Mixed patterns of transmission of human herpesvirus-8 (Kaposi's sarcoma-associated herpesvirus) in Malawian families

Highly Heterogeneous Kaposi Sarcoma-Associated Herpesvirus Oral Shedding Kinetics Among People With and Without Kaposi Sarcoma and Human Immunodeficiency Virus Coinfection

Background

An improved understanding of oral Kaposi sarcoma-associated herpesvirus (KSHV) viral dynamics could provide insights into transmission risk and guide vaccine development.

Methods

We evaluated KSHV oral shedding dynamics in Ugandan adults stratified by Kaposi sarcoma (KS) and human immunodeficiency virus (HIV) status. Participants were followed for ≥4 weeks, with daily home oral swab collection to quantify KSHV using polymerase chain reaction. Shedding rates were defined by number of days with KSHV DNA detected divided by total days with swabs and compared by group using hurdle models.

Results

Two hundred ninety-five participants were enrolled; median age was 35 years (range, 18-71 years), and 134 (45%) were male. KSHV was detected more frequently among participants with KS (HIV positive [HIV+]/KS+, 56/76 [74%]; HIV negative [HIV-]/KS+, 9/18 [50%]) than those without KS (HIV+/KS-, 36/125 [29%]; HIV-/KS-, 16/76 [21%]); odds of shedding did not differ significantly by HIV status. Among participants with KSHV detected, shedding rates did not differ significantly by group. Median per-participant viral loads among positive samples were lowest in HIV+/KS+ (3.1 log10 copies/mL) and HIV-/KS+ (3.3 log10 copies/mL) participants relative to HIV+/KS- (3.8 log10 copies/mL) and HIV-/KS- (4.0 log10 copies/mL) participants. All groups had participants with low viral load intermittent shedding and participants with high viral load persistent shedding. Within each group, individual KSHV shedding rate positively correlated with median KSHV log10 copies/mL, and episode duration positively correlated with peak viral load.

Conclusions

Oral KSHV shedding is highly heterogeneous across Ugandan adults with and without KS and HIV. Persistent shedding is associated with higher median viral loads regardless of HIV and KS status.

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

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

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.

Oral EBV and KSHV Infection in HIV

The gamma herpesviruses, Kaposi’s-sarcoma-associated herpesvirus (KSHV) and Epstein-Barr virus (EBV), are tightly associated with the development of AIDS-associated oral disease and malignancy during immune suppression. The objective of this investigation was to characterize oral infection and pathogenesis in healthy and immune-suppressed individuals. To characterize oral EBV and KSHV infection, we examined throat washings and oral epithelial cells from HIV-positive and HIV-negative individuals. Quantitative/real-time polymerase-chain-reaction (PCR) assays, transmission electronmicroscopy, immunostaining, and sequence analysis were used to identify viral infection. Virus was isolated from throat-wash samples and was used to infect epithelial and lymphoid cell lines. We detected EBV and KSHV in the oral cavity in healthy and immune-suppressed individuals. Viral strain analysis of KSHV K1 in multiple clones from the oral cavities of healthy persons and immunosuppressed patients detected several strains previously detected in KS lesions, with minor strain variation within individuals. Immunoelectron microscopy for multiple viral antigens detected consistent expression of viral proteins and oral epithelial specimens. In oral epithelial cells infected with wild-type KSHV in vitro, the K8.1 glycoprotein associated with lytic KSHV infection was detected in both primary and telomerase immortalized oral epithelial cultures by 24 hours post-infection. Virions were detected, subsequent to infection, by scanning electron microscopy. Oral epithelial cells were also infected in vitro with wild-type EBV originating from throat washes. Analysis of these data suggests that, like EBV, KSHV infection is present in the oropharynx of healthy individuals, is transmissible in vitro, and may be transmitted by saliva.

Kaposi sarcoma in HIV-seronegative children presenting to the paediatric oncology ward in The Queen Elizabeth Central Hospital, Blantyre, Malawi during 2002-2014

One of the most common malignancies in HIV-endemic, resource-poor countries is Kaposi sarcoma (KS). It is an AIDS-defining disease and as Malawi's incidence and prevalence of HIV is high, KS is now the most common cancer in adult male Malawians and the second most common in women and children. Most attention has focused on HIV-seropositive adults as their number far outweighs those of children. This audit concerns the presentation and outcome of HIV-seronegative children with KS who presented in a 12-year period (2002-2014) to The Queen Elizabeth Central Hospital. Twenty (10.5%) of the 191 children with KS presenting to the paediatric oncology ward during 2002-2014 were HIV-seronegative. They were usually younger than seropositive children and 62% had severe anaemia. The main presenting complaints in the HIV-seronegative group were woody oedema, commonly of a limb, and lymphadenopathy. Woody oedema was common in children with or without HIV infection. Seronegative children with KS were less likely to have oral KS than HIV infected children. Of 11 children who completed courses of chemotherapy, seven (63%) had complete cure sustained over a 1-year follow-up period. KS is potentially curable in this group of children. Chemotherapy regimens are equally effective in HIV-seropositive and HIV-seronegative children. The presentation of HIV-seronegative children with KS differs from adults and HIV-seropositive children. Further research is necessary to determine possible triggers for developing KS in HIV-seronegative children.

Comparison of salivary collection and processing methods for quantitative HHV-8 detection

OBJECTIVES

Saliva is a proved diagnostic fluid for the qualitative detection of infectious agents, but the accuracy of viral load determinations is unknown. Stabilising fluids impede nucleic acid degradation, compared with collection onto ice and then freezing, and we have shown that the DNA Genotek P-021 prototype kit (P-021) can produce high-quality DNA after 14 months of storage at room temperature. Here we evaluate the quantitative capability of 10 collection/processing methods.

METHODS

Unstimulated whole mouth fluid was spiked with a mixture of HHV-8 cloned constructs, 10-fold serial dilutions were produced, and samples were extracted and then examined with quantitative PCR (qPCR). Calibration curves were compared by linear regression and qPCR dynamics.

RESULTS

All methods extracted with commercial spin columns produced linear calibration curves with large dynamic range and gave accurate viral loads. Ethanol precipitation of the P-021 does not produce a linear standard curve, and virus is lost in the cell pellet. DNA extractions from the P-021 using commercial spin columns produced linear standard curves with wide dynamic range and excellent limit of detection.

CONCLUSION

When extracted with spin columns, the P-021 enables accurate viral loads down to 23 copies μl(-1) DNA. The quantitative and long-term storage capability of this system makes it ideal for study of salivary DNA viruses in resource-poor settings.

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

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

Kaposi's sarcoma in the pediatric population: the critical need for a tissue diagnosis

Kaposi's sarcoma (KS) is a low-grade vascular neoplasm mediated by the human herpesvirus-8. Only 1 clinical subtype, the endemic/African subtype, commonly affects the pediatric population. Although adults with KS often present with cutaneous findings and generalized lymphadenopathy, African children are more likely to present without classic skin findings. Definitive diagnosis requires histologic examination from tissue biopsy; however, as pathology resources are scarce in many developing African countries where KS is prominent, appropriate diagnosis and treatment of the condition are challenging. We report the case of a Malawian child who presented with generalized lymphadenopathy and was presumptively treated for lymphoma, with clinical worsening of his lesions. A diagnosis of KS was made after excisional biopsy of a superficial lymph node, with the initiation of appropriate therapy. The literature regarding pediatric KS is reviewed and recommendations are offered to allow accurate and timely diagnosis of the condition.

Mortality among HIV-1- and human herpesvirus type 8-affected mother-infant pairs in Zambia

OBJECTIVE

To determine the respective trends in mortality of Zambian mother-infant pairs based on maternal infection with HIV-1 and human herpesvirus type 8 (HHV-8).

METHODS

A prospective cohort study was done on Zambian mother-infant pairs, stratified by maternal serologic status and followed from 6 weeks postdelivery for 48 months. Statistical analysis of the differences in the calculated mortality rates among the four groups was done using Stata 7.0. Kaplan-Meier analysis and Cox proportional hazard models were used to measure subject survival time.

RESULTS

Between September 1998 and March 2002, a total of 1,425 mother-infant pairs were enrolled. The crude mortality rate among children born to dually infected mothers was approximately 9 times higher (245.90 deaths per 1,000 live births) when compared with the death ratio of children born to seronegative mothers (24.63 deaths per 1,000 live births). The incidence rate for death was 0.34/1,000 in infants of co-infected mothers in comparison with 0.32/1,000 among HIV-1-infected mothers, 0.0336/1,000 among uninfected mothers, and 0.0403/1,000 among HHV-8-infected mothers (chi(2) = 154.56; P < 0.01). Infants of co-infected mothers had a comparable risk of death in comparison with infants infected with HIV-1 alone [hazard ratio, 9.91 [95% confidence interval (95% CI), 5.08-19.37] for co-infected versus 9.26 [95% CI, 4.75-18.07] for HIV-1-infected alone]. Infants of mothers infected only with HHV-8 also had comparable survival in comparison with uninfected infants (hazard ratio, 1.21; 95% CI, 0.56-2.61).

CONCLUSION

Infants born to mothers dually infected with both HIV-1 and HHV-8 have comparable survival with infants exposed to HIV-1 alone. Infants born to mothers infected only with HHV-8 have comparable survival with uninfected infants.

Significance of variation within HIV, EBV, and KSHV subtypes

Since their initial transmission to humans, viruses have diversified extensively through recombination and mutation. The presence of intra- and inter-individual viral diversity influences disease progression, drug resistance, and therapy and presumably explains the conflicting results in many studies, including the failure of peptide-based vaccination strategies. Although HIV is a small RNA virus, coinfection with large DNA viruses, notably the oncogenic gamma-herpesviridae human herpesvirus-8 and Epstein Barr virus, is common. This coinfection occurs secondary to immunosuppression and shared transmission routes with high-risk predisposing behavior. In addition, all 3 of these viruses can lead to chronic infections, long periods of latency, and reactivation characterized by pain and suffering. The efficient targeting of their genetic diversity represents one of the major challenges in their control, both in prophylactic and therapeutic strategies. An understanding of diversity will help delineate whether population-specific vaccine strategies are necessary.

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.

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.

Human herpesvirus 8 genoprevalence in populations at disparate risks of Kaposi's sarcoma

The prevalence of human herpesvirus 8 (HHV-8) in populations at different risks of developing Kaposi's sarcoma (KS) was assessed using a protocol involving immunomagnetic fractionation of CD45+ blood cells prior to detection of the HHV-8 genome by nested PCR. Preliminary studies using blood of eight gay men infected by human immunodeficiency virus-1 (HIV-1) revealed that, for the detection of HHV-8 DNA derived from open reading frame (ORF) 26 of the HHV-8 genome, this protocol provided substantially higher rates (100%) compared to one involving red blood cell (RBC) lysis (0%) and to another requiring double density gradient centrifugation (DDGC) of leukocytes (13%). When the CD45+ fractionation protocol was applied to samples from 103 other HIV-1-infected patients (the vast majority of whom were gay men) and 100 blood donors, the ORF 26 DNA detection rates obtained were 37% and 8%, respectively. When DNA from the variable region 1 of ORF K1 was additionally amplified from samples of the blood donors, a detection rate of 9% was achieved. This rate was highly concordant with the ORF 26 DNA detection rate. Furthermore, the ORF K1 sequences were predominantly unique, assignable to genotypes A1, A4, and C3. When assays for anti-HHV-8 and anti-herpes simplex viruses (HSV) 1 and 2 were applied, significant concordances between HHV-8 DNA detection rates and those relating to anti-HHV-8 and to anti-HSV 1 and 2 were more frequently observed for HIV-1-infected patients than for blood donors. The higher-than-expected HHV-8 genoprevalence rate in blood donors requires further confirmation in view of its implications for post-transfusion HHV-8 transmission.

Salivary human herpesvirus 8 shedding in renal allograft recipients with Kaposi's sarcoma

Renal allograft recipients in the Middle East are at high risk of developing Kaposi's sarcoma. This report describes the extent of oral human herpesvirus 8 shedding and the genomic diversity of the virus in five Saudi Arabian kidney transplantation patients in whom Kaposi's sarcoma had developed. PCR protocols were applied to amplify three fragments of the viral genome from whole-mouth saliva, parotid saliva, buccal and palatal exfoliates, plasma, peripheral blood leukocytes and biopsy of the Kaposi's sarcoma lesion, and to quantify the viral load in whole-mouth saliva. Viral DNA was detected in all plasma and biopsy samples, 80% of whole-mouth saliva, 20% of each of the other oral samples, and none of the leukocyte samples. The viral load in the cell-free fraction of whole-mouth saliva ranged between approximately 1.2 x 10(3) and 2.2 x 10(6) genome-copies/ml. Genotypically distinct viral strains were evident: intra-lesionally in 1 patient; intra-orally in one patient; between an oral sample and biopsy in two patients; and in four patients, between an oral sample and plasma, and between plasma and biopsy. Thus, in the patients studied, salivary shedding of human herpesvirus 8 was frequent and could be extensive, and they were prone to multiple infections. Measures to curtail salivary viral transmission to pre- and post-transplantation patients might reduce the incidence of post-transplantation Kaposi's sarcoma.

Regulation of intracellular signalling by the terminal membrane proteins of members of the Gammaherpesvirinae

The human gamma(1)-herpesvirus Epstein-Barr virus (EBV) and the gamma(2)-herpesviruses Kaposi's sarcoma-associated herpesvirus (KSHV), rhesus rhadinovirus (RRV), herpesvirus saimiri (HVS) and herpesvirus ateles (HVA) all contain genes located adjacent to the terminal-repeat region of their genomes, encoding membrane proteins involved in signal transduction. Designated 'terminal membrane proteins' (TMPs) because of their localization in the viral genome, they interact with a variety of cellular signalling molecules, such as non-receptor protein tyrosine kinases, tumour-necrosis factor receptor-associated factors, Ras and Janus kinase (JAK), thereby initiating further downstream signalling cascades, such as the MAPK, PI3K/Akt, NF-kappaB and JAK/STAT pathways. In the case of TMPs expressed during latent persistence of EBV and HVS (LMP1, LMP2A, Stp and Tip), their modulation of intracellular signalling pathways has been linked to the provision of survival signals to latently infected cells and, hence, a contribution to occasional cellular transformation. In contrast, activation of similar pathways by TMPs of KSHV (K1 and K15) and RRV (R1), expressed during lytic replication, may extend the lifespan of virus-producing cells, alter their migration and/or modulate antiviral immune responses. Whether R1 and K1 contribute to the oncogenic properties of KSHV and RRV has not been established satisfactorily, despite their transforming qualities in experimental settings.

Oral manifestations of syphilis

The past decade has shown a significant rise in the prevalence of infective syphilis in the developed world, and striking increases in its frequency have occurred in Eastern Europe, particularly the UK, and in the US. Although oral manifestations of syphilis are most likely to be observed during secondary disease, all stages of the disease can give rise to oral lesions. Significant oral lesions such as gumma-associated bony destruction and a possible predisposition to oral squamous cell carcinoma are associated with tertiary disease. Since the prevalence of infective syphilis in heterosexuals has been increasing, there has now been a gradual rise in the number of children born with congenital syphilis. Consequently, the congenital disease gives rise to dental anomalies as well as bone, skin, and neurological anomalies of the face. The aim of this report is to review syphilis-related oral lesions, as well as to summarize the relations between human immunodeficiency virus (HIV) and syphilis.

Characterization of the Kaposi's sarcoma-associated herpesvirus K1 signalosome

Kaposi's sarcoma (KS) is a multifocal angiogenic tumor and appears to be a hyperplastic disorder caused, in part, by local production of inflammatory cytokines. The K1 lymphocyte receptor-like protein of KS-associated herpesvirus (KSHV) efficiently transduces extracellular signals to elicit cellular activation events through its cytoplasmic immunoreceptor tyrosine-based activation motif (ITAM). To further delineate K1-mediated signal transduction, we purified K1 signaling complexes and identified its cellular components. Upon stimulation, the K1 ITAM was efficiently tyrosine phosphorylated and subsequently interacted with cellular Src homology 2 (SH2)-containing signaling proteins Lyn, Syk, p85, PLCgamma2, RasGAP, Vav, SH2 domain-containing protein tyrosine phosphatase 1/2, and Grab2 through its phosphorylated tyrosine residues. Mutational analysis demonstrated that each tyrosine residue of K1 ITAM contributed to the interactions with cellular signaling proteins in distinctive ways. Consequently, these interactions led to the marked augmentation of cellular signal transduction activity, evidenced by the increase of cellular tyrosine phosphorylation and intracellular calcium mobilization, the activation of NF-AT and AP-1 transcription factor activities, and the production of inflammatory cytokines. These results demonstrate that KSHV K1 effectively recruits a set of cellular SH2-containing signaling molecules to form the K1 signalosome, which elicits downstream signal transduction and induces inflammatory cytokine production.

Current trends of HIV disease of the mouth

HIV infection affects residents of all countries of the world, but the greater majority of affected individuals reside in the developing world. In the past decade there have been substantial changes in the management of HIV disease, particularly the introduction of highly active antiretroviral therapy (HAART). Such agents have reduced significantly the morbidity and mortality associated with HIV disease, however, they are not available for most HIV-infected individuals in the developing world. There is now considerable understanding of the molecular epidemiology, transmission and therapy of the common opportunistic oral infections of HIV disease, and as a consequence of improved anti-HIV strategies, the frequency and severity of oral disease associated with HIV infection have reduced considerably, although HAART may predispose to human papilloma virus infection of the mouth and potentially increase the risk of later oral squamous cell carcinoma. Despite advances in clinical care the majority of individuals with HIV disease worldwide will continue to develop oral disease, as they are resident in the developing world and do not have ready access to even simple therapies.

Molecular characterization of Kaposi's sarcoma associated herpesvirus (KSHV) from patients with AIDS-associated Kaposi's sarcoma in Sao Paulo, Brazil

BACKGROUND

Kaposi's sarcoma (KS) is caused by Kaposi's sarcoma associated herpesvirus (KSHV/HHV-8), the eighth Herpesvirus found to infect humans. The molecular epidemiology of KSHV is related closely to ethnicity and geographical location of studied populations. There is little epidemiological and molecular information about KSHV strains circulating in Brazil.

OBJECTIVES

To characterize KSHV strains isolated from AIDS patients with Kaposi's sarcoma (AIDS-KS) in Sao Paulo, Brazil, and to examine associations between KSHV subtypes, ethnicity and HIV risk categories.

METHODS

AIDS-KS patients were recruited consecutively at the largest AIDS reference hospital in Sao Paulo. Fragments (420 bp) of the VR1 and VR2 regions of KSHV open reading frame (ORF) K1 were amplified by nested PCR and sequenced directly.

RESULTS

We analysed 37 samples from 33 patients, and found subtypes A-C in 48%, 21% and 30% of patients respectively, including two patients infected with subtype A5, a first report from Brazil. Sexual orientation was associated with subtype: 12/14 (86%) patients with subtype A were male homo/bisexual, compared with 3/8 (38%) among patients infected with subtype C (P = 0.05). A higher proportion of male patients with subtype C were of Caucasian origin (7/8 (87%)), compared with 7/16 (44%) among male patients with subtype A (P = 0.08).

CONCLUSIONS

This first detailed report of KSHV subtypes among AIDS-KS patients in Brazil reports the first isolation of KSHV subtype A5 in this country, and suggests KSHV strain transmission between different ethnic groups, and association of specific strains with sexual orientation.

Inter- and intra-person cytomegalovirus infection in Malawian families

Sequence polymorphisms in the gN and gO genes of cytomegalovirus (CMV) amplified from mouth rinse and urine samples of 19 Malawian patients with Kaposi's sarcoma (KS) and 58 of their first-degree relatives were investigated. CMV-DNA was amplified from 41 people (53%) from either the gN or gO region in at least one sample, from 14 people (18%) in both domains in at least one sample, and from 13 (17%) in either domain in both samples. Twenty-one (51%) were seropositive for human immunodeficiency virus-1 (HIV). Identical gN sequences were recovered from eight families and non-identical sequences in six, while identical gO sequences were found in three families and non-identical sequences in five. Five people, four of whom were children, each carried multitypic gN sequences or gO sequences. The findings are consistent with CMV spread along intra- and extra-household routes, and with multiple intra-host CMV infection.

Interactions between human immunodeficiency virus and herpes viruses within the oral mucosa

There is evidence from clinical case reports and epidemiological studies that human immunodeficiency virus (HIV) can be transmitted through oral sex. Herpes viruses that appear in the oral mucosa might influence the oral replication of HIV. A review of data suggesting that interactions occur between HIV and herpes viruses indicates that such interactions might operate in the oral mucosa. Defining the mechanisms by which herpes viruses interact with HIV in the oral mucosa should permit intervention measures to be targeted more precisely.

Genotypic profile of human herpesvirus 8 (Kaposi's sarcoma-associated herpesvirus) in urine

Human herpesvirus 8 (HHV-8) open reading frame K1 sequences amplified from the urine of 5 of 78 (6.4%) infected people in Malawi were monotypic. In two people, urinary and oral sequences were genotypically different. Comprehensive evaluation of HHV-8 transmission may require characterization of HHV-8 shed both in urine and orally.

Transmission and disease association of Kaposi's sarcoma-associated herpesvirus: recent developments

PURPOSE OF REVIEW

Kaposi's sarcoma-associated herpesvirus or human herpesvirus 8, common in sub-Saharan Africa and around the Mediterranean Sea but rare in most other countries, is known to be transmitted in childhood within families in endemic regions, and through sexual contacts among high-risk groups in Western countries. Nevertheless recent developments on other modes of transmission of the virus have been made during the last years and are summarized in this review. Furthermore, recent published disease associations are discussed.

RECENT FINDINGS

The last year has seen research addressing the question of parenteral transmission, sexual transmission through heterosexual contact, transmission of Kaposi's sarcoma-associated herpesvirus-infected cells from organ donors to recipient, as well as the first suggestion that host genetic factors may facilitate infection in childhood. Additional clinical manifestations of infection with the virus such as primary pulmonary hypertension and germinotropic lymphoproliferative disorder have been identified.

SUMMARY

Evidence of Kaposi's sarcoma-associated herpesvirus transmission other than between homosexual adults and during childhood - namely transmission through heterosexual contact or injection drug use - is growing although these issues are still incompletely analysed and far away from being fully understood. Despite our increasing knowledge on transmission and disease associations of the virus, implications on the clinical management of associated diseases and public health have to be further evaluated in the coming years.

Wild-type Kaposi's sarcoma-associated herpesvirus isolated from the oropharynx of immune-competent individuals has tropism for cultured oral epithelial cells

Based on the observation that wild-type Kaposi's sarcoma-associated herpesvirus (KSHV) DNA can be detected in the oral cavity of healthy, immunocompetent individuals, we hypothesized that epithelial cells could be infected in vitro by wild-type (WT) KSHV isolated from immunocompetent individuals. Primary oral epithelial (P-EPI) cells and telomerase-immortalized oral epithelial cells were generated from human gingival tissue and were then infected in vitro with WT KSHV isolated from throat wash samples. Markers of lytic and latent KSHV infection were detected in cultures by 24 h postinfection by immunofluorescence confocal microscopic assays. The infectivity of the WT and BCBL virus was blocked by neutralizing antibodies against KSHV gB. The presence of KSHV DNA in these cells was confirmed by real-time PCR amplification of different regions of the viral genome. The significant in vitro viral replication that had occurred was inhibited by ganciclovir and by neutralizing antibodies against gB. When infected cultures were examined by scanning electron microscopy, thousands of KSHV particles were clearly visible across the surfaces of P-EPI cells. The detection of enveloped particles indicated that the infectious cycle had proceeded through assembly and egress. We thus demonstrated that oral WT KSHV isolated from immunocompetent individuals was able to infect and replicate in vitro in a relevant primary cell type. Furthermore, our results provide compelling evidence for KSHV transmission within infected oral epithelial cells derived from healthy, immunocompetent populations.

Model-Based Inference of Recombination Hotspots in a Highly, Variable Oncogene

An emergent problem in the study of pathogen evolution is our ability to determine the extent to which their rapidly evolving genomes recombine. Such information is necessary and essential for locating pathogenicity loci using association studies, and it also directs future screening, therapeutic and vaccination strategies. Recombination also complicates the use of phylogenetic approaches to infer evolutionary parameters including selection pressures. Reliable methods that identify the presence of regions of recombination are therefore vital. We illustrate the use of an integrated model-based approach to inferring recombination structure using all available sequences of the highly variable, transforming Kaposi's sarcoma-associated herpesviral gene, ORF-K1. This technique learns the parameters of a statistical model that takes recombination hotspots, population genetic effects, and variable rates of mutation into account. As there are no known mechanisms to explain the high mutation rate in this DNA viral gene, recombination may account for some of the variability observed. We infer recombination hotspots in conserved sites such as the tyrosine kinase signaling motif, referred to here as recombination drift, as well as in nonconserved sites, a process described as recombination shift.

Epidemiological characteristics of human herpesvirus-8 infection in a large population of antenatal women in Zambia

Comprehensive data describing epidemiological characteristics of the human herpesvirus-8 or Kaposi's sarcoma-associated herpesvirus (HHV-8 or KSHV) infection among pregnant women in a central sub-Saharan Africa are not available. This study determined virus prevalence estimates and the risk factors associated with HHV-8 infection. Cross-sectional, enrollment visit data were analyzed from a prospective cohort study of perinatal transmission of HHV-8 in Lusaka, Zambia. Exposure data were obtained via structured interview, physical examination, medical chart review, and laboratory testing. Among 3,160 antenatal women serologically screened for HHV-8 between September 1998 and October 2000, 40.2% were seropositive. The HHV-8 positive women were more likely to be co-infected with HIV-1 than those who were HHV-8 negative (34% vs. 26%; P < 0.0001). Of 154 variables evaluated by logistic regression analyses, only three risk factors, have emerged as independent predictors of HHV-8 positive serology: diagnosis of genital warts, HIV-1 co-infection and primary education. The association of HHV-8 infection with genital warts and HIV-1 co-infection suggests heterosexual transmission of HHV-8. HIV-1 infection may also act as a marker for particular behaviors, which could be sexual in nature, that are associated with both HIV-1 and HHV-8 transmission. Since HHV-8 facilitates development of AIDS-related Kaposi's sarcoma (KS), the results of this study could be utilized to identify specific population groups of pregnant women who are at increased risk for this disease.

Structural analysis of the Kaposi's sarcoma-associated herpesvirus K1 protein

The K1 protein of Kaposi's sarcoma-associated herpesvirus (KSHV) efficiently transduces extracellular signals to elicit cellular activation events through its cytoplasmic immunoreceptor tyrosine-based activation motif (ITAM). In addition, the extracellular domain of K1 demonstrates regional homology with the immunoglobulin (Ig) family and contains conserved regions (C1 and C2) and variable regions (V1 and V2). To generate mouse monoclonal antibodies directed against the KSHV K1 protein, BALB/c mice were primed and given boosters with K1 protein purified from mammalian cells. Twenty-eight hybridomas were tested for reactivity with K1 protein by enzyme-linked immunosorbent assay, immunofluorescence, flow cytometry, immunohistochemistry, and immunoblotting. Deletion mutants of the K1 extracellular domain were used to map the epitope of each antibody. All antibodies were directed to the Ig, C1, and C2 regions of K1. Furthermore, antibody recognition of a short sequence (amino acids 92 to 125) of the C2 region overlapping with the Ig region of K1 efficiently induced intracellular free calcium mobilization; antibody recognition of the other regions of K1 did not. The efficient signal transduction of K1 induced by antibody stimulation required both the ITAM sequence of the cytoplasmic domain and the normal structure of the extracellular domain. Finally, immunological assays showed that K1 was expressed during the early lytic cycle of viral replication in primary effusion lymphoma cells. K1 was readily detected in multicentric Castleman's disease tissues, whereas it was not detected in Kaposi's sarcoma lesions, suggesting that K1 is preferentially expressed in lymphoid cells. Thus, these results indicate that the conserved regions, particularly the Ig and C2 regions, of the K1 extracellular domain are exposed on the outer surface and play an important role in K1 structure and signal transduction, whereas the variable regions of K1 appear to be away from the surface.

Tracking familial transmission of Kaposi's sarcoma-associated herpesvirus using restriction fragment length polymorphism analysis of latent nuclear antigen

Intra-familial transmission of Kaposi's sarcoma associated herpesvirus (KSHV) is likely to occur in geographical regions where KSHV infection is highly endemic. Transmission has been studied previously indirectly using serological techniques, however direct documentation of specific transmission routes has yet to be reported. The internal repeat domain (IRD) of the KSHV opening reading frame (ORF) 73 was shown previously to exhibit restriction-fragment length polymorphism (RFLP). Analysis of such polymorphism was undertaken using nested ORF 73 IRD PCR products derived from the blood and mouth rinse samples of individuals in Malawian family groups. The resulting RFLP patterns were unique to an individual and could be compared between family members. In three of eight families studied, identical RFLP patterns were recovered from family members; in the remaining five families, dissimilar RFLP patterns were revealed. Results from RFLP analysis were compared to sequencing data recovered from family members for the first variable region of the hypervariable KSHV ORF K1. Patterns of intra- and extra-familial transmission inferred from ORF K1 sequencing data were corroborated mainly using ORF 73 IRD RFLP analysis.