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Shah JS, Caoili E, Patton MF, Tamhankar S, Myint MM, Poruri A, Mark O, Horowitz RI, Ashbaugh AD, Ramasamy R. Combined Immunofluorescence (IFA) and Fluorescence In Situ Hybridization (FISH) Assays for Diagnosing Babesiosis in Patients from the USA, Europe and Australia. Diagnostics (Basel) 2020; 10:diagnostics10100761. [PMID: 32998244 PMCID: PMC7650773 DOI: 10.3390/diagnostics10100761] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 09/18/2020] [Accepted: 09/27/2020] [Indexed: 11/16/2022] Open
Abstract
Apicomplexan parasites of the genus Babesia cause babesiosis in humans and animals worldwide. Human babesiosis is a predominantly zoonotic disease transmitted by hard ticks that is of increasing health concern in the USA and many other countries. Microscopic examination of stained blood smears, detection of serum antibodies by immunoassays and identification of parasite nucleic acid in blood by qPCR and fluorescence in situ hybridization (FISH) are some methods available for diagnosing babesiosis. This study investigated the use of a Babesia genus-specific FISH test for detecting Babesia parasites in blood smears and immunofluorescence assay (IFA) for detecting serum antibodies to Babesia duncani and Babesia microti, two common species that cause human babesiosis in the USA. The findings with clinical samples originating from USA, Australia, Europe and elsewhere demonstrate that the parallel use of Babesia genus-specific FISH and IFA tests for B. duncani and B. microti provides more useful diagnostic information in babesiosis and that B. duncani infections are more widespread globally than presently recognized.
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Affiliation(s)
- Jyotsna S. Shah
- ID-FISH Technology Inc., Milpitas, CA 95035, USA
- IGenex Inc., 556 Gibraltar Drive, Milpitas, CA 95035, USA; (E.C.); (M.F.P.); (S.T.); (M.M.M.); (A.P.); (O.M.)
- Correspondence: (J.S.S.); (R.R.)
| | - Eddie Caoili
- IGenex Inc., 556 Gibraltar Drive, Milpitas, CA 95035, USA; (E.C.); (M.F.P.); (S.T.); (M.M.M.); (A.P.); (O.M.)
| | - Marie Fe Patton
- IGenex Inc., 556 Gibraltar Drive, Milpitas, CA 95035, USA; (E.C.); (M.F.P.); (S.T.); (M.M.M.); (A.P.); (O.M.)
| | - Snehal Tamhankar
- IGenex Inc., 556 Gibraltar Drive, Milpitas, CA 95035, USA; (E.C.); (M.F.P.); (S.T.); (M.M.M.); (A.P.); (O.M.)
| | - Mu Mu Myint
- IGenex Inc., 556 Gibraltar Drive, Milpitas, CA 95035, USA; (E.C.); (M.F.P.); (S.T.); (M.M.M.); (A.P.); (O.M.)
| | - Akhila Poruri
- IGenex Inc., 556 Gibraltar Drive, Milpitas, CA 95035, USA; (E.C.); (M.F.P.); (S.T.); (M.M.M.); (A.P.); (O.M.)
| | - Olivia Mark
- IGenex Inc., 556 Gibraltar Drive, Milpitas, CA 95035, USA; (E.C.); (M.F.P.); (S.T.); (M.M.M.); (A.P.); (O.M.)
| | - Richard I. Horowitz
- Hudson Valley Healing Arts Center, New York, NY 12538, USA;
- HHS Subcommittee on Babesia and Tick-Borne Pathogens, US Department of Health and Human Services, Washington, DC 20201, USA
| | - Alan D. Ashbaugh
- College of Medicine, University of Cincinnati, Cincinnati, OH 45221, USA;
| | - Ranjan Ramasamy
- ID-FISH Technology Inc., Milpitas, CA 95035, USA
- Correspondence: (J.S.S.); (R.R.)
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A Fluorescence in Situ Hybridization (FISH) Test for Diagnosing Babesiosis. Diagnostics (Basel) 2020; 10:diagnostics10060377. [PMID: 32517217 PMCID: PMC7344499 DOI: 10.3390/diagnostics10060377] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 05/23/2020] [Accepted: 06/02/2020] [Indexed: 11/16/2022] Open
Abstract
Apicomplexan parasites of the genus Babesia cause babesiosis in humans and animals. The microscopic examination of stained blood smears, detection of serum antibodies by immunoassays, and PCR-based identification of parasite nucleic acid in blood are common laboratory methods for diagnosing babesiosis. The present study evaluated a commercially available Babesia genus-specific fluorescence in situ hybridization (FISH) test for detecting Babesia parasites in blood smears. The FISH test detected Babesia duncani and Babesia microti, two common species that cause human infections in the USA, and other Babesia species of human and veterinary importance in less than two hours. The Babesia genus-specific FISH test supplements other existing laboratory methods for diagnosing babesiosis and may be particularly useful in resource-limited laboratories.
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Pallikkuth S, Chaudhury S, Lu P, Pan L, Jongert E, Wille-Reece U, Pahwa S. A delayed fractionated dose RTS,S AS01 vaccine regimen mediates protection via improved T follicular helper and B cell responses. eLife 2020; 9:51889. [PMID: 32342859 PMCID: PMC7213985 DOI: 10.7554/elife.51889] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2019] [Accepted: 04/14/2020] [Indexed: 12/15/2022] Open
Abstract
Malaria-071, a controlled human malaria infection trial, demonstrated that administration of three doses of RTS,S/AS01 malaria vaccine given at one-month intervals was inferior to a delayed fractional dose (DFD) schedule (62.5% vs 86.7% protection, respectively). To investigate the underlying immunologic mechanism, we analyzed the B and T peripheral follicular helper cell (pTfh) responses. Here, we show that protection in both study arms was associated with early induction of functional IL-21-secreting circumsporozoite (CSP)-specific pTfh cells, together with induction of CSP-specific memory B cell responses after the second dose that persisted after the third dose. Data integration of key immunologic measures identified a subset of non-protected individuals in the standard (STD) vaccine arm who lost prior protective B cell responses after receiving the third vaccine dose. We conclude that the DFD regimen favors persistence of functional B cells after the third dose.
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Affiliation(s)
- Suresh Pallikkuth
- Department of Microbiology and Immunology, University of Miami Miller School of Medicine, Miami, United States
| | - Sidhartha Chaudhury
- Biotechnology HPC Software Applications Institute, Telemedicine and Advanced Technology Research Center, U.S. Army Medical Research and Development Command, Fort Detrick, United States
| | - Pinyi Lu
- Biotechnology HPC Software Applications Institute, Telemedicine and Advanced Technology Research Center, U.S. Army Medical Research and Development Command, Fort Detrick, United States.,Henry M. Jackson Foundation for the Advancement of Military Medicine, Rockville, United States
| | - Li Pan
- Department of Microbiology and Immunology, University of Miami Miller School of Medicine, Miami, United States
| | | | | | - Savita Pahwa
- Department of Microbiology and Immunology, University of Miami Miller School of Medicine, Miami, United States
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Line Immunoblot Assay for Tick-Borne Relapsing Fever and Findings in Patient Sera from Australia, Ukraine and the USA. Healthcare (Basel) 2019; 7:healthcare7040121. [PMID: 31640151 PMCID: PMC6955669 DOI: 10.3390/healthcare7040121] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Revised: 09/25/2019] [Accepted: 10/16/2019] [Indexed: 12/22/2022] Open
Abstract
Tick-borne relapsing fever (TBRF) is caused by spirochete bacteria of the genus Borrelia termed relapsing fever Borreliae (RFB). TBRF shares symptoms with Lyme disease (LD) caused by related Lyme disease Borreliae (LDB). TBRF and LD are transmitted by ticks and occur in overlapping localities worldwide. Serological detection of antibodies used for laboratory confirmation of LD is not established for TBRF. A line immunoblot assay using recombinant proteins from different RFB species, termed TBRF IB, was developed and its diagnostic utility investigated. The TBRF IBs were able to differentiate between antibodies to RFB and LDB and had estimated sensitivity, specificity, and positive and negative predictive values of 70.5%, 99.5%, 97.3%, and 93.4%, respectively, based on results with reference sera from patients known to be positive and negative for TBRF. The use of TBRF IBs and analogous immunoblots for LD to test sera of patients from Australia, Ukraine, and the USA with LD symptoms revealed infection with TBRF alone, LD alone, and both TBRF and LD. Diagnosis by clinical criteria alone can, therefore, underestimate the incidence of TBRF. TBRF IBs will be useful for laboratory confirmation of TBRF and understanding its epidemiology worldwide.
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Tannous S, Ghanem E. A bite to fight: front-line innate immune defenses against malaria parasites. Pathog Glob Health 2018; 112:1-12. [PMID: 29376476 DOI: 10.1080/20477724.2018.1429847] [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: 12/20/2022] Open
Abstract
Malaria infection caused by Plasmodium parasites remains a major health burden worldwide especially in the tropics and subtropics. Plasmodium exhibits a complex life cycle whereby it undergoes a series of developmental stages in the Anopheles mosquito vector and the vertebrate human host. Malaria severity is mainly attributed to the genetic complexity of the parasite which is reflected in the sophisticated mechanisms of invasion and evasion that allow it to overcome the immune responses of both its invertebrate and vertebrate hosts. In this review, we aim to provide an updated, clear and concise summary of the literature focusing on the interactions of the vertebrate innate immune system with Plasmodium parasites, namely sporozoites, merozoites, and trophozoites. The roles of innate immune factors, both humoral and cellular, in anti-Plasmodium defense are described with particular emphasis on the contribution of key innate players including neutrophils, macrophages, and natural killer cells to the clearance of liver and blood stage parasites. A comprehensive understanding of the innate immune responses to malaria parasites remains an important goal that would dramatically help improve the design of original treatment strategies and vaccines, both of which are urgently needed to relieve the burden of malaria especially in endemic countries.
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Affiliation(s)
- Stephanie Tannous
- a Faculty of Natural and Applied Sciences, Department of Sciences , Notre Dame University , Louaize , Lebanon
| | - Esther Ghanem
- a Faculty of Natural and Applied Sciences, Department of Sciences , Notre Dame University , Louaize , Lebanon
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Shah JS, D' Cruz I, Ward S, Harris NS, Ramasamy R. Development of a sensitive PCR-dot blot assay to supplement serological tests for diagnosing Lyme disease. Eur J Clin Microbiol Infect Dis 2017; 37:701-709. [PMID: 29282568 PMCID: PMC5978905 DOI: 10.1007/s10096-017-3162-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Accepted: 12/06/2017] [Indexed: 11/28/2022]
Abstract
Laboratory diagnosis of Lyme disease is difficult and presently dependent on detecting Borrelia burgdorferi-specific antibodies in patient serum with the disadvantage that the immune response to B. burgdorferi can be weak or variable, or alternatively, the slow and inefficient culture confirmation of B. burgdorferi. PCR tests have previously shown poor sensitivity and are not routinely used for diagnosis. We developed a sensitive and specific Lyme Multiplex PCR-dot blot assay (LM-PCR assay) applicable to blood and urine samples to supplement western blot (WB) serological tests for detecting B. burgdorferi infection. The LM-PCR assay utilizes specific DNA hybridization to purify B. burgdorferi DNA followed by PCR amplification of flagellin and OspA gene fragments and their detection by southern dot blots. Results of the assay on 107 and 402 clinical samples from patients with suspected Lyme disease from Houston, Texas or received at the IGeneX laboratory in Palo Alto, California, respectively, were analyzed together with WB findings. The LM-PCR assay was highly specific for B. burgdorferi. In the Texas samples, 23 (21.5%) patients antibody-negative in WB assays by current US Centers for Disease Control (CDC) recommended criteria were positive by LM-PCR performed on urine, serum or whole blood samples. With IGeneX samples, of the 402 LM-PCR positive blood samples, only 70 met the CDC criteria for positive WBs, while 236 met IGeneX criteria for positive WB. Use of the LM-PCR assay and optimization of current CDC serological criteria can improve the diagnosis of Lyme disease.
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Affiliation(s)
- J S Shah
- IGeneX Inc., 795 San Antonio Road, Palo Alto, CA, 94303, USA.
| | - I D' Cruz
- IGeneX Inc., 795 San Antonio Road, Palo Alto, CA, 94303, USA
| | - S Ward
- IGeneX Inc., 795 San Antonio Road, Palo Alto, CA, 94303, USA
| | - N S Harris
- IGeneX Inc., 795 San Antonio Road, Palo Alto, CA, 94303, USA
| | - R Ramasamy
- IGeneX Inc., 795 San Antonio Road, Palo Alto, CA, 94303, USA
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Maskus DJ, Królik M, Bethke S, Spiegel H, Kapelski S, Seidel M, Addai-Mensah O, Reimann A, Klockenbring T, Barth S, Fischer R, Fendel R. Characterization of a novel inhibitory human monoclonal antibody directed against Plasmodium falciparum Apical Membrane Antigen 1. Sci Rep 2016; 6:39462. [PMID: 28000709 PMCID: PMC5175200 DOI: 10.1038/srep39462] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Accepted: 11/22/2016] [Indexed: 01/07/2023] Open
Abstract
Malaria remains a major challenge to global health causing extensive morbidity and mortality. Yet, there is no efficient vaccine and the immune response remains incompletely understood. Apical Membrane Antigen 1 (AMA1), a leading vaccine candidate, plays a key role during merozoite invasion into erythrocytes by interacting with Rhoptry Neck Protein 2 (RON2). We generated a human anti-AMA1-antibody (humAbAMA1) by EBV-transformation of sorted B-lymphocytes from a Ghanaian donor and subsequent rescue of antibody variable regions. The antibody was expressed in Nicotiana benthamiana and in HEK239-6E, characterized for binding specificity and epitope, and analyzed for its inhibitory effect on Plasmodium falciparum. The generated humAbAMA1 shows an affinity of 106-135 pM. It inhibits the parasite strain 3D7A growth in vitro with an expression system-independent IC50-value of 35 μg/ml (95% confidence interval: 33 μg/ml-37 μg/ml), which is three to eight times lower than the IC50-values of inhibitory antibodies 4G2 and 1F9. The epitope was mapped to the close proximity of the RON2-peptide binding groove. Competition for binding between the RON2-peptide and humAbAMA1 was confirmed by surface plasmon resonance spectroscopy measurements. The particularly advantageous inhibitory activity of this fully human antibody might provide a basis for future therapeutic applications.
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Affiliation(s)
- Dominika J. Maskus
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany
- Institute for Molecular Biotechnology, RWTH Aachen University, Aachen, Germany
| | - Michał Królik
- Institute for Molecular Biotechnology, RWTH Aachen University, Aachen, Germany
| | - Susanne Bethke
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany
| | - Holger Spiegel
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany
| | - Stephanie Kapelski
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany
| | - Melanie Seidel
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany
| | - Otchere Addai-Mensah
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany
- Institute for Molecular Biotechnology, RWTH Aachen University, Aachen, Germany
- Faculty of Allied Health Sciences, Kwame Nkrumah University of Science and Technology, KNUST, Kumasi, Ghana
| | - Andreas Reimann
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany
| | - Torsten Klockenbring
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany
| | - Stefan Barth
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany
- Institute for Applied Medical Engineering at RWTH Aachen University and Hospital, Department of Experimental Medicine and Immunotherapy, Aachen, Germany
| | - Rainer Fischer
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany
- Institute for Molecular Biotechnology, RWTH Aachen University, Aachen, Germany
| | - Rolf Fendel
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany
- Institute for Molecular Biotechnology, RWTH Aachen University, Aachen, Germany
- Institute for Applied Medical Engineering at RWTH Aachen University and Hospital, Department of Experimental Medicine and Immunotherapy, Aachen, Germany
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Radin K, Clement F, Jongert E, Sterckx YGJ, Ockenhouse C, Regules J, Lemiale F, Leroux-Roels G. A monoclonal antibody-based immunoassay to measure the antibody response against the repeat region of the circumsporozoite protein of Plasmodium falciparum. Malar J 2016; 15:543. [PMID: 27825382 PMCID: PMC5101676 DOI: 10.1186/s12936-016-1596-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2016] [Accepted: 10/31/2016] [Indexed: 12/15/2022] Open
Abstract
Background The malaria vaccine candidate RTS,S/AS01 (GSK Vaccines) induces high IgG concentration against the circumsporozoite protein (CSP) of Plasmodium falciparum. In human vaccine recipients circulating anti-CSP antibody concentrations are associated with protection against infection but appear not to be the correlate of protection. However, in a humanized mouse model of malaria infection prophylactic administration of a human monoclonal antibody (MAL1C), derived from a RTS,S/AS01-immunized volunteer, directed against the CSP repeat region, conveyed full protection in a dose-dependent manner suggesting that antibodies alone are able to prevent P. falciparum infection when present in sufficiently high concentrations. A competition ELISA was developed to measure the presence of MAL1C-like antibodies in polyclonal sera from RTS,S/AS01 vaccine recipients and study their possible contribution to protection against infection. Results MAL1C-like antibodies present in polyclonal vaccine-induced sera were evaluated for their ability to compete with biotinylated monoclonal antibody MAL1C for binding sites on the capture antigen consisting of the recombinant protein encompassing 32 NANP repeats of CSP (R32LR). Serum samples were taken at different time points from participants in two RTS,S/AS01 vaccine studies (NCT01366534 and NCT01857869). Vaccine-induced protection status of the study participants was determined based on the outcome of experimental challenge with infected mosquito bites after vaccination. Optimal conditions were established to reliably detect MAL1C-like antibodies in polyclonal sera. Polyclonal anti-CSP antibodies and MAL1C-like antibody content were measured in 276 serum samples from RTS,S/AS01 vaccine recipients using the standard ELISA and MAL-1C competition ELISA, respectively. A strong correlation was observed between the results from these assays. However, no correlation was found between the results of either assay and protection against infection. Conclusions The competition ELISA to measure MAL1C-like antibodies in polyclonal sera from RTS,S/AS01 vaccine recipients was robust and reliable but did not reveal the elusive correlate of protection. Electronic supplementary material The online version of this article (doi:10.1186/s12936-016-1596-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Kristina Radin
- Center for Vaccinology (CEVAC), Ghent University, Ghent, Belgium
| | - Frederic Clement
- Center for Vaccinology (CEVAC), Ghent University, Ghent, Belgium
| | - Erik Jongert
- GSK Vaccines, Rue de l'Institut 89, B-1330, Rixensart, Belgium
| | - Yann G J Sterckx
- Structural Biology Research Center (SBRC), VIB, Pleinlaan 2, B-1050, Brussels, Belgium.,Research Unit for Cellular and Molecular Immunology (CMIM), VUB, Pleinlaan 2, B-1050, Brussels, Belgium
| | - Christian Ockenhouse
- PATH Malaria Vaccine Initiative (MVI), 455 Massachusetts Avenue NW, Washington, DC, 20001, USA
| | - Jason Regules
- Walter Reed Army Institute of Research (WRAIR), 503 Robert Grant Ave., Silver Spring, MD, 20910, USA
| | - Franck Lemiale
- PATH Malaria Vaccine Initiative (MVI), 455 Massachusetts Avenue NW, Washington, DC, 20001, USA
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Buitrago SP, Garzón-Ospina D, Patarroyo MA. Size polymorphism and low sequence diversity in the locus encoding the Plasmodium vivax rhoptry neck protein 4 (PvRON4) in Colombian isolates. Malar J 2016; 15:501. [PMID: 27756311 PMCID: PMC5069803 DOI: 10.1186/s12936-016-1563-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2016] [Accepted: 10/07/2016] [Indexed: 11/12/2022] Open
Abstract
Background Designing a vaccine against Plasmodium vivax has focused on selecting antigens involved in invasion mechanisms that must have domains with low polymorphism for avoiding allele-specific immune responses. The rhoptry neck protein 4 (RON4) forms part of the tight junction, which is essential in the invasion of hepatocytes and/or erythrocytes; however, little is known about this locus’ genetic diversity. Methods DNA sequences from 73 Colombian clinical isolates from pvron4 gene were analysed for characterizing their genetic diversity; pvron4 haplotype number and distribution, as well as the evolutionary forces determining diversity pattern, were assessed by population genetics and molecular evolutionary approaches. Results ron4 has low genetic diversity in P. vivax at sequence level; however, a variable amount of tandem repeats at the N-terminal region leads to extensive size polymorphism. This region seems to be exposed to the immune system. The central region has a putative esterase/lipase domain which, like the protein’s C-terminal fragment, is highly conserved at intra- and inter-species level. Both regions are under purifying selection. Conclusions pvron4 is the locus having the lowest genetic diversity described to date for P. vivax. The repeat regions in the N-terminal region could be associated with immune evasion mechanisms while the central region and the C-terminal region seem to be under functional or structural constraint. Bearing such results in mind, the PvRON4 central and/or C-terminal portions represent promising candidates when designing a subunit-based vaccine as they are aimed at avoiding an allele-specific immune response, which might limit vaccine efficacy. Electronic supplementary material The online version of this article (doi:10.1186/s12936-016-1563-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Sindy P Buitrago
- Fundación Instituto de Inmunología de Colombia (FIDIC), Carrera 50 No. 26-20, Bogotá D.C., Colombia.,Microbiology Postgraduate Program, Universidad Nacional de Colombia, Bogotá D.C., Colombia
| | - Diego Garzón-Ospina
- Fundación Instituto de Inmunología de Colombia (FIDIC), Carrera 50 No. 26-20, Bogotá D.C., Colombia.,School of Medicine and Health Sciences, Universidad del Rosario, Bogotá D.C., Colombia
| | - Manuel A Patarroyo
- Fundación Instituto de Inmunología de Colombia (FIDIC), Carrera 50 No. 26-20, Bogotá D.C., Colombia. .,School of Medicine and Health Sciences, Universidad del Rosario, Bogotá D.C., Colombia.
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10
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Chaudhury S, Ockenhouse CF, Regules JA, Dutta S, Wallqvist A, Jongert E, Waters NC, Lemiale F, Bergmann-Leitner E. The biological function of antibodies induced by the RTS,S/AS01 malaria vaccine candidate is determined by their fine specificity. Malar J 2016; 15:301. [PMID: 27245446 PMCID: PMC4886414 DOI: 10.1186/s12936-016-1348-9] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Accepted: 05/18/2016] [Indexed: 01/01/2023] Open
Abstract
Background Recent vaccine studies have shown that the magnitude of an antibody response is often insufficient to explain efficacy, suggesting that characteristics regarding the quality of the antibody response, such as its fine specificity and functional activity, may play a major role in protection. Previous studies of the lead malaria vaccine candidate, RTS,S, have shown that circumsporozoite protein (CSP)-specific antibodies and CD4+ T cell responses are associated with protection, however the role of fine specificity and biological function of CSP-specific antibodies remains to be elucidated. Here, the relationship between fine specificity, opsonization-dependent phagocytic activity and protection in RTS,S-induced antibodies is explored. Methods A new method for measuring the phagocytic activity mediated by CSP-specific antibodies in THP-1 cells is presented and applied to samples from a recently completed phase 2 RTS,S/AS01 clinical trial. The fine specificity of the antibody response was assessed using ELISA against three antigen constructs of CSP: the central repeat region, the C-terminal domain and the full-length protein. A multi-parameter analysis of phagocytic activity and fine-specificity data was carried out to identify potential correlates of protection in RTS,S. Results Results from the newly developed assay revealed that serum samples from RTS,S recipients displayed a wide range of robust and repeatable phagocytic activity. Phagocytic activity was correlated with full-length CSP and C-terminal specific antibody titres, but not to repeat region antibody titres, suggesting that phagocytic activity is primarily driven by C-terminal antibodies. Although no significant difference in overall phagocytic activity was observed with respect to protection, phagocytic activity expressed as ‘opsonization index’, a relative measure that normalizes phagocytic activity with CS antibody titres, was found to be significantly lower in protected subjects than non-protected subjects. Conclusions Opsonization index was identified as a surrogate marker of protection induced by the RTS,S/AS01 vaccine and determined how antibody fine specificity is linked to opsonization activity. These findings suggest that the role of opsonization in protection in the RTS,S vaccine may be more complex than previously thought, and demonstrate how integrating multiple immune measures can provide insight into underlying mechanisms of immunity and protection. Electronic supplementary material The online version of this article (doi:10.1186/s12936-016-1348-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Sidhartha Chaudhury
- Biotechnology High Performance Computing Software Applications Institute, Telemedicine and Advanced Technology Research Center, U.S. Army Medical Research and Materiel Command, Fort Detrick, MD, USA
| | | | - Jason A Regules
- Department of Clinical Research, United States Army Medical Research Institute of Infectious Diseases, Ft. Detrick, MD, USA
| | - Sheetij Dutta
- Malaria Vaccine Branch, U.S. Military Malaria Research Program, Walter Reed Army Institute of Research, 503 Robert Grant Ave, 3W53, Silver Spring, MD, 20910, USA
| | - Anders Wallqvist
- Biotechnology High Performance Computing Software Applications Institute, Telemedicine and Advanced Technology Research Center, U.S. Army Medical Research and Materiel Command, Fort Detrick, MD, USA
| | | | - Norman C Waters
- Malaria Vaccine Branch, U.S. Military Malaria Research Program, Walter Reed Army Institute of Research, 503 Robert Grant Ave, 3W53, Silver Spring, MD, 20910, USA
| | | | - Elke Bergmann-Leitner
- Malaria Vaccine Branch, U.S. Military Malaria Research Program, Walter Reed Army Institute of Research, 503 Robert Grant Ave, 3W53, Silver Spring, MD, 20910, USA.
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11
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Farooq F, Bergmann-Leitner ES. Immune Escape Mechanisms are Plasmodium's Secret Weapons Foiling the Success of Potent and Persistently Efficacious Malaria Vaccines. Clin Immunol 2015; 161:136-43. [PMID: 26342537 DOI: 10.1016/j.clim.2015.08.015] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Accepted: 08/27/2015] [Indexed: 10/23/2022]
Abstract
Despite decades of active research, an efficacious vaccine mediating long-term protection is still not available. This review highlights various mechanisms and the different facets by which the parasites outsmart the immune system. An understanding of how the parasites escape immune recognition and interfere with the induction of a protective immune response that provides sterilizing immunity will be crucial to vaccine design.
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Affiliation(s)
- Fouzia Farooq
- Malaria Vaccine Branch, U.S. Military Malaria Research Program, Walter Reed Army Institute of Research, Silver Spring, MD 20910
| | - Elke S Bergmann-Leitner
- Malaria Vaccine Branch, U.S. Military Malaria Research Program, Walter Reed Army Institute of Research, Silver Spring, MD 20910.
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Escape of pathogens from the host immune response by mutations and mimicry. Possible means to improve vaccine performance. Med Hypotheses 2015; 85:664-9. [PMID: 26341417 DOI: 10.1016/j.mehy.2015.08.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Accepted: 08/13/2015] [Indexed: 11/21/2022]
Abstract
The ability of certain pathogens, such as human immunodeficiency, hepatitis C, herpes simplex, influenza viruses, Plasmodium falciparum, etc., to escape from host immune response is generally ascribed to high mutation rate of their genome. We challenge this assumption and propose that molecular mimicry of host antigens by these pathogens could also participate to this resistance. Several studies show that there is no correlation between the mutation rate value of a pathogen and the possibility to develop an effective vaccine. On the other hand, pathogens which do not respond to vaccine are usually reported to display host protein mimicry. We propose to suppress in the thymus the epitopes of the self which are in common with the pathogen. This could be achieved by intrathymic injection of antibodies against this microorganism. These antibodies would be obtained by vaccination of a foreign animal species. It is expected that the negative selection of the CD4(+) and CD8(+) T lymphocytes specific for these epitopes would be prevented, that the number of epitopes recognized as foreign to the host would be increased and that the immune response diversity would be enhanced.
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Maskus DJ, Bethke S, Seidel M, Kapelski S, Addai-Mensah O, Boes A, Edgü G, Spiegel H, Reimann A, Fischer R, Barth S, Klockenbring T, Fendel R. Isolation, production and characterization of fully human monoclonal antibodies directed to Plasmodium falciparum MSP10. Malar J 2015; 14:276. [PMID: 26174014 PMCID: PMC4502606 DOI: 10.1186/s12936-015-0797-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Accepted: 07/07/2015] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND Semi-immunity against the malaria parasite is defined by a protection against clinical episodes of malaria and is partially mediated by a repertoire of inhibitory antibodies directed against the blood stage of Plasmodium falciparum, in particular against surface proteins of merozoites, the invasive form of the parasite. Such antibodies may be used for preventive or therapeutic treatment of P. falciparum malaria. Here, the isolation and characterization of novel human monoclonal antibodies (humAbs) for such applications is described. METHODS B lymphocytes had been selected by flow cytometry for specificity against merozoite surface proteins, including the merozoite surface protein 10 (MSP10). After Epstein-Barr virus (EBV) transformation and identification of promising resulting lymphoblastoid cell lines (LCLs), human immunoglobulin heavy and light chain variable regions (Vh or Vl regions) were secured, cloned into plant expression vectors and transiently produced in Nicotiana benthamiana in the context of human full-size IgG1:κ. The specificity and the affinity of the generated antibodies were assessed by ELISA, dotblot and surface plasmon resonance (SPR) spectroscopy. The growth inhibitory activity was evaluated based on growth inhibition assays (GIAs) using the parasite strain 3D7A. RESULTS Supernatants from two LCLs, 5E8 and 5F6, showed reactivity against the second (5E8) or first (5F6) epidermal growth factor (EGF)-like domain of MSP10. The isolated V regions were recombinantly expressed in their natural pairing as well as in combination with each other. The resulting recombinant humAbs showed affinities of 9.27 × 10(-7) M [humAb10.1 (H5F6:κ5E8)], 5.46 × 10(-9) M [humAb10.2 (H5F6:κ5F6)] and 4.34 × 10(-9) M [humAb10.3 (H5E8:κ5E8)]. In GIAs, these antibodies exhibited EC50 values of 4.1 mg/ml [95% confidence interval (CI) 2.6-6.6 mg/ml], 6.9 mg/ml (CI 5.5-8.6 mg/ml) and 9.5 mg/ml (CI 5.5-16.4 mg/ml), respectively. CONCLUSION This report describes a platform for the isolation of human antibodies from semi-immune blood donors by EBV transformation and their subsequent characterization after transient expression in plants. To our knowledge, the presented antibodies are the first humAbs directed against P. falciparum MSP10 to be described. They recognize the EGF-like folds of MSP10 and bind these with high affinity. Moreover, these antibodies inhibit P. falciparum 3D7A growth in vitro.
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Affiliation(s)
- Dominika J Maskus
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany.
- Institute for Molecular Biotechnology, RWTH Aachen University, Aachen, Germany.
| | - Susanne Bethke
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany.
| | - Melanie Seidel
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany.
| | - Stephanie Kapelski
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany.
- Institute for Molecular Biotechnology, RWTH Aachen University, Aachen, Germany.
| | - Otchere Addai-Mensah
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany.
- Institute for Molecular Biotechnology, RWTH Aachen University, Aachen, Germany.
- Faculty of Allied Health Sciences, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana.
| | - Alexander Boes
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany.
| | - Güven Edgü
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany.
| | - Holger Spiegel
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany.
| | - Andreas Reimann
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany.
| | - Rainer Fischer
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany.
- Institute for Molecular Biotechnology, RWTH Aachen University, Aachen, Germany.
| | - Stefan Barth
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany.
- Department of Experimental Medicine and Immunotherapy, Institute for Applied Medical Engineering at RWTH Aachen University and Hospital, Aachen, Germany.
| | - Torsten Klockenbring
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany.
| | - Rolf Fendel
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany.
- Institute for Molecular Biotechnology, RWTH Aachen University, Aachen, Germany.
- Department of Experimental Medicine and Immunotherapy, Institute for Applied Medical Engineering at RWTH Aachen University and Hospital, Aachen, Germany.
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Mendes T, Lobo F, Rodrigues T, Rodrigues-Luiz G, daRocha W, Fujiwara R, Teixeira S, Bartholomeu D. Repeat-Enriched Proteins Are Related to Host Cell Invasion and Immune Evasion in Parasitic Protozoa. Mol Biol Evol 2013; 30:951-63. [DOI: 10.1093/molbev/mst001] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Immunological disturbances associated with malarial infection. J Parasit Dis 2012; 37:11-5. [PMID: 24431533 PMCID: PMC3590368 DOI: 10.1007/s12639-012-0174-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2012] [Accepted: 09/07/2012] [Indexed: 11/23/2022] Open
Abstract
Malaria is a reemerging disease in the countries where it was eradicated previously, whereas it is endemic in many countries including tropical countries. In India, malarial infection is on rise due to rapid urbanization and overcrowding in all major metropolitan cities. The incidence of morbidity and mortality due to malaria infection is increasing and could be attributed to drug resistance in strains of malarial parasite. Combining immune modulation strategies with anti-malarial drugs has a beneficial effect in an attempt to improve treatment for malaria. Along with clinical presentation and outcome of this parasitic infection, it is important to understand immunological disturbances associated with biological mechanisms underlying these actions in better understanding of pathogenesis of malarial infection. Immune and inflammatory responses in malarial infection are controlled and co-ordinated by various cytokines and chemokines. This review focuses on commonly seen immunological disturbances associated with malarial infection resulting in related humoral and cell mediated immune functions primarily with innate to subsequent adaptive immunity in tackling this parasitic infection.
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Ramasamy R, Surendran SN. Global climate change and its potential impact on disease transmission by salinity-tolerant mosquito vectors in coastal zones. Front Physiol 2012; 3:198. [PMID: 22723781 PMCID: PMC3377959 DOI: 10.3389/fphys.2012.00198] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2012] [Accepted: 05/22/2012] [Indexed: 11/19/2022] Open
Abstract
Global climate change can potentially increase the transmission of mosquito vector-borne diseases such as malaria, lymphatic filariasis, and dengue in many parts of the world. These predictions are based on the effects of changing temperature, rainfall, and humidity on mosquito breeding and survival, the more rapid development of ingested pathogens in mosquitoes and the more frequent blood feeds at moderately higher ambient temperatures. An expansion of saline and brackish water bodies (water with <0.5 ppt or parts per thousand, 0.5–30 ppt and >30 ppt salt are termed fresh, brackish, and saline respectively) will also take place as a result of global warming causing a rise in sea levels in coastal zones. Its possible impact on the transmission of mosquito-borne diseases has, however, not been adequately appreciated. The relevant impacts of global climate change on the transmission of mosquito-borne diseases in coastal zones are discussed with reference to the Ross–McDonald equation and modeling studies. Evidence is presented to show that an expansion of brackish water bodies in coastal zones can increase the densities of salinity-tolerant mosquitoes like Anopheles sundaicus and Culex sitiens, and lead to the adaptation of fresh water mosquito vectors like Anopheles culicifacies, Anopheles stephensi, Aedes aegypti, and Aedes albopictus to salinity. Rising sea levels may therefore act synergistically with global climate change to increase the transmission of mosquito-borne diseases in coastal zones. Greater attention therefore needs to be devoted to monitoring disease incidence and preimaginal development of vector mosquitoes in artificial and natural coastal brackish/saline habitats. It is important that national and international health agencies are aware of the increased risk of mosquito-borne diseases in coastal zones and develop preventive and mitigating strategies. Application of appropriate counter measures can greatly reduce the potential for increased coastal transmission of mosquito-borne diseases consequent to climate change and a rise in sea levels. It is proposed that the Jaffna peninsula in Sri Lanka may be a useful case study for the impact of rising sea levels on mosquito vectors in tropical coasts.
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Affiliation(s)
- Ranjan Ramasamy
- Institute of Health Sciences, Universiti Brunei Darussalam, Gadong Brunei Darussalam
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Moreno-Perez DA, Montenegro M, Patarroyo ME, Patarroyo MA. Identification, characterization and antigenicity of the Plasmodium vivax rhoptry neck protein 1 (PvRON1). Malar J 2011; 10:314. [PMID: 22024312 PMCID: PMC3215230 DOI: 10.1186/1475-2875-10-314] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2011] [Accepted: 10/24/2011] [Indexed: 01/16/2023] Open
Abstract
Background Plasmodium vivax malaria remains a major health problem in tropical and sub-tropical regions worldwide. Several rhoptry proteins which are important for interaction with and/or invasion of red blood cells, such as PfRONs, Pf92, Pf38, Pf12 and Pf34, have been described during the last few years and are being considered as potential anti-malarial vaccine candidates. This study describes the identification and characterization of the P. vivax rhoptry neck protein 1 (PvRON1) and examine its antigenicity in natural P. vivax infections. Methods The PvRON1 encoding gene, which is homologous to that encoding the P. falciparum apical sushi protein (ASP) according to the plasmoDB database, was selected as our study target. The pvron1 gene transcription was evaluated by RT-PCR using RNA obtained from the P. vivax VCG-1 strain. Two peptides derived from the deduced P. vivax Sal-I PvRON1 sequence were synthesized and inoculated in rabbits for obtaining anti-PvRON1 antibodies which were used to confirm the protein expression in VCG-1 strain schizonts along with its association with detergent-resistant microdomains (DRMs) by Western blot, and its localization by immunofluorescence assays. The antigenicity of the PvRON1 protein was assessed using human sera from individuals previously exposed to P. vivax malaria by ELISA. Results In the P. vivax VCG-1 strain, RON1 is a 764 amino acid-long protein. In silico analysis has revealed that PvRON1 shares essential characteristics with different antigens involved in invasion, such as the presence of a secretory signal, a GPI-anchor sequence and a putative sushi domain. The PvRON1 protein is expressed in parasite's schizont stage, localized in rhoptry necks and it is associated with DRMs. Recombinant protein recognition by human sera indicates that this antigen can trigger an immune response during a natural infection with P. vivax. Conclusions This study shows the identification and characterization of the P. vivax rhoptry neck protein 1 in the VCG-1 strain. Taking into account that PvRON1 shares several important characteristics with other Plasmodium antigens that play a functional role during RBC invasion and, as shown here, it is antigenic, it could be considered as a good vaccine candidate. Further studies aimed at assessing its immunogenicity and protection-inducing ability in the Aotus monkey model are thus recommended.
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Affiliation(s)
- Darwin A Moreno-Perez
- Fundación Instituto de Inmunología de Colombia, Carrera 50 No, 26-20, Bogotá, Colombia
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Arévalo-Pinzón G, Curtidor H, Patiño LC, Patarroyo MA. PvRON2, a new Plasmodium vivax rhoptry neck antigen. Malar J 2011; 10:60. [PMID: 21401956 PMCID: PMC3068128 DOI: 10.1186/1475-2875-10-60] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2011] [Accepted: 03/14/2011] [Indexed: 11/29/2022] Open
Abstract
Background Rhoptries are specialized organelles from parasites belonging to the phylum Apicomplexa; they secrete their protein content during invasion of host target cells and are sorted into discrete subcompartments within rhoptry neck or bulb. This distribution is associated with these proteins' role in tight junction (TJ) and parasitophorous vacuole (PV) formation, respectively. Methods Plasmodium falciparum RON2 amino acid sequence was used as bait for screening the codifying gene for the homologous protein in the Plasmodium vivax genome. Gene synteny, as well as identity and similarity values, were determined for ron2 and its flanking genes among P. falciparum, P. vivax and other malarial parasite genomes available at PlasmoDB and Sanger Institute databases. Pvron2 gene transcription was determined by RT-PCR of cDNA obtained from the P. vivax VCG-1 strain. Protein expression and localization were assessed by Western blot and immunofluorescence using polyclonal anti-PvRON2 antibodies. Co-localization was confirmed using antibodies directed towards specific microneme and rhoptry neck proteins. Results and discussion The first P. vivax rhoptry neck protein (named here PvRON2) has been identified in this study. PvRON2 is a 2,204 residue-long protein encoded by a single 6,615 bp exon containing a hydrophobic signal sequence towards the amino-terminus, a transmembrane domain towards the carboxy-terminus and two coiled coil α-helical motifs; these are characteristic features of several previously described vaccine candidates against malaria. This protein also contains two tandem repeats within the interspecies variable sequence possibly involved in evading a host's immune system. PvRON2 is expressed in late schizonts and localized in rhoptry necks similar to what has been reported for PfRON2, which suggests its participation during target cell invasion. Conclusions The identification and partial characterization of the first P. vivax rhoptry neck protein are described in the present study. This protein is homologous to PfRON2 which has previously been shown to be associated with PfAMA-1, suggesting a similar role for PvRON2.
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de Matos Macchi B, Quaresma JAS, Herculano AM, Crespo-López ME, DaMatta RA, do Nascimento JLM. Pathogenic action of Plasmodium gallinaceum in chickens: Brain histology and nitric oxide production by blood monocyte-derived macrophages. Vet Parasitol 2010; 172:16-22. [DOI: 10.1016/j.vetpar.2010.04.032] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2009] [Revised: 04/13/2010] [Accepted: 04/27/2010] [Indexed: 11/29/2022]
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Addai FK. Natural cocoa as diet-mediated antimalarial prophylaxis. Med Hypotheses 2009; 74:825-30. [PMID: 20044213 DOI: 10.1016/j.mehy.2009.12.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2009] [Accepted: 12/05/2009] [Indexed: 10/20/2022]
Abstract
BACKGROUND The Maya of Central America are credited with the first consumption of cocoa and maintaining its ancient Olmec name kakawa translated in English as "God Food", in recognition of its multiple health benefits. The legend of cocoa is receiving renewed attention in recent years, on account of epidemiological and scientific studies that support its cardiovascular health benefits. Increasing numbers of scientific reports corroborating cocoa's antiquated reputation as health food persuaded this author to promote regular consumption of cocoa in Ghana since 2004. Cocoa is readily available in Ghana; the country is the second largest producer accounting for 14% of the world's output. Numerous anecdotal reports of reduced episodic malaria in people who daily drink natural unsweetened cocoa beverage prompted a search for scientific mechanisms that possibly account for cocoa's antimalarial effects. This paper presents the outcome as a hypothesis. METHODS Internet search for literature on effects of cocoa's ingredients on malaria parasites and illness using a variety of search tools. RESULTS Evidential literature suggests five mechanisms that possibly underpin cocoa's anecdotal antimalarial effects. (i) Increased availability of antioxidants in plasma, (ii) membrane effects in general and erythrocyte membrane in particular, (iii) increased plasma levels of nitric oxide, (iv) antimalarial activity of cocoa flavanoids and their derivatives, and (v) boosted immune system mediated by components of cocoa including cocoa butter, polyphenols, magnesium, and zinc. CONCLUSION A hypothesis is formulated that cocoa offers a diet-mediated antimalarial prophylaxis; and an additional novel tool in the fight against the legendary scourge.
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Affiliation(s)
- F K Addai
- Department of Anatomy, University of Ghana Medical School (U.G.M.S.), College of Health Sciences, University of Ghana, Accra, Ghana.
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Prieur E, Druilhe P. The malaria candidate vaccine liver stage antigen-3 is highly conserved in Plasmodium falciparum isolates from diverse geographical areas. Malar J 2009; 8:247. [PMID: 19874576 PMCID: PMC2774867 DOI: 10.1186/1475-2875-8-247] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2009] [Accepted: 10/29/2009] [Indexed: 01/13/2023] Open
Abstract
Background A high level of genetic stability has been formerly identified in segments of the gene coding for the liver stage antigen-3 (LSA-3), a subunit vaccine candidate against Plasmodium falciparum. The exploration of lsa-3 polymorphisms was extended to the whole sequence of this large antigen in 20 clinical isolates from four geographical areas; Senegal, Comoro islands, Brazil and Thailand. Methods The whole 4680 bp genomic sequence of lsa-3 was amplified by polymerase chain reaction and sequenced. The clinical isolate sequences were aligned on the sequence of the laboratory reference P. falciparum strain 3D7. Results The non-repeated sequence of lsa-3 was very well conserved with only a few allelic variations scattered along the sequence. Interestingly, a formerly identified immunodominant region, employed for the majority of pre-clinical vaccine development, was totally conserved at the genetic level. The most significant variations observed were in the number and organization of tetrapeptide repeated units, but not in their composition, resulting in different lengths of these repeated regions. The shorter repeated regions were from Brazilian origin. A correlation between the geographical distribution of the parasites with single nucleotide polymorphisms was not detected. Conclusion The lack of correlation between allelic polymorphisms with a specific transmission pressure suggests that LSA-3 is a structurally constrained molecule. The unusual characteristics of the lsa-3 gene make the molecule an interesting candidate for a subunit vaccine against malaria.
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Affiliation(s)
- Eric Prieur
- Biochemical Parasitology Unit, Institut Pasteur, Paris, France.
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22
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Identification of a vaccine candidate antigen, PfMAg-1, from Plasmodium falciparum with monoclonal antibody M26-32. Parasitol Res 2009; 105:1723-32. [PMID: 19777263 DOI: 10.1007/s00436-009-1617-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2009] [Accepted: 08/24/2009] [Indexed: 10/20/2022]
Abstract
Monoclonal antibody M26-32 has been shown to strongly inhibit the growth of Plasmodium falciparum in vitro. To identify the target antigen of M26-32, a P. falciparum Dd2 asexual stage cDNA expression library was screened with this antibody, and a full open reading frame cDNA was obtained. This gene, named pfmag-1, encodes a polypeptide of 589 amino acids. The protein PfMAg-1 was characterized as a membrane-associated protein that expressed on the surface of merozoite during erythrocytic stage. Remarkably, at the C terminus of PfMAg-1, there are 14 copies of a deca-peptide sequence of QTDEIKND (H/N) I. This tandem repeat domain was identified to harbor the epitope of the protective M26-32 monoclonal antibody, and was also recognized by sera of patients infected with P. falciparum. Rabbit antibody elicited against this deca-peptide repeat domain effectively inhibited P. falciparum invasion in vitro. Our work suggests that PfMAg-1 is a promising malaria vaccine candidate.
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Immune responses to protozoans. Clin Immunol 2008. [DOI: 10.1016/b978-0-323-04404-2.10028-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Seed CR, Kitchen A, Davis TME. The current status and potential role of laboratory testing to prevent transfusion-transmitted malaria. Transfus Med Rev 2005; 19:229-40. [PMID: 16010653 DOI: 10.1016/j.tmrv.2005.02.004] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Malaria remains a rare but serious complication of transfusion because of the asymptomatic persistence of parasites in some donors. In nonendemic countries, the predominant strategy of deferral or cellular component discard from "risk" donors is effective in minimizing the incidence but is wasteful. In endemic countries where recipients are commonly immune, transfusion strategies focus on chemoprophylaxis for the donor and recipient or ensure that blood collected in highly endemic regions is not transfused to patients from areas of low endemicity. Donors implicated in transfusion-transmitted malaria are predominantly "semi-immune" with very low parasite loads. Their detection by even the most sensitive antigen or polymerase chain reaction (PCR) assays cannot be guaranteed and, in a number of cases, is unlikely because the infectious dose is estimated to be 1 to 10 parasites in a unit of blood. Retrospective analysis of implicated donors has confirmed the presence of high titer antibodies in such individuals. In regions of low immunity, serological assays offer an efficient method to identify such infectious donors. The recent development of enzyme immunoassays (EIAs) with improved sensitivity to Plasmodium falciparum and Plasmodium vivax , the predominant transfusion threats, has heightened the appeal of serological testing. Although universal serological screening in nonendemic regions is not cost-effective, targeted screening of donors identified at risk by travel-based questioning can significantly reduce wastage through reinstatement. Importantly, transfusion safety does not appear to be compromised by this approach as evidenced by the lack of a documented transmission in France between 1983 and September 2002, where such a strategy has been used since 1976. The development of automated protein microarray-based technology has the potential to further enhance antibody/antigen sensitivity; however, its application to donor screening is likely to be some years off. There is also the potential that pathogen inactivation techniques currently under development to address the bacterial contamination of blood components may also be effective against malaria parasites to make malarial testing redundant or at least reduce its cost/benefit ratio. Nonetheless, there are still significant problems to be solved in respect of validating and licensing these systems. Assuming that they are successfully marketed, their high cost may also impact their cost-effectiveness in comparison with targeted malaria testing strategies already in place in some jurisdictions.
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Affiliation(s)
- Clive R Seed
- Australian Red Cross Blood Service, Perth, Australia.
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Seed CR, Cheng A, Davis TME, Bolton WV, Keller AJ, Kitchen A, Cobain TJ. The efficacy of a malarial antibody enzyme immunoassay for establishing the reinstatement status of blood donors potentially exposed to malaria. Vox Sang 2005; 88:98-106. [PMID: 15720607 DOI: 10.1111/j.1423-0410.2005.00605.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND AND OBJECTIVES The two key objectives of the study were, first, to evaluate the sensitivity and specificity of a recombinant antigen-based malarial enzyme-linked immunoassay (EIA) and, second, to estimate the risk associated with implementing this test with a shortened cellular component restriction period (6 months rather than the standard 12-36 months) for blood donors with a malarial risk exposure. MATERIALS AND METHODS Blood donors were recruited into four distinct groups [non-exposed (control), malarial area 'visitors', 'residents' and 'previous infection') and screened by using the Newmarket malarial antibody EIA. Assay specificity was evaluated in unexposed blood donors, and sensitivity was determined in acute clinical samples. RESULTS No parasitaemic donors were detected amongst 337 malarial 'visitors' who had returned from a malaria-endemic area less than 6 months previously, or for 402 'visitors' or 'residents' who had returned from a malaria-endemic area more than 6 months previously. The incidence of malarial antibodies within the exposed blood donor groups was 1.33% (10/751). In acute clinical non-donor samples, the Newmarket EIA detected 106/108 (98.1; 93.5-99.5%) 'film' positive Plasmodium falciparum infections and 12/12 (100, 75.7-100.0%) P. vivax infections. The estimated additional risk exposure of the proposed new strategy was one infectious P. falciparum donation per 175 years or 1 per 4.2 years for P. vivax. CONCLUSIONS The study findings support the efficacy and safety of a targeted screening strategy combining antibody screening with a 6-month cellular component restriction period for donors with a declared malarial risk.
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Affiliation(s)
- C R Seed
- Australian Red Cross Blood Service, Perth, Australia.
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Abstract
DNA vaccines, although successful in many animal models of various diseases, remain insufficiently immunogenic in humans. Among the countless approaches to improve them is the stimulation of the innate immune system by promoting the apoptotic death of the transfected host cells, which is the focus of this review.
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Affiliation(s)
- Elke S Bergmann-Leitner
- Department of Immunology, Walter Reed Army Institute of Research, Silver Spring, MD 20910, USA.
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Zhang N, Harrex AL, Holland BR, Fenton LE, Cannon RD, Schmid J. Sixty alleles of the ALS7 open reading frame in Candida albicans: ALS7 is a hypermutable contingency locus. Genome Res 2003; 13:2005-17. [PMID: 12952872 PMCID: PMC403672 DOI: 10.1101/gr.1024903] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2002] [Accepted: 06/30/2003] [Indexed: 12/22/2022]
Abstract
The ALS (agglutinin-like sequence) gene family encodes proteins that play a role in adherence of the yeast Candida albicans to endothelial and epithelial cells. The proteins are proposed as virulence factors for this important fungal pathogen of humans. We analyzed 66 C. albicans strains, representing a worldwide collection of 266 infection-causing isolates, and discovered 60 alleles of the ALS7 open reading frame (ORF). Differences between alleles were largely caused by rearrangements of repeat elements in the so-called tandem repeat domain (21 different types occurred) and the VASES region (19 different types). C. albicans is diploid, and combinations of ALS7 alleles generated 49 different genotypes. ALS7 expression was detected in samples isolated directly from five oral candidosis patients. ORFs in the opposite direction contained within the ALS7 ORF were also transcribed in all strains tested. Isolates representing a more pathogenic general-purpose genotype (GPG) cluster of strains tended to have more tandem repeats than other strains. Two types of VASES regions were largely exclusive to GPG strains; the remaining types were largely exclusive to noncluster strains. Our results provide evidence that ALS7 is a hypermutable contingency locus and important for the success of C. albicans as an opportunistic pathogen of humans.
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Affiliation(s)
- Ningxin Zhang
- Institute of Molecular BioSciences, Massey University, Palmerston North, New Zealand
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Norimine J, Mosqueda J, Suarez C, Palmer GH, McElwain TF, Mbassa G, Brown WC. Stimulation of T-helper cell gamma interferon and immunoglobulin G responses specific for Babesia bovis rhoptry-associated protein 1 (RAP-1) or a RAP-1 protein lacking the carboxy-terminal repeat region is insufficient to provide protective immunity against virulent B. bovis challenge. Infect Immun 2003; 71:5021-32. [PMID: 12933845 PMCID: PMC187345 DOI: 10.1128/iai.71.9.5021-5032.2003] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Rhoptry-associated protein 1 (RAP-1) is a targeted vaccine antigen for Babesia bovis and Babesia bigemina infections of cattle. The 60-kDa B. bovis RAP-1 is recognized by antibodies and T lymphocytes from cattle that recovered from infection and were immune to subsequent challenge. Immunization with native or recombinant protein was reported to reduce parasitemias in challenged animals. We recently reported that the NT domain of B. bovis RAP-1 contained immunodominant T-cell epitopes, whereas the repeat-rich CT domain was less immunostimulatory for T lymphocytes from cattle immune to B. bovis. The present study was therefore designed to test the hypothesis that the NT region of RAP-1, used as a vaccine with interleukin-12 and RIBI (catalog no. R-730; RIBI Immunochem Research, Inc., Hamilton, Mont. [now Corixa, Seattle, Wash.]) adjuvant to induce a type 1 response, would prime calves for antibody and T-helper cell responses comparable to or greater than those induced by full-length RAP-1 containing the C-terminal repeats. Furthermore, a type 1 immune response to RAP-1 was hypothesized to induce protection against challenge. Following four inoculations of either recombinant full-length RAP-1 or RAP-1 NT protein, RAP-1-specific immunoglobulin G (IgG) titers, T-lymphocyte proliferation, and gamma interferon production were similar. Similar numbers of NT region peptides were recognized. However, in spite of the presence of strong RAP-1-specific IgG and CD4(+)-T-lymphocyte responses that were recalled upon challenge, neither antigen stimulated a protective immune response. We conclude that successful priming of calves with recombinant RAP-1 and adjuvants that elicit strong Th1 cell and IgG responses is insufficient to protect calves against virulent B. bovis challenge.
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Affiliation(s)
- Junzo Norimine
- Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, Washington 99164, USA
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Pfaff AW, Candolfi E. Immune responses to protozoan parasites and its relevance to diagnosis in immunocompromised patients. Eur J Protistol 2003. [DOI: 10.1078/0932-4739-00016] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Kennedy MC, Wang J, Zhang Y, Miles AP, Chitsaz F, Saul A, Long CA, Miller LH, Stowers AW. In vitro studies with recombinant Plasmodium falciparum apical membrane antigen 1 (AMA1): production and activity of an AMA1 vaccine and generation of a multiallelic response. Infect Immun 2002; 70:6948-60. [PMID: 12438374 PMCID: PMC133034 DOI: 10.1128/iai.70.12.6948-6960.2002] [Citation(s) in RCA: 211] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Apical membrane antigen 1 (AMA1) is regarded as a leading malaria blood-stage vaccine candidate. While the overall structure of AMA1 is conserved in Plasmodium spp., numerous AMA1 allelic variants of P. falciparum have been described. The effect of AMA1 allelic diversity on the ability of a recombinant AMA1 vaccine to protect against human infection by different P. falciparum strains is unknown. We characterize two allelic forms of AMA1 that were both produced in Pichia pastoris at a sufficient economy of scale to be usable for clinical vaccine studies. Both proteins were used to immunize rabbits, singly and in combination, in order to evaluate their immunogenicity and the ability of elicited antibodies to block the growth of different P. falciparum clones. Both antigens, when used alone, elicited high homologous anti-AMA1 titers, with reduced strain cross-reactivity. Similarly, sera from rabbits immunized with a single antigen were capable of blocking the growth of homologous parasite strains at levels theoretically sufficient to clear parasite infections. However, heterologous inhibition was significantly reduced, providing experimental evidence that AMA1 allelic diversity is a result of immune pressure. Encouragingly, rabbits immunized with a combination of both antigens exhibited titers and levels of parasite inhibition as good as those of the single-antigen-immunized rabbits for each of the homologous parasite lines, and consequently exhibited a broadening of allelic diversity coverage.
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Affiliation(s)
- Michael C Kennedy
- Malaria Vaccine Development Unit, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland 20852, USA
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Abstract
Respiratory tract infections are a major cause of morbidity and mortality in adults and children worldwide. Because of its anatomical features, which allow gaseous exchange, the respiratory tract is constantly exposed to the outer environment and to the systemic and pulmonary circulation, which may allow infectious microbes, toxins, allergens, dust, and other antigens to enter the lung. The human host is a perpetual battleground between the body's immune system and invading antigens, whether they are microorganisms, chemicals, or cancer cells. Although a vast amount of literature is accumulating on the subject of immune responses to pathogens, the mechanisms underlying specific immunity to many organisms remain unknown. Paradoxically, while the immune response has evolved to confer protection against invading antigens, much human pathology arises when the immune responses are evoked.
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Affiliation(s)
- Alimuddin I Zumla
- Center for Infectious Diseases and International Health, University College London, Windeyer Institute of Medical Sciences, Room G41, 46 Cleveland Street, London W1P 6DB, UK.
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Abstract
There is considerable interest in using merozoite proteins in a vaccine against falciparum malaria. Observations that antibodies to merozoite surface proteins block invasion are a basis for optimism. This article draws attention to important and varied aspects of how antibodies to Plasmodium falciparum merozoites affect red blood cell invasion.
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Affiliation(s)
- R Ramasamy
- Dept. of Genetics, University of Groningen, Kerklaan 30, 9751 NN, Haren, The Netherlands.
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33
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Lamarre C, Deslauriers N, Bourbonnais Y. Expression cloning of the Candida albicans CSA1 gene encoding a mycelial surface antigen by sorting of Saccharomyces cerevisiae transformants with monoclonal antibody-coated magnetic beads. Mol Microbiol 2000; 35:444-53. [PMID: 10652105 DOI: 10.1046/j.1365-2958.2000.01715.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The mycelial surface antigen recognized by monoclonal antibody (mAb) 4E1 has previously been shown to be present predominantly in the terminal third of the hyphal structures in Candida albicans. We report here the expression cloning of the corresponding gene (CSA1 ) by mAb 4E1-coated magnetic beads sorting of Saccharomyces cerevisiae transformants expressing a C. albicans genomic library. The strategy is both highly selective and highly sensitive and provides an additional genetic tool for the cloning and characterization of C. albicans genes encoding surface proteins. CSA1 is an intronless gene encoding a 1203-residue protein composed of repetitive motifs and domains. Northern analysis indicates that CSA1 is preferentially expressed during the mycelial growth phase, although a low level of CSA1 mRNA can be detected in the yeast form. As evidenced by indirect immunofluorescence microscopy with mAb 4E1, Csa1p is not randomly distributed over the surface of yeast cells, but localizes predominantly in the growing buds. This suggests that the distribution of Csa1p may be restricted to sites of cell surface elongation. Both heterozygous and homozygous C. albicans csa1Delta mutants are viable. Upon induction of mycelial growth, the number and size of hyphal structures derived from the mutants are similar to those observed in the parental wild-type strain. The physiological role of Csa1p has yet to be determined. However, the presence in Csa1p of repeated cysteine-rich hydrophobic domains with significant sequence similarity to motifs found in surface proteins (Ag2 and Pth11) from two distantly related fungal pathogens (Coccidioides immitis and Magnaporthe grisea respectively) suggests a common function in host interaction.
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MESH Headings
- Amino Acid Sequence
- Antibodies, Fungal/immunology
- Antibodies, Monoclonal/immunology
- Antigens, Fungal/genetics
- Antigens, Fungal/immunology
- Antigens, Fungal/metabolism
- Antigens, Surface/genetics
- Antigens, Surface/immunology
- Antigens, Surface/metabolism
- Blotting, Northern
- Candida albicans/genetics
- Candida albicans/growth & development
- Candida albicans/immunology
- Cloning, Molecular
- Fluorescent Antibody Technique, Indirect
- Genes, Fungal
- Immunomagnetic Separation
- Molecular Sequence Data
- Mutagenesis, Insertional
- Restriction Mapping
- Saccharomyces cerevisiae/genetics
- Saccharomyces cerevisiae/immunology
- Saccharomyces cerevisiae/metabolism
- Sequence Alignment
- Transformation, Genetic
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Affiliation(s)
- C Lamarre
- Département de biochimie et de microbiologie, Centres de Recherche, la Fonction et l'Ingénierie des Protéines (CREFSIP) de l'Université Laval, Québec, Canada G1K 7P4
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Zhu D, Thompsett AR, Bedu-Addo G, Stevenson FK, Bates I. VH gene sequences from a novel tropical splenic lymphoma reveal a naive B cell as the cell of origin. Br J Haematol 1999; 107:114-20. [PMID: 10520031 DOI: 10.1046/j.1365-2141.1999.01679.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The prevalence of malaria and other infections in tropical Africa provides a setting for the emergence of B-cell tumours distinct from that in Western countries. Attempts to draw comparisons with Western lymphomas have led to difficulties, with so-called African chronic lymphocytic leukaemia (CLL) having a different pattern of incidence from Western CLL. Splenomegaly is common in African CLL, and this has posed diagnostic problems in differentiating the tumour from malaria-associated hyper-reactive malarial splenomegaly (HMS). One feature of the splenomegalic form of African CLL is that the tumour cells often possess short but fine cytoplasmic projections reminiscent of those observed in Western splenic lymphoma with villous lymphocytes (SLVL). Analysis of Ig VH genes both facilitates discrimination between clonal B-cell tumours and HMS, and reveals the differentiation status of the cell of origin. This study indicated that VH genes of nine cases of clonal splenic B-cell tumours with villous lymphocytes from Ghana were relatively unmutated, consistent with an origin from a naive B cell. These features differ from SLVL which arises from a post-follicular antigen-selected B cell. One possibility is that these splenic B-cell tumours derive from a splenic T-independent B cell, with malaria infection as a potential influence.
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Affiliation(s)
- D Zhu
- Molecular Immunology Group, Tenovus Research Laboratory, Southampton University Hospitals, Southampton, U.K
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Ramasamy R, Yasawardena S, Kanagaratnam R, Buratti E, Baralle FE, Ramasamy MS. Antibodies to a merozoite surface protein promote multiple invasion of red blood cells by malaria parasites. Parasite Immunol 1999; 21:397-407. [PMID: 10417674 DOI: 10.1046/j.1365-3024.1999.00239.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The 40-50 kDa merozoite surface antigen (MSA2) is a candidate molecule for use in a malaria vaccine. The gene for MSA2 from the 3D7 isolate of Plasmodium falciparum was amplified by polymerase chain reaction and cloned into the bacterial expression vector pGEX-3X to obtain a fusion protein of MSA2 with Schistosoma japonicum glutathione S-transferase. The recombinant fusion protein was used to immunize rabbits. After four injections, the sera had Western blotting and immunofluorescence titres of 10(-6). Immune sera, and immunoglobulin (Ig)G, F(ab)'2, F(ab) prepared from the immune sera, were assessed for their effects on the growth of 3D7 parasites in vitro by microscopy and a [3H]-hypoxanthine incorporation assay. The antibodies did not significantly inhibit red blood cell invasion and parasite growth when added to cultures as 10% v/v serum or as immunoglobulin preparations at concentrations up to 200 microg ml(-1). However, in the presence of IgG or F(ab)'2, but not F(ab), antibodies to MSA2, the proportions of red blood cells invaded by more than one merozoite increased significantly. Multiple invasion is attributed to merozoites cross-linked by bivalent antibodies, attaching to and subsequently invading the same red cell. These observations have a bearing on the evasion of host immune responses by the parasite and the use of full-length recombinant MSA2 protein in a malaria vaccine.
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Affiliation(s)
- R Ramasamy
- Molecular Biology and Immunology Laboratories, Division of Life Sciences, Institute Fundamental Studies, Kandy, Sri Lanka
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Ramasamy R, Yasawardena SG, Kanagaratnam R, Buratti E, Baralle FE, Ramasamy MS. Mammalian cell expression of malaria merozoite surface proteins and experimental DNA and RNA immunisation. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1453:1-13. [PMID: 9989240 DOI: 10.1016/s0925-4439(98)00056-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The gene for a 45 kDa merozoite surface protein (MSA-2) of the human malaria parasite Plasmodium falciparum was PCR amplified and cloned into eukaryotic expression vectors VR1012 and pcDNA3 to yield plasmids P1 and P2, respectively. The coding sequences for two N-terminal fragments of the 185 kDa merozoite surface protein (MSA-1) gene were similarly PCR amplified and cloned into vectors VR1020 and VR1012 to yield plasmids P3 and P4, respectively. The MSA-1 signal peptide sequence, present in P4, was replaced with the human tissue plasminogen activator signal sequence in P3. The four plasmids expressed the cloned genes under the control of the cytomegalovirus promoter and carried 3' bovine growth hormone termination/poly A signals. P1, P3 and P4 also contained the cytomegalovirus intron A enhancer sequence. MSA-1 expression was more readily detected than MSA-2 in Cos cells transfected with P3/P4 and P1/P2 respectively. The MSA-2 gene was also cloned into the phagemid pBluescript IISK+ with and without a 3' poly A tail composed of 35 A residues. MSA-2 was synthesised in HeLa cells infected with a recombinant vaccinia virus carrying T7 RNA polymerase when MSA-2 recombinant pBluescript was transfected into the cells. Inoculation with P1 intramuscularly or intradermally and with P2 intradermally into rabbits led to the production of antibodies to MSA-2 detectable by immunofluorescence and Western blotting. Antibodies were also produced against MSA-1 after intramuscular/intradermal inoculation with P3 and P4. Inoculation of rabbits with MSA-2 mRNA yielded better antibody titres when a poly A tail was present. Antibody levels were maintained for > 9 weeks after the final immunisation. However the immune sera failed to inhibit in vitro parasite growth.
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Affiliation(s)
- R Ramasamy
- Molecular Biology and Immunology Laboratories, Institute of Fundamental Studies, Kandy, Sri Lanka.
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37
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Ramasamy R, Kanagaratnam R, Chandanie PD, Kulachelvy K, Ramasamy MS, Dharmasena PM. Model multiple antigenic and homopolymeric peptides from non-repetitive sequences of malaria merozoite proteins elicit biologically irrelevant antibodies. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1453:115-25. [PMID: 9989251 DOI: 10.1016/s0925-4439(98)00091-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Three model peptides containing B-epitopes from conserved, non-repetitive regions of the merozoite surface antigens, MSA2 and MSA1, and the erythrocyte binding protein EBP of Plasmodium falciparum were synthesised. The peptides incorporated GPG spacers and C residues at the N and C termini, and were polymerised by oxidation to form cystine bridges. Multiple copies of essentially the same peptide sequences were also synthesised on a branching lysyl matrix to form a tetrameric multiple antigen peptide. Rabbits were immunised with the polymerised and multiple antigen peptides, in alum followed by Freund's adjuvant, and the antibody responses examined by IFA and ELISA. Reproducible antibody responses were obtained against the MSA1 and EBP but not MSA2 peptides. IgG antibody levels detected by ELISA after three injections of antigen in alum, increased significantly after further immunisation in Freund's adjuvant. IgG levels were largely maintained for at least 23 weeks after the final immunisation. IgM antibodies, generally detectable only after immunisation in Freund's adjuvant, were absent 23 weeks later. Antibody titres against the native protein on fixed parasites, assayed by IFA, were three to five orders of magnitude lower than the corresponding ELISA titres against the peptides. Antibody-dependent inhibition of P. falciparum growth in vitro could not be demonstrated with the immune rabbit sera. The MSA1 and EBP peptides elicited cross-reactive antibodies. The results suggest that the selected non-repetitive sequences are conformationally constrained in the native proteins and only a small proportion of the anti-peptide antibodies bind to the native proteins. The significance of the findings for the development of peptide vaccines and the use of peptides in immunoassays is discussed.
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Affiliation(s)
- R Ramasamy
- Molecular Biology Laboratory, Institute of Fundamental Studies, Kandy, Sri Lanka.
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