1.

Department of Biochemistry and J B Tropical Disease Research Centre, Mahatma Gandhi Institute of Medical Sciences, Sevagram 442 102, Wardha, Maharashtra, India.

Lymphatic filariasis caused mainly by infection from W. bancrofti and B. malayi remains a major cause of clinical morbidity in tropical and subtropical countries. Analysis of B.malayi mf. infective larval and adult worm lysates for the activity of enzymes led to the demonstration of activities of three key enzymes of carbohydrate metabolism viz. Malate dehydrogenase (MDH), Malic enzyme (ME) and Glucose -6- phosphate dehydrogenase (G6PDH) in all the three stages of the parasite. The specific activity of all the three dehydrogenases was significantly high in mf lysate compared to their activity in lysates of the two stages (P<0.001). Analysis by native polyacrylamide gel electrophoresis ( PAGE) using 7.5% non-gradient gel showed the presence of two isoforms of each of the three enzymes ( MDH, ME & G6PDH) in mf lysate, while only one form of each enzyme was present in L3 larval and adult worm lysates. Further proteolytic enzyme activity was demonstrated both in microfilarial and infective larval lysates of B.malayi. while both mf and L3 larval lysates showed optimal protease activity at alkaline pH 9.0 . the mf lysate showed increased activity also at pH 3.0. The infective larval lysate was markedly inhibited by Tosylamide –L-Phenylalanine chromethyl ketone (TPCK), a thiol protease inhibitor, while the protease activity in mf lysate was significantly inhibited by both TPCK and a serine protease inhibitor Phenyl Methyl Sulphonyl Flouride (PMSF). In sodium do-decyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE), using gelatin copolymerized gel, the microfilarial lysate showed 3 protease molecules of 40 kDa, 180 kDa and 200 kDa and L₃ larval lysate had 6 protease molecules of 18,25, 37, 49, 70 and 200 kDa size.

2.

Dabir P, Dabir S, Siva Prasad BV, Reddy MVR.  Isolation and analysis of partial cDNA sequence coding for superoxide dismutase in Wuchereria bancrofti.  Infection. Genetics and Evolution 2005. (PMID: 16199210).

Department of Biochemistry and J B Tropical Disease Research Centre, Mahatma Gandhi Institute of Medical Sciences, Sevagram 442 102, Wardha, Maharashtra, India.

Molecular characterization of Wuchereria bancrofti is essential to develop suitable anti-filarial drugs and vaccines. We describe here isolation, sequence analysis and cloning of a partial cDNA of an enzyme superoxide dismutase from this parasite. The immunoscreening of a lambda zap W. bancrofti microfilarial (Mf) cDNA library with microfilaremic sera had resulted in the isolation of several seroreactive clones including, WbSOD. This clone contained a 309bp insert and showed significant nucleotide and deduced amino acid sequence homologies to the superoxide dismutases of other nematode parasites. The antioxidant property of this enzyme may have important contribution in the defense mechanism of the parasite against host immune response

3.

Hoerauf A, Satoguina J, Saeftel M, Specht S. Immunomodulation by filarial nematodes. Parasite Immunol. 2005 Oct-Nov;27(10-11):417-29. Review. 

Institute for Medical Parasitology, University Clinic Bonn, Sigmund Freud Strasse 25, 53105 Bonn, Germanyhoerauf@parasit.meb.uni-bonn.de  In order to chronically infect their hosts, filarial nematodes have generated a range of strategies to evade and down-modulate the host's immune system. The recent concept of suppression of immune responses by regulatory T cells has in part benefited from examinations in human and murine filariasis. Its further development in basic immunology animal models has in turn helped to better understand down-regulatory immune mechanisms in filariasis. Thus, filarial nematodes orchestrate down-regulation by inducing regulatory T cells and alternatively activated macrophages, which are able to suppress both Th1 and Th2 responses. Regulatory T cells can also induce the secretion of IgG4 from B cells as another arm of modulation. Dendritic cells are down-regulated upon first encounter with infective L3 larvae. Failure to respond to down-regulatory induction is based on genetic traits in hosts and leads to reduced parasite loads, albeit at the expense of pathology and disease. Since down- regulation in chronically and heavily infected hosts extends to third-party antigens, it is essential to analyse the impact of filarial infection for vaccination, allergy and important coinfections such as malaria, in order to foresee and avert potentially disastrous consequences of filariasis control programmes.

4

Nuchprayoon S, Junpee A, Poovorawan Y, Scott AL. Detection and differentiation of filarial parasites by universal primers and polymerase chain reaction-restriction fragment length polymorphism analysis. Am J Trop Med Hyg. 2005 Nov;73(5):895-900.

Lymphatic Filariasis Research Unit, Department of Parasitology and Department of Pediatrics, Chula Medical Research Center, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand. fmedstt@md2.md.chula.ac.th

Filarial nematode parasites are a serious cause of morbidity in humans and animals. Identification of filarial infection using traditional morphologic criteria can be difficult and lead to misdiagnosis. We report on a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP)-based method to detect and differentiate a broad range of filarial species in a single PCR. The first internal transcribed spacer 1 (ITS1) along with the flanking 18S and 5.8S ribosomal DNA (rDNA) were isolated and cloned from Wuchereria bancrofti, Brugia malayi, and Brugia pahangi. Sequence analysis identified conserved sites in the 18S and 5.8S rDNA sequence that could be used as universal priming sites to generate ITS1- distinctive PCR products that were useful for distinguishing filariae at the genus level. The addition of a digestion of the ITS1 PCR product with the restriction endonuclease Ase I generated a fragment profile that allowed differentiation down to the species level for W. bancrofti, B. malayi, B. pahangi, Dirofilaria immitis, and D. repens. The PCR-RFLP of ITS1 rDNA will be useful in diagnosing and differentiating filarial parasites in human, animal reservoir hosts, and mosquito vectors in disease-endemic areas.