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Geary TG. New paradigms in research on Dirofilaria immitis. Parasit Vectors 2023; 16:247. [PMID: 37480077 PMCID: PMC10362759 DOI: 10.1186/s13071-023-05762-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Accepted: 03/30/2023] [Indexed: 07/23/2023] Open
Abstract
BACKGROUND Since the advent of ivermectin (along with melarsomine and doxycycline), heartworm has come to be viewed as a solved problem in veterinary medicine, diminishing investment into non-clinical research on Dirofilaria immitis. However, heartworm infections continue to pose problems for practitioners and their patients and seem to be increasing in frequency and geographic distribution. Resistance to preventative therapies (macrocyclic lactones) complicates the picture. The use of chemotherapy for other kinds of pathogens has benefitted enormously from research into the basic biology of the pathogen and on the host-pathogen interface. A lack of basic information on heartworms as parasites and how they interact with permissive and non-permissive hosts greatly limits the ability to discover new ways to prevent and treat heartworm disease. Recent advances in technical platforms will help overcome the intrinsic barriers that hamper research on D. immitis, most notably, the need for experimentally infected dogs to maintain the life cycle and provide material for experiments. Impressive achievements in the development of laboratory animal models for D. immitis will enhance efforts to discover new drugs for prevention or treatment, to characterize new diagnostic biomarkers and to identify key parasite-derived molecules that are essential for survival in permissive hosts, providing a rational basis for vaccine discovery. A 'genomics toolbox' for D. immitis could enable unprecedented insight into the negotiations between host and parasite that enable survival in a permissive host. The more we know about the pathogen and how it manipulates its host, the better able we will be to protect companion animals far into the future.
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Affiliation(s)
- Timothy G Geary
- Institute of Parasitology, McGill University, Ste-Anne-de-Bellevue, QC, Canada.
- School of Biological Sciences, Queen's University-Belfast, Belfast, Northern Ireland.
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Paul R, Ilamaran M, Khatri V, Amdare N, Reddy MVR, Kaliraj P. Immunological evaluation of fusion protein of Brugia malayi abundant larval protein transcript-2 (BmALT-2) and Tuftsin in experimental mice model. Parasite Epidemiol Control 2019; 4:e00092. [PMID: 30847408 PMCID: PMC6378782 DOI: 10.1016/j.parepi.2019.e00092] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Revised: 02/06/2019] [Accepted: 02/06/2019] [Indexed: 12/01/2022] Open
Abstract
Introduction Filariasis, a neglected tropical helminth disease needs vaccine besides mass drug administration for its successful eradication. Methods An attempt was made to produce a fusion protein (P-TUFT-ALT-2) of abundant larval transcript protein-2 and Tuftsin to enhance its immunogenicity. The fusion construct was expressed in Pichia pastoris, a nonexpensive commercial expression system. This study focused on the evaluation of immunological response produced by P-TUFT-ALT-2 in Balb/c mice. Result and discussion P-TUFT-ALT-2 showed an enhanced IgG peak titre compared to E. coli expressed E-ALT-2 and P. pastoris expressed P-ALT-2. IgG2b, IgG2a and IgG1 production were predominant indicating a balanced Th1/Th2 response. P-TUFT-ALT-2 also induced about 28% and 9.5% higher splenocyte proliferation over control and E-ALT-2 respectively. Splenocytes produced predominant IFN-γ followed by IL-5, IL-2 and IL-10 specifying a balanced Th1/Th2 response. P-TUFT-ALT-2 showed 55% to 80% with an average of 65% cytotoxicity in B. malayi L3 larvae in in vitro ADCC assay. Conclusion This experiment validates P-TUFT-ALT-2 as a potential vaccine candidate for human lymphatic filariasis.
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Affiliation(s)
- Rajkumar Paul
- Centre for Biotechnology, Anna University, Sardar Patel Road, Guindy, Chennai 600025, Tamil Nadu, India
| | - Meganathan Ilamaran
- Centre for Biotechnology, Anna University, Sardar Patel Road, Guindy, Chennai 600025, Tamil Nadu, India
| | - Vishal Khatri
- Department of Biochemistry & J.B. Tropical Disease Research Centre, Mahatma Gandhi Institute of Medical Sciences, Sevagram, Maharashtra, India
| | - Nitin Amdare
- Department of Biochemistry & J.B. Tropical Disease Research Centre, Mahatma Gandhi Institute of Medical Sciences, Sevagram, Maharashtra, India
| | - Maryada Venkata Rami Reddy
- Department of Biochemistry & J.B. Tropical Disease Research Centre, Mahatma Gandhi Institute of Medical Sciences, Sevagram, Maharashtra, India
| | - Perumal Kaliraj
- Centre for Biotechnology, Anna University, Sardar Patel Road, Guindy, Chennai 600025, Tamil Nadu, India
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Paul R, Karthik S, Vimalraj P, Meenakshisundaram S, Kaliraj P. Cloning, large-scale production and characterization of fusion protein (P-TUFT-ALT-2) of Brugian abundant larval transcript-2 with tuftsin in Pichia pastoris. Prep Biochem Biotechnol 2018; 48:823-833. [PMID: 30303452 DOI: 10.1080/10826068.2018.1514511] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Lymphatic filariasis is a "disease of poor people" due to a large section of affected people with economic backwardness. Therefore, successful elimination of this disease requires a cost-effective prophylactic agent such as vaccine along with conventional drugs. The Abundant Larval Transcript-2 (BmALT-2) protein of Brugia malayi has been recognized as the most potential vaccine candidate. Tuftsin, a tetra-peptide immunopotentiator has already shown the enhanced immunogenicity of various vaccine antigens in earlier studies. This study deals with the development of tuft-alt-2 fusion construct and a suitable culture condition for its large-scale production in Pichia pastoris. The recombinant P. pastoris/tuft-alt-2 with 9-11 copies of the gene construct exhibited the highest expression level. The molecular weight of P-TUFT-ALT-2 was determined as 28 kDa in SDS-PAGE including 3 kDa due to glycosylation. The dry cell biomass was 57.4 gL-1 in the bioreactor. The P-TUFT-ALT-2 expression was measured as about 35 mg L-1, which was 102% higher than flask culture. The P-TUFT-ALT-2 produced the highest 65,000 IgG peak titer in Balb/c mice. Moreover, P-TUFT-ALT-2 exhibited about 9.46% higher splenocyte proliferation than E. coli expressed E-ALT-2 alone. The enhanced secreted production of P-TUFT-ALT-2 in bioreactor would step up its commercialization as an inexpensive commercial vaccine for human lymphatic filariasis.
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Affiliation(s)
- Rajkumar Paul
- a Centre for Biotechnology , Anna University , Chennai , India
| | | | | | | | - Perumal Kaliraj
- a Centre for Biotechnology , Anna University , Chennai , India
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Paul R, Saha G, Selvaraja V, Kaliraj P. Cloning, expression and characterization of Brugia malayi abundant larval protein transcript-2 (BmALT-2) expressed in Pichia pastoris. BIOTECHNOL BIOTEC EQ 2016. [DOI: 10.1080/13102818.2016.1264274] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Affiliation(s)
- Rajkumar Paul
- Centre for Biotechnology, Anna University, Chennai, India
| | - Gundappa Saha
- Centre for Biotechnology, Anna University, Chennai, India
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Ramachandran S, Kumar MP, Rami RMV, Chinnaiah HB, Nutman T, Kaliraj P, McCarthy J. The Larval Specific Lymphatic Filarial ALT-2: Induction of Protection Using Protein or DNA Vaccination. Microbiol Immunol 2013; 48:945-55. [PMID: 15611611 DOI: 10.1111/j.1348-0421.2004.tb03624.x] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Genes from the infective stage of lymphatic filarial parasites expressed at the time of host invasion have been identified as potential vaccine candidates. By screening an L3 cDNA library with sera from uninfected longstanding residents of an area endemic for onchocerciasis, so-called "endemic normals" (EN), we have cloned and characterized one such gene termed the abundant larval transcript two (ALT-2). The stage specificity of ALT-2 gene transcription and protein synthesis was confirmed by PCR using genespecific primers, and by western blot analysis of protein extracts from various stages of the parasite life cycle using specific antisera. Significant differences in antibody response to the recombinant ALT-2 were observed in endemic populations with differing clinical manifestations of lymphatic filariasis with an antibody response present in sera from 18 of 25 (72%) EN subjects compared to 9 of 25 (36%) with subclinical microfilaracmia (MF) and 14 of 25 (52%) of those with chronic lymphatic obstruction (CP) (P=0.01 for comparison of EN to CP or to MF). This differential responsiveness suggests that the protective immunity postulated to account for their uninfected status might be associated with a response to this protein. When the utility of ALT-2 as a vaccine candidate was tested in a murine model using either recombinant protein or a DNA vaccine construct, statistically significant protection was observed when compared to a control filarial gene product expressed across all stages of the parasite lifecycle (SXP-1; P=0.02 for protein and P=0.01 for the DNA vaccine) or compared to adjuvant alone. This level of protection indicates that this vaccine is a promising candidate for further development.
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Geary J, Satti M, Moreno Y, Madrill N, Whitten D, Headley SA, Agnew D, Geary T, Mackenzie C. First analysis of the secretome of the canine heartworm, Dirofilaria immitis. Parasit Vectors 2012; 5:140. [PMID: 22781075 PMCID: PMC3439246 DOI: 10.1186/1756-3305-5-140] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2012] [Accepted: 06/13/2012] [Indexed: 12/18/2022] Open
Abstract
Background The characterization of proteins released from filariae is an important step in addressing many of the needs in the diagnosis and treatment of these clinically important parasites, as well as contributing to a clearer understanding of their biology. This report describes findings on the proteins released during in vitro cultivation of adult Dirofilaria immitis , the causative agent of canine and feline heartworm disease. Differences in protein secretion among nematodes in vivo may relate to the ecological niche of each parasite and the pathological changes that they induce. Methods The proteins in the secretions of cultured adult worms were run on Tris-Glycine gels, bands separated and peptides from each band analysed by ultra mass spectrometry and compared with a FastA dataset of predicted tryptic peptides derived from a genome sequence of D. immitis. Results This study identified 110 proteins. Of these proteins, 52 were unique to D. immitis . A total of 23 (44%) were recognized as proteins likely to be secreted. Although these proteins were unique, the motifs were conserved compared with proteins secreted by other nematodes. Conclusion The present data indicate that D. immitis secretes proteins that are unique to this species, when compared with Brugia malayi. The two major functional groups of molecules represented were those representing cellular and of metabolic processes. Unique proteins might be important for maintaining an infection in the host environment, intimately involved in the pathogenesis of disease and may also provide new tools for the diagnosis of heartworm infection.
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Affiliation(s)
- James Geary
- Department of Pathobiology and Diagnostic Investigation, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824, USA
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Immune responses generated by intramuscular DNA immunization of Brugia malayi transglutaminase (BmTGA) in mice. Parasitology 2009; 136:887-94. [DOI: 10.1017/s0031182009006143] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
SUMMARYAn attempt was made to evaluate the immunoprophylactic efficacy of Brugia malayi transglutaminase (BmTGA) as a DNA vaccine, for human lymphatic filariasis. BmTGA was cloned and characterized in the DNA vaccine vector pVAX1. Further, the tissue distribution study of the DNA construct, pVAX-TGA was carried out in mice and the DNA vaccine was shown to be efficiently distributed to all the organs, was accessible to the immune system, and at the same time was metabolized quickly and did not pose problems of toxicity. Intramuscular immunization in mice showed significant antibody production and splenocyte proliferation upon antigenic stimulation. The immune responses were biased towards the Th1 arm, as evaluated in terms of isotype antibody distribution and cytokine profile. Thus, analysis of the humoral and cellular immune responses indicated that BmTGA is a potent immunogen. However, protection studies as determined by the micropore chamber method using live microfilarial larvae, showed that the DNA vaccine could confer only partial protection in the mouse model. We conclude that despite the induction of sufficient humoral and cellular immune responses, BmTGA as a DNA vaccine could not confer much protection against subsequent challenge and other aspects of the immune responses need to be further investigated.
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Anand SB, Gnanasekar M, Thangadurai M, Prabhu PR, Kaliraj P, Ramaswamy K. Immune response studies with Wuchereria bancrofti vespid allergen homologue (WbVAH) in human lymphatic filariasis. Parasitol Res 2007; 101:981-8. [PMID: 17558521 PMCID: PMC2763210 DOI: 10.1007/s00436-007-0571-2] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2007] [Accepted: 04/26/2007] [Indexed: 10/23/2022]
Abstract
A homologue of Brugia malayi venom allergen (BmVAH) was cloned from the infective stages (L3) of Wuchereria bancrofti. Sequence analysis showed 90% sequence identity between WbVAH and BmVAH. Recombinant WbVAH was then expressed and purified. VAH from other nematode parasites is being evaluated as potential vaccine candidates. Because W. bancrofti infections are more prevalent than B. malayi, it will significantly benefit using W. bancrofti antigens for vaccine development. In this study, we have evaluated the human immune responses to rWbVAH in putatively immune individuals who live in the endemic regions (endemic normal, EN) to determine the vaccine potential of WbVAH. These responses were then compared to those in infected individuals (microfilaraemic, MF and chronic pathology, CP). Results show that EN subjects carry WbVAH-specific IgG1, IgG2, and IgG3 circulating antibodies. It is interesting to note that CP patients also carried antibodies against WbVAH that was mainly of the IgG3 isotype. Peripheral blood mononuclear cells (PBMC) from EN individuals responded strongly to rWbVAH by proliferating and secreting IFN-gamma. PBMC from MF patients also proliferated in response to rWbVAH but secreted mainly IL-10. Thus, there was a clear dichotomy in the cytokine production by infected patients vs individuals who are putatively immune (EN). Although vaccine potential of WbVAH has not been established yet, our findings suggest that WbVAH mediated immune responses in EN individuals is primarily Th1-biased. Further vaccination studies are underway in animal models to determine the role of WbVAH in protective immunity against W. bancrofti and B. malayi infections.
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Marcos-Atxutegi C, Kramer LH, Fernandez I, Simoncini L, Genchi M, Prieto G, Simón F. Th1 response in BALB/c mice immunized with Dirofilaria immitis soluble antigens: a possible role for Wolbachia? Vet Parasitol 2003; 112:117-30. [PMID: 12581590 DOI: 10.1016/s0304-4017(02)00419-3] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The immune response to filarial infection has been shown to be of both the Th1 and Th2 types. Studies aimed at developing immunization strategies against Dirofilaria immitis infection in dogs have shown that protection against larval challenge is of the Th2 type and that several proteins are recognized by immunized or infected animals. The bacterial endosymbiont Wolbachia, harbored by many filarial species including D. immitis, has recently been shown to interact with the host immune system. Specific antibodies to the Wolbachia recombinant surface protein (WSPr) have been observed in cats infected with D. immitis. In this work the authors have determined cytokine production and antibody response in BALB/c mice inoculated with soluble antigens from third stage larvae or from adult worms of D. immitis. Inoculated mice first produced IFN-gamma followed by a peak in IL-4. Specific antibodies to the Wolbachia protein WSPr were exclusively IgG2a, while antibodies against peptides derived from antigens of D. immitis were in the IgG1 and IgE subclasses. The cytokine response is thus similar to that reported for other filarial infection, where Th1 response shifts towards Th2. Antibody response indicates that Wolbachia may induce preferentially a Th1 response during filarial infection, while nematode antigens may be involved in Th2 response. There is thus an overall agreement with current opinions on the role of bacterial versus nematode molecules in driving the response towards the different directions.
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Affiliation(s)
- C Marcos-Atxutegi
- Laboratorio de Parasitologia, Facultad de Farmacia, Universidad de Salamanca, Avda. Campo Charro s/n, 37007 Salamanca, Spain
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Abstract
Lymphatic filariasis has afflicted people in the tropical areas of the world for thousands of years but even up to comparatively recent times it has been poorly understood and its importance under recognised. In the last 2 decades or so there has been a flurry of activity in filariasis research, which has provided new insights into the global problem of filariasis, the pathogenesis of filarial disease, diagnosis and control.
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Affiliation(s)
- Wayne D Melrose
- Lymphatic Filariasis Support Centre, School of Public Health and Tropical Medicine, James Cook University, Townsville, QLD 4811, Australia.
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Abstract
Despite the advances of modern medicine, the threat of chronic illness, disfigurement, or death that can result from parasitic infection still affects the majority of the world population, retarding economic development. For most parasitic diseases, current therapeutics often leave much to be desired in terms of administration regime, toxicity, or effectiveness and potential vaccines are a long way from market. Our best prospects for identifying new targets for drug, vaccine, and diagnostics development and for dissecting the biological basis of drug resistance, antigenic diversity, infectivity and pathology lie in parasite genome analysis, and international mapping and gene discovery initiatives are under way for a variety of protozoan and helminth parasites. These are far from ideal experimental organisms, and the influence of biological and genomic characteristics on experimental approaches is discussed, progress is reviewed and future prospects are examined.
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Affiliation(s)
- D A Johnston
- Department of Zoology, Natural History Museum, London, United Kingdom
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Tsuji N, Morales TH, Ozols VV, Carmody AB, Chandrashekar R. Molecular characterization of a calcium-binding protein from the filarial parasite Dirofilaria immitis. Mol Biochem Parasitol 1998; 97:69-79. [PMID: 9879888 DOI: 10.1016/s0166-6851(98)00131-5] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
A full length D. immitis cDNA (nDiCal) encoding a protein with significant similarity to the calreticulin protein family was isolated from a 6-day fourth-stage larval cDNA expression library by immunoscreening, using serum from a rabbit immunized by repeated injection of small numbers of third-stage larvae. nDiCal is 1538 bp long and contains the 21 bp nematode splice leader sequence SL1 at the 5' end. nDiCal encodes for a protein (pDiCal) with a predicted molecular mass of 46 kDa. pDiCal sequence analysis revealed similarities with calreticulin, a protein that typically resides in the endoplasmic reticulum. pDiCal possesses three consensus sequences of the calreticulin family of proteins: a neutral N-terminal region with a putative signal sequence; a proline- and tryptophan-rich P region; and a highly acidic C-terminal region. A 45Ca2+-overlay assay showed that recombinant pDiCal (rDiCal) is a Ca2+-binding protein. Antibodies to rDiCal identified a 56 kDa native antigen in all developmental stages including the excretory-secretory products derived from larvae and adult worms. Localization studies demonstrated the ubiquitous presence of pDiCal with intense expression in the hypodermis and syncitial muscle cells in both male and female adult worms. Labeling was also seen in the developing embryos within the uterus of the female worms. Sera from immune as well as chronically-infected microfilaremic dogs contained antibodies that bind rDiCal. In addition, immunoblot analysis showed that serum from a rabbit immunized with L3 cuticles reacted with rDiCal.
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Affiliation(s)
- N Tsuji
- Heska Corporation, Fort Collins, CO 80525, USA
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Langy S, Plichart C, Luquiaud P, Williams SA, Nicolas L. The immunodominant Brugia malayi paramyosin as a marker of current infection with Wuchereria bancrofti adult worms. Infect Immun 1998; 66:2854-8. [PMID: 9596759 PMCID: PMC108281 DOI: 10.1128/iai.66.6.2854-2858.1998] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/1997] [Accepted: 03/18/1998] [Indexed: 02/07/2023] Open
Abstract
The full-length cDNA sequence encoding Brugia malayi L3 paramyosin has been isolated by immunoscreening a cDNA library with a mouse antiserum raised against Wuchereria bancrofti L3 infective larvae. A recombinant truncated form of paramyosin was expressed as a glutathione S-transferase fusion protein and used to evaluate humoral responses of adults from a W. bancrofti-endemic area in French Polynesia according to their parasitological status. Immunoglobulin G4 (IgG4) preferentially bound to paramyosin in W. bancrofti-parasitized individuals, in contrast to unparasitized individuals, who harbored neither microfilaria nor Og4C3 adult worm circulating antigen. Reduction of the anti-paramyosin IgG4 titer following combined chemotherapy with diethylcarbamazine and ivermectin was significantly correlated with a reduction in the adult worm burden. This indicates that the presence of paramyosin-reactive IgG4 is associated with the presence of parasites and that reduction can be used as an immunological marker for W. bancrofti clearance.
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Affiliation(s)
- S Langy
- Institut Territorial de Recherches Médicales Louis Malardé, Papeete, Tahiti, French Polynesia
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