Relationship between human leukocyte antigen alleles and risk of Kaposi's sarcoma in Cameroon.

Several studies published to date report associations between human leukocyte antigen (HLA) alleles and different types of Kaposi's Sarcoma (KS). However, there is little concordance between the HLA alleles identified and the populations studied. To test whether HLA alleles associate with KS in a Cameroonian case-control study, we performed high-resolution HLA typing in KSHV seropositive individuals. Among HIV-positive individuals, carriers of HLA-B*14:01 were at a significantly higher risk of AIDS-KS (p = 0.033). For HIV-negative patients, a gene-wise comparison of allele frequencies identified the HLA-B (p = 0.008) and -DQA1 (p = 0.002) loci as possible risk factors for endemic KS. Our study provides additional understanding of genetic determinants of KS and their implications in disease pathogenesis. Further validation of these findings is needed to define the functional relevance of these associations.

Serodiagnosis for tumor viruses.

The known human tumor viruses include the DNA viruses Epstein-Barr virus (EBV), Kaposi sarcoma herpesvirus (KSHV), Merkel cell polyomavirus (MCPyV), human papillomavirus (HPV), and hepatitis B virus (BV). RNA tumor viruses include human T-cell lymphotrophic virus type 1 (HTLV-1) and hepatitis C virus (HCV). The serological identification of antigens/antibodies in serum is a rapidly progressing field with utility for both scientists and clinicians. Serology is useful for conducting seroepidemiology studies and to inform on the pathogenesis and host immune response to a particular viral agent. Clinically, serology is useful for diagnosing current or past infection and for aiding in clinical management decisions. Serology is useful for screening blood donations for infectious agents and for monitoring the outcome of vaccination against these viruses. Serodiagnosis of human tumor viruses has improved in recent years with increased specificity and sensitivity of the assays, as well as reductions in cost and the ability to assess multiple antibody/antigens in single assays. Serodiagnosis of tumor viruses plays an important role in our understanding of the prevalence and transmission of these viruses and ultimately in the ability to develop treatments/preventions for these globally important diseases.

Reactivation of Kaposi's sarcoma-associated herpesvirus by natural products from Kaposi's sarcoma endemic regions.

Kaposi's sarcoma (KS) and its causative agent, Kaposi's sarcoma associated herpesvirus (KSHV/HHV-8), a gamma2 herpesvirus, have distinctive geographical distributions that are largely unexplained. We propose the "oncoweed" hypothesis to explain these differences, namely that environmental cofactors present in KS endemic regions cause frequent reactivation of KSHV in infected subjects, leading to increased viral shedding and transmission leading to increased prevalence of KSHV infection as well as high viral load levels and antibody titers. Reactivation also plays a role in the pathogenesis of KSHV-associated malignancies. To test this hypothesis, we employed an in vitro KSHV reactivation assay that measured increases in KSHV viral load in KSHV infected primary effusion lymphoma (PEL) cells and screened aqueous natural product extracts from KS endemic regions. Of 4,842 extracts from 38 countries, 184 (5%) caused KSHV reactivation. Extracts that caused reactivation came from a wide variety of plant families, and extracts from Africa, where KSHV is highly prevalent, caused the greatest level of reactivation. Time course experiments were performed using 28 extracts that caused the highest levels of reactivation. The specificity of the effects on viral replication was examined using transcriptional profiling of all viral mRNAs. The array data indicated that the natural extracts caused an ordered cascade of lytic replication similar to that seen after induction with synthetic activators. These in vitro data provide support for the "oncoweed" hypothesis by demonstrating basic biological plausibility.

Real-time PCR assay for detection and quantification of hepatitis B virus genotypes A to G.

The detection and quantification of hepatitis B virus (HBV) DNA play an important role in diagnosing and monitoring HBV infection as well as assessing therapeutic response. The great variability among HBV genotypes and the enormous range of clinical HBV DNA levels present challenges for PCR-based amplification techniques. In this study, we describe the development, evaluation, and validation of a novel real-time PCR assay designed to provide accurate quantification of DNA from all eight HBV genotypes in patient plasma specimens. A computer algorithm was used to design degenerate real-time PCR primers and probes based upon a large number (n = 340) of full-length genomic sequences including HBV genotypes A to H from Europe, Africa, Asia, and North and South America. Genotype performance was tested and confirmed using 59 genotype A to G specimens from two commercially available worldwide genotype panels. This assay has a dynamic range of at least 8 log(10) without the need for specimen dilution, good clinical intra- and interassay precision, and excellent correlation with the Bayer Diagnostics VERSANT HBV DNA 3.0 (branched DNA) assay (r = 0.93). Probit analysis determined the 95% detection level was 56 IU/ml, corresponding to 11 copies per PCR well. The high sensitivity, wide linear range, good reproducibility, and genotype inclusivity, combined with a small sample volume requirement and low cost, make this novel quantitative HBV real-time PCR assay particularly well suited for application to large clinical and epidemiological studies.

Provirus load in breast milk and risk of mother-to-child transmission of human T lymphotropic virus type I.

In a prospective study of 101 mother-child pairs in Jamaica, we examined the association of provirus load in breast milk and the risk of mother-to-child transmission of human T lymphotropic virus type I. The provirus load in breast milk was a strong predictor of risk of transmission to children (relative risk, 2.34/quartile), after adjustment for other known risk factors. The risk of transmission increased from 4.7/1000 person-months when the provirus load in breast milk was <0.18% to 28.7/1000 person-months when it was >1.5%. Provirus detection in maternal breast milk predicted transmission months before infection in children was detected by serologic testing.

Virus markers associated with vertical transmission of human T lymphotropic virus type 1 in Jamaica.

In a prospective study involving 150 mothers and their offspring in Jamaica, we examined maternal viral factors associated with the risk of transmission of human T lymphotropic virus type 1 (HTLV-1). Overall, the incidence of HTLV-1 infection among children was 8.3 occurrences per 1000 person-months. A higher maternal provirus level (odds ratio [OR], 1.9 per quartile) and a higher HTLV-1 antibody titer (OR, 2.2 per quartile) were independently associated with transmission to children, whereas the presence of anti-Tax antibody was not. Higher maternal antibody titers also were associated with older age at infection among children who were breast-fed for