Immunomodulation of streptozotocin induced Type 1 diabetes mellitus in mouse model by Macrophage migration inhibitory factor-2 (MIF-2) homologue of human lymphatic filarial parasite, Wuchereria bancrofti

Helminth parasites modulate the host immune system to ensure a long-lasting asymptomatic form of infection generally, mediated by the secretion of immunomodulatory molecules and one such molecule is a homologue of human host cytokine, Macrophage migratory Inhibitory Factor (hMIF). In this study, we sought to understand the role of homologue of hMIF from the lymphatic filarial parasite, Wuchereria bancrofti (Wba-MIF2), in the immunomodulation of the Streptozotocin (STZ)-induced Type1 Diabetes Mellitus (T1DM) animal model. Full-length recombinant Wba-MIF2 was expressed and found to have both oxidoreductase and tautomerase activities. Wba-MIF2 recombinant protein was treated to STZ induced T1DM animals, and after 5 weeks pro-inflammatory (IL-1, IL-2, IL-6, TNF-α, IFN-γ) and anti-inflammatory (IL-4, IL-10) cytokines and gene expressions were determined in sera samples and spleen respectively. Pro-inflammatory and anti-inflammatory cytokine levels were significantly (p<0.05) up-regulated and down-regulated respectively, in the STZ-T1DM animals, as compared to treated groups. Histopathology showed macrophage infiltration and greater damage of islets of beta cells in the pancreatic tissue of STZ-T1DM animals, than Wba-MIF2 treated STZ-T1DM animals. The present study clearly showed the potential of Wba-MIF2 as an immunomodulatory molecule, which could modulate the host immune system in the STZ-T1DM mice model from a pro-inflammatory to anti-inflammatory milieu.

Nation-wide vector surveillance on Zika and Dengue did not indicate transmission of the American lineage-pandemic Zika virus in India

OBJECTIVES

Following the Public Health Emergency of International Concern declared on Zika by the World Health Organization during 2016, the Indian Council of Medical Research carried out nationwide vector surveillance for Zika and Dengue viruses (ZIKV and DENV) in India as a preparedness measure in 2016-19.

METHODS

High-risk zones distributed to 49 Districts in 14 states/union territories were included in the study. Seven ICMR institutions participated, following a standard operating protocol. Aedes specimens sampled weekly were processed by multiplex reverse transcriptase-polymerase chain reaction (RT-PCR) for ZIKV/DENV and random samples crosschecked with real-time RT-PCR for ZIKV.

RESULTS

Altogether, 79 492 Aedes specimens in 6492 pools were processed; 3 (0.05%) and 63 (0.97%) pools, respectively, were found positive for ZIKV and DENV. ZIKV infections were recorded in Aedes aegypti sampled during the 2018 sporadic Zika outbreak in Jaipur, Rajasthan. However, these belonged to the Asian lineage of the virus, already circulating in the country. Both Ae. aegypti and Aedes albopictus distributed to 8 states/union territories were found to be infected with DENV. Both sexes of Ae. albopictus were infected, indicating transovarial transmission.

CONCLUSION

This investigation evinced no active transmission of the American lineage-pandemic Zika virus in India during the pandemic period.

Operationalising the "One Health" approach in India: facilitators of and barriers to effective cross-sector convergence for zoonoses prevention and control

BACKGROUND

There is a strong policy impetus for the One Health cross-sectoral approach to address the complex challenge of zoonotic diseases, particularly in low/lower middle income countries (LMICs). Yet the implementation of this approach in LMIC contexts such as India has proven challenging, due partly to the relatively limited practical guidance and understanding on how to foster and sustain cross-sector collaborations. This study addresses this gap by exploring the facilitators of and barriers to successful convergence between the human, animal and environmental health sectors in India.

METHODS

A mixed methods study was conducted using a detailed content review of national policy documents and in-depth semi-structured interview data on zoonotic disease management in India. In total, 29 policy documents were reviewed and 15 key informant interviews were undertaken with national and state level policymakers, disease managers and experts operating within the human-animal-environment interface of zoonotic disease control.

RESULTS

Our findings suggest that there is limited policy visibility of zoonotic diseases, although global zoonoses, especially those identified to be of pandemic potential by international organisations (e.g. CDC, WHO and OIE) rather than local, high burden endemic diseases, have high recognition in the existing policy agenda setting. Despite the widespread acknowledgement of the importance of cross-sectoral collaboration, a myriad of factors operated to either constrain or facilitate the success of cross-sectoral convergence at different stages (i.e. information-sharing, undertaking common activities and merging resources and infrastructure) of cross-sectoral action. Importantly, participants identified the lack of supportive policies, conflicting departmental priorities and limited institutional capacities as major barriers that hamper effective cross-sectoral collaboration on zoonotic disease control. Building on existing informal inter-personal relationships and collaboration platforms were suggested by participants as the way forward.

CONCLUSION

Our findings point to the importance of strengthening existing national policy frameworks as a first step for leveraging cross-sectoral capacity for improved disease surveillance and interventions. This requires the contextual adaptation of the One Health approach in a manner that is sensitive to the underlying socio-political, institutional and cultural context that determines and shapes outcomes of cross-sector collaborative arrangements.

Prevalence and spectrum of mutations causing G6PD deficiency in Indian populations

BACKGROUND

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is one of the most common human erythroenzymopathy affecting around 10% of the world population. India is endemic for malaria and antimalarial drugs are known to induce haemolysis in G6PD deficient individuals. Here we report the prevalence as well as the molecular diversity of G6PD deficiency in geographical regions of India.

METHODS AND RESULTS

A total of 20,896 individuals (11,838 males and 9058 females) were screened by DPIP dye decolorisation method followed by quantitation of G6PD enzyme activity on the suspected samples. Molecular analysis was undertaken in a total of 350 G6PD deficient individuals by PCR-RFLP and DNA sequencing. A structural characteristic of the novel variant was deduced by using DynaMut web-server. The prevalence rate of G6PD deficiency varied between 0.8 and 6.3% with an overall prevalence of 1.9%. A total of twelve mutations were identified. Of the total deleterious alleles detected G6PD Orissa (56.5%) was found to be the most predominant variant followed by G6PD Mediterranean (23.6%). G6PD Mediterranean, G6PD Kaiping and G6PD Mahidol were found to be severely deficient variant and 14.1% of them showed undetectable activity. A novel mutation c.544C➔G (R182G) in exon 6 was identified in one tribal male where substitution of arginine by glycine, likely causes the alteration in the alpha helix leading to disruption of secondary structure of the protein.

CONCLUSION

There are large differences in the distribution of G6PD causal variants between Indian states, and this may have implications for the treatment in the malaria endemic areas.

Functional studies of Plasmodium falciparum's prohibitin1 and prohibitin 2 in yeast

Prohibitins (PHBs) are evolutionarily conserved mitochondrial integral membrane proteins, shown to regulate mitochondrial structure and function, and can be classified into PHB1 and PHB2. PHB1 and PHB2 have been shown to interact with each other, and form heterodimers in mitochondrial inner membrane. Plasmodium falciparum has orthologues of PHB1 and PHB2 in its genome, and their role is unclear. Here, by homology modelling and yeast two-hybrid analysis, we show that putative Plasmodium PHBs (Pf PHB1 and Pf PHB2) interact with each other, which suggests that they could form supercomplexes of heterodimers in Plasmodium, the functional form required for optimum mitochondrial function.

Thiosemicarbazone derivatives: Design, synthesis and in vitro antimalarial activity studies

Different types of thiosemicarbazone derivatives were designed and tested for their Drug-Like Molecular (DLM) nature by using Lipinski and Veber rules. Subsequently, compounds with DLM properties were synthesized and characterized by spectral methods. In vitro antimalarial activity studies of the synthesized thiosemicarbazone derivatives have been carried out against Plasmodium falciparum, 3D7 strain using fluorescence assay method and found that the compounds, (E)-2-(1-(4-fluorophenyl)ethylidene)hydrazine-1-carbothioamide (6), (E)-2-(1-(3-bromophenyl) ethylidene) hydrazine-1-carbothioamide (15) and (E)-2-(3,4,5-trimethoxybenzylidene) hydrazine-1-carbothioamide (29) showed notable antimalarial activity with EC₅₀ values of 13.54 μM, 15.83 μM and 14.52 μM respectively.

RNA interference in mosquito: understanding immune responses, double-stranded RNA delivery systems and potential applications in vector control

RNA interference (RNAi) refers to the process of post-transcriptional silencing of cellular mRNA by the application of double-stranded RNA (dsRNA). RNAi strategies have been widely employed to regulate gene expression in plants and animals including insects. With the availability of the full genome sequences of major vector mosquitoes, RNAi has been increasingly used to conduct genetic studies of human pathogens in mosquito vectors and to study the evolution of insecticide resistance in mosquitoes. This review summarizes the recent progress in our understanding of mosquito-pathogen interactions using RNAi and various methods of dsRNA delivery in mosquitoes at different stages. We also discuss potential applications of this technology to develop novel tools for vector control.

Scope of detectability of circulating antigens of human lymphatic filarial parasite Wuchereria bancrofti with smaller amount of serum by Og4C3 assay: its application in lymphatic filariasis elimination programme

Filarial antigen detection is an appropriate epidemiological indicator for mapping lymphatic filariasis and impact evaluation of filariasis elimination programme in view of low sensitivity of parasite detection. Monoclonal antibody-based Og4C3 immunological test requires 100 µl serum, which is difficult to collect by finger prick method during community based surveys. Hence, we tested lesser volume of serum compared to standard volume of 100 µl to compare its sensitivity and specificity in detecting the circulating filarial antigens. Blood samples were collected from individuals who tested positive [with titer groups 4 (border line positives), 6 (medium positives), and 8 (high positives)] and negative (titre group 3) for Og4C3 assay. Different volumes of serum samples were used to make-up required volume (100 µl) with appropriate dilutions and subjected to Og4C3 assay. The results showed that known negative samples tested negative at all the serum volumes tested. All positives (titer groups 6 and 8) showed positivity at all reduced volumes of serum sample. However one of the medium positive sample showed negative reaction in 5 µl volume of serum and two of the border line positives showed negative at all the serum volume tested. The results thus showed as less as 15 µl serum is adequate for use in Og4C3 assay. So the test can be performed without losing its sensitivity even with 5 µl serum samples at high titre of antigen (titre group 8) and 15 µl for other groups and this method has scope in programme evaluation.

Novel synthesis of silver nanoparticles using Bauhinia variegata: a recent eco-friendly approach for mosquito control

Mosquito vectors are responsible for transmitting diseases such as malaria, dengue, chikungunya, Japanese encephalitis, dengue, and lymphatic filariasis. The use of synthetic insecticides to control mosquito vectors has caused physiological resistance and adverse environmental effects, in addition to high operational cost. Biosynthesis of silver nanoparticles has been proposed as an alternative to traditional control tools. In the present study, green synthesis of silver nanoparticles (AgNPs) using aqueous leaf extract of Bauhinia variegata by reduction of Ag(+) ions from silver nitrate solution has been investigated. The bioreduced silver nanoparticles were characterized by UV–visible spectrophotometry, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray analysis (EDX), and X-ray diffraction analysis (XRD). Leaf extract and synthesized AgNPs were evaluated against the larvae of Anopheles subpictus, Aedes albopictus, and Culex tritaeniorhynchus. Compared to aqueous extract, synthesized AgNPs showed higher toxicity against An. subpictus, Ae. albopictus, and Cx. tritaeniorhynchus with LC50 and LC90 values of 41.96, 46.16, and 51.92 μg/mL and 82.93, 89.42, and 97.12 μg/mL, respectively. Overall, this study proves that B. variegata is a potential bioresource for stable, reproducible nanoparticle synthesis and may be proposed as an efficient mosquito control agent.

Facile fabrication of eco-friendly nano-mosquitocides: Biophysical characterization and effectiveness on neglected tropical mosquito vectors

Mosquito (Diptera: Culicidae) vectors are solely responsible for transmitting important diseases such as malaria, dengue, chikungunya, Japanese encephalitis, lymphatic filariasis and Zika virus. Eco-friendly control tools of Culicidae vectors are a priority. In this study, we proposed a facile fabrication process of poly-disperse and stable silver nanoparticles (Ag NPs) using a cheap leaf extract of Ichnocarpus frutescens (Apocyanaceae). Bio-reduced Ag NPs were characterized by UV-vis spectrophotometry, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The acute toxicity of I. frutescens leaf extract and green-synthesized Ag NPs was evaluated against larvae of the malaria vector Anopheles subpictus, the dengue vector Aedes albopictus and the Japanese encephalitis vector Culex tritaeniorhynchus. Compared to the leaf aqueous extract, Ag NPs showed higher toxicity against A. subpictus, A. albopictus, and C. tritaeniorhynchus with LC₅₀ values of 14.22, 15.84 and 17.26μg/mL, respectively. Ag NPs were found safer to non-target mosquito predators Anisops bouvieri, Diplonychus indicus and Gambusia affinis, with LC₅₀ values ranging from 636.61 to 2098.61μg/mL. Overall, this research firstly shed light on the mosquitocidal potential of I. frutescens, a potential bio-resource for rapid, cheap and effective synthesis of poly-disperse and highly stable silver nanocrystals.

An alternative strategy to generate coding sequence of macrophage migration inhibitory factor-2 of Wuchereria bancrofti

Background & objectives:

Different developmental stages of Wuchereria bancrofti, the major causal organism of lymphatic filariasis (LF), are difficult to obtain. Beside this limitation, to obtain complete coding sequence (CDS) of a gene one has to isolate mRNA and perform subsequent cDNA synthesis which is laborious and not successful at times. In this study, an alternative strategy employing polymerase chain reaction (PCR) was optimized and validated, to generate CDS of Macrophage migration Inhibitory Factor-2 (wbMIF-2), a gene expressed in the transition stage between L3 to L4.

Methods:

The genomic DNA of W. bancrofti microfilariae was extracted and used to amplify the full length wbMIF-2 gene (4.275 kb). This amplified product was used as a template for amplifying the exons separately, using the overlapping primers, which were then assembled through another round of PCR.

Results:

A simple strategy was developed based on PCR, which is used routinely in molecular biology laboratories. The amplified CDS of 363 bp of wbMIF-2 generated using genomic DNA splicing technique was devoid of any intronic sequence.

Interpretation & conclusions:

The cDNA of wbMIF-2 gene was successfully amplified from genomic DNA of microfilarial stage of W. bancrofti thus circumventing the use of inaccessible L3-L4 transitional stage of this parasite. This strategy is useful for generating CDS of genes from parasites that have restricted availability.

Simultaneous determination of vasicine and vasicinone by high-performance liquid chromatography in roots of eight Sida species

Introduction:

Sida L. is a medicinally important genus widely used in conventional systems of medicine in India.

Aim:

The present study aims toward simultaneous determination of two bioactive compounds vasicine and vasicinone in root extracts of eight Sida spp. from Western Ghats, India.

Materials and Methods:

Determination of vasicine and vasicinone was undertaken in methanolic root extracts (10% w/v) of Sida acuta, Sida cordata, Sida cordifolia, Sida rhombifolia, Sida spinosa, Sida indica, Sida retusa and Sida mysorensis by high performance liquid chromatography (HPLC) method. The standards were prepared with the concentration of mg/mL. Data were expressed as mean values of three reading and relative standard deviations. The separation was achieved on a Waters, Nova-Pack, C18 (250 mm × 4.6 mm, 5 μ) column, with acetonitrile - 0.1 M phosphate buffer-glacial acetic acid (15: 85: 1, v/v/v) as solvent system at a flow-rate of 1.0 mL/min. The effluent was monitored using ultraviolet detection at a wavelength of 300 nm.

Results:

Both calibration curves of standard showed good linear regression (R² > 0.994). The limit of detection and the limit of quantification for vasicine was 0.110 and 0.333 μg/mL and for vasicinone was 0.059 and 0.179 μg/mL respectively. The vasicine content was highest in S. cordifolia (9.891 ± 0.495 μg/100 mg) and vasicinone content was rich in S. cordata (33.013 ± 1.651 μg/100 mg.) The content of vasicinone was higher than vasicine.

Conclusion:

HPLC method provides simple, accurate, and reproducible quantitative analysis for simultaneous determination of vasicine and vasicinone. Among the selected Sida species, S. cordifolia and S. cordata were found to be rich in the vasicine and vasicinone contents, respectively.

Green synthesis and characterization of silver nanoparticles fabricated using Anisomeles indica: Mosquitocidal potential against malaria, dengue and Japanese encephalitis vectors

Mosquitoes (Diptera: Culicidae) represent a key threat for millions of people worldwide, since they act as vectors for devastating parasites and pathogens. In this scenario, eco-friendly control tools against mosquito vectors are a priority. Green synthesis of silver nanoparticles (AgNP) using a cheap, aqueous leaf extract of Anisomeles indica by reduction of Ag(+) ions from silver nitrate solution has been investigated. Bio-reduced AgNP were characterized by UV-visible spectrophotometry, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive spectroscopy (EDX) and X-ray diffraction analysis (XRD). The acute toxicity of A. indica leaf extract and biosynthesized AgNP was evaluated against larvae of the malaria vector Anopheles subpictus, the dengue vector Aedes albopictus and the Japanese encephalitis vector Culex tritaeniorhynchus. Both the A. indica leaf extract and AgNP showed dose dependent larvicidal effect against all tested mosquito species. Compared to the leaf aqueous extract, biosynthesized AgNP showed higher toxicity against An. subpictus, Ae. albopictus, and Cx. tritaeniorhynchus with LC50 values of 31.56, 35.21 and 38.08 μg/mL, respectively. Overall, this study firstly shed light on the mosquitocidal potential of A. indica, a potential bioresource for rapid, cheap and effective AgNP synthesis.

Di-rhamnolipid is a mosquito pupicidal metabolite from Pseudomonas fluorescens (VCRC B426)

Pseudomonas fluorescens Migula (VCRC B426) produces a secondary metabolite, which was found to be active against pupae of vector mosquitoes namely Culex quinquefasciatus, Anopheles stephensi and Aedes aegypti. The mosquito pupicidal metabolite from P. fluoescens was mass produced and separated by ethyl acetate extraction and purified further by silica gel column chromatography, FPLC, HPLC and TLC. The purified metabolite was characterized by NMR, FT-IR, LC-MS and MALDI-TOF. The FT-IR, (1)H and (13)C NMR results showed that it is a rhamnolipid (di-rhamnolipid). The matrix assisted laser desorption and ionization-time-of-flight spectrum of the sample showed predominant pupicidal component produced by P. fluorescens was the molecule mass of 673.40 Da. Owing to its high toxicity to mosquito pupae, especially Anopheles sp., and Aedes sp., the di-rhamnolipd has potential in the control of the vectors of dengue, chikungunya, yellow fever and malaria. This is the first report of mosquito pupicidal di-rhamnolipid from P. fluorescens.

Synthesis and characterization of silver nanoparticles using Gmelina asiatica leaf extract against filariasis, dengue, and malaria vector mosquitoes

Mosquitoes are blood-feeding insects and serve as the most important vectors for spreading human diseases such as malaria, yellow fever, dengue fever, and filariasis. The continued use of synthetic insecticides has resulted in resistance in mosquitoes. Synthetic insecticides are toxic and affect the environment by contaminating soil, water, and air, and then natural products may be an alternative to synthetic insecticides because they are effective, biodegradable, eco-friendly, and safe to environment. Botanical origin may serve as suitable alternative biocontrol techniques in the future. The present study was carried out to establish the larvicidal potential of leaf extracts of Gmelina asiatica and synthesized silver nanoparticles using aqueous leaf extract against late third instar larvae of Anopheles stephensi, Aedes aegypti, and Culex quinquefasciatus. Larvae were exposed to varying concentrations of plant extracts and synthesized AgNPs for 24 h. The results were recorded from UV-visible spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, and energy-dispersive X-ray spectroscopy analysis support the biosynthesis and characterization of AgNPs. The maximum efficacy was observed in synthesized AgNPs against the larvae of An. stephensi (lethal dose (LC₅₀) = 22.44 μg/mL; LC₉₀ 40.65 μg/mL), Ae. aegypti (LC₅₀ = 25.77 μg/mL; LC₉₀ 45.98 μg/mL), and C. quinquefasciatus (LC₅₀ = 27.83 μg/mL; LC₉₀ 48.92 μg/mL), respectively. No mortality was observed in the control. This is the first report on mosquito larvicidal activity of plant-synthesized nanoparticles. Thus, the use of G. asiatica to synthesize silver nanoparticles is a rapid, eco-friendly, and a single-step approach and the AgNps formed can be potential mosquito larvicidal agents.

Evaluation of plant-mediated synthesized silver nanoparticles against vector mosquitoes

Diseases transmitted by blood-feeding mosquitoes, such as dengue fever, dengue hemorrhagic fever, Japanese encephalitis, malaria, and filariasis, are increasing in prevalence, particularly in tropical and subtropical zones. To control mosquitoes and mosquito-borne diseases, which have worldwide health and economic impacts, synthetic insecticide-based interventions are still necessary, particularly in situations of epidemic outbreak and sudden increases of adult mosquitoes. Green nanoparticle synthesis has been achieved using environmentally acceptable plant extract and eco-friendly reducing and capping agents. In view of the recently increased interest in developing plant origin insecticides as an alternative to chemical insecticide, in the present study, the adulticidal activity of silver nanoparticles (AgNPs) synthesized using Heliotropium indicum plant leaf extract against adults of Anopheles stephensi, Aedes aegypti, and Culex quinquefasciatus was determined. Adult mosquitoes were exposed to varying concentrations of aqueous extract of H. indicum and synthesized AgNPs for 24 h. AgNPs were rapidly synthesized using the leaf extract of H. indicum, and the formation of nanoparticles was observed within 6 h. The results recorded from UV-vis spectrum, Fourier transform infrared, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy support the biosynthesis and characterization of AgNPs. The maximum efficacy was observed in synthesized AgNPs against the adult of A. stephensi (lethal dose (LD)₅₀ = 26.712 μg/mL; LD₉₀ = 49.061 μg/mL), A. aegypti (LD₅₀ = 29.626 μg/mL; LD₉₀ = 54.269 μg/mL), and C. quinquefasciatus (LD₅₀ = 32.077 μg/mL; LD₉₀ = 58.426 μg/mL), respectively. No mortality was observed in the control. These results suggest that the leaf aqueous extracts of H.indicum and green synthesis of AgNPs have the potential to be used as an ideal eco-friendly approach for the control of the A. stephensi, A. aegypti, and C. quinquefasciatus. This is the first report on the adulticidal activity of the plant extracts and AgNPs.

Binding sites of mosquitocidal toxins of Pseudomonas fluorescens and Bacillus subtilis on pupae and larvae of Culex quinquefasciatus

Two of the potential bacterial isolates, viz., Pseudomonas fluorescens (VCRC B-426) and Bacillus subtilis (VCRC B-471) whose toxins kill the mosquito pupae/larvae have been identified at our center. As the mode of action of these bacteria are not known, an attempt was made to find out the binding sites of the toxic proteins through immunological methods. Antibodies were raised in BALB/c mice and egg yolk system of chicken layers against the mosquitocidal proteins. The antibodies showed specific binding on to the cephalic and thoracic cuticle of the pupae as well as the paddles of the larvae, indicating the binding of the mosquitocidal proteins.

Association between proinflammatory cytokines and lipid peroxidation in patients with severe dengue disease around defervescence

OBJECTIVES

Proinflammatory cytokines and the oxidative stress response are reported to be involved in dengue viral disease. The present study investigated the correlation of proinflammatory cytokines and lipid peroxidation with dengue severity.

METHODS

Clinical samples from 27 dengue fever (DF) cases, 30 dengue haemorrhagic fever (DHF) cases, and 24 dengue shock syndrome (DSS) cases were studied around defervescence, along with samples from 30 healthy controls. Plasma samples were analysed for tumour necrosis factor alpha (TNF-α) and interferon gamma (IFN-γ) by ELISA and for malondialdehyde (MDA) by thiobarbituric acid assay.

RESULTS

Dengue-infected individuals had significantly higher levels of TNF-α, IFN-γ, and MDA in comparison to controls. The ratio of TNF-α to IFN-γ was significantly higher in DHF and DSS than in DF. A TNF-α/IFN-γ ratio value of 5.69 around defervescence predicted DHF and DSS with moderate accuracy and thus may serve as an indicator to study dengue severity. The study observed a significant positive correlation of lipid peroxides with TNF-α levels and the TNF-α/IFN-γ ratio in severe dengue cases.

CONCLUSIONS

We propose that the oxidative stress response induced by the dengue virus may trigger the inflammatory cytokine responses in dengue severity and thereby contributes to the pathogenesis of the disease; however the interplay between the oxidative response and inflammatory activity in disease virulence needs further study.

Filamentation temperature-sensitive protein Z (FtsZ) of Wolbachia, endosymbiont of Wuchereria bancrofti: a potential target for anti-filarial chemotherapy

Lymphatic filariasis (LF) is a leading cause of morbidity in the tropical world. It is caused by the filarial parasites Wuchereria bancrofti, Brugia malayi and Brugia timori and transmitted by vector mosquitoes. Currently a programme for the elimination of LF, Global programme for Elimination of Lymphatic Filariasis (GPELF), is underway with the strategy of mass administration of single dose of diethylcarbamazine or ivermectin, in combination with an anthelmintic drug, albendazole. However, antifilarial drugs used in the programme are only microfilaricidal but not or only partially macrofilaricidal. Hence, there is a need to identify new targets for developing antifilarial drugs. Filarial parasites harbor rickettsial endosymbionts, Wolbachia sp., which play an important role in their biology and hence are considered as potential targets for antifilarial chemotherapy development. In this study, one of the cell division proteins of Wolbachia of the major lymphatic filarial parasite, W. bancrofti, viz., filamentation temperature-sensitive protein Z (FtsZ), was explored as a drug target. The gene coding for FtsZ protein was amplified from the genomic DNA of W. bancrofti, cloned and sequenced. The derived amino acid sequence of the gene revealed that FtsZ protein is 396 amino acids long and contained the tubulin motif (GGGTGTG) involved in GTP binding and the GTP hydrolyzing motif (NLDFAD). The FtsZ gene of endosymbiont showed limited sequence homology, but exhibited functional homology with β-tubulin of its host, W. bancrofti, as it had both the functional motifs and conserved amino acids that are critical for enzymatic activity. β-tubulin is the target for the anti-helminthic activity of albendazole and since FtsZ shares functional homology with, β-tubulin it may also be sensitive to albendazole. Therefore, the effect of albendazole was tested against Wolbachia occurring in mosquitoes instead of filarial parasites as the drug has lethal effect on the latter. Third instar larvae of Culex quinquefasciatus were treated with 0.25mg/ml of albendazole (test) or tetracycline (positive control) in the rearing medium for different intervals and tested for the presence of Wolbachia by FtsZ PCR. All the treated larvae were negative for the presence of the FtsZ band, whereas all the control larvae were positive. The findings of the study, thus indicated that FtsZ is sensitive to albendazole. In view of this albendazole appears to have dual targets; FtsZ in Wolbachia and β-tubulin in W. bancrofti. Further, the functional domain of the gene was assessed for polymorphism among recombinant clones representing 120 W. bancrofti parasites, prevalent across wide geographic areas of India and found to be highly conserved among them. Since it is highly conserved and plays an important role in Wolbachia cell division it appears to be a potential target for anti-filarial chemotherapy development.

Use of a simple DNA extraction method for high-throughput detection of filarial parasite Wuchereria bancrofti in the vector mosquitoes

Molecular xenomonitoring of filariasis is the detection of filarial DNA in mosquitoes by PCR and a useful tool for monitoring transmission. DNA extraction coupled with PCR allows rapid detection of the presence or absence of the filarial parasite in vector mosquitoes compared to traditional method of manual dissection of the mosquito and observation for parasite under a microscope. A Tris-EDTA (TE) buffer-based boiling method of DNA extraction developed earlier by us was employed and explored for its suitability in the detection of Wuchereria bancrofti DNA in pools of Culex quinquefasciatus mosquitoes in real-time PCR assay. In this preliminary study, 1,000 laboratory-reared C. quinquefasciatus were made into 40 pools, each containing 25 mosquitoes spiked with 2mf. DNA from the first 20 pools was extracted using Qiagen DNeasy blood and tissue kit as standard, and the other 20 pools were subjected to TE buffer-based boiling method of DNA extraction. When the results (Ct values) obtained for DNA samples extracted by TE buffer-based boiling method were compared with that of the DNA samples extracted by the standard Qiagen method, they were found to be highly concordant without any significant difference (P = 0.9). Besides being cost- and time-effective, this protocol was found useful in extracting filarial DNA from two other mosquito genus Aedes and Anopheles, species of which have been reported as important vectors of W. bancrofti in other endemic regions of the world. Thus, TE buffer-based boiling method of DNA extraction is useful for the high-throughput detection of W. bancrofti in vector mosquitoes.

Ag@AgI, core@shell structure in agarose matrix as hybrid: synthesis, characterization, and antimicrobial activity

A novel in situ core@shell structure consisting of nanoparticles of Ag (Ag Nps) and AgI in agarose matrix (Ag@AgI/agarose) has been synthesized as a hybrid, in order to have an efficient antibacterial agent for repetitive usage with no toxicity. The synthesized core@shell structure is very well characterized by XRD, UV-visible, photoluminescence, and TEM. A detailed antibacterial studies including repetitive cycles are carried out on Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus) bacteria in saline water, both in dark and on exposure to visible light. The hybrid could be recycled for the antibacterial activity and is nontoxic toward human cervical cancer cells (HeLa cells). The water insoluble Ag@AgI in agarose matrix forms a good coating on quartz, having good mechanical strength. EPR and TEM studies are carried out on the Ag@AgI/agarose and the bacteria, respectively, to elucidate a possible mechanism for killing of the bacteria.

Characterization of cofactor-independent phosphoglycerate mutase isoform-1 (Wb-iPGM) gene: a drug and diagnostic target from human lymphatic filarial parasite, Wuchereria bancrofti

The inter-conversion of 3-phosphoglycerate and 2-phosphoglycerate during glycolysis and gluconeogenesis in filarial nematodes, is catalyzed by a co-factor-independent phosphoglycerate mutase (iPGM). The gene encoding iPGM isoform-1 was amplified from Wuchereria bancrofti, the major causative agent of human lymphatic filariasis. Partial genomic DNA (gDNA) fragment of the gene was also amplified from periodic and sub-periodic forms of W. bancrofti and Brugia malayi and sequenced. The Wb-iPGM isoform-1 gene encodes an ORF of 515 amino acids and is found to share 99.4%, 96.0%, and 64.0% amino acid sequence identity with iPGM of B. malayi, Onchocerca volvulus, and Caenorhabditis elegans, respectively. Serine and all the other 13 amino acid residues involved in the catalytic function of iPGM are highly conserved. Further comparison of iPGM nucleotide and amino acid sequences of Wolbachia of B. malayi with Wb-iPGM showed 41% and 54.4% similarity, respectively. The analysis of partial genomic and amino acid sequences and phylogenetic tree of Wb-iPGM indicated that this gene, apart from being a potential drug target, could provide diagnostic, taxonomical, and evolutionary markers. This is the first report of the characterization of iPGM gene from W. bancrofti.

Effect of a single dose of diethylcarbamazine, albendazole or both on the clearance of Wuchereria bancrofti microfilariae and antigenaemia among microfilaria carriers: a randomized trial

BACKGROUND

Lymphatic filariasis is a major vector-borne parasitic disease. The global programme to eliminate lymphatic filariasis was launched in 1997 and currently over 570 million people are covered under it in 48 countries. Mass annual single-dose drug administration of diethylcarbamazine (DEC), co-administrated with albendazole for 5-6 years and mass distribution of diethylcarbamazine-fortified salt are the two strategies for elimination of filariasis.

METHODS

Asymptomatic volunteers residing in Puducherry, India were screened for microfilaria (mf) by examining nocturnal thick blood smears. Those testing positive were randomly assigned to receive a single dose of DEC (6 mg/kg body weight) or albendazole 400 mg or both. Participants were hospitalized for 5 days. Membrane filtration count was used to assess microfilaraemia and ELISA (Og4C3) assay to measure circulating filarial antigens (CFA). Measurements were done before treatment and at 1, 2 and 3 years post-treatment. Viability of the adult worms was assessed by looking for the filarial dance sign (FDS) using ultrasound examination of the scrotum in men with hydrocele.

RESULTS

Fifty-four microfilaraemic Individuals were studied. The mf prevalence started decreasing only by day 180 posttreatment in the DEC group but much earlier in the other two groups (day 30 in the albendazole and day 90 in the DEC with albendazole group). The decrease in mfwas marginal (17.6%, 26.3% and 27.8%, respectively) by the end of year 1 posttreatment, but significant (96.7%, 78.6% and 93.3%, respectively) by the end of year 2 post-treatment (p < 0.05). By the end of year 3, the level decreased to 80% in the DEC, 90% in the albendazole and to 100% in the DEC and albendazole groups. However, the mf intensity decreased significantly (by 39%; p < 0.05) by day 7 post-treatment in both the DEC and DEC with albendazole groups, but only by day 30 in the albendazole group. In all the drug groups, the prevalence as well as intensity of CFA returned to pretreatment levels by the end of year 3 post-treatment.

CONCLUSION

Annual single-dose administration of all the 3 drug regimens significantly reduced antigenaemia levels. There were no significant differences in the efficacy and overall pattern of CFA clearance between the 3 drug regimens.

A review of the complexity of biology of lymphatic filarial parasites

There are about five more common, including Wuchereria bancrofti and Brugia malayi, and four less common filarial parasites infecting human. Genetic analysis of W. bancrofti populations in India showed that two strains of the species are prevalent in the country. The adult filarial parasites are tissue specific in the human host and their embryonic stage, called microfilariae (mf), are found in the blood or skin of the host, depending upon the species of the parasite. Three genetically determined physiological races exist in W. bancrofti and B. malayi, based on the microfilarial periodicity. They are the nocturnally periodic, nocturnally subperiodic and diurnally subperiodic forms. The susceptibility of a mosquito species to filarial infection depends on various factors, which could be genetic, physiological or physical. Survival analysis of Culex quinquefasciatus infected with W. bancrofti showed that the parasite load in the mosquito is a risk factor of vector survival. The extrinsic life cycle of the parasite is initiated when the mf are ingested by a mosquito vector during feeding on the host blood. On maturity, most of the infective L3 stage larvae migrate to the head and proboscis of the mosquito to get transmitted to the mammalian host during subsequent feeding. They develop to the adult L5 stage and the period of development and the longevity of the parasites varies according to the species of the nematode and the mammalian host. The rate of production of mf by the adult female was found to be stable at least for a period of five years. The life span of the mf has some influence on the dynamics of transmission of filariasis. Recent studies show that the endosymbiont, Wolbachia, plays an important role in the survival of filarial parasites. The possibility of in vitro and in vivo culture of filarial parasites is also reviewed.

Oxidative stress in severe dengue viral infection: association of thrombocytopenia with lipid peroxidation

Oxidative stress in viral infections has been suggested. The study was carried out to assess the oxidative stress in the different clinical spectrums of dengue infection and to evaluate if thrombocytopenia is associated with lipid and protein oxidative injury. Twenty-seven dengue fever (DF), 32 dengue hemorrhagic fever (DHF) and 21 dengue shock syndrome (DSS) cases were studied at 3, 5 and 7 days of illness. Sixty-three healthy subjects were selected as controls. Serum protein carbonyls (PCOs), malendialdehyde (MDA) and total antioxidant status (TAS) were estimated in blood. Dengue infected individuals had significantly high levels of PCOs and MDA on the three days tested in comparison to controls. In DF cases, no significant changes in the levels of MDA and PCOs were found in course of time. However, among DHF and DSS, significant increase in MDA levels was found in the fifth and seventh day samples in comparison to their respective third day sample (P < 0.05). Using one way ANOVA, high PCOs levels were found in DSS in comparison to DF and DHF cases on all the three days tested (P < 0.001). TAS levels were found to be low among DSS on days 5 and 7 and day 7 in DHF when compared with DF cases. Correlation analysis between MDA and hematocrit revealed a significant positive association between them in DHF and DSS on day 5 (DHF r = 0.372; p = 0.024 and DSS r = 0.535; p = 0.0-01) and day 7 (DHF r = 0.412; p = 0.003 and DSS r = 0.765; p < 0.0001). There was an important negative correlation between platelet count and plasma lipid peroxidation levels among DHF and DSS on all three days tested [day 3 (DHF r = -0.392; p = 0.012 and DSS r = -0.453; p = 0.004), day 5 (DHF r = -0.592; p < 0.001 and DSS r = -0.581; p < 0.001) and day 7 (DHF r = -0.418; p = 0.001 and DSS r = -0.515; p = 0.002)]. This study concludes that an increase in oxidative stress was found in dengue viral infection. The level of oxidative stress was maximal in DSS followed by DHF and its severity was minimal in DF. The thrombocytopenia of dengue infection was associated with the extent of lipid peroxidation. Future studies might be carried out to find the role of oxidative damage in the ethiopathogenesis of thrombocytopenia and vascular leakage in dengue infection.

An allele specific PCR assay for screening for drug resistance among Wuchereria bancrofti populations in India

BACKGROUND & OBJECTIVE

Albendazole, a commonly used anthelminthic drug that targets the polymerization of alpha- and beta-tubulin dimer is currently co-administered with the antifilarial drug, diethylcarbamazine citrate (DEC) in the ongoing Global Programme for Elimination of Lymphatic Filariasis (GPELF). The experience in veterinary field has shown that there can be a rapid development of resistance to this drug, which therefore, needs to be monitored regularly in GPELF. Hence, we investigated the nucleotide polymorphism in the albendazole-binding domain of the isotype 1 beta-tubulin gene from several populations of Wuchereria bancrofti and developed an AS-PCR assay useful in screening for sensitive/resistance alleles among parasite populations and also evaluated its utility.

METHODS

For studying the polymorphism of isotype 1 beta-tubulin gene, a 475 bp fragment spanning exon 5 and 6 of the gene was amplified and sequenced from the genomic DNA of W. bancrofti collected from six geographic regions of India. An allele specific (AS) PCR for screening albendazole sensitivity/resistance was developed and a total of 55 mf samples from blood smears on slides collected from Thiruvannamalai, Thanjavur and Puducherry were screened. Selective therapy with DEC was in place in three areas, mass drug administration (MDA) with DEC alone was implemented in four areas, while DEC plus albendazole was administered in one district.

RESULTS

The analysis of the nucleotide sequence of the fragment from 20 W. bancrofti populations showed the domain to be highly conserved. An allele-specific PCR assay developed was used to detect sensitive/resistance alleles among 55 isolates of W. bancrofti and no albendazole resistance alleles were detected among the populations tested.

INTERPRETATION & CONCLUSION

The drug-binding domain of isotype 1 beta-tubulin gene of W. bancrofti from different geographical locations was highly conserved. The AS-PCR developed showed potential application as a tool for monitoring albendazole sensitivity/resistance alleles among W. bancrofti populations, in areas where combination therapy of DEC-albendazole is being mass administered in the LF elimination programme.

A method for detecting microfilaraemia, filarial specific antigens and antibodies and typing of parasites for drug resistance and genotypes using finger prick blood sample

Monitoring and evaluation of programme to eliminate lymphatic filariasis (LF) depends on epidemiological assessment using appropriate indicators. Minimum efforts using reliable tests are necessary to guide the programme managers in decision-making. Impact of Mass Drug Administration (MDA) towards filariasis elimination can be assessed by the detection of microfilariae (mf) or parasite DNA (infective), filarial antigens (infected) and antibodies (exposure). It is also important to monitor drug resistance and variation in genetic structure of parasite populations using molecular markers. We developed a method to carry out parasitological, molecular, immunological and genetic analysis from a minimum volume of blood sample (about 150 microl) drawn from finger tip of an individual residing in LF endemic area. The method involves separation of sera for immunological assays and isolation of mf of Wuchereria bancrofti from the blood clots for counting, which were then used for W. bancrofti specific PCR, screening for albendazole sensitivity/resistance alleles by AS-PCR, RAPD profiling and ITS 2 PCR for genotyping. A protocol is also suggested for the separation of sera for assays to detect antigen and antibodies and isolation of mf from clots for genetic analysis. The protocol developed has shown potential application in monitoring several immunological, parasitological and molecular parameters from a limited amount of blood sample collected by finger prick, in large-scale operations.

RT-PCR assay for the detection of infective (L3) larvae of lymphatic filarial parasite, Wuchereria bancrofti, in vector mosquito Culex quinquefasciatus

BACKGROUND & OBJECTIVES

Periodic monitoring of vector population for infection and infectivity rates is central to the evaluation of the filariasis elimination strategies in endemic areas to monitor the success of MDA and also to establish endpoints for intervention. The main objective of this study was to develop a RT-PCR assay, based on L3 stage-specific primers to detect the presence of infective stage larvae of filarial parasite, Wuchereria bancrofti in the vector Culex quinquefasciatus.

MATERIAL & METHODS

Subtracted probe development technique was employed for the identification of infective stage (L3) specific genes. The subtracted cDNA was labeled by non-radioisotopic method and used for screening cDNA library of L3 stage larvae of W. bancrofti constructed in UniZap XR. Recombinants were probed and identified from the library. The inserts of the recombinant clones were purified and sequenced. Primers were designed based on the sequence information of three recombinant clones for detecting L3 larvae of W. bancrofti in the vector by RT-PCR assay. Preliminary laboratory evaluation was carried out to assess the sensitivity and specificity of WbL31 RT-PCR assay.

RESULTS

cDNA library of L3 stage of W. bancrofti constructed in UniZap XR vector, constituted 5 x 10(5) phages with 80-90% recombinant phages and the size of inserts varied from 0.1 to 1.0 kb. When subtracted cDNA was random prime labeled and used for screening cDNA library of L3 stage of W. bancrofti constructed in UniZap XR, 18 clones were identified from the library. Three genes were found up-regulated in the L3 stage, out of which WbL31 (cuticular collagen) was found to be useful in detecting L3 larvae of W. bancrofti in the vector by RT-PCR assay with high specificity and sensitivity (98-100%).

CONCLUSION

Present paper marks first report on the development of an infective stage-specific RT-PCR assay (WbL31 RT-PCR assay) to detect L3 stage W. bancrofti in the vector. This assay will have potential application in assessing the transmission of infection and hence in decision-making related to elimination programme.

Application of different downstream processing methods and their comparison for the large-scale preparation of Bacillus thuringiensis var. israelensis after fermentation for mosquito control

Bacillus thuringiensis var. israelensis, a gram positive, spore-forming bacillus, produces parasporal crystal protein during sporulation, which is toxic in the mosquito larvae gut. An efficient downstream processing method for separating the spore crystal complex (SCC) from the fermented broth of B. thuringiensis var. israelensis is required to achieve maximum mosquitocidal activity. The different downstream processing methods, viz., tangential flow ultra-filtration, continuous centrifugation and acid precipitation were compared for their efficiency in separating SCC from broth obtained from a pilot-scale fermentor (100 l capacity). Among the three downstream processing methods, tangential flow ultra-filtration yielded the maximum amount of biomass (53.3g/l), maximum number of spores (2.30 x 10(18)CFU/ml) and highest level of larvicidal activity (LC(50) 28 nl/ml) against Aedes aegypti Bora-Bora strain followed by continuous centrifugation and acid precipitation methods.

Polymorphisms of the TAP 1 and 2 gene may influence clinical outcome of primary dengue viral infection

Antigen peptides are actively transported across the endoplasmic reticulum by the transporters associated with antigen presentation (TAP). TAP genes polymorphism could influence the selection process that determines which antigen peptides play a role in the pathogenesis of dengue infection. The aim of this study was to investigate the association of TAP genes polymorphism in diverse pathogenesis of dengue infection. This study included 197 dengue-infected patients who were further categorized into 64, 23 and 11 primary dengue fever (DF), dengue hemorrhagic fever (DHF), dengue shock syndrome (DSS) cases, respectively and 26, 52, and 21 secondary DF, DHF and DSS cases, respectively as per WHO grading system. TAP1 and 2 gene polymorphisms were performed by the amplification refractory mutation system-polymerase chain reaction (ARMS-PCR). Analysis of TAP1 gene polymorphism demonstrated decreased frequency of Ile/Ile genotype at TAP1(333) in primary DHF cases (39.1%) when compared with primary DF (64.1%, P < 0.034, OR = 0.611). The genotype frequency of Val/Val at TAP2(379) locus was significantly decreased among primary DHF (43.5%) in comparison to primary DF (71.9%, P = 0.015, OR = 0.605). Significant low proportion of primary DSS were found to have TAP1(637) Asp/Asp genotypes (54.5%) when compared with primary DF (70.3%, P = 0.043). Asp/Asp genotype at TAP1(637) was found to reduce the risk by 0.643 times for primary DSS. There was no significant difference in the genotypes studied between primary and secondary infection and also within secondary dengue infection in all three clinical groups. This report on TAP gene polymorphisms in dengue suggested that among the primary-infected individuals, homozygous patterns for Ile at TAP1(333) Val at TAP2(379) loci and Asp at TAP1(637) were found to be a protective factor against development of DHF and DSS, respectively.

Immobilization of alginate-encapsulated Bacillus thuringiensis var. israelensis containing different multivalent counterions for mosquito control

Immobilized techniques have been used widely for the controlled release formulation of mosquitoes. Among the microbial formulations, polymeric matrices play an important role in the controlled release of microbial pesticide at rates sufficiently effective to kill mosquitoes in the field. The advantage of these matrices is that they enhance the stability of both spores and toxin against pH, temperature variations, and UV irradiation. The disadvantage of using calcium alginate beads is that they are unstable upon contact with phosphate of potassium or sodium ions rich in the mosquito habitats. To overcome these problems, attempts were made to encapsulate Bacillus thuringiensis var. israelensis within alginate by using different multivalent counterions, namely, calcium chloride, zinc sulfate, copper sulfate, cobalt chloride, and ferric chloride, and the beads formed were tested for its mosquito larvicidal activity. Among all the beads tested, zinc alginate beads resulted in maximum larvicidal activity of 98% (+/-1.40 SE) against Culex quinquefasciatus IIIrd instar larvae and maximum spore count of 3.36 x 10(5) (+/-5291.50 SE) CFU/ml. Zinc alginate beads maintained their structure for up to 48 h when shaken vigorously on a rotary shaker at 180 rpm in the presence of 10 mM potassium phosphate buffer (pH 6.8 +/- 0.1). In conclusion, our results suggest that the use of zinc sulfate as counterions to encapsulate B. thuringiensis var. israelensis within alginate may be a potent mosquito control program in the habitats where more phosphate ions are present.

Monoclonal antibodies generated against excretory/secretory antigens of mammalian stage larvae of the lymphatic filarial parasite Wuchereria bancrofti

Monoclonal antibodies (Mabs) against excretory/secretary (e/s) antigens of fourth stage (L4) larvae of Wuchereria bancrofti were raised and screened for their specificity and sensitivity and evaluated for their potential in detecting homologous e/s antigens in human blood samples. Five Mabs were obtained and, among them, Mab A7 showed high reactivity against e/s antigens of L4 and crude somatic antigens of microfilariae (mf) of W. bancrofti, and infective stage (L3) and adult stage larvae of Brugia malayi. It reacted strongly with sera of Mastomys coucha harbouring L4 stage of B. malayi moderately against sera of the animal having later stages of the parasite. But, it exhibited a low and negligible reactivity against the crude antigens of Setaria cervi and Ascaris lumbricoides, respectively. Another Mab, A6, showed very high reactivity against mf antigens of W. bancrofti and B. malayi and a moderate reactivity against antigens of S. cervi and A. lumbricoides. The two Mabs were tested for their reactivity against filarial antigens in human sera, whose microfilaraemic status was determined by membrane filtration of 1 mL blood sample collected during night. When Mab A7 was tested, 7 out of 22 serum samples (32.0%) from amicrofilaraemic normal individuals from filariasis endemic areas showed positive reactions for filarial antigens, indicating the presence of early stage (L4) of the parasite in them. It also reacted with 84% (n=19) mf positive samples and 11% of non endemic normal serum samples (n=17). Mab A6 showed high reactivity with 86% (n=26) of mf positive serum samples, but did not react with non-endemic normal serum samples (n=17). The results, thus, indicate that the Mab A7 has potential in the detection of e/s antigens of L4 stage larvae of filarial parasites in humans, enabling early diagnosis of filariasis. Mab A6 could be used in the diagnosis of patent infection with microfilaraemia. Western blotting with Mab A7 reacted with the 29.0 kDa protein band of L4 e/s antigens of W. bancrofti.

Immobilization in alginate as a technique for the preservation of Bacillus thuringiensis var. israelensis for long-term preservation

Technique for immobilization using sodium alginate as the matrix to preserve Bacillus thuringiensis var. israelensis isolates for long time storage was developed. Two strains of B. thuringiensis var. israelensis viz., VCRC B-17 and WHO standard strain IPS-82 were immobilized in alginate matrix and preserved at 4 degrees C and when tested both were found to have maintained excellent viability and mosquito larvicidal activity for 10 years. Mosquito larvicidal activity of B-17 and IPS-82 alginate beads, in term of LC(50) values before storage was 72.07 ng/ml and 47.07 ng/ml, respectively and after storage at 4 degrees C for a period of 1 to 10 years the values ranged from 69.88 to 73.86 ng/ml with a mean of 72.38 ng/ml and 45.32 to 48.60 ng/ml with a mean of 47.49 ng/ml, respectively. Similarly spore count of the beads of the respective strains was 4.37 x 10(8) and 3.33 x 10(10) CFU/mg before storage. After storage at 4 degrees C for a period of 1 to 10 years the counts of the beads of the respective strains ranged from 4.23 x 10(8) to 4.83 x 10(8) CFU/mg (mean of 4.49 x 10(8) CFU/mg) and 3.2 x 10(10) to 3.87 x 10(10) CFU/mg (mean of 3.54 x 10(10) CFU/mg). The alginate matrix immobilization technique has many advantages over free cells are that they enhance the stability of both spores and toxin against several physicochemical conditions and confer reduced susceptibility to contamination.

Immunopathogenesis of dengue hemorrhagic fever and shock syndrome: role of TAP and HPA gene polymorphism

Clinical outcomes of dengue infection such as dengue fever (DF), dengue hemorrhagic fever (DHF), and dengue shock syndrome (DSS) could be attributed to host genetic factors. The transporters associated with antigen processing (TAP) genes are polymorphic genes located in the human leukocyte antigen (HLA) class II region and are essentially involved in class I antigen presentation. Therefore, these genes might grant susceptibility to severe dengue infection. Hence, the aim of the study was to type the TAP1 gene (using amplification refraction mutation system [ARMS] polymerase chain reaction [PCR]) and HPA1 and HPA2 gene polymorphism (by PCR-sequence specific primers) in different clinical spectrums of dengue infection. The study included 100 controls and 91 DF, 75 DHF, and 32 DSS patients. The results revealed that the frequencies of valine at TAP1 333 and HPA 1b at HPA1 were increased among DHF and DSS, respectively, in comparison to controls (p <0.05). The frequency of genotype TAP1 333 ILE/VAL (61.3%) was significantly higher in DHF compared with control (37%, p = 0.005) or DF (38.9%, p = 0.007) patients. A significantly greater proportion of DHF patients demonstrated HPA1a/1a and HPA 2a/2b genotypes than DF patients. DSS patients were more likely to be heterozygous at HPA1 than DHF (OR = 4.75, p = 0.003). A positive correlation existed between TAP1 333 and HPA1 in DHF (p = 0.017, r = 0.229). This first report on TAP and HPA gene polymorphism in dengue suggested that the heterozygous pattern at the TAP1 333 locus and HPA1a/1a and HPA2a/2b genotypes confer susceptibility to DHF and the HPA1a/1b genotype was determined to be a genetic risk factor for DSS.

Polymorphism of gp15/400 allergen gene of Wuchereria bancrofti from different regions of India endemic for lymphatic filariasis

Nematode polyprotein allergens (NPA) are lipid-binding/transport molecules that elicit elevated levels of IgE response in the infected host, leading to Th2 type of immune response. They also transport arachidonic acid and metabolites that is known to be the action of antifilarial drug, diethylcarbamazine, and hence are of great significance to the control of lymphatic filariasis. We investigated the polymorphism of gp15/400 polyprotein of 35 isolates of lymphatic filarial parasite Wuchereria bancrofti collected from different geographic locations of India. The repeat subunit of the gene was found to be highly conserved in all the isolates with only two nucleotide synonymous changes at positions 369 (A-G) and 375 (C-T). As this molecule is highly conserved and has multifarious roles in the survival and pathogenesis of the parasite, it has good potential as a target for drug, immunodulation tools and immunotherapy development.

Identification of a molecular marker for genotyping human lymphatic filarial nematode parasite Wuchereria bancrofti

In India, Mass Drug Administration is on going towards elimination of lymphatic filariasis in many areas, which might lead to intense selection pressure on the parasite populations and their genetic restructuring. This calls for molecular finger printing of Wuchereria bancrofti parasite populations at national level and monitoring genetic changes in the future. For this purpose a reliable, less expensive, rapid, and reproducible molecular tool is necessary, which is not available for W. bancrofti at this time. We identified robust molecular markers based on the comparison of random amplified polymorphic DNA (RAPD) and amplified fragment length polymorphism (AFLP) profiles and the genetic data generated from parasite populations collected from areas in Northern (Varanasi, Uttar Pradesh state), Southern (Kozhikode, Kerala State) and Central regions (Jagdalpur, Chattisgarh state) of India, where lymphatic filariasis is endemic for many decades. RAPD profiles for these parasite populations were generated using three different primers and the dendrograms constructed using the profiles were all different. In order to identify appropriate RAPD primer(s), we compared the results of RAPD with the fingerprint profile and genetic data obtained by the more reliable AFLP technique, using the parasite populations from the same areas. RAPD marker (OP8) primer produced phylogenetic data almost similar to that of AFLP analysis. The marker was able to reveal variations between the parasite populations collected from Varanasi, Kozhikode, and Jagdalpur. Most importantly, RAPD primer OP8 produced reproducible results, when tested in three different trials. In view of the limited availability of W. bancrofti parasite DNA, along with a lower cost and ease of performance, RAPD appears to be more suitable compared to AFLP at the present juncture, since complete genome information of this parasite is still not available. Thus, RAPD primer OP8 can be a very useful molecular maker for DNA finger printing of W. bancrofti populations at present.

Development of lymphatic filarial parasite Wuchereria bancrofti (Spirurida: Onchocercidae) in mosquito species (Diptera: Culicidae) fed artificially on microfilaremic blood

The efficiency of laboratory colonies of mosquitoes such as Anopheles stephensi Liston, Aedes aegypti (L.) Liverpool strain, Ae. aegypti wild type, Aedes albopictus (Skuse), Culex tritaeniorhynchus Giles, Culex sitiens Wiedemann, and Armigeres subalbatus Coquillett in supporting the development of Wuchereria bancrofti (Cobbold) (Spirurida: Onchocercidae) microfilariae to infective larvae was investigated. The mosquitoes were fed on heparinized microfilaremic human blood by using a membrane-feeding unit with Parafilm as membrane. The rate of infection, parasite development, and parasite burden were compared with that in the known vector mosquito Culex quinquefasciatus Say. Cx. quinquefasciatus showed the highest percentage of infection, followed by Ae. aegypti Liverpool strain and An. stephensi. The rate of development of the parasite was more or less similar in all the three species, and infective larvae were found on day 13. When the larvae were harvested on day 17, Cx. quinquefasciatus yielded the highest numbers, followed by Ae. aegypti Liverpool strain and An. stephensi. The percentage of infection was low, and the development was slow in Cx. tritaeniorhynchus compared with the other susceptible species. The parasite developed to second-stage larvae only by day 22 and to infective larvae by day 28. When 2-wk-old Cx. tritaeniorhynchus were fed on microfilaremic blood, they could develop the parasite to infective larvae by day 13 postfeeding. All other species of mosquitoes tested were found to be refractory to parasite development. It is shown that Cx. quinquefasciatus is the most suitable mosquito host for the production of infective larvae. However, Ae. aegypti Liverpool strain, which is commonly used for Brugia malayi filarial parasite, also can be used for generation of W. bancrofti infective larvae to circumvent the problem of maintaining two mosquito species.

Polymorphism of gp15/400 allergen gene of W. bancrofti from different regions of India endemic for lymphatic filariasis

Nematode polyprotein allergens (NPA) are lipid binding/transport molecules that elicit elevated levels of IgE response in the infected host, leading to Th2 type of immune response. They also transport arachidonic acid and its metabolites that are known to be involved in the action of antifilarial drug, Diethylcarbamazine and hence are of great significance for the control of lymphatic filariasis. We investigated the polymorphism of gp15/400 polyprotein of 35 isolates of lymphatic filarial parasite Wuchereria bancrofti collected from different geographic locations of India. The repeat sub-unit of the gene was found to be highly conserved in all the isolates with only two nucleotide synonymous changes at positions 286 (A-G) and 337 (C-T). Since this molecule is highly conserved and has multifarious roles in the survival and pathogenesis of the parasite it has good potential as a target for drug, immunodulation tool and immunotherapy development.

Isolation of Wuchereria bancrofti microfilariae from archived stained blood slides for use in genetic studies and amplification of parasite and endosymbiont genes

Information on change in genetic diversity of Wuchereria bancrofti is important in view of the launching of the Global Lymphatic Filariasis Elimination Programme, as it may have important consequences on the control operations and on the potential resurgence after their withdrawal. Since attention was not paid to generate such information when the programme was launched, use of archived parasite material will provide an opportunity to derive this information in a prospective manner. In this paper a simple and effective technique is reported for isolation of microfilariae of W. bancrofti from dried and stained slides archived for several years and their utility in analysis of genetic structure and amplification of certain genes of the parasite is tested. The method was found to be efficient in purifying mf from the dried smears and the DNA of the parasite found to be useful in studying the genetic structure of Wuchereria bancrofti populations using random amplified polymorphic DNA (RAPD)-PCR and for amplifying genes of the parasite and its endosymbiont, Wolbachia sp.

Phylogeography of human lymphatic filarial parasite, Wuchereria bancrofti in India

Wuchereria bancrofti, a nematode parasite causing human lymphatic filariasis is widely distributed in India. The phylogeography of this parasite was studied by constructing RAPD profiles of parasite populations collected from 71 microfilaria carriers residing in different geoclimatic regions of India. The analysis showed that the phylogeography of W. bancrofti populations is complex, with a high genetic divergence and gene flow among populations. The total genetic diversity (H(T)) and genetic differentiation (G(ST)) estimated for all the parasite populations were 0.0926 and 0.5859, respectively. The gene flow (Nm) between different regions indicated that two strains of W. bancrofti were prevalent in the country, one in the eastern side and the other on the western side of the Western Ghats. A highly significant genetic differentiation (F(ST) [theta] = 0.7978) was estimated between these two strains (chi 2 = 308.2789; P < 0.001). The gene flow between these strains was very low (0.2338). These two strains appear to have drifted genetically because of their geographic isolation by this thickly forested mountain range. The strain in the eastern side was found to be monophyletic in origin and is undergoing genetic divergence as the major parasite population in the country, spanning from eastern peninsular region to the northern plains. The variable geoclimatic factors and the antifilarial chemotherapeutical pressure on the parasite, which is in place for the past half a century, might have contributed for the high genetic heterogeneity its strains/populations in the country. The route of entry of the parasite into Indian sub-continent possibly appeared to be from an ancient origin from the countries of the Southeast Asian archipelago, through the eastern coastal line of the southern peninsula.