Major Histocompatibility Complex Class I Chain-Related A and B (MICA and MICB) Gene, Allele, and Haplotype Associations With Dengue Infections in Ethnic Thais.

BACKGROUND: Major histocompatibility complex class I chain-related (MIC) A and B (MICA and MICB) are polymorphic stress molecules recognized by natural killer cells. This study was performed to analyze MIC gene profiles in hospitalized Thai children with acute dengue illness. METHODS: MIC allele profiles were determined in a discovery cohort of patients with dengue fever or dengue hemorrhagic fever (DHF) (n = 166) and controls (n = 149). A replication cohort of patients with dengue (n = 222) was used to confirm specific MICB associations with disease. RESULTS: MICA*045 and MICB*004 associated with susceptibility to DHF in secondary dengue virus (DENV) infections (odds ratio [OR], 3.22; [95% confidence interval (CI), 1.18-8.84] and 1.99 [1.07-2.13], respectively), and MICB*002 with protection from DHF in secondary DENV infections (OR, 0.41; 95% CI, .21-.68). The protective effect of MICB*002 against secondary DHF was confirmed in the replication cohort (OR, 0.43; 95% CI, .22-.82) and was stronger when MICB*002 is present in individuals also carrying HLA-B*18, B*40, and B*44 alleles which form the B44 supertype of functionally related alleles (0.29, 95% CI, .14-.60). CONCLUSIONS: Given that MICB*002 is a low expresser of soluble proteins, these data indicate that surface expression of MICB*002 with B44 supertype alleles on DENV-infected cells confer a protective advantage in controlling DENV infection using natural killer cells.

HLA Class I Supertype Associations With Clinical Outcome of Secondary Dengue Virus Infections in Ethnic Thais.

BACKGROUND: Human leukocyte antigen (HLA) supertypes are groups of functionally related alleles that present structurally similar antigens to the immune system. OBJECTIVES: To analyze HLA class I supertype associations with clinical outcome in hospitalized Thai children with acute dengue illness. METHODS: Seven hundred sixty-two patients and population-matched controls recruited predominantly in Bangkok were HLA-A and -B typed. HLA supertype frequencies were compared and tested for significant dengue disease associations using logistic regression analyses. Multivariable models were built by conducting forward stepwise selection procedures. RESULTS: In the final logistic regression model, the HLA-B44 supertype was protective against dengue hemorrhagic fever (DHF) in secondary infections (odds ratio [OR] = 0.46, 95% confidence interval [CI], .30-.72), while the HLA-A02 supertype (OR = 1.92, 95% CI, 1.30-2.83) and the HLA-A01/03 supertype (OR = 3.01, 95% CI, 1.01-8.92) were associated with susceptibility to secondary dengue fever. The B07 supertype was associated with susceptibility to secondary DHF in the univariate analysis (OR = 1.60, 95% CI, 1.05-2.46), whereas that was not retained in the final model. CONCLUSIONS: As the HLA-B44 supertype is predicted to target conserved epitopes in dengue, our results suggest that B44 supertype-restricted immune responses to highly conserved regions of the dengue proteome may protect against secondary DHF.

TNF and LTA gene, allele, and extended HLA haplotype associations with severe dengue virus infection in ethnic Thais.

Severe dengue virus (DENV) infection is characterized by a cascade of cytokine production, including the production of tumor necrosis factor-alpha (TNF-alpha) and lymphotoxin-alpha (LT-alpha). We have analyzed a variety of polymorphisms in the TNF and LTA genes of 435 ethnic Thais who had subclinical DENV infection, primary or secondary dengue fever (DF), or primary or secondary dengue hemorrhagic fever (DHF). The TNF -238A polymorphism marking the TNF-4,LTA-3 haplotype occurred in a significantly greater number of patients with secondary DHF (20 [15.2%] of 132) than patients with secondary DF (7 [4.1%] of 169) (P < .001; P corrected by use of Bonferroni adjustment, .022; odds ratio, 4.13 [95% confidence interval, 1.59-11.17]). In a subset of patients, the LTA-3 haplotype was associated with in vivo intracellular production of LT-alpha and TNF-alpha during the acute viremic phase of infection. Two extended human major histocompatibility complex (MHC) haplotypes containing TNF-4 and LTA-3, together with HLA-B48, HLA-B57, and HLA-DPB1*0501, were detected only in patients with secondary DHF. These observations indicate that polymorphism in functionally distinct MHC-encoded proteins contributes to the risk of developing severe secondary DENV infection and warrants further investigation.

TNF alpha and NRAMP1 polymorphisms in leprosy.

OBJECTIVE: To determine the association of TNF alpha and NRAMP1 polymorphisms in leprosy. MATERIAL AND METHOD: The polymorphisms of TNF alpha at -238, -308, and NRAMP1 at INT4, D543N, and3' UTR were examined in 37 patients with leprosy (24 multibacillary and 13 paucibacillary) and 140 healthy controls. PCR-SSP and PCR-SSO method were used to type TNF and NRAMP1 polymorphisms. RESULTS: The genotype frequency of TNF-308 G/A was significantly increased in all leprosy patients compared to the controls (p = 0.04, OR = 2.69). When leprosy types were divided, the allele frequency of TNF-308A was significantly increased in multibacillary leprosy compared to the normal controls (p = 0.04, OR = 2.93). There was no significant difference in the distribution of the genotypes and allele frequencies of TNF -238 and NRAMP1 polymorphisms between the patients and controls. CONCLUSION: TNF-308A was associated with susceptibility to multibacillary leprosy.

NRAMP1 and TNF-alpha polymorphisms and susceptibility to tuberculosis in Thais.

OBJECTIVE AND BACKGROUND: Polymorphisms in the natural resistance-associated macrophage protein gene 1 (NRAMP1) and tumour necrosis factor (TNF)-alpha gene have been found to be associated with susceptibility to tuberculosis in different populations. However, the results are inconsistent. This study aimed to determine whether NRAMP1 and TNF-alpha variants are associated with tuberculosis in Thais. METHODS: Polymorphisms of NRAMP1 at INT4, D543N and the 3' untranslated region, and of TNF-alpha at +488, -238, and -308, were examined in 149 tuberculosis patients and 147 healthy controls. PCR using sequence-specific oligonucleotides and sequence-specific priming were used to genotype the NRAMP1 and TNF polymorphisms, respectively. RESULTS: There were no significant differences in the distribution of the genotype frequencies for the NRAMP1 and TNF-alpha polymorphisms between the patients and controls. CONCLUSIONS: The NRAMP1 and TNF-alpha genes are not associated with susceptibility to tuberculosis in Thais.