HHV-8 infection: a model for reactivation and transmission

Virus–Host Interplay Between Poly (ADP-Ribose) Polymerase 1 and Oncogenic Gammaherpesviruses

The gammaherpesviruses, include the Epstein–Barr virus, Kaposi’s sarcoma-associated herpesvirus, and murine gammaherpesvirus 68. They establish latent infection in the B lymphocytes and are associated with various lymphoproliferative diseases and tumors. The poly (ADP-ribose) polymerase-1 (PARP1), also called ADP-ribosyltransferase diphtheria-toxin-like 1 (ARTD1) is a nuclear enzyme that catalyzes the transfer of the ADP-ribose moiety to its target proteins and participates in important cellular activities, such as the DNA-damage response, cell death, transcription, chromatin remodeling, and inflammation. In gammaherpesvirus infection, PARP1 acts as a key regulator of the virus life cycle: lytic replication and latency. These viruses also develop various strategies to regulate PARP1, facilitating their replication. This review summarizes the roles of PARP1 in the viral life cycle as well as the viral modulation of host PARP1 activity and discusses the implications. Understanding the interactions between the PARP1 and oncogenic gammaherpesviruses may lead to the identification of effective therapeutic targets for the associated diseases.

LL-37 disrupts the Kaposi's sarcoma-associated herpesvirus envelope and inhibits infection in oral epithelial cells

Oral epithelial cells (OECs) represent the first line of defense against viruses that are spread via saliva, including Kaposi's sarcoma-associated herpesvirus (KSHV). Infection of humans by KSHV and viral pathogenesis begins by infecting OECs. One method OECs use to limit viral infections in the oral cavity is the production of antimicrobial peptides (AMPs), or host defense peptides (HDPs). However, no studies have investigated the antiviral activities of any HDP against KSHV. The goal of this study was to determine the antiviral activity of one HDP, LL-37, against KSHV in the context of infecting OECs. Our results show that LL-37 significantly decreased KSHV's ability to infect OECs in both a structure- and dose-dependent manner. However, this activity does not stem from affecting OECs, but instead the virions themselves. We found that LL-37 exerts its antiviral activity against KSHV by disrupting the viral envelope, which can inhibit viral entry into OECs. Our data suggest that LL-37 exhibits a marked antiviral activity against KSHV during infection of oral epithelial cells, which can play an important role in host defense against oral KSHV infection. Thus, we propose that inducing LL-37 expression endogenously in oral epithelial cells, or potentially introducing as a therapy, may help restrict oral KSHV infection and ultimately KSHV-associated diseases.

Prevalence of Human Herpesvirus-8 Salivary Shedding in HIV Increases with CD4 Count

Human herpesvirus-8 (HHV-8) is the etiologic agent of Kaposi’s sarcoma (KS), which occurs in epidemic form in human immunodeficiency virus(HIV)-infected individuals. Saliva is the only mucosal fluid in which infectious HHV-8 has been identified, although factors associated with HHV-8 salivary shedding remain unclear. Our study performed PCR analysis for HHV-8 DNA in saliva (and other body fluids) in 66 HIV- and HHV-8-co-infected women without KS so that we could examine predictors for HHV-8 DNA detection. CD4 count was the most significant predictor of HHV-8 salivary shedding, with increased prevalence of HHV-8 salivary DNA at higher CD4 counts. The odds of salivary HHV8 shedding at CD4 counts > = 350 cells/μL was 63 times the odds of shedding at CD4 < 350 (95%CI, 1.3–3078), with an increase in effect size when the analysis was restricted to those with a CD4 nadir > 200. Analysis of these data suggests an increased potential for HHV-8 transmission early in HIV infection, with implications for HHV-8 prevention.

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.

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

Background

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

Methods

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

Results

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

Conclusions

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

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.

Reduced human herpesvirus-8 oropharyngeal shedding associated with protease inhibitor-based antiretroviral therapy

BACKGROUND

Human herpesvirus 8 (HHV-8) replication increases the risk of Kaposi sarcoma (KS). Highly-active antiretroviral therapy (HAART) reduces the incidence of KS, and regimens that contain protease inhibitors (PIs) may be particularly effective.

OBJECTIVE

To determine whether PI-based HAART regimens may more effectively inhibit HHV-8 shedding compared to regimens without PIs.

STUDY DESIGN

Prospective, observational study of 142 HIV-1 and HHV-8 co-infected men conducted in Seattle, Washington. Quantitative HHV-8 PCR testing was performed on daily swabs of the oropharynx, the primary site of HHV-8 replication. Associations between antiretroviral regimen and detection of HHV-8 DNA in swabs were evaluated using generalized estimating equations.

RESULTS

HHV-8 DNA was detected in 3016 (26%) of 11,608 specimens collected. PI-based HAART was associated with a statistically significantly lower frequency of detection (RR 0.2; 95% CI 0.1-0.5) compared to ART-naïve persons, whereas HAART without a PI was not (RR 0.7; 95% CI 0.4-1.3). Compared to ART-naïve persons, there was also a trend toward lower quantities of HHV-8 detected during treatment with HAART regimens that contained a PI. These associations between PIs and measures of HHV-8 shedding could not be attributed to use of nelfinavir, which inhibits HHV-8 replication in vitro, and were independent of CD4 count and HIV plasma viral load (VL).

CONCLUSIONS

HAART regimens that contain PIs appear to decrease HHV-8 shedding compared to NNRTIs. Further study of PI-based HAART is warranted to determine the optimal regimens for prevention and treatment of KS.

Molecular biology of Kaposi's sarcoma-associated herpesvirus and related oncogenesis

Kaposi's Sarcoma-associated Herpesvirus (KSHV), also known as human herpesvirus 8 (HHV-8), is the most recently identified human tumor virus,and is associated with the pathogenesis of Kaposi's sarcoma and two lymphoproliferative disorders known to occur frequently in AIDS patients-primary effusion lymphoma and multicentric Castleman disease. In the 15 years since its discovery, intense studies have demonstrated an etiologic role for KSHV in the development of these malignancies. Here, we review the recent advances linked to understanding KSHV latent and lytic life cycle and the molecular mechanisms of KSHV-mediated oncogenesis in terms of transformation, cell signaling, cell growth and survival, angiogenesis, immune invasion and response to microenvironmental stress, and highlight the potential therapeutic targets for blocking KSHV tumorigenesis.

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.

Reflections on the interpretation of heterogeneity and strain differences based on very limited PCR sequence data from Kaposi's sarcoma-associated herpesvirus genomes

Ever since the original identification of fragments of KSHV DNA in Kaposi's sarcoma (KS) tissue by Chang et al. in 1994, PCR has been used successfully and extensively to detect the virus in clinical samples from the accepted etiological diseases of KS, PEL and MCD. However, a number of other clinical and epidemiological studies claiming evidence for KSHV in multiple myeloma or sarcoid and more recently in primary pulmonary hypertension, as well as claims about the biological significance of DNA sequence polymorphisms based just on small ORF26 PCR DNA fragments have not been convincing. Here, we evaluate the validity and interpretations of previous results in the context of both the observed rates and global patterns of sequence variability within an extended ORF26 locus, as well as from the perspective of the overall levels of KSHV variability found after sampling multiple loci across the complete KSHV genome. The results cast doubts on most claims for biological significance for these polymorphisms, which instead correlate with viral subtype clustering arising from geographic and ethnic divergence of the ancestral human hosts. In addition, we describe several observations that help to explain likely sources of the often either unexpectedly high or unexpectedly low levels of sporadic variability seen in the PCR DNA sequence data reported in some of those studies.

Human herpesvirus-8 infection and oral shedding in Amerindian and non-Amerindian populations in the Brazilian Amazon region

BACKGROUND

Human herpesvirus type 8 (HHV-8) is hyperendemic in Amerindian populations, but its modes of transmission are unknown.

METHODS

Antibodies against either HHV-8 lytic antigen or HHV-8 latency-associated nuclear antigen (LANA) were detected, by immunofluorescence assays, in 339 Amerindians and 181 non-Amerindians from the Brazilian Amazon. Serological markers of oro-fecal (hepatitis A), parenteral (hepatitis B and C), and sexual (herpes simplex virus type 2 and syphilis) transmission were measured by specific ELISAs. Salivary HHV-8 DNA was detected by use of a nested polymerase chain reaction assay and was sequenced.

RESULTS

Antibodies against either lytic antigen or LANA were detected in 79.1% of Amerindians and in 6.1% of non-Amerindians (adjusted seroprevalence ratio [SR], 12.63 [95% confidence interval {CI}, 7.1-22.4]; P<.0001). HHV-8 seroprevalence increased with age among Amerindians (P(Trend) < .001) and already had high prevalence in childhood but was not sex specific in either population. The 2 populations did not differ in seroprevalence of oro-fecal or parenteral markers, but seroprevalence of markers of sexual transmission was lower among Amerindians. HHV-8 DNA in saliva was detected in 47 (23.7%) of 198 HHV-8 seropositive Amerindians. Detection of HHV-8 DNA decreased with age (P(Trend) < .04) and was more common in men (SR, 2.14 [95% CI, 1.3-3.5]; P=.003). A total of 36 (76.6%) of the 47 saliva HHV-8 DNA samples were sequenced, and all clustered as subtype E.

CONCLUSION

The data support the hypothesis of early acquisition and horizontal transmission, via saliva, of HHV-8 subtype E in Amerindian populations.

Human herpesvirus-8 in Peruvian blood donors: a population with hyperendemic disease?

Serum samples from 128 blood donors were tested for antibodies specific for human herpesvirus-8 by an immunofluorescence assay that detects antibodies against mainly lytic antigens. An overall seroprevalence of 56.25% was found (male donors, 54.68%; female donors, 57.11%). These findings indicate that human herpesvirus-8 infection is hyperendemic in Peruvian blood donors.

Age-prevalence of Otarine Herpesvirus-1, a tumor-associated virus, and possibility of its sexual transmission in California sea lions

Otarine Herpesvirus-1 (OtHV-1) is a gammaherpesvirus routinely detected in urogenital tumor tissues of adult sea lions dying during rehabilitation, To investigate the epidemiology of this virus and guide the development of a mathematical model of its role in the multifactorial etiology of cancer in California sea lions, polymerase chain reaction (PCR) amplification of an OtHV-1 specific fragment of the DNA polymerase gene was used to look for evidence of OtHV-1 infection in urogenital and pharyngeal swabs and peripheral blood mononuclear cells (PBMC) of sea lions of different ages. Samples were also examined from pregnant females and their late term in utero or aborted fetuses to investigate potential for vertical transmission. Prevalence of infection in 72 adult females was 22%, whereas it was 46% in 52 adult males, and was significantly lower in 120 juvenile animals (6%). OtHV-1 DNA was most often detected in the lower reproductive tract of the adult animals, especially the males, and rarely in the pharynx or urogenital tract of juvenile animals. These data suggest sexual transmission may an important route of transmission. Additional studies are required to confirm this mode of transmission. Additionally, the virus was detected in a single prematurely born pup, suggesting the possibility of perinatal transmission. No indication of a PBMC associated viremia was evident in adults using standard PCR or in juveniles using standard and real time PCR.

Is there a relationship between the detection of human herpesvirus 8 and Epstein-Barr virus in Waldeyer's ring tissues?

OBJECTIVE

Human herpesvirus 8 (HHV-8) and Epstein-Barr virus (EBV) are human pathogens associated to a number of neoplasms, including tumors of the Waldeyer's ring. Both viruses have been previously detected by in situ methods in tonsils and adenoids from children. HHV-8 was found in 6.8% of the cases and EBV in about one third of the cases. As they belong to the same gamma-herpesvirus subfamily and share some biological characteristics, it is of medical interest to further explore their possible relationship in the Waldeyer's ring, an issue not yet addressed in the specialized literature. The purpose of the present study is to compare the presence of EBV by in situ hybridization (ISH) in tonsils and adenoids from children up to 14 years of age in cases previously shown to be positive and negative for HHV-8.

METHODS

Paraffin wax-embedded sections consisting of 38 tonsils and two adenoids from 40 patients were analyzed. HHV-8 was detected by ISH, using the T1-1 probe for the viral mRNA. EBV was also detected by ISH, using the EBER probe. Both probes and the detection systems were provided by Novocastra.

RESULTS

HHV-8 was detected in 19 tonsils and one adenoid. The other 19 tonsils and one adenoid taken from the HHV-8-negative group were selected by pairing age and gender of patients with the HHV-8-positive group. In both groups EBV was detected in 13 cases and was negative in other 7.

CONCLUSION

Although both viruses are related in many aspects, some biological and epidemiological features differ. This is reflected in the present results, as EBV is similarly detected in the groups negative and positive for HHV-8, favoring different mechanisms of spread.

High prevalence of multiple human herpesviruses in saliva from human immunodeficiency virus-infected persons in the era of highly active antiretroviral therapy

Human immunodeficiency virus (HIV) infection is associated with an increased risk for human herpesviruses (HHVs) and their related diseases. Methods for limiting the transmission of HHVs require a better understanding of the prevalence and infectiousness of oral HHVs in HIV-infected patients. We performed quantitative PCR to investigate the prevalence, quantity, risk, and correlates of salivary HHVs from 58 HIV-seropositive individuals in a case control study. HHVs were significantly more prevalent in the salivas of HIV-seropositive persons than in those of the controls (odds ratios [ORs], 4.2 to 26.2; P<or=0.008). In HIV-infected patients, Epstein-Barr virus (EBV), human herpesvirus 8 (HHV-8), cytomegalovirus (CMV), and herpes simplex virus type 1 (HSV-1) were detected in 90%, 57%, 31% and 16% of samples, respectively, compared with 48%, 24%, 2%, and 2%, respectively, of samples from controls. Multiple HHVs were observed in 71% of HIV-seropositive persons and only 16% of controls (OR, 13.0; 95% confidence interval, 5.29 to 32.56). HIV-positive patients had significantly higher EBV loads than HIV-negative persons (P<0.0001). HIV-infected patients with CD4 counts above 200 cells/microl had increased probability for having HHV-8 in saliva (P=0.009) compared with patients whose counts were less than 200. In contrast, HSV-1, EBV, and CMV were detected more often when CD4 counts were low. High salivary HHV loads were detected for those (n=7) with oral lesions. These findings suggest that saliva is a potential risk factor for the acquisition of multiple HHVs, and several host factors may function to accelerate HHV reactivation or replication in patients with HIV infection.

HIV serodiscordant sex partners and the prevalence of human herpesvirus 8 infection among HIV negative men who have sex with men: baseline data from the EXPLORE Study

OBJECTIVES

Human herpesvirus 8 (HHV-8) infection is common among men who have sex with men (MSM), especially those infected with HIV, and is frequently detected in saliva. We sought to determine whether oral or anogenital contact with HIV discordant, or unknown serostatus sexual partners is associated with HHV-8 seroprevalence among HIV negative MSM.

METHODS

HIV negative MSM participating in a behavioural intervention trial for the prevention of HIV infection (the EXPLORE study) were recruited from the Seattle and Denver areas for participation in this cross sectional study. Participants completed detailed questionnaires regarding sexual behaviour, focusing on activities with possible exposure to the oropharynx. Serum samples from study enrollment were tested for the presence of HHV-8 antibodies using whole virus enzyme immunoassay and immunofluorescence assay to latent and lytic proteins.

RESULTS

198/819 MSM (24.3%) were HHV-8 antibody positive. Exposure to saliva with HIV positive and HIV unknown serostatus sex partners was reported by 83% and 90% of all men, respectively. In a multivariate model, reporting more than the median number of lifetime sex partners (OR 2.2, p = 0.03) or lifetime sex partners of unknown HIV status (OR 1.7, p = 0.03), and the performance of oro-anal sex ("rimming") on partners whose HIV status is unknown (OR 2.7, p = 0.04) were independently associated with HHV-8 infection.

CONCLUSIONS

The oropharynx may be an important anatomical site in HHV-8 acquisition, and contact with HIV serodiscordant or unknown sex partners is associated with higher HHV-8 seroprevalence among HIV negative MSM.

Detection of herpesvirus type 8 (HHV8) in children's tonsils and adenoids by immunohistochemistry and in situ hybridization

OBJECTIVE

Human herpesvirus 8 (HHV8) has been associated with multicentric Castleman's disease, Kaposi's sarcoma and effusion non-Hodgkin's lymphoma. Epidemiological studies have shown seropositivity in variable proportions of populations. It seems to be sexually transmitted among adults and through oral contact among children. The virus has been demonstrated in desquamating oral epithelial cells, but there is no report on its presence in the Waldeyer's ring. The purpose of the present study is to detect HHV8 in tonsils and adenoids from children up to 20 years of age in which these organs had been surgically removed due to hypertrophy, using immunohistochemistry and in situ hybridization.

METHODS

Paraffin wax-embedded sections consisting of 181 tonsils and 162 adenoids from 293 patients were analyzed. HHV8 was detected by immunohistochemistry (IHC) using the anti-LNA1 antibody (Novocastra) and the LSAB+ detection system (Dako). For the in situ hybridization (ISH), the T1-1 probe for the viral mRNA and the detection system used were provided by Novocastra.

RESULTS

In 20 cases (6.83%), HHV8 was detected in cells morphologically characterized as lymphoid. In three of them epithelial cells were also positive. In 19 cases, the virus was detected in tonsils and in just 1 case in an adenoid. In all 20 cases detection was possible by ISH, whereas in only 2 of them there was a concomitant positivity by IHC.

CONCLUSION

Our data support the oral route of contamination by HHV8 in children, in whom tonsils and adenoids may harbor the virus. It is found especially in tonsils and only rarely in adenoids. In these organs, ISH is the method of choice to detect this virus, probably due to the small amount of viral proteins.

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.

Salivary lactoferrin is recognized by the human herpesvirus-8

Human herpesvirus-8 (HHV-8) is commonly detected in all epidemiologic forms of Kaposi's sarcoma. Despite the broad cellular tropism of HHV-8, studies on mucosal shedding of HHV-8 have shown that infectious particles are restricted to saliva isolated from the oropharynx. We used biotinylated purified HHV-8 particles in a direct binding assay to whole clarified human salivary samples isolated from HHV-8-infected and uninfected individuals. We found that the major binding activity was carried out by a protein of 78-kDa size, which was further characterized as human lactoferrin (hLf) using 2-D electrophoresis and MALDI-ToF analysis. Preliminary comparison of HHV-8 binding activity of 76 salivary samples from HHV-8-infected and uninfected individuals showed that 7.8% of the uninfected population exhibited a form of Lf not recognized by HHV-8. Deglycosylation of hLf by PNGase F did not reduce HHV-8 binding activity, whereas endoproteinase cleavage of native hLf generated a non-glycosylated 8-kDa peptide recognized by HHV-8 particles and was located at the position Ala606-Tyr679 in the native hLf amino acid sequence, corresponding to the C-terminal region of the glycoprotein. This work identify the lactoferrin in saliva as a ligand for HHV-8 and suggests that this glycoprotein could be used as a carrier for the viral particles.

Human Herpesvirus 8 DNA in Serum During Seroconversion in Allogeneic Bone Marrow Transplant Recipients

To determine the prevalence of human herpesvirus 8 (HHV-8) infection, the rate of HHV-8 seroconversion, and the presence of serum HHV-8 DNA after bone marrow transplantation (BMT), we evaluated sera from 187 Italian BMT donor-recipient pairs. Antibodies to lytic and latent HHV-8 antigens were detected by immunofluorescence. Sera of donor-recipient pairs who seroconverted were examined by real-time polymerase chain reaction (RT-PCR). Before BMT, 24 (13%) of 187 donors and 20 (11%) of 187 recipients were seropositive; after BMT, 28 (15%) of 187 recipients were seropositive. Seroconversion occurred in 19 (11%) of 167 recipients seronegative at baseline: 14 (9%) from 149 seronegative donors and five (28%) from 18 seropositive donors (relative risk of seroconversion with BMT from a seropositive donor = 2.96, 95% confidence interval = 1.21 to 7.25; P = .02, two-sided Fisher's exact test). One donor and two recipients who seroconverted after BMT were positive for HHV-8 by RT-PCR. No HHV-8-related complications were observed after a median follow-up of 6 years. BMT-associated HHV-8 seroconversion is relatively common in seronegative recipients from seropositive donor, but factors other than BMT may also contribute to seroconversion.

Classic Kaposi's sarcoma in the Inuit of northern Quebec

BACKGROUND

Classic Kaposi's sarcoma (KS) is predominantly a disease of eastern Mediterranean and Ashkenazi Jewish elderly men. Nevertheless, the disease has been reported to occur in people from various other ethnic and regional backgrounds.

OBJECTIVE

We report, for the first time, the occurrence of classic KS in five Inuit people living in northern Quebec, Canada.

METHODS AND RESULTS

We describe the case of a 69-year-old Inuit man with classic KS, and report four other cases of KS in the Inuit population, identified by a review of our hospital's dermatopathology records.

CONCLUSION

The discovery of classic KS in the Inuit population of northern Quebec brings with it new questions as to the origins of the KS-associated herpes virus in this population. It is our belief that the answers to these questions are in the genotype of the virus that is present in this community.

Human herpesvirus 8: an update

The discovery of human herpesvirus 8 (HHV-8) has opened a new field in the biology and in the clinical definition of HHV-8-associated diseases. Various aspects of epidemiology, laboratory diagnosis and treatment of HHV-8 infection are still controversial. This review will summarise the most recent findings on the modalities of viral transmission in geographic areas where the virus is endemic as compared with those where the infection is sporadic. The studies on the interactions between HHV-8 and Epstein-Barr virus in the promotion of tumorigenesis will be then emphasised. This review will finally address the problems still open in the laboratory diagnosis and in the definition of antiviral drug susceptibility of HHV-8. Solving satisfactorily these issues will be necessary to better understand the epidemiology of HHV-8 infection, to reduce the risk of viral transmission, the progression of infected hosts to HHV-8-related malignancies and to achieve more active treatment options for these clinical conditions.

Correlates of human herpes virus-8 and herpes simplex virus type 2 infections in Northern Cameroon

The association between sexual activity and human herpes virus-8 (HHV-8) infection has been established, but the mode of acquisition is still unclear. Blood samples from 238 individuals from Northern Cameroon were tested to evaluate the incidence of herpes simplex virus-2 (HSV-2), human immunodeficiency virus (HIV), Treponema pallidum, and HHV-8 infections and to identify their possible association. The presence of HSV-2 antibodies was associated significantly with gender, age, and HIV, HHV-8 antilatent, and T. pallidum antibodies, but not with HHV-8 antilytic antibodies. In a multivariate model older age, female gender, seropositivity for HIV, for HHV-8 latent antigens and for T. pallidum were associated independently with seropositivity for HSV-2. HSV-2-seropositive individuals had significantly higher titers of antibodies to both lytic (P = 0.019) and latent (P = 0.021) HHV-8 antigens. These results suggest that HSV-2 infection can contribute to sexual transmission of HHV-8 infection.

Bone marrow failure associated with herpesvirus 8 infection in a patient undergoing autologous peripheral blood stem cell transplantation

We describe a fatal case of human herpesvirus 8-associated bone marrow failure in a patient who had received intense treatment for Hodgkin lymphoma and was undergoing bone marrow transplantation. Bone marrow failure was resistant to antiviral treatment and a second infusion of autologous stem cells. Human herpesvirus 8 infection continues to be a major concern in transplant recipients in critical condition.