Phylogenetic analysis of two new complete genomes of the hepatitis E virus (HEV) genotype 3 from Thailand.

Hepatitis E virus (HEV) is a causative agent of acute viral hepatitis globally. Evolutionary phylogeny classifies the HEV into eight genotypes that correlate with the viral transmission. Only four genotypes have been proven to be responsible for transmission in humans.

A Nationwide Survey of the Seroprevalence of Hepatitis E Virus Infections Among Blood Donors in Thailand.

Hepatitis E virus (HEV) is a common cause of acute hepatitis infections. Our previous 3-year study at two large Thai hospitals established an occurrence of 4-5% of HEV infections from swine HEV genotype 3 in suspected acute hepatitis patients, with the high incidence in older adults. This study was a serosurvey to determine the prevalence of HEV infections among Thai adults.

Cross-reactive antibodies against H7N9 and H5N1 avian influenza viruses in Thai population.

Backgroud: Avian influenza H5N1 and H7N9 viruses have jumped across species from avian to humans and become a threat to public health. Not much is known about pre-existing cross-reactive antibodies against these avian viruses in human population.

Objective: To determine the prevalence of cross-reactive anti-HA and anti-NA antibodies to avian influenza H5N1 and H7N9 viruses in Thai population.

Safety and immune responses following administration of H1N1 live attenuated influenza vaccine in Thais.

Background: Emergence and rapid spread of influenza H1N1 virus prompted health authorities to develop a safe and effective influenza vaccine for domestic use. The Thai Government Pharmaceutical Organization (GPO) with technical support from Russia through WHO had prepared a pandemic live attenuated vaccine (PLAIV) using ca-ts attenuated candidate strain A/17/CA/2009/38 (H1N1) for Thais.

Methods: Each participant received two doses of intranasal H1N1 vaccine or placebo 21 days apart.

The distribution of hepatitis B virus genotypes in Thailand.

Phylogenetic analysis was performed on hepatitis B virus (HBV) strains obtained from 86 hepatitis B surface antigen (HBsAg) positive donors from Thailand originating throughout the country. Based on the S gene, 87.5% of strains were of genotype C while 10.

Serological response to the 2009 pandemic influenza A (H1N1) virus for disease diagnosis and estimating the infection rate in Thai population.

Background: Individuals infected with the 2009 pandemic virus A(H1N1) developed serological response which can be measured by hemagglutination-inhibition (HI) and microneutralization (microNT) assays.

Methodology/principal Findings: MicroNT and HI assays for specific antibody to the 2009 pandemic virus were conducted in serum samples collected at the end of the first epidemic wave from various groups of Thai people: laboratory confirmed cases, blood donors and health care workers (HCW) in Bangkok and neighboring province, general population in the North and the South, as well as archival sera collected at pre- and post-vaccination from vaccinees who received influenza vaccine of the 2006 season. This study demonstrated that goose erythrocytes yielded comparable HI antibody titer as compared to turkey erythrocytes.

Occult hepatitis B virus infection in Thai blood donors.

Background: An evaluation by the National Blood Center, the Thai Red Cross Society, of two commercial multiplex nucleic acid tests (NATs; the Chiron PROCLEIX ULTRIO test and the Roche Cobas TaqScreen MPX test) for screening Thai blood donors for hepatitis B virus (HBV), hepatitis C virus, and human immunodeficiency virus Type 1 identified 175 HBV NAT-reactive/hepatitis B surface antigen (HBsAg)-negative donors. The classification of the HBV infection of these donors was confirmed by follow-up testing.

Study Design And Methods: Index samples were tested for HBV serologic markers and HBV viral loads were determined.

Erythrocyte binding preference of 16 subtypes of low pathogenic avian influenza and 2009 pandemic influenza A (H1N1) viruses.

All 16 subtypes of avian influenza viruses of low pathogenicity (LPAIV) as well as their hemagglutinin (H) antigens, and four 2009 pandemic influenza A (H1N1) virus isolates were assayed for hemagglutinating activity against 5 erythrocyte species: goose, guinea pig, human group O, chicken and horse. Of all viruses and antigens assayed, the highest hemagglutination (HA) titers were obtained with goose and guinea pig erythrocytes. Hemagglutinating activity of replicating LPAIV and LPAIV antigens decreased, in order, with chicken and human group O; meanwhile, horse erythrocytes yielded lowest or no HA titer.

HIV-1 subtype B Tat gene activities and disease progression in HIV-1 CRF01_AE infection.

HIV-1 tat gene function and immunogenicity of HIV-1 Tat protein from 3 low (PS01, PS40, PS58) and 3 high (PS19, PS65, LP22) viral load infected, untreated and asymptomatic individuals from Thailand were compared. Levels of Tat-dependent chloramphenicol acetyltransferase (CAT) induced in HL3T1 cells with tat1 gene from HIV-1 isolates of high viral load group was significantly higher than those from low viral load group. HIV-1 subtype determination using env (C2-V4) gene demonstrated that 2/3 (PS01 and PS40) and 1/3 (PS58) from low viral load group were CRF01_AE and subtype B, while all 3 HIV-1 isolates from high viral load group were CRF01_AE.

Kinetics and longevity of antibody response to influenza A H5N1 virus infection in humans.

Anti-H5N1 antibody was determined by microneutralization, hemagglutination inhibition, and Western blotting assays in serial blood samples collected from eight Thai patients, including four fatal cases and four survivors. The antibody was detected as early as 5 days and, typically, with an increase in titer in paired blood at about 15 days after disease onset. The anti-H5 antibody response was long-lasting, for almost 5 years in cases which can be followed that far.

One-year experience of nucleic acid technology testing for human immunodeficiency virus Type 1, hepatitis C virus, and hepatitis B virus in Thai blood donations.

Background: Blood donations collected at the National Blood Center, the Thai Red Cross Society, Bangkok, in 2007 were tested by nucleic acid amplification technology (NAT) using the Chiron TIGRIS/Procleix Ultrio test and the Roche cobas s 201/cobas TaqScreen multiplex (MPX) test.

Study Design And Methods: The sensitivity, specificity, and robustness were determined by testing 486,676 seronegative blood donations. Samples from each day of collection were divided into two sets; the odd-numbered samples were tested individually on the TIGRIS and the even-numbered samples were tested in pools of 6 on the cobas s 201.

Serum levels of MIP-1beta and RANTES in HIV-1 subtype CRF01_AE infected patients with different rates of disease progression.

The beta-chemokines have been shown to inhibit HIV replication in vitro. To evaluate the role of serum beta-chemokines in disease progression and their anti-viral role in vivo, we determined serum levels of macrophage inflammatory protein-1beta (MIP-1beta) and regulated upon activation normal T-cell expressed and secreted (RANTES) of twenty HIV-1 subtype CRF01_AE infected patients: nine progressors (PRs, follow-up CD4+ cell count < 200/mm3 and progression to AIDS or death) and eleven slower progressors (SPs, asymptomatic and/or follow-up CD4+ cell counts > 350/mm3 at the end of follow-up) and determined their plasma viral loads. The subjects were followed for at least 36 months.

Novel 2-chloro-8-arylthiomethyldipyridodiazepinone derivatives with activity against HIV-1 reverse transcriptase.

Based on the molecular modeling analysis against Y181C HIV-1 RT, dipyridodiazepinone derivatives containing an unsubstituted lactam nitrogen and 2-chloro-8-arylthiomethyl were synthesized via an efficient route. Some of them were evaluated for their antiviral activity against HIV-1 RT subtype E and were found to exhibit virustatic activity comparable to some clinically used therapeutic agents.

An avian influenza H5N1 virus that binds to a human-type receptor.

Avian influenza viruses preferentially recognize sialosugar chains terminating in sialic acid-alpha2,3-galactose (SAalpha2,3Gal), whereas human influenza viruses preferentially recognize SAalpha2,6Gal. A conversion to SAalpha2,6Gal specificity is believed to be one of the changes required for the introduction of new hemagglutinin (HA) subtypes to the human population, which can lead to pandemics. Avian influenza H5N1 virus is a major threat for the emergence of a pandemic virus.

Erythrocyte binding preference of avian influenza H5N1 viruses.

Five erythrocyte species (horse, goose, chicken, guinea pig, and human) were used to agglutinate avian influenza H5N1 viruses by hemagglutination assay and to detect specific antibody by hemagglutination inhibition test. We found that goose erythrocytes confer a greater advantage over other erythrocyte species in both assays.

Hepatitis B virus DNA in unusual serological profiles of hepatitis B surface antigen-positive sera.

On the basis of a seroepidemiological survey of hepatitis B virus (HBV) infection conducted on 6208 random serum samples from four provinces of Thailand, we found 19 of 246 (7.7%) hepatitis B surface antigen (HBsAg)-positive samples with unusual serological constellations of HBV infection. Ten samples tested positive for HBsAg, anti-HBc (anti-hepatitis B core antibody), and anti-HBs (anti-hepatitis B surface antibody) markers (group I), 3 specimens were HBsAg and anti-HBs positive without detectable anti-HBc (group II), and the remaining 6 specimens showed only HBsAg (group III).

Trends of HIV seropositivity at Siriraj Hospital: 13 year's observation from 1992-2004.

Objective: The aim of the present report was to observe the trend of seroprevalence rates of HIV seropositivity for routine services at Siriraj Hospital for 13 years.

Material And Method: The prevalence rate of HIV seropositivity was analyzed in three groups of subjects: 1) patients who attended the hospital with HIV related diseases; 2) pregnant women at first visit to the antenatal care clinic; 3) emigrating workers who have applied for employment in foreign countries.

Results: Of the 13 year-observation, HIV seroprevalence rates in the groups of patients, pregnant women and emigrating workers was 10.

HBsAg diagnostic kits in the detection of hepatitis B virus mutation within "a" determinant.

The performance of currently available hepatitis B surface antigen (HBsAg) commercial kits was analyzed by using a panel of 212 well-characterized plasma donors all over the country and a panel of nine recombinant HBsAg mutants containing single point or combinations of mutations between amino acid residues 124 and 147 of the "a" determinant. HBsAg commercial kits in this study were machine-based immunoassays with a one-step sandwich ELISA method using either an automatic closed system or manual system. The sensitivity of all machine-based assays evaluated with 105 HBsAg plasma panels was 100% (95% CL = 95.

Studies on the potential use of CD38 expression as a marker for the efficacy of anti-retroviral therapy in HIV-1-infected patients in Thailand.

The monitoring of the efficacy of anti-retroviral therapy (ART) is becoming an important issue in the developing world. The current use of CD4 counts, plasma viral loads, and monitoring of drug-resistant viruses are at present either uninformative or costly. Thus, more new cost-effective and practical techniques need to be established and implemented.

Usage of dried blood spots for molecular diagnosis and monitoring HIV-1 infection.

The usage of dried blood spots as specimens for diagnosis and monitoring of HIV-1 infection in Thailand was evaluated. EDTA blood samples, which were collected from 100 HIV seronegative and 109 HIV seropositive individuals, were tested on dried blood spots; Whatman, Schleicher and Schuell (S&S) No. 903 and S&S IsoCode filter paper.

Binding antibody to neutralizing epitope gp41 in HIV-1 subtype CRF 01_AE infection related to stage of disease.

The responsiveness of gp41 antibody against epitope ELDKWA in HIV-1 infected subjects is of importance in neutralizing viral infectivity and for being related to disease progression. In this study, antibody titers to this neutralizing epitope from HIV-1 infected subjects at asymptomatic and AIDS stages in Thailand were investigated by peptide ELISA. The results showed that the frequency of antibody production against this neutralizing epitope was low (15-35%).

Functional variation of HIV-1 Rev Response Element in a longitudinally studied cohort.

We showed previously that HIV-1 Rev Response Element (RRE) contains a certain degree of structural variation, and in a set of limited samples, RRE from HIV-1 natural isolates were found to have functional variability. The significance of the RRE heterogeneity is addressed further by analyzing the functional variation of RREs in a longitudinal cohort. While the RRE activity at early time points was not a good predictor of disease outcome, the RRE activity at late time points was correlated with rates of CD4+ count decline.

Mutation of the "a" determinant of HBsAg with discordant HBsAg diagnostic kits.

Sera from 1003 in- and out-patients were investigated for hepatitis B surface antigen (HBsAg) mutation at Siriraj Hospital, Bangkok, Thailand. Individual samples were screened using two commercial HBsAg kits on automatic machine-based assays set up in parallel. The first kit was a sandwich ELISA kit that used monoclonal capture/monoclonal conjugate and color detection whereas the second was a sandwich MEIA, using monoclonal capture/polyclonal indicator and fluorochrome determination.