Veenu Minhas

Early Childhood Infection by Human Herpesvirus 8 in Zambia and the Role of Human Immunodeficiency Virus Type 1 Coinfection in a Highly Endemic Area

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

Development of an Immunofluorescence Assay Using Recombinant Proteins Expressed in Insect Cells To Screen and Confirm Presence of Human Herpesvirus 8-Specific Antibodies

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

Epidemiology and Transmission of Kaposi’s Sarcoma-Associated Herpesvirus

This review summarizes the current knowledge pertaining to Kaposi sarcoma-associated herpesvirus (KSHV) epidemiology and transmission. Since the identification of KSHV twenty years ago, it is now known to be associated with Kaposi’s sarcoma (KS), primary effusion lymphoma, and multicentric Castleman’s disease. Many studies have been conducted to understand its epidemiology and pathogenesis and their results clearly show that the worldwide distribution of KSHV is uneven. Some geographical areas, such as sub-Saharan Africa, the Mediterranean region and the Xinjiang region of China, are endemic areas, but Western Europe and United States have a low prevalence in the general population. This makes it imperative to understand the risk factors associated with acquisition of infection. KSHV can be transmitted via sexual contact and non-sexual routes, such as transfusion of contaminated blood and tissues transplants, or via saliva contact. There is now a general consensus that salivary transmission is the main route of transmission, especially in children residing in endemic areas. Therefore, there is a need to better understand the sources of transmission to young children. Additionally, lack of animal models to study transmission, gold standard serological assay and the lack of emphasis on endemic KS research has hampered the efforts to further delineate KSHV transmission in order to design effective prevention strategies.

Human Herpesvirus 8 Seroprevalence, China

To summarize the seroprevalence of human herpesvirus 8 (HHV-8) in mainland China, we conducted a systematic review and meta-analysis based on available literature. Data show that differences in HHV-8 prevalence vary considerably among different ethnic groups and geographic regions. Blood-borne transmission could be a potential route for HHV-8 infection in China.

Short Communication: Antiretroviral Therapy Resistance Mutations Present in the HIV Type 1 Subtype C pol and env Regions from Therapy-Naive Patients in Zambia

The prevalence of antiretroviral therapy (ART) resistance mutations present in HIV-1 subtype C pol and env regions of the proviral DNA was analyzed and compared from therapy-naive individuals before (Cohort A) and after (Cohort B) the availability of free ART in Zambia. Mutations present in sequences published in a previous study from Zambian ART-naive individuals infected with subtype C were analyzed using current parameters for the classification of ART drug resistance and compared with Cohorts A and B. No statistically significant differences were observed when comparing mutations present in the pol and env of these cohorts. However, an increase in the number of minor, borderline, or partial resistance mutations as well as the presence of major resistance mutations were observed in Cohort B. These results suggest there is an increasing trend of drug resistance-associated mutations that could be a result of the availability of free ART in Zambia. Moreover, the high prevalence of resistance mutations observed for maraviroc and vicriviroc in both cohorts may suggest a limited efficacy of entry inhibitors on HIV-1 subtype C.

Risk Factors for Early Childhood Infection of Human Herpesvirus-8 in Zambian Children: The Role of Early Childhood Feeding Practices

Background: Human herpesvirus-8 (HHV-8) infection in early childhood is common throughout sub-Saharan Africa with prevalence increasing throughout childhood. Specific routes of transmission have not been clearly delineated, though HHV-8 is present in high concentrations in saliva. Methods: To understand the horizontal transmission of HHV-8 within households to children, we enrolled for cross-sectional analysis, 251 households including 254 children, age two and under, in Lusaka, Zambia. For all children, plasma was screened for HHV-8 and HIV type I (HIV-1) and health and behavioral questionnaires were completed. Multilevel logistic regression analysis was conducted to assess independent factors for HHV-8 infection in children. Results: Risk factors for HHV-8 infection included increasing number of HHV-8–positive household members [OR = 2.5; 95% confidence interval (CI), 1.9–3.3; P < 0.01] and having a primary caregiver who tested the temperature of food with their tongue before feeding the child (OR = 2.4; 95% CI, 1.93–3.30; P = 0.01). Breastfeeding was protective against infection with HHV-8 for children (OR = 0.3; 95% CI, 0.16–0.72; P < 0.01). Conclusions: These results indicate that exposure to HHV-8 in the household increases risk for early childhood infection, with specific feeding behaviors likely playing a role in transmission. Impact: Interventions to protect children from infection should emphasize the possibility of infection through sharing of foods. Cancer Epidemiol Biomarkers Prev; 23(2); 300–8. ©2013 AACR.

The zinc finger DNA-binding domain of K-RBP plays an important role in regulating Kaposi's sarcoma-associated herpesvirus RTA-mediated gene expression.

K-RBP is a KRAB-containing zinc finger protein with multiple zinc finger motifs and represses Kaposis sarcoma-associated herpesvirus (KSHV) transactivator RTA-mediated transactivation of several viral lytic gene promoters, including the ORF57 promoter. Whether K-RBP binds DNA through its zinc fingers and the role of zinc finger domain in repressing gene expression are unclear. Here we report that K-RBP binds DNA through its zinc finger domain and the target DNA sequences contain high GC content. Furthermore, K-RBP binds to KSHV ORF57 promoter, which contains a GC-rich motif. K-RBP suppresses the basal ORF57 promoter activity as well as RTA-mediated activation. The zinc finger domain of K-RBP is sufficient for the suppression of ORF57 promoter activation mediated by the viral transactivator RTA. Finally, we show that K-RBP inhibits RTA binding to ORF57 promoter. These findings suggest that the DNA-binding activity of K-RBP plays an important role in repressing viral promoter activity.

Primary gamma-herpesviral infection in Zambian children

BackgroundHHV-8 is closely related to Epstein-Barr virus (EBV), but the clinical presentations of these two infections in early childhood are not well understood. Also, it is not known whether infection by one virus correlates with another. Here, we compare the natural history of infection by these two viruses along with the clinical manifestations and risk factors that are associated with early childhood infection in Zambia, which is an endemic area for HHV-8.MethodsThis study was conducted in a cohort of 12 month old Zambian children (N = 677). Data on socio-economic status and a wide range of clinical manifestations were collected. Logistic regression was used to test for significant associations between the collected variables and HHV-8 or EBV serostatus at 12 months of age.ResultsWe observed a significantly higher seroprevalence for EBV (58.9%) as compared to HHV-8 (13.4%). HIV-1 infected children had at a significantly higher risk of being infected with HHV-8 (Odds ratio [OR] 3.69, 95% confidence interval [CI] 1.64 - 8.32). HIV-1 infection of the mothers was a significant risk factor for increased acquisition of EBV but not HHV-8 by children (OR 1.86, 05% CI 1.20 - 2.87). Self reported rash was marginally associated with primary infection for HHV-8 and EBV.ConclusionsThese results suggest that there is no correlation between EBV and HHV-8 infections. Infection by one does not increase the susceptibility for the second virus. Primary HHV-8 and EBV infection in early childhood may clinically present as rash but remains largely asymptomatic and may remain undetected in this population. HIV infection in the mother or child are important risk factors that contribute to EBV or HHV-8 infection.

Identification and characterization of a new Kaposi's sarcoma-associated herpesvirus replication and transcription activator (RTA)-responsive element involved in RTA-mediated transactivation.

Kaposis sarcoma-associated herpesvirus (KSHV) replication and transcription activator (RTA) is well established as a key transcriptional activator that regulates the KSHV life cycle from latency to lytic replication. It is expressed immediately after infection and activates a number of viral genes leading to virus replication. The RTA-responsive element (RRE) in the RTA target gene promoters is critical for RTA to mediate this transactivation. A number of non-conserved RREs have been identified in various RTA-responsive promoters, and AT-rich sequences have been proposed to serve as RTA targets, but no consensus RRE sequence has been identified so far. Two non-conserved RREs (RRE1 and RRE2) containing AT-rich sequences have been identified previously in the promoter of one of the KSHV lytic genes, ORF57, which can be strongly activated by RTA. Based on homology with the consensus sequence of the Epstein-Barr virus Rta RRE, this study identified a third RTA-responsive element (RRE3) in the ORF57 promoter. This RRE comprised a GC-rich sequence that could bind RTA both in vitro and in vivo, and plays a role in RTA-mediated transactivation of the ORF57 promoter. The presence of two of the three RREs in close proximity to each other was required for optimal RTA-mediated transactivation of the ORF57 promoter, even though the presence of only one RRE is needed for RTA binding. These results suggest that the ability of RTA to mediate transcriptional activation is distinct from its ability to bind to its target elements.

Prevalence of human herpesvirus 8 and hepatitis C virus in a rural community with a high risk for blood‐borne infections in central China

Illegal blood donation in the past decade has caused human immunodeficiency virus (HIV) outbreaks in some rural areas in China. Other HIV-associated virus infections, such as those caused by human herpesvirus 8 (HHV8), in such areas are still not well defined. In order to explore HHV8 and hepatitis C virus (HCV) seroprevalence and potential risk factors in such areas, a cross-sectional study with 305 HIV-positive and 315 HIV-negative subjects recruited from a rural county in Shanxi province was conducted, in which illegal blood collection was reported. Interview questionnaires and serum testing were carried out with these participants. HCV and HHV8 seroprevalence were found to be higher in the HIV-positive than in the HIV-negative group (76.4% vs. 2.5% and 15.4% vs. 4.8%, respectively), whereas the difference in HBV seroprevalence was not significant. Co-infection with HCV and HHV8 was also more prevalent in the HIV-positive group. HIV status (OR 2.71; 95% CI 1.16-6.30) and HBV status (OR 2.56; 95% CI 1.14-5.75) were independently associated with HHV8 infection. HIV status (OR 23.03; 95% CI 9.95-53.27) and blood/plasma selling history (OR 14.57; 95% CI 7.49-28.23) were strongly associated with HCV infection. These findings demonstrate that both HHV8 and HCV infections are prevalent in this community. HIV infection is an important risk factor for both HHV8 and HCV infection. HBV infection is associated with HHV8 infection but not with HCV infection. It is possible that HHV8 and hepatitis B virus, but not HCV, have similar modes of transmission in this population.