear-cut patterns. CONCLUSIONS: Among men, HHV-8 transmission may occur through sexual activity, particularly sex with other men. No evidence was observed for heterosexual transmission to women.

Transmission of Kaposi sarcoma-associated herpesvirus between mothers and children in a South African population.

BACKGROUND: To assess whether Kaposi sarcoma-associated herpesvirus (KSHV) with or without HIV coinfection in South African mothers is associated with higher KSHV seropositivity in their children. METHODS: We tested sera from 1287 South African children and 1179 mothers using assays for KSHV lytic K8.1 and latent ORF73 antigens. We computed odds ratios (ORs) and 95% confidence intervals (CIs) to assess associations between KSHV serostatus and risk factors. RESULTS: KSHV seroprevalence was 15.9% (204 of 1287 subjects) in children and 29.7% (350 of 1179 subjects) in mothers. The risk of KSHV seropositivity was significantly higher in children of KSHV-seropositive mothers compared with those of KSHV-seronegative mothers. The HIV status of mothers was marginally associated with an increased risk of KSHV seropositivity in their children (OR = 1.6, 95% CI: 1.0 to 2.6; P = 0.07). KSHV seroprevalence was significantly higher in HIV-infected subjects (P = 0.0005), and HIV-infected subjects had significantly higher lytic and latent KSHV antibody levels than HIV-negative subjects. CONCLUSIONS: The risk of acquisition of KSHV was higher among children of KSHV-seropositive mothers. Although KSHV seroprevalence was significantly higher in children and mothers who were infected with HIV, the HIV status of the mother was only marginally associated with an increased risk of KSHV seropositivity in the child.

Virologic, hematologic, and immunologic risk factors for classic Kaposi sarcoma.

BACKGROUND: Classic Kaposi sarcoma (CKS) is an inflammatory-mediated neoplasm that develops in the presence of KS-associated herpesvirus (KSHV) and immune perturbation. In the current study, the authors compared CKS cases with age-matched and sex-matched KSHV-seropositive controls without human immunodeficiency virus-1 infection and markers of viral control, blood counts, CD4-positive and CD8-positive lymphocytes, and serum beta-2-microglobulin and neopterin levels. METHODS: Viral loads were detected using real-time amplification of the KSHV-K6 and EBV-pol genes, anti-K8.1 (lytic) titers were detected by enzyme-linked immunoadsorbent assay, and antilatent nuclear antigen (LANA) titers were detected using immunofluorescence. Odds ratios (OR) and 95% confidence intervals (95% CI) were calculated using logistic regression adjusted for sex, age, and study site. RESULTS: Peripheral blood mononuclear cells (PBMC) KSHV DNA detection (P < or = .0001) and high KSHV lytic (>1:1745; P < or = .0001) and latent (>1:102,400; P = .03) antibody titers were found to be positively associated with CKS risk. Antibody titers were higher in cases with lesions compared with cases without lesions (P < or =.05). The detection of Epstein-Barr virus (EBV) DNA in PBMCs was not found to be associated with CKS (P = .95). Independent of PBMC KSHV DNA, CKS risk was found to be positively associated with reduced hematocrit (<37.4%; P = .03), hemoglobin (<12g/dL; P = .04), and lymphocytes (<1000 cells/microL; P = .004), including CD4-positive (+) cells (<457 cells/microL; P = .07) and CD8+ cells (<213cells/microL; P = .04), and with increased monocytes (> or =638 cells/microL; P = .009). Nonsignificant elevations of beta-2-microglobulin and neopterin were observed among cases regardless of disease burden (P > or = .08). In a multivariate model, the CKS risk was found to be associated with PBMC KSHV DNA (OR of 2.7; 95% CI, 1.4-5.3), a high KSHV lytic antibody titer (OR of 3.7; 95% CI, 1.9-7.4), and low lymphocytes, particularly among those patients age <70 years (OR of 8.0; 95% CI, 2.7-23.7). CONCLUSIONS: The findings of the current study appear to corroborate the specificity of KSHV and highlight the hematologic and immunologic correlates involved in the pathogenesis of CKS.

Associations of classic Kaposi sarcoma with common variants in genes that modulate host immunity.

Classic Kaposi sarcoma (CKS) is an inflammatory-mediated neoplasm primarily caused by Kaposi sarcoma-associated herpesvirus (KSHV). Kaposi sarcoma lesions are characterized, in part, by the presence of proinflammatory cytokines and growth factors thought to regulate KSHV replication and CKS pathogenesis. Using genomic DNA extracted from 133 CKS cases and 172 KSHV-latent nuclear antigen-positive, population-based controls in Italy without HIV infection, we examined the risk of CKS associated with 28 common genetic variants in 14 immune-modulating genes. Haplotypes were estimated for IL1A, IL1B, IL4, IL8, IL8RB, IL10, IL12A, IL13, and TNF. Compared with controls, CKS risk was decreased with 1235T/-1010G-containing diplotypes of IL8RB (odds ratio, 0.49; 95% confidence interval, 0.30-0.78; P = 0.003), whereas risk was increased with diplotypes of IL13 containing the promoter region variant 98A (rs20541, alias +130; odds ratio, 1.88; 95% confidence interval, 1.15-3.08; P = 0.01) when considered in multivariate analysis. Risk estimates did not substantially vary by age, sex, incident disease, or disease burden. Our data provide preliminary evidence for variants in immune-modulating genes that could influence the risk of CKS. Among KSHV-seropositive Italians, CKS risk was associated with diplotypes of IL8RB and IL13, supporting laboratory evidence of immune-mediated pathogenesis.

Molecular evidence for mother-to-child transmission of Kaposi sarcoma-associated herpesvirus in Uganda and K1 gene evolution within the host.

BACKGROUND: Epidemiological studies of Kaposi sarcoma (KS)-related herpesvirus (KSHV) indicate that having a KSHV-seropositive mother is a risk factor for KSHV infection in children. METHODS: We determined the KSHV K1 sequences in concordantly polymerase chain reaction-positive Ugandan mother-child pairs, to ascertain whether they shared the same viral strain. We also examined sequences amplified from saliva and buffy coat samples from the same subjects, to investigate potential intrasubject sequence differences. RESULTS: We obtained K1 sequences from 6 of 10 mother-child pairs. In 1 pair, the subtypes differed between mother and child. The mother and child in 2 other pairs shared the same subtype, but the sequences differed. The mother and child in 2 pairs shared KSHV strains with exact (100%) nucleotide homology. The last pair showed evidence of viral strain concordance between mother and child but also showed evidence of evolution of the viral sequence within the child. Of 26 study subjects, 19 showed no evidence of intrasubject K1 sequence variability, but, in 7 subjects, all of whom were children, amino acid variation of 1%-4% was observed. CONCLUSIONS: Our findings are consistent with KSHV transmission from maternal and nonmaternal sources in KS-endemic regions. Our results also provide evidence for ongoing evolution of the K1 gene in KSHV-infected children.

Host immunogenetics and control of human herpesvirus-8 infection.

BACKGROUND: Kaposi sarcoma (KS) is primarily caused by human herpesvirus (HHV)-8 infection, and the risk is increased with high HHV-8 lytic or latent antibody titers or the detection of HHV-8 DNA in peripheral blood mononuclear cells (PBMCs). Host genes important for control of HHV-8 infection are not well characterized. METHODS: In 172 HHV-8 latent nuclear antigen (LANA)-seropositive adults in Italy without KS, we examined correlations of common variants in host immune genes with the detection of HHV-8 DNA in PBMCs and with high lytic and latent antibody titers. Twenty-eight single-nucleotide polymorphisms in 14 genes were analyzed. We detected HHV-8 DNA in PBMCs with real-time amplification of the K6 gene, anti-K8.1 (lytic) titers with enzyme-linked immunosorbent assay, and anti-LANA (latent) titers with immunofluorescence. RESULTS: Detection of HHV-8 DNA in PBMCs was not significantly related to any variant examined. In contrast, a 3-locus haplotype of IL4, which contains the -1098G allele (rs2243248), was overrepresented among subjects with high lytic titers (odds ratio [OR], 2.8 [95% confidence interval {CI}, 1.1-6.7]), compared with those with low titers, as was the functional promoter variant of IL6, C-236C (rs1800795) (OR, 3.7 [95% CI, 1.1-12.8]). Compared with subjects with low HHV-8 latent antibody titers, analysis of inferred haplotypes for IL12A revealed an overrepresentation of -798T/277A in subjects with high HHV-8 latent antibody titers (OR, 2.4 [95% CI, 1.1-5.2]). CONCLUSIONS: Our observations are the first to provide preliminary evidence suggesting that common variants in key host immune genes could influence the control of HHV-8 infection.

Differential effects of interleukin-7 and interleukin-15 on NK cell anti-human immunodeficiency virus activity.

The ability of interleukin-7 (IL-7) and IL-15 to expand and/or augment effector cell functions may be of therapeutic benefit to human immunodeficiency virus (HIV)-infected patients. The functional effects of these cytokines on innate HIV-specific immunity and their impact on cells harboring HIV are unknown. We demonstrate that both IL-7 and IL-15 augment natural killer (NK) function by using cells (CD3(-) CD16(+) CD56(+)) from both HIV-positive and -negative donors. Whereas IL-7 enhances NK function through upregulation of Fas ligand, the effect of IL-15 is mediated through upregulation of tumor necrosis factor-related apoptosis-inducing ligand. The difference in these effector mechanisms is reflected by the ability of IL-15-treated but not IL-7-treated NK cells to reduce the burden of replication-competent HIV in autologous peripheral blood mononuclear cells (PBMC) (infectious units per million for control NK cells, 6.79; for IL-7-treated NK cells, 236.17; for IL-15-treated cells, 1.01; P = 0.01 versus control). In addition, the treatment of PBMC with IL-15-treated but not IL-7-treated NK cells causes undetectable HIV p24 (five of five cases), HIV RNA (five of five cases), or HIV DNA (three of five cases). These results support the concept of adjuvant immunotherapy of HIV infection with either IL-7 or IL-15 but suggest that the NK-mediated antiviral effect of IL-15 may be superior.

Antiretroviral therapy influences cellular susceptibility to apoptosis in vivo.

It has been proposed that antiretroviral therapies (ART) possess both antiviral and immunomodulatory activities when used in HIV infected patients. Few studies have addressed whether these putative immunomodulatory effects are also seen in HIV negative patients, for example, when used for post exposure prophylaxis (PEP). We chose to evaluate immunologic function in HIV negative patients who received Nelfinavir and Combivir (AZT and 3TC) as PEP. Lymphocytes from patients taken immediately before, during, and after PEP were analyzed. No changes were seen in absolute or percent CD4 or CD8 T lymphocyte numbers, nor in markers of activation, memory, or co-stimulatory molecules. Surface expression of apoptosis-related ligands and receptors were unaltered, but apoptosis susceptibility was significantly inhibited by PEP (P less than 0.05). These data confirm in vitro that apoptosis susceptibility is altered by ART, including in HIV-negative patients who take PEP.