A Study on Gene Expression Profile of Endogenous Antioxidant Enzymes: CAT, MnSOD and GPx in Dengue Patients

Life as a Vector of Dengue Virus: The Antioxidant Strategy of Mosquito Cells to Survive Viral Infection

Dengue fever is a mosquito-borne viral disease of increasing global importance. The disease has caused heavy burdens due to frequent outbreaks in tropical and subtropical areas of the world. The dengue virus (DENV) is generally transmitted between human hosts via the bite of a mosquito vector, primarily Aedes aegypti and Ae. albopictus as a minor species. It is known that the virus needs to alternately infect mosquito and human cells. DENV-induced cell death is relevant to the pathogenesis in humans as infected cells undergo apoptosis. In contrast, mosquito cells mostly survive the infection; this allows infected mosquitoes to remain healthy enough to serve as an efficient vector in nature. Overexpression of antioxidant genes such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione S-transferase (GST), glutaredoxin (Grx), thioredoxin (Trx), and protein disulfide isomerase (PDI) have been detected in DENV2-infected mosquito cells. Additional antioxidants, including GST, eukaryotic translation initiation factor 5A (eIF5a), and p53 isoform 2 (p53-2), and perhaps some others, are also involved in creating an intracellular environment suitable for cell replication and viral infection. Antiapoptotic effects involving inhibitor of apoptosis (IAP) upregulation and subsequent elevation of caspase-9 and caspase-3 activities also play crucial roles in the ability of mosquito cells to survive DENV infection. This article focused on the effects of intracellular responses in mosquito cells to infection primarily by DENVs. It may provide more information to better understand virus/cell interactions that can possibly elucidate the evolutionary pathway that led to the mosquito becoming a vector.

Oxidative stress response in the pathogenesis of dengue virus virulence, disease prognosis and therapeutics: an update

Dengue virus (DENV) is a mosquito-borne arbovirus that causes febrile illness and can lead to a potentially lethal disease. The mechanism of disease pathogenesis is not completely understood, and there are currently no vaccines or therapeutic drugs available to protect against all four serotypes of DENV. Although many reasons have been suggested for the development of the disease, dengue studies have shown that, during DENV infection, there is an imbalance between oxidants and antioxidants that disrupts homeostasis. An increase in reactive oxygen species (ROS) levels triggers the sudden release of cytokines, which can lead to plasma leakage and other severe symptoms. In the present review, we give an overview of the oxidative stress response and its effect on the progression of dengue disease. We also discuss the role of oxidative-stress-associated molecules in disease prognostic and therapeutics.

Expression Pattern of Selected Toll-like Receptors (TLR's) in the PBMC's of Severe and Non-severe Dengue Cases

Objective: The role of TLR's in the pathogenesis of dengue is not explored well. Differential expression of TLR2 and TLR4 was reported in dengue cases. In the present study in order to understand the expression pattern of various TLR's, including TLR2, TLR3, TLR4 and TLR9, mRNA levels were determined in various dengue study groups compared to control groups, at the time of admission and around defervescence using quantitative real-time PCR (RT-PCR).Methods: A total of 88 dengue cases with 32 severe and 56 non-severe cases were involved in the study. Gene expression pattern of the study groups was compared with 31 other febrile illness (OFI) cases and 63 healthy controls. Transcript levels of the target genes were estimated from the peripheral blood mononuclear cells (PBMC) samples collected from cases and controls using quantitative real-time PCR.Results: We have noted a significant alteration in the levels of all TLR's in dengue and OFI cases compared to healthy controls at the time of admission. Interestingly we have noted a significant alteration in the levels of TLR9 in severe and non-severe cases during defervescence. The same was not detected in the OFI group.Conclusion: The present study found a change in TLR's during dengue infection. This suggests us to explore the TLR's as therapeutic candidate for anti-dengue virus strategies. However, in order to ascertain the involvement of TLR's in the disease pathology and its role as biomarkers for prognosis, a complete dynamics of TLR's expression needs to be studied.

Endogenous gene selection for relative quantification PCR and IL6 transcript levels in the PBMC's of severe and non-severe dengue cases

Objectives

Dengue viral infection ranges from dengue fever to dengue haemorrhagic fever and lethal dengue shock syndrome. Currently no means are available to monitor the progression of disease. Real time PCR based gene expression analyses are used to find potential molecular markers for effective prediction of dengue clinical outcome. The accuracy of qPCR analysis is strongly dependent on transcript normalization using stably expressed endogenous genes, which if selected imprecisely can lead to misinterpreted results. We aimed to determine the best fit for endogenous gene among six genes namely COX, ACTB, GAPDH, HMBS, HPRT and B2M for dengue viral infection cases. Gene stability was inferred from qPCR data by normalizing with two algorithms geNorm and Normfinder and the rankings generated were validated by gene expression analysis against target gene IL-6.

Results

Both the algorithms showed ACTB, HPRT, GAPDH as most stable genes. Normalizing with the stable genes revealed a significant fold change (p < .05) in IL-6 levels of .32, .52, .69, and .62 in non-dengue febrile illness, non severe, severe and All Dengue groups respectively compared to healthy controls. based on our study, we suggest ACTB with HPRT/GAPDH combination for normalization in qPCR for precise quantification of transcripts in dengue infected studies.

Electronic supplementary material

The online version of this article (10.1186/s13104-018-3620-2) contains supplementary material, which is available to authorized users.

Diagnosis of Acute Q Fever by Detection of Coxiella burnetii DNA using Real-Time PCR, Employing a Commercial Genesig Easy Kit

INTRODUCTION

Query (Q) fever is an important zoonosis and a cause of concern for humans, due to the potential bioterrorism threat posed by the causative agent, Coxiella burnetii. Because of the danger of contracting the illness, isolation attempts are seldom made. Serological and molecular diagnostic tests are the main option.

AIM

To study the prevalence of acute Q fever in Puducherry and surrounding districts of Tamil Nadu, India, employing a new commercial Real-Time Polymerase Chain Reaction (RT-PCR) kit and confirming it by the gold standard Immunofluorescence Assay (IFA).

MATERIALS AND METHODS

Acute phase blood samples from 72 consecutive febrile patients and 24 healthy individuals were included in this prospective study. DNA was extracted from the buffy coats and preserved at -80°C. Detection of C. burnetii was carried out employing a commercial Real-Time PCR kit. Serum samples were tested for IgM (Phase I+II) and IgG (Phase I+II) by QM-120 and QG-120, Coxiella burnetii IFA Fuller Laboratories, California, USA. Sensitivity, Specificity, Positive Predictive Value (PPV) and Negative Predictive Value (NPV) were calculated keeping IFA as the reference.

RESULTS

Presumptive diagnosis of acute Q fever was made in two febrile patients by the Genesig Easy kit (2.78%). In addition to these two PCR positive cases, one more patient was positive for both Phase II IgM and Phase II IgG antibodies by the gold standard IFA. All 24 healthy controls were negative for Q fever by both PCR and IFA. The sensitivity, specificity, NPV and PPV for Genesig Easy kit PCR were: 66.67%, 100%, 100% and 98.57 % respectively against IFA as the reference.

CONCLUSION

The true prevalence of Q fever in India and other developing countries is poorly understood, owing to the difficulties in the diagnosis of this infection. Since molecular diagnostic tests have good specificity and are mandated for confirmation of single acute samples, validation of commercial Q fever PCR kits is the need of the hour. Genesig Easy kit in our hands was found to be reliable with the moderate sensitivity and high specificity. Performing both PCR (with acute specimens) and IFA (with paired sera) would be ideal for Q fever diagnosis.