Strain-based HLA association analysis identified HLA-DRB1*09:01 associated with modern strain tuberculosis.

Tuberculosis (TB) occurs as a result of complex interactions between the host immune system and pathogen virulence factors. Human leukocyte antigen (HLA) class II molecules play an important role in the host immune system. However, no study has assessed the association between HLA class II genes and susceptibility to TB caused by specific strains. This study investigated the possible association of HLA class II genes with TB caused by modern and ancient Mycobacterium tuberculosis (MTB). The study included 682 patients with TB and 836 control subjects who were typed for HLA-DRB1 and HLA-DQB1 alleles. MTB strains were classified using a large sequence polymorphism typing method. Association analysis was performed using common HLA alleles and haplotypes in different MTB strains. HLA association analysis of patients infected with modern MTB strains showed significant association for HLA-DRB1*09:01 (odds ratio [OR] = 1.82; P-value = 9.88 × 10-4 ) and HLA-DQB1*03:03 alleles (OR = 1.76; P-value = 1.31 × 10-3 ) with susceptibility to TB. Haplotype analysis confirmed that these alleles were in strong linkage disequilibrium and did not exert an interactive effect. Thus, the results of this study showed an association between HLA class II genes and susceptibility to TB caused by modern MTB strains, suggesting the importance of strain-specific analysis to determine susceptibility genes associated with TB.

NAT2 slow acetylator associated with anti-tuberculosis drug-induced liver injury in Thai patients.

BACKGROUND: Anti-tuberculosis drug-induced liver injury (AT-DILI) is one of the most common forms of drug-induced liver injury (DILI) in high tuberculosis (TB) burden countries. Among anti-tuberculosis drugs, isoniazid is the main cause of hepatotoxicity in patients with AT-DILI. OBJECTIVE: To investigate the association of AT-DILI with N-acetyltransferase 2 (NAT2) genotype status in Thai TB patients. METHODS: We enrolled 53 patients diagnosed with AT-DILI and 85 patients who tolerated anti-tuberculosis treatment as controls. Acetylator status was determined based on the inferred NAT2 haplotypes from four common single-nucleotide polymorphisms (SNPs) in Thais using Sanger sequencing. RESULTS: Phenotype frequencies of the NAT2 acetylator in AT-DILI patients were respectively 71.7%, 22.6% and 5.7% for slow, intermediate and rapid acetylators. Among slow, intermediate, and rapid acetylators in treatment tolerant controls, phenotype frequencies were respectively 22.4%, 62.4% and 15.3%. Slow NAT2 acetylators demonstrated a significant association with risk of AT-DILI. The odds ratio of comparing slow NAT2 acetylator in DILI patients and tolerance was 8.80 (95%CI 4.01-19.31, P = 1.53 × 10-8). CONCLUSIONS: Slow acetylator status in the NAT2 genotype is a significant risk factor for DILI in Thai patients with TB. This evidence provides confirmatory data in support of the role of NAT2 in AT-DILI in the Thai population.

Diagnostic value of blood gene expression signatures in active tuberculosis in Thais: a pilot study.

Tuberculosis (TB) is a major global health problem. Routine laboratory tests or newly developed molecular detection are limited to the quality of sputum sample. Here we selected genes specific to TB by a minimum redundancy-maximum relevancy package using publicly available microarray data and determine level of selected genes in blood collected from a Thai TB cohort of 40 active TB patients, 38 healthy controls and 18 previous TB patients using quantitative real-time PCR. FCGR1A, FCGR1B variant 1, FCGR1B variant 2, APOL1, GBP5, PSTPIP2, STAT1, KCNJ15, MAFB and KAZN had significantly higher expression level in active TB individuals as compared with healthy controls and previous TB cases (P<0.01). A mathematical method was applied to calculate TB predictive score, which contains the level of expression of seven genes and this score can identify active TB cases with 82.5% sensitivity and 100% specificity as compared with conventional culture confirmation. In addition, TB predictive scores in active TB patients were reduced to normal after completion of standard short-course therapy, which was mostly in concordant with the disease outcome. These finding suggested that blood gene expression measurement and TB Sick Score could have potential value in terms of diagnosis of TB and anti-TB treatment monitoring.

Chronic hepatitis B and C co-infection increased all-cause mortality in HAART-naive HIV patients in Northern Thailand.

A total of 755 highly active antiretroviral therapy (HAART)-naive HIV-infected patients were enrolled at a government hospital in Thailand from 1 June 2000 to 15 October 2002. Census dateo f survival was on 31 October 2004 or the date of HAART initiation. Of 700 (92.6%) patients with complete data, the prevalence of hepatitis B virus (HBV) surface antigen and anti-hepatitis C virus (HCV) antibody positivity was 11.9% and 3.3%, respectively. Eight (9.6%) HBV co-infected patients did not have anti-HBV core antibody (anti-HBcAb). During 1166.7 person-years of observation (pyo), 258 (36.9%) patients died [22.1/100 pyo, 95% confidence interval (CI) 16.7­27.8]. HBV and probably HCV co-infection was associated with a higher mortality with adjusted hazard ratios (aHRs) of 1.81 (95% CI 1.30­2.53) and 1.90 (95% CI0.98­3.69), respectively. Interestingly, HBV co-infection without anti-HBc Ab was strongly associated with death (aHR 6.34, 95% CI 3.99­10.3). The influence of hepatitis co-infection on the natural history of HAART-naive HIV patients requires greater attention.

Detection of human immunodeficiency virus type 1 (HIV-1) proviral DNA in breast milk and colostrum of seropositive mothers.

There is increasing evidence of vertical transmission of HIV-1 to infants through breast feeding of milk from HIV-1 infected mothers. It has been postulated that transmission occurs mainly via ingestion of infected cells in breast milk and colostrum. In this study, detection of HIV-1 proviral DNA was used to prove that cells from colostrum and milk do contain HIV. DNA were extracted from these cells of colostrum and milk of 18 seropositive mothers and amplified by nested PCR for HIV-1 gag and pol and 44 per cent were positive mostly by two primers. All ten negative control samples from seronegative mothers were negative. This study demonstrated the infectivity of breast milk and colostrum. Nevertheless, recommendation against breast-feeding should be weighed against poor alternatives in low socioeconomic families.

PIP: In Thailand clinicians gathered breast milk and colostrum samples (1 ml) at 1-10 days postpartum from 18 HIV-1 seropositive mothers at Ramathibodi Hospital and Maharaj Hospital and from 10 HIV-1 seronegative mothers at the same hospitals. Researchers used polymerase chain reaction to detect HIV-1 proviral DNA in cells in the breast milk and colostrum. Breast milk and colostrum samples from 44% of the HIV-1 seropositive women tested positive for HIV-1 DNA. The pol primers were superior to the gag primers. All of the colostrum samples of the HIV-1 seronegative women tested negative. These results suggest that HIV-1 seropositive lactating mothers can transmit HIV-1 via breast feeding after childbirth. The Obstetrics and Gynaecology Department at Ramathibodi Hospital in Bangkok advises HIV-1 infected mothers to not breast feed if there is a suitable alternative available. Health professionals should weigh breast feeding against poor alternatives in impoverished families.