HIV drug resistance transmission threshold survey in Bangkok, Thailand.

BACKGROUND: Antiretroviral therapy (ART) began in Thailand in the Bangkok Metropolitan Area (BMA) in 1988 and scale-up began in 2001. The national first-line regimen is stavudine, lamivudine and nevirapine in fixed-dose combination, which is a regimen with a low genetic barrier for resistance. Because viral load and resistance testing are not widely available, unidentified HIV drug resistance (HIVDR) may occur during treatment and could be transmitted. METHODS: We undertook a threshold survey to assess HIVDR transmission in two subsets of recently infected individuals in the BMA. The first group consisted of returning blood donors tested at the Thai Red Cross National Blood Centre who seroconverted within the past 12 months. The second group comprised recently infected (as defined by BED assay) clients of the Thai Red Cross voluntary counselling and testing centre (VCT). RESULTS: Genotyping of 50 consecutive specimens each from blood donors and VCT clients during 2005-2006 showed no mutations associated with HIVDR in the reverse transcriptase or protease regions of the HIV pol gene. These results are categorized by the WHO HIV drug resistance threshold survey method as representing a low prevalence (<5%) of transmitted HIV drug resistance. CONCLUSIONS: Every effort should be made to minimize the emergence of resistance in treated individuals and to prevent primary and secondary HIV transmission. To continue to monitor HIVDR transmission, Thailand has planned additional surveys--including longitudinal surveys--in these and additional groups of individuals.

Detection of Hpdel among Thais, a deleted allele of the haptoglobin gene that causes congenital haptoglobin deficiency.

BACKGROUND: Congenital haptoglobin deficiency is a risk factor for anaphylactic nonhemolytic transfusion reactions in Japan. The deleted allele of the haptoglobin gene, Hp(del), which causes congenital haptoglobin deficiency, has also been observed in other Northeast Asian populations, such as Korean and Chinese persons. It has not been reported in several African and European-African populations, however, or investigated in other countries. STUDY DESIGN AND METHODS: To investigate the distribution of congenital haptoglobin deficiency in Southeast Asian countries, blood samples collected from 200 randomly selected healthy Thai volunteers were analyzed for serum haptoglobin and the haptoglobin gene. Plasma haptoglobin concentration was measured to identify haptoglobin deficiency. Haptoglobin phenotyping was performed with sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by Western blotting. The presence of the Hp(del) allele was determined with genomic DNA by an Hp(del)-specific polymerase chain reaction (PCR) method. RESULTS: There were no haptoglobin-deficient subjects detected among the 200 Thais. Their haptoglobin phenotypes were as follows: Hp 1-1 in 10, Hp 2-1 in 81, and Hp 2-2 in 109. Six individuals heterozygous for Hp(del) were detected. The frequency of the Hp(del) allele was calculated to be 0.015. The prevalence of haptoglobin deficiency caused by Hp(del) homozygosity was estimated to be approximately 1 in 4000. CONCLUSION: Congenital haptoglobin deficiency caused by Hp(del) homozygosity is presumed to be present in Thailand as a risk factor for anaphylactic transfusion reactions with a frequency similar to that in Japan. The causative deleted allele of the haptoglobin gene, Hp(del), is distributed among Southeast Asian populations as well as among Northeast Asian populations.

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 = 95.6-99.9%), whereas the specificity with 107 HBsAg negative plasma ranged from 99.07% to 100% (95% CL = 94.2-99.9%). The relative performance of these kits to detect the hepatitis B virus (HBV) mutant panel members of the "a" determinant was found to differ. Interestingly, any commercial kits with monoclonal antibody capture and polyclonal antibody detection (mono/poly), but not mono/mono Ab capture and detection, could pick up the common HBsAg Gly145Arg mutant either solely or in combination with other mutations within the "a" determinant. New versions of HBsAg test kits should recognize multiple HBsAg epitopes in order to detect mutant HBsAg, together with providing good analytical sensitivity and specificity, because of the importance of these assays in HBV diagnosis and in protecting the safety of the blood supply.

Outcome of pediatric hematopoietic stem cell transplantations from Thai unrelated donors matched with high-resolution HLA typing.

The authors evaluated the outcome of ten children given hematopoietic stem cell transplantations from Thai unrelated donors (URD-HSCT) selected using DNA high-resolution typing of both HLA class I and II loci. Six patient/donor pairs (60%) were fully matched; four (40%) were 5/6 matched. Patients had either non-malignant (n=9) or malignant (n=1) diseases. In most cases, graft-versus-host disease (GVHD) prophylaxis composed of cyclosporine and short-term methotrexate. The probability of hematopoietic recovery at day 30 was 90%. The cumulative probability of acute GVHD and of chronic GVHD equaled 44.4 and 0%, respectively. Three patients died of transplant-related complications. The probability of transplant-related mortality (TRM) at 30, 100, and 180 days were 10, 30, and 30%, respectively. The overall and disease-free survival rates were 70 and 70%, respectively. URD-HSCT with donor selection based on high-resolution HLA typing is associated with a low incidence of both severe acute GVHD and graft failure. The observed outcome is comparable to that of children transplanted from HLA-identical siblings.

Umbilical cord blood transplantation in children with beta-thalassemia diseases.

To evaluate factors affecting the outcome of sibling and unrelated donor umbilical cord blood transplantation (CBT) in Thai children with beta-thalassemia diseases. The case-series study of all children undergoing such transplants in our institute was conducted Six children with thalassemia major were diagnosed at a median age of 1.5 years and CBT was performed at a median age of 5.5 years (range 2-15). Six donors consisted of three HLA-identical siblings, one two-allele, one three-antigen mismatched sibling, and one one-allele mismatched unrelated cord blood. The median number of nucleated cells infused was 2.83 x 10(7)/kg (range 1.49-5.3); the median number of CD34+ cells infused was 1.94 x 10(5)/kg (range 0.2-5.3). In all, two patients had complete donor engraftment; three had mixed chimerism (MC); one patient died of cerebral thrombosis and neutropenic septicemia. Of the two complete donor-engrafted patients, two developed grade 2 acute graft-versus-host disease (GVHD) which responded well to immunosuppressive therapy. Of the three mixed-chimeric patients, two were clinically cured. With a median follow-up of 7 months (range 2-30), five children survived and have done well with transfusion-independent. Umbilical cord blood provides a reasonable option for hematopoietic stem cell source to transplant for beta-thalassemia diseases and the outcome in the present study was good.

Cord blood collection for the National Cord Blood Bank in Thailand.

Umbilical cord blood is an effective alternative source of hematopoietic stem cells transplantation in children and adolescents. However, the efficacy and safety of cord blood transplantation correlates with the quantity and quality of cord blood. To evaluate the collection systems and processing of cord blood donations, a pilot research program to optimize recruitment, collection and processing of cord blood donations was developed. The present results showed that the quality of the cord blood (volume, total white blood cells (WBC) count, CD34+ and sterility control) collected was satisfactory and discard rate of collecting units (24.2%) were comparable with data reported from other cord blood banks. To find the optimal mode of collection, comparison of 3 cord blood collection methods (Method 1 = Hanging method after delivering the placenta, Method 2 = Aspiration from in utero placenta, Method 3 = Aspiration from in utero placenta and Syringe-assisted aspiration) using the closed system showed that method 3 was the best method but it required more trained personnel and involved a complicated procedure. The National Cord Blood Bank started its activity in 2002 after several years of pre-clinical studies. To date, a number of transplants using cord blood from related and unrelated cord blood (first report in Thailand) donors have been successfully performed.