Genotyping hepatitis C viruses from Southeast Asia by a novel line probe assay that simultaneously detects core and 5' untranslated regions.

Hepatitis C viruses (HCVs) display a high level of sequence diversity and are currently divided into six genotypes. A line probe assay (LiPA), which targets the 5' untranslated region (5'UTR) of the HCV genome, is widely used for genotyping. However, this assay cannot distinguish many genotype 6 subtypes from genotype 1 due to high sequence similarity in the 5'UTR. We investigated the accuracy of a new generation LiPA (VERSANT HCV genotype 2.0 assay), in which genotyping is based on 5'UTR and core sequences, by testing 75 selected HCV RNA-positive sera from Southeast Asia (Vietnam and Thailand). For comparison, sera were tested on the 5'UTR based VERSANT HCV genotype assay and processed for sequence analysis of the 5'UTR-to-core and NS5b regions as well. Phylogenetic analysis of both regions revealed the presence of genotype 1, 2, 3, and 6 viruses. Using the new LiPA assay, genotypes 6c to 6l and 1a/b samples were more accurately genotyped than with the previous test only targeting the 5'UTR (96% versus 71%, respectively). These results indicate that the VERSANT HCV genotype 2.0 assay is able to discriminate genotypes 6c to 6l from genotype 1 and allows a more accurate identification of genotype 1a from 1b by using the genotype-specific core information.

Assessing the performance of overseas tuberculosis screening programs: a study among US-bound immigrants in Vietnam.

BACKGROUND: Tuberculosis cases in foreign-born persons account for more than 50% of all tuberculosis cases in the United States. The Institute of Medicine has recommended enhancing overseas screening as one measure to support tuberculosis elimination efforts. We assessed the ability of overseas tuberculosis screening (chest radiograph followed by 3 acid-fast bacilli sputum smears for persons with abnormal chest radiographs [suggestive of active tuberculosis]) to detect pulmonary tuberculosis disease among US-bound immigrants with abnormal chest radiographs. METHODS: During October 1998 to October 1999, 14 098 US immigrant visa applicants were screened overseas in Vietnam. Adult applicants with abnormal chest radiographs were enrolled to assess screening test characteristics among this group using mycobacterial culture as the gold standard for pulmonary tuberculosis disease diagnosis. Risk factors for pulmonary tuberculosis disease were also evaluated. RESULTS: Among 1179 adult applicants with abnormal chest radiographs, 82 (7.0%) had positive acid-fast bacilli smear results, and 183 (15.5%) had positive Mycobacterium tuberculosis culture results (pulmonary tuberculosis disease). The sensitivity, specificity, and positive and negative predictive values of serial acid-fast bacilli screening among this group were 34.4% (63/183), 98.1% (977/996), 76.8% (63/82), and 89.1% (977/1097), respectively. Risk factors for pulmonary tuberculosis disease included younger age (18-34 years), no history of tuberculosis or treatment, reported symptoms, and cavitation or consolidation on chest radiograph. CONCLUSIONS: The ability of current overseas screening to detect tuberculosis among immigrants with abnormal chest radiographs is low. Improved diagnostic methods, enhanced screening measures, and postmigration follow-up are essential to control tuberculosis among immigrants and support US and global tuberculosis elimination.

Some techniques for genotyping of hepatitis C virus

Genotypes of hepatitis C virus are clinically relevant to epidemiology, prognosis and therapeutical management of HCV infection. Our study aims to compare different methods for HCV genotyping. Hepatitis C genotypes and subtypes of infected patients in Ho Chi Minh city was determined by serological typing using HCV serotyping 1-6 (Murex company), by molecular typing using Innolipa HCV II assay (Innogenetics NY) and direct sequencing of core and NS5b region. Our results show that the hepatitis C virus by analysing the sequences of the core and NS5b regions gave concordant results. The NS5b region is reliable for the identification of HCV subtype 6 circulating in Viet Nam.

Role of natural killer cell in natural protection against HIV-I infection among exposed uninfected IDUs in Vietnam

The role of natural killer cell in natural protection against HIV-1 infection was studies on 37 injected drug users (IDUs) who had been in high risk of exposure to HIV-1 but remain uninfected (EU) for many years follow-up. A comparison had been conducted between 10 IDUs who underwent seroconversion and 28 unexposed blood donors (controls). The results showed that the lytic activities and cytokines production of natural killer cells were significantly augmented in EU IDUs. This findings supports the role of natural killers cells in contribution to the natural immune response against HIV-1 infection among exposed uninfected IDUs

Study on factors of natural protection against HIV-1 infection among some exposed uninfected IDUs in Vietnam

The initial study of natural protection against HIV-1 infection among exposed uninfected intravenous drug users in Vietnam showed that this people had more immune system with activation than normal people. The peripheral blood monocysts in some people resist disease-induced viruses in vitro by two mechanisms: target cells (T CD4) resist or less sensitivity with HIV-1 virus or inhibit viruses from T CD8 cells

Study on molecular epidemiology of the HIV infection in Vietnam

Molecular epidemiological study of the HIV infection in Vietnam showed that recombinated HIV-1 subtype CRF01 (E subtype according to old classification) is still largely predominant either among injection drug users or persons infected though sexual intercourse. However, the presence of other HIV-1 subtypes B, C and other recombinated viruses indicated that HIV infection in Vietnam might become more complex with entry of different generic HIV-1 subtypes and other recombinated viruses