Analysis of TLR4 (Asp299Gly and Thr399Ile) gene polymorphisms and mRNA level in patients with dengue infection: A case-control study.

BACKGROUND: Dengue is a systemic viral infection that spreads to humans by the bite of infected Aedes mosquitoes. The secreted NS1 protein of dengue virus activates macrophages and human PBMCs via TLR4 and induce the release of pro-inflammatory cytokines which is responsible for the pathogenesis of disease. Mutations in TLR4 gene have been associated with the increased susceptibility to many viral, bacterial and parasitic diseases. OBJECTIVE: To study the impact of TLR4 Asp299Gly (rs4986790) and Thr399Ile (rs4986791) gene polymorphisms with susceptibility to dengue infection. METHODS: A total of 120 dengue infected (57; DHF/DSS and 63; DF) and 200 healthy controls were included in the study. TLR4 Asp299Gly and Thr399Ile gene polymorphisms was studied by PCR-RFLP. Expression of TLR4 mRNA was evaluated by rRT-PCR. RESULTS: Individuals with heterozygous genotype for TLR4 Asp299Gly and Thr399Ile polymorphisms had increased susceptibility to dengue infection (OR-1.70, 95% CI=1.01-2.86 P=0.042 and OR-2.17, 95% CI=1.10-4.28, P=0.024, respectively). The frequency of Gly and Ile alleles were higher in dengue patients as compared to controls (OR-1.67, 95% CI=1.05-2.64, P=0.029 and OR-2.20, 95% CI=1.19-4.07, P=0.011, respectively). IIe/Gly haplotype was associated with the risk of the disease when compared with controls (OR=3.15, 95% CI=1.09-9.09, P=0.035). The mRNA expression was higher in DF when compared with DHF/DSS and controls (P=0.040 and 0.009, respectively). CONCLUSION: A higher expression of TLR4 mRNA was associated with DF. The TLR4 Asp299Gly and Thr399Ile gene polymorphisms were associated with the susceptibility of dengue infection probably by altering the immune response.

Association of ICAM-1 K469E polymorphism with dengue infection in North Indian population.

Dengue infection is caused by flavivirus is one of the leading cause of mortality. There are certain factors which play role in the transformation of a mild form of the disease (DF) into a severe form (DHF) but the most important ones are: viral strain virulence, host genetics, and host immune status. In severe dengue infection, plasma leakage occurs due to vascular endothelial cell activation through expression of adhesion molecule like intercellular cell adhesion molecule-1 (ICAM-1). A total of 100 dengue patients (DF; n = 53 and DHF/DSS; n = 47) and 200 healthy controls were included in the study. ICAM-1 K469E genotyping was done by polymerase chain reaction-restriction fragment length polymorphism (PCR- RFLP). Expression of ICAM-1 mRNA was done by Real time reverse transcription- PCR (rRT-PCR). Patients with homozygous genotype (EE) have 3.22 fold risk (P = 0.008) of developing severe form of disease (DHF/DSS) as compared to other genotypes. Patients with DHF/DSS exhibit higher expression of ICAM-1 mRNA as compared to dengue fever and controls (P = 0.001 and < 0.001). Patients (DHF/DSS) with homozygous (EE) genotype exhibit higher expression of ICAM-1 mRNA when compared with wild type (KK) genotype (P = 0.005). This study suggests a possible association between the ICAM-1 polymorphism and the disease severity.

Entomological and serological investigation of Japanese encephalitis in endemic area of eastern Uttar Pradesh, India.

BACKGROUND & OBJECTIVES: Japanese encephalitis virus (JEV), a mosquito borne pathogen, is one of the major causes of viral encephalitis in eastern Uttar Pradesh, India. The objective of this work was to evaluate the entomological based virological surveillance of Japanese encephalitis (JE) in the highly endemic area of eastern Uttar Pradesh. METHODS: The study was carried out during September 2010 to March 2013 in Gorakhpur district of Uttar Pradesh. A total of 251 adult mosquito pools and 64 water samples containing larvae were collected from the District of Gorakhpur. Water pH, turbidity, and oxygen level were analyzed for vector breeding index (BI). In addition, 393 serum/cerebrospinal fluid (CSF) samples of acute encephalitis syndrome (AES) suspected cases were collected from the district hospital. RESULTS: The various Culex species found included, Cx. quinquefasciatus (26.83%), Cx. vishnui (22.29%), Cx. pseudovishnui (20.73%), Cx. tritaeniorhynchus (12.71%), Cx. whitmorei (9.04%), and Cx. gelidus (8.25%). Highest minimum infection rate (MIR) was calculated for Cx. tritaeniorhynchus (2.32), followed by Cx. vishnui (1.98) and Cx. pseudovishnui (0.71). All the larvae samples were negative for JEV. The mean number larvae of Cx. tritaeniorhynchus and Cx. pseudovishnui was negatively correlated with pH (r = - 0.45 and r = - 0.63) and turbidity (r = - 0.30 and r = - 0.37). In contrast, positive correlation was observed in case of Cx. quinquefasciatus. A total of 41 clinical samples were found positive for JEV by IgM ELISA. The rainfall was significantly associated with Japanese encephalitis incidence and showed positive correlation to disease transmission (p = 0.02, r = 0. 66). INTERPRETATION & CONCLUSION: The findings showed the rapid dissemination of JEV within a population, facilitated by different species of Culex in the region. As JE is a vaccine-preventable disease, an immunization programme, an effective vector control strategy and application of standard hygiene practices in these endemic areas could result in a considerable reduction in morbidity and mortality due to JE.