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

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

Hepatitis B and C virus infection and the risk of biliary tract cancer: a population-based study in China.

Emerging data suggest that chronic hepatitis B virus (HBV) and hepatitis C virus (HCV) infections may also play a role in extrahepatic bile duct cancers. To test the HBV hypothesis, we examined the relationship of HBV/HCV infection with risks of biliary tract cancer and biliary stones in a population-based case-control study conducted in Shanghai, China. Standard assays were used to detect HBV surface antigen (HBsAg) and antibodies against HBV core antigen (anti-HBc) and hepatitis C virus (anti-HCV) in sera from 417 patients with biliary tract cancers, 517 with biliary stones, and 762 healthy controls randomly selected from the population. Unconditional logistic regression was used to calculate the odds ratios (ORs) and 95% confidence intervals (CIs) for each disease type. HBsAg seroprevalence was 7.3% among population controls and 14.2% among patients with extrahepatic bile duct cancer, resulting in a 2.4-fold risk of extrahepatic bile duct cancer (95% CI 1.2-4.5). No association was found for cancers of the gallbladder (prevalence 8.2%) or the ampulla of Vater (6.1%), or for stones in the gallbladder (10.1%) or bile duct (9.3%). Further adjustment for education, smoking, body mass index, diabetes and gallstones did not materially change the results. Prevalence of HCV infection in this population was low (2%), limiting our ability to detect an association with biliary diseases. In Shanghai, an HBV endemic area, chronic HBV infection was associated with a 2.4-fold risk of extrahepatic bile duct cancer. These results should be confirmed in other populations with varying risks of HBV and HCV infection.

Seroprevalence of hepatitis C virus and hepatitis B virus among San Francisco injection drug users, 1998 to 2000.

UNLABELLED: Previous studies suggest that most injection drug users (IDUs) become infected with hepatitis C virus (HCV) and hepatitis B virus (HBV) soon after initiating drug use. The Urban Health Study (UHS) recruited serial cross-sections of IDUs in the San Francisco Bay area from 1986 to 2005. In the current study, we determined the prevalence of antibody to HCV and HBV (core) among UHS participants during 1998 to 2000. To examine whether the time from onset of injection to acquisition of viral hepatitis has increased, we also compared the findings among recent (<10 years) initiates to drug use who participated during 1998-2000 with those who participated in 1987. Of 2,296 IDUs who participated during 1998-2000, 91.1% had antibody to HCV and 80.5% to HBV. The number of years a person had injected drugs strongly predicted infection with either virus (P(trend) < 0.0001). HCV seroprevalence among recent initiates in 1998-2000, by years of injection drug use, was:

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.

Hepatitis C virus genotype 4 in Ugandan children and their mothers.

In Kampala, Uganda, in 2001, hepatitis C virus antibodies were found in 27 (4%) of 603 children and in 62 (12%) of 525 of their mothers. However, only approximately 10% of positive results were confirmed by reverse transcription-PCR, which suggests frequent false-positive results or viral clearance. All sequenced types were genotype 4.

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.

Serum concentrations of 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) and 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE) and risk of primary liver cancer.

BACKGROUND: 1,1,1-Trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) exposure has been demonstrated to cause liver tumors in laboratory rodents. DDT's persistent metabolite and environmental degradation product, 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE), has also been associated with liver tumors in laboratory animals. Whether DDT and DDE are associated with hepatocarcinogenesis in humans is not clear. METHODS: We carried out a nested case-control study among the participants of the Nutritional Intervention Trials in Linxian, China. The case group included 168 individuals who developed liver cancer during the trials, and the control group included 385 individuals frequency-matched on age and sex who were alive and well at the end of the study. Serum concentrations of DDT and DDE were measured by gas chromatography-mass spectrometry. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using multivariable analysis. RESULTS: In multivariable-adjusted models, the risk of developing liver cancer increased with increased serum DDT concentration (OR for quintile 1 versus quintile 5 = 3.8, 95% CI = 1.7 to 8.6, P(trend) = .0024). In contrast, there was no statistically significant association between liver cancer and serum DDE concentration. The association between high serum DDT concentration and liver cancer was stronger among individuals with DDE concentrations below the median value (odds ratio for tertile 3 versus tertile 1 = 3.55, 95% CI = 1.45 to 8.74) than those with concentrations above the median (OR = 1.70, 95% CI = 0.97 to 2.98). A calculation of crude liver cancer risk found that there would be 26 liver cancers per 100 000 persons per year in the lowest quintile of DDT exposure versus 46 liver cancers per 100 000 persons per year in the highest quintile of DDT exposure. CONCLUSIONS: DDT may be a risk factor for liver cancer, particularly among persons with lower DDE concentrations. Risk may be particularly increased among persons exposed directly to DDT (resulting in a higher ratio of DDT to DDE) or, alternatively, risk may be associated with individual ability to metabolize DDT to DDE.

Distribution of Epstein-Barr viral load in serum of individuals from nasopharyngeal carcinoma high-risk families in Taiwan.

The utility of EBV load as a tumor marker in nasopharyngeal carcinoma (NPC) patients suggests that it might also serve as a screening test for individuals who are at high risk for developing NPC. We previously demonstrated that unaffected individuals from high-risk families had elevated anti-EBV antibody levels compared to community controls. In this study, we measured EBV load using 2 different real-time PCR assays (targeting BamH1W and polymerase gene sequences, respectively) carried out in 2 independent research labs in serum samples from 19 untreated NPC cases, 11 healthy community controls and 100 unaffected individuals from families in which 2 or more individuals were affected with NPC. EBV genomes were detectable in 68% of NPC cases by the EBV BamH1W assay and in 74% by the EBV polymerase assay (kappa = 0.64). Patients with stage III or IV disease had significantly higher EBV load compared to those with stage I or II disease (p = 0.008). EBV DNA was detected in a single community control sample by the EBV BamH1W assay and in none of the samples by the EBV polymerase assay. Only one of 100 unaffected family members tested positive by both assays. An additional 14 were positive by only one of the 2 EBV load assays used and usually in only one of the duplicate wells tested, all with very low viral loads (3-50 copies/ml). In addition, EBV load did not correlate with EBV serology results (anti-VCA, anti-DNase, anti-EBNA-1) among these unaffected family members. In conclusion, our study suggests limited clinical utility of the EBV load test, in its current configuration, to screen individuals from high-risk families. Should a more sensitive or specific molecular assay be developed that is capable of detecting and distinguishing tumor-derived EBV genomes or gene products from true negatives, it could be evaluated as a possible screening tool for asymptomatic and early-stage NPC.