1
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Geens R, Stanisich J, Beyens O, D'Hondt S, Thiberge J, Ryckebosch A, De Groot A, Magez S, Vertommen D, Amino R, De Winter H, Volkov AN, Tompa P, Sterckx YG. Biophysical characterization of the Plasmodium falciparum circumsporozoite protein's N-terminal domain. Protein Sci 2024; 33:e4852. [PMID: 38059674 PMCID: PMC10749493 DOI: 10.1002/pro.4852] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Revised: 11/28/2023] [Accepted: 12/04/2023] [Indexed: 12/08/2023]
Abstract
The circumsporozoite protein (CSP) is the main surface antigen of the Plasmodium sporozoite (SPZ) and forms the basis of the currently only licensed anti-malarial vaccine (RTS,S/AS01). CSP uniformly coats the SPZ and plays a pivotal role in its immunobiology, in both the insect and the vertebrate hosts. Although CSP's N-terminal domain (CSPN ) has been reported to play an important role in multiple CSP functions, a thorough biophysical and structural characterization of CSPN is currently lacking. Here, we present an alternative method for the recombinant production and purification of CSPN from Plasmodium falciparum (PfCSPN ), which provides pure, high-quality protein preparations with high yields. Through an interdisciplinary approach combining in-solution experimental methods and in silico analyses, we provide strong evidence that PfCSPN is an intrinsically disordered region displaying some degree of compaction.
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Affiliation(s)
- Rob Geens
- Laboratory of Medical Biochemistry (LMB)University of AntwerpAntwerpBelgium
- Structural Biology BrusselsVrije Universiteit BrusselBrusselsBelgium
| | - Jessica Stanisich
- Cellular and Molecular ImmunologyVrije Universiteit BrusselBrusselsBelgium
| | - Olivier Beyens
- Laboratory of Medicinal Chemistry (UAMC)University of AntwerpAntwerpBelgium
| | - Stijn D'Hondt
- Laboratory of Medicinal Chemistry (UAMC)University of AntwerpAntwerpBelgium
| | | | - Amber Ryckebosch
- Laboratory of Medical Biochemistry (LMB)University of AntwerpAntwerpBelgium
| | - Anke De Groot
- Laboratory of Medical Biochemistry (LMB)University of AntwerpAntwerpBelgium
| | - Stefan Magez
- Cellular and Molecular ImmunologyVrije Universiteit BrusselBrusselsBelgium
- Ghent University Global CampusIncheonSouth Korea
| | - Didier Vertommen
- de Duve Institute and MASSPROT Platform, UCLouvainBrusselsBelgium
| | - Rogerio Amino
- Unit of Malaria Infection & ImmunityInstitut PasteurParisFrance
| | - Hans De Winter
- Laboratory of Medicinal Chemistry (UAMC)University of AntwerpAntwerpBelgium
| | - Alexander N. Volkov
- Structural Biology BrusselsVrije Universiteit BrusselBrusselsBelgium
- VIB‐VUB Center for Structural BiologyVlaams Instituut voor Biotechnologie (VIB)BrusselsBelgium
- Jean Jeener NMR CentreVrije Universiteit BrusselBrusselsBelgium
| | - Peter Tompa
- Structural Biology BrusselsVrije Universiteit BrusselBrusselsBelgium
- VIB‐VUB Center for Structural BiologyVlaams Instituut voor Biotechnologie (VIB)BrusselsBelgium
- Institute of Enzymology, Biological Research CenterHungarian Academy of SciencesBudapestHungary
| | - Yann G.‐J. Sterckx
- Laboratory of Medical Biochemistry (LMB)University of AntwerpAntwerpBelgium
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2
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Huang HY, Liang XY, Lin LY, Chen JT, Ehapo CS, Eyi UM, Li J, Jiang TT, Zheng YZ, Zha GC, Xie DD, He JQ, Chen WZ, Liu XZ, Mo HT, Chen XY, Lin M. Genetic polymorphism of Plasmodium falciparum circumsporozoite protein on Bioko Island, Equatorial Guinea and global comparative analysis. Malar J 2020; 19:245. [PMID: 32660484 PMCID: PMC7359586 DOI: 10.1186/s12936-020-03315-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Accepted: 07/04/2020] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND Plasmodium falciparum circumsporozoite protein (PfCSP) is a potential malaria vaccine candidate, but various polymorphisms of the pfcsp gene among global P. falciparum population become the major barrier to the effectiveness of vaccines. This study aimed to investigate the genetic polymorphisms and natural selection of pfcsp in Bioko and the comparison among global P. falciparum population. METHODS From January 2011 to December 2018, 148 blood samples were collected from P. falciparum infected Bioko patients and 96 monoclonal sequences of them were successfully acquired and analysed with 2200 global pfcsp sequences mined from MalariaGEN Pf3k Database and NCBI. RESULTS In Bioko, the N-terminus of pfcsp showed limited genetic variations and the numbers of repetitive sequences (NANP/NVDP) were mainly found as 40 (35%) and 41 (34%) in central region. Most polymorphic characters were found in Th2R/Th3R region, where natural selection (p > 0.05) and recombination occurred. The overall pattern of Bioko pfcsp gene had no obvious deviation from African mainland pfcsp (Fst = 0.00878, p < 0.05). The comparative analysis of Bioko and global pfcsp displayed the various mutation patterns and obvious geographic differentiation among populations from four continents (p < 0.05). The global pfcsp C-terminal sequences were clustered into 138 different haplotypes (H_1 to H_138). Only 3.35% of sequences matched 3D7 strain haplotype (H_1). CONCLUSIONS The genetic polymorphism phenomena of pfcsp were found universal in Bioko and global isolates and the majority mutations located at T cell epitopes. Global genetic polymorphism and geographical characteristics were recommended to be considered for future improvement of malaria vaccine design.
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Affiliation(s)
- Hui-Ying Huang
- School of Food Engineering and Biotechnology, Hanshan Normal University, Chaozhou, People's Republic of China
- Department of Medical Genetics, Shantou University Medical College, Shantou, Guangdong Province, People's Republic of China
| | - Xue-Yan Liang
- School of Food Engineering and Biotechnology, Hanshan Normal University, Chaozhou, People's Republic of China
- Department of Medical Genetics, Shantou University Medical College, Shantou, Guangdong Province, People's Republic of China
| | - Li-Yun Lin
- School of Food Engineering and Biotechnology, Hanshan Normal University, Chaozhou, People's Republic of China
| | - Jiang-Tao Chen
- Department of Medical Laboratory, Huizhou Central Hospital, Huizhou, Guangdong Province, People's Republic of China
- The Chinese Medical Aid Team to the Republic of Equatorial Guinea, Guangzhou, Guangdong Province, People's Republic of China
| | - Carlos Salas Ehapo
- Department of Medical Laboratory, Malabo Regional Hospital, Malabo, Equatorial Guinea
| | - Urbano Monsuy Eyi
- Department of Medical Laboratory, Malabo Regional Hospital, Malabo, Equatorial Guinea
| | - Jian Li
- Department of Human Parasitology, School of Basic Medical Sciences, Department of Infectious Diseases, Renmin Hospital, Hubei University of Medicine, Shiyan, Hubei Province, People's Republic of China
| | - Ting-Ting Jiang
- Department of Human Parasitology, School of Basic Medical Sciences, Department of Infectious Diseases, Renmin Hospital, Hubei University of Medicine, Shiyan, Hubei Province, People's Republic of China
| | - Yu-Zhong Zheng
- School of Food Engineering and Biotechnology, Hanshan Normal University, Chaozhou, People's Republic of China
| | - Guang-Cai Zha
- School of Food Engineering and Biotechnology, Hanshan Normal University, Chaozhou, People's Republic of China
| | - Dong-De Xie
- The Chinese Medical Aid Team to the Republic of Equatorial Guinea, Guangzhou, Guangdong Province, People's Republic of China
| | - Jin-Quan He
- The Chinese Medical Aid Team to the Republic of Equatorial Guinea, Guangzhou, Guangdong Province, People's Republic of China
| | - Wei-Zhong Chen
- Department of Medical Laboratory, Chaozhou People's Hospital Affiliated to Shantou University Medical College, Chaozhou, Guangdong Province, People's Republic of China
| | - Xiang-Zhi Liu
- Department of Medical Laboratory, Chaozhou People's Hospital Affiliated to Shantou University Medical College, Chaozhou, Guangdong Province, People's Republic of China
| | - Huan-Tong Mo
- Department of Medical Laboratory, Chaozhou People's Hospital Affiliated to Shantou University Medical College, Chaozhou, Guangdong Province, People's Republic of China
| | - Xin-Yao Chen
- Department of Medical Laboratory, Chaozhou People's Hospital Affiliated to Shantou University Medical College, Chaozhou, Guangdong Province, People's Republic of China
| | - Min Lin
- School of Food Engineering and Biotechnology, Hanshan Normal University, Chaozhou, People's Republic of China.
- Department of Medical Laboratory, Chaozhou People's Hospital Affiliated to Shantou University Medical College, Chaozhou, Guangdong Province, People's Republic of China.
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3
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Saroja C, Lakshmi P, Bhaskaran S. Recent trends in vaccine delivery systems: A review. Int J Pharm Investig 2012; 1:64-74. [PMID: 23071924 PMCID: PMC3465129 DOI: 10.4103/2230-973x.82384] [Citation(s) in RCA: 100] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2011] [Revised: 02/14/2011] [Accepted: 02/21/2011] [Indexed: 12/17/2022] Open
Abstract
Vaccines are the preparations given to patients to evoke immune responses leading to the production of antibodies (humoral) or cell-mediated responses that will combat infectious agents or noninfectious conditions such as malignancies. Alarming safety profile of live vaccines, weak immunogenicity of sub-unit vaccines and immunization, failure due to poor patient compliance to booster doses which should potentiate prime doses are few strong reasons, which necessitated the development of new generation of prophylactic and therapeutic vaccines to promote effective immunization. Attempts are being made to deliver vaccines through carriers as they control the spatial and temporal presentation of antigens to immune system thus leading to their sustained release and targeting. Hence, lower doses of weak immunogens can be effectively directed to stimulate immune responses and eliminate the need for the administration of prime and booster doses as a part of conventional vaccination regimen. This paper reviews carrier systems such as liposomes, microspheres, nanoparticles, dendrimers, micellar systems, ISCOMs, plant-derived viruses which are now being investigated and developed as vaccine delivery systems. This paper also describes various aspects of "needle-free technologies" used to administer the vaccine delivery systems through different routes into the human body.
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Affiliation(s)
- Ch Saroja
- Department of Pharmaceutics, G. Pulla Reddy College of Pharmacy, Hyderabad, Andhra Pradesh, India
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4
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Chinchilla M, Pasetti MF, Medina-Moreno S, Wang JY, Gomez-Duarte OG, Stout R, Levine MM, Galen JE. Enhanced immunity to Plasmodium falciparum circumsporozoite protein (PfCSP) by using Salmonella enterica serovar Typhi expressing PfCSP and a PfCSP-encoding DNA vaccine in a heterologous prime-boost strategy. Infect Immun 2007; 75:3769-79. [PMID: 17502396 PMCID: PMC1951980 DOI: 10.1128/iai.00356-07] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Two Salmonella enterica serovar Typhi strains that express and export a truncated version of Plasmodium falciparum circumsporozoite surface protein (tCSP) fused to Salmonella serovar Typhi cytolysin A (ClyA) were constructed as a first step in the development of a preerythrocytic malaria vaccine. Synthetic codon-optimized genes (t-csp1 and t-csp2), containing immunodominant B- and T-cell epitopes present in native P. falciparum circumsporozoite surface protein (PfCSP), were fused in frame to the carboxyl terminus of the ClyA gene (clyA::t-csp) in genetically stabilized expression plasmids. Expression and export of ClyA-tCSP1 and ClyA-tCSP2 by Salmonella serovar Typhi vaccine strain CVD 908-htrA were demonstrated by immunoblotting of whole-cell lysates and culture supernatants. The immunogenicity of these constructs was evaluated using a "heterologous prime-boost" approach consisting of mucosal priming with Salmonella serovar Typhi expressing ClyA-tCSP1 and ClyA-tCSP2, followed by parenteral boosting with PfCSP DNA vaccines pVR2510 and pVR2571. Mice primed intranasally on days 0 and 28 with CVD 908-htrA(pSEC10tcsp2) and boosted intradermally on day 56 with PfCSP DNA vaccine pVR2571 induced high titers of serum NANP immunoglobulin G (IgG) (predominantly IgG2a); no serological responses to DNA vaccination were observed in the absence of Salmonella serovar Typhi-PfCSP priming. Mice primed with Salmonella serovar Typhi expressing tCSP2 and boosted with PfCSP DNA also developed high frequencies of gamma interferon-secreting cells, which surpassed those produced by PfCSP DNA in the absence of priming. A prime-boost regimen consisting of mucosal delivery of PfCSP exported from a Salmonella-based live-vector vaccine followed by a parenteral PfCSP DNA boosting is a promising strategy for the development of a live-vector-based malaria vaccine.
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Affiliation(s)
- Magaly Chinchilla
- Center for Vaccine Development, University of Maryland, 685 W. Baltimore Street, HSF I, Room 480, Baltimore, MD 21201, USA.
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5
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Jalloh A, van Thien H, Ferreira MU, Ohashi J, Matsuoka H, Kanbe T, Kikuchi A, Kawamoto F. Sequence variation in the T-cell epitopes of the Plasmodium falciparum circumsporozoite protein among field isolates is temporally stable: a 5-year longitudinal study in southern Vietnam. J Clin Microbiol 2006; 44:1229-35. [PMID: 16597843 PMCID: PMC1448650 DOI: 10.1128/jcm.44.4.1229-1235.2006] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In an effort to decipher the nature and extent of antigen polymorphisms of malaria parasites in a setting where malaria is hypomesoendemic, we conducted a 5-year longitudinal study (1998 to 2003) by sequencing the Th2R and Th3R epitopes of the circumsporozoite protein (CSP) of 142 Plasmodium falciparum field isolates from Bao Loc, Vietnam. Samples were collected during the high-transmission season, September through December 1998 (n = 43), as well as from July 2000 to August 2001 (n = 34), September 2001 to July 2002 (n = 33), and August 2002 to July 2003 (n = 32). Marked sequence diversity was noted during the high-transmission season in 1998, but no significant variation in allele frequencies was observed over the years (chi(2) = 70.003, degrees of freedom = 57, P = 0.116). The apparent temporal stability in allele frequency observed in this Bao Loc malaria setting may suggest that polymorphism in the Th2R and Th3R epitopes is not maintained by frequency-dependent immune selection. By including 36 isolates from Flores Island, Indonesia, and 19 isolates from Thaton, Myanmar, we investigated geographical patterns of sequence polymorphism for these epitopes in Southeast Asia; among the characterized isolates, a globally distributed variant appears to be predominant in Vietnam (75 of 142 isolates, or 52.8%) as well as in Myanmar (15 of 19 isolates, or 78.9%) and Indonesia (31 of 36 isolates, or 86.1%). Further analyses involving worldwide CSP sequences revealed distinct regional patterns, a finding which, together with the unique mutations observed here, may suggest a possible role for host or local factors in the generation of sequence diversity in the T-cell epitopes of CSP.
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Affiliation(s)
- Amadu Jalloh
- Division of Molecular Mycology and Medicine, Department of Advanced Medical Science, Center for Neurological Disease and Cancer, Nagoya University Graduate School of Medicine, 65 Tsurumai, Showa-ku, Nagoya, Aichi 466-8550, Japan.
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6
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Kumkhaek C, Phra-Ek K, Rénia L, Singhasivanon P, Looareesuwan S, Hirunpetcharat C, White NJ, Brockman A, Grüner AC, Lebrun N, Alloueche A, Nosten F, Khusmith S, Snounou G. Are extensive T cell epitope polymorphisms in the Plasmodium falciparum circumsporozoite antigen, a leading sporozoite vaccine candidate, selected by immune pressure? THE JOURNAL OF IMMUNOLOGY 2005; 175:3935-9. [PMID: 16148140 DOI: 10.4049/jimmunol.175.6.3935] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Protective cellular immune responses depend on MHC presentation of pathogen-derived Ag fragments. MHC diversity renders this process sensitive to point mutations coding for altered amino acid sequence of the short target Ag-derived peptides epitopes. Thus, in a given host, a pathogen with an altered epitope sequence will be more likely to escape detection and elimination by the immune system. At a population level, selection by immune pressure will increase the likelihood of polymorphism in important pathogen antigenic epitopes. This mechanism of immune evasion is found in viruses and other pathogens. The detection of polymorphic hot spots in an Ag is often taken as a strong indication of its role in protective immunity. We provide evidence that polymorphisms in the T cell epitopes of a malaria vaccine candidate are unlikely to have been selected by immune pressure in the human host.
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Affiliation(s)
- Chutima Kumkhaek
- Department of Microbiology and Immunology, Mahidol University, Bangkok, Thailand
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7
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Rathore D, Nagarkatti R, Jani D, Chattopadhyay R, de la Vega P, Kumar S, McCutchan TF. An immunologically cryptic epitope of Plasmodium falciparum circumsporozoite protein facilitates liver cell recognition and induces protective antibodies that block liver cell invasion. J Biol Chem 2005; 280:20524-9. [PMID: 15781464 DOI: 10.1074/jbc.m414254200] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Circumsporozoite, a predominant surface protein, is involved in invasion of liver cells by Plasmodium sporozoites, which leads to malaria. We have previously reported that the amino terminus region (amino acids 27-117) of P. falciparum circumsporozoite protein plays a critical role in the invasion of liver cells by the parasite. Here we show that invasion-blocking antibodies are induced by a polypeptide encoding these 91 amino acids, only when it is presented in the absence of the rest of the protein. This suggests that when present in the whole protein, the amino terminus remains immunologically cryptic. A single reactive epitope was identified and mapped to a stretch of 21 amino acids from position 93 to 113. The epitope is configurational in nature, since its recognition was affected by deleting as little as 3 amino acids from either end of the 21-residue peptide. Lysine 104, the only known polymorphic position in the epitope, affected its recognition by the antibodies, and its conversion to leucine in the protein led to a substantial loss of binding activity of the protein to the hepatocytes. This indicated that in the protein, the epitope serves as a binding ligand and facilitates the interaction between sporozoite and hepatic cells. When considered along with the observation that in its native state this motif is immunologically unresponsive, we suggest that hiding functional moieties of the protein from the immune system is an evasion strategy to preserve liver cell binding function and may be of importance in designing anti-sporozoite vaccines.
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Affiliation(s)
- Dharmendar Rathore
- Virginia Bioinformatics Institute, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA.
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8
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Rathore D, Hrstka SCL, Sacci JB, De la Vega P, Linhardt RJ, Kumar S, McCutchan TF. Molecular mechanism of host specificity in Plasmodium falciparum infection: role of circumsporozoite protein. J Biol Chem 2003; 278:40905-10. [PMID: 12904297 DOI: 10.1074/jbc.m306250200] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Plasmodium falciparum sporozoites invade liver cells in humans and set the stage for malaria infection. Circumsporozoite protein (CSP), a predominant surface antigen on sporozoite surface, has been associated with the binding and invasion of liver cells by the sporozoites. Although CSP across the Plasmodium genus has homology and conserved structural organization, infection of a non-natural host by a species is rare. We investigated the role of CSP in providing the host specificity in P. falciparum infection. CSP from P. falciparum, P. gallinaceum, P. knowlesi, and P. yoelii species representing human, avian, simian, and rodent malaria species were recombinantly expressed, and the proteins were purified to homogeneity. The recombinant proteins were evaluated for their capacity to bind to human liver cell line HepG2 and to prevent P. falciparum sporozoites from invading these cells. The proteins showed significant differences in the binding and sporozoite invasion inhibition activity. Differences among proteins directly correlate with changes in the binding affinity to the sporozoite receptor on liver cells. P. knowlesi CSP (PkCSP) and P. yoelii CSP (PyCSP) had 4,790- and 17,800-fold lower affinity for heparin in comparison to P. falciparum CSP (PfCSP). We suggest that a difference in the binding affinity for the liver cell receptor is a mechanism involved in maintaining the host specificity by the malaria parasite.
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Affiliation(s)
- Dharmendar Rathore
- Growth and Development Section, Laboratory of Malaria and Vector Research, NIAID, National Institutes of Health, Bethesda, Maryland 20892, USA
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9
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Chattopadhyay R, Rathore D, Fujioka H, Kumar S, de la Vega P, Haynes D, Moch K, Fryauff D, Wang R, Carucci DJ, Hoffman SL. PfSPATR, a Plasmodium falciparum protein containing an altered thrombospondin type I repeat domain is expressed at several stages of the parasite life cycle and is the target of inhibitory antibodies. J Biol Chem 2003; 278:25977-81. [PMID: 12716913 DOI: 10.1074/jbc.m300865200] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The annotated sequence of chromosome 2 of Plasmodium falciparum was examined for genes encoding proteins that may be of interest for vaccine development. We describe here the characterization of a protein with an altered thrombospondin Type I repeat domain (PfSPATR) that is expressed in the sporozoite, asexual, and sexual erythrocytic stages of the parasite life cycle. Immunoelectron microscopy indicated that this protein was expressed on the surface of the sporozoites and around the rhoptries in the asexual erythrocytic stage. An Escherichia coli-produced recombinant form of the protein bound to HepG2 cells in a dose-dependent manner and antibodies raised against this protein blocked the invasion of sporozoites into a transformed hepatoma cell line. Sera from Ghanaian adults and from a volunteer who had been immunized with radiation-attenuated P. falciparum sporozoites specifically recognized the expression of this protein on transfected COS-7 cells. These data support the evaluation of this protein as a vaccine candidate.
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Affiliation(s)
- Rana Chattopadhyay
- Malaria Program, Naval Medical Research Center, Silver Spring, Maryland 20910-7500, USA
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10
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Schnittger L, Katzer F, Biermann R, Shayan P, Boguslawski K, McKellar S, Beyer D, Shiels BR, Ahmed JS. Characterization of a polymorphic Theileria annulata surface protein (TaSP) closely related to PIM of Theileria parva: implications for use in diagnostic tests and subunit vaccines. Mol Biochem Parasitol 2002; 120:247-56. [PMID: 11897130 DOI: 10.1016/s0166-6851(02)00013-0] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Theileria annulata is a tick-transmitted protozoan that causes tropical theileriosis, an often fatal leukoproliferative disorder of cattle. To characterize and identify parasite proteins suitable as diagnostic antigens and/or vaccine candidates, a cDNA clone encoding a macroschizont stage protein was isolated and characterized (here designated TaSP). The gene, present as a single copy within the parasite genome, is transcribed in the sporozoite and schizont stage and codes for a protein of about 315 amino acids, having a predicted molecular weight of 36 kDa. Allelic variants were found within single parasite isolates and between isolates originating from different geographical regions. The N-terminal part contains a predicted signal peptide and the C-terminal section encodes membrane-spanning regions. Comparison of a number of cDNA clones showed that both these sequence regions are conserved while the central region shows both size and amino acid sequence polymorphism. High identity of the N- and C-terminal regions with the polymorphic immunodominant molecule (PIM) of Theileria parva (identity of 93%), the existence of a central polymorphic region and two short introns within genomic clones suggest that the presented gene/protein may be the T. annulata homologue of PIM. However, the central region of TaSP has no significant identity with PIM, contains no repetitive peptide motifs and is shorter, resulting in a lower molecular weight. The existence of the predicted secretion signal peptide and membrane spanning regions suggest that TaSP is located at the parasite membrane.
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MESH Headings
- Amino Acid Sequence
- Animals
- Antigens, Protozoan/chemistry
- Antigens, Protozoan/genetics
- Antigens, Protozoan/immunology
- Antigens, Surface/chemistry
- Antigens, Surface/genetics
- Antigens, Surface/immunology
- Blotting, Western
- Genes, Protozoan/genetics
- Molecular Sequence Data
- Polymorphism, Genetic/genetics
- Protozoan Proteins/chemistry
- Protozoan Proteins/genetics
- Protozoan Proteins/immunology
- Protozoan Vaccines/chemistry
- Protozoan Vaccines/immunology
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Reverse Transcriptase Polymerase Chain Reaction
- Sequence Homology, Amino Acid
- Theileria annulata/genetics
- Theileria annulata/growth & development
- Theileria annulata/immunology
- Theileria parva/genetics
- Theileria parva/growth & development
- Theileria parva/immunology
- Theileriasis/diagnosis
- Theileriasis/immunology
- Theileriasis/parasitology
- Vaccines, Subunit/chemistry
- Vaccines, Subunit/immunology
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11
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Rathore D, Sacci JB, de la Vega P, McCutchan TF. Binding and invasion of liver cells by Plasmodium falciparum sporozoites. Essential involvement of the amino terminus of circumsporozoite protein. J Biol Chem 2002; 277:7092-8. [PMID: 11751898 DOI: 10.1074/jbc.m106862200] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Plasmodium sporozoites display circumsporozoite (CS) protein on their surface, which is involved in the attachment of sporozoites to liver cells. CS protein is a member of the thrombospondin type I repeat (TSR) domain family and possess a single copy of TSR domain toward its carboxyl terminus. We show by a direct measurement the correlation between the binding activity of various segments of the CS protein and their ability to inhibit the invasion of liver cells by the sporozoites. We made eight truncated versions of Plasmodium falciparum CS protein to elucidate the role of various regions in the binding and invasion process. Deletion of the TSR domain actually enhanced binding activity by 2-3-fold without the loss of receptor specificity, indicating that TSR may not be the only domain in defining the specificity of binding. These same deletions blocked invasion of live sporozoites more efficiently than proteins that include the TSR domain. Deletion of as little as six amino acids from amino terminus of the protein, however, renders it incapable of binding to liver cells and as an inhibitor of sporozoite invasion. Hence, the binding of CS protein to liver cells and its ability to inhibit the invasion process are affected in a parallel manner, both positively and negatively, by sequence changes in the encoded CS gene. This indicates that both assays are measuring interrelated phenomenon and points to the essential involvement for the amino-terminal portion of the CS protein in these processes.
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Affiliation(s)
- Dharmendar Rathore
- Growth and Development Section, Laboratory of Malaria and Vector Research, NIAID/National Institutes of Health, 4 Center Drive MSC 0425, Bethesda, MD 20892-0425, USA
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12
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Rathore D, Kumar S, Lanar DE, McCutchan TF. Disruption of disulfide linkages of the Plasmodium falciparum circumsporozoite protein: effects on cytotoxic and antibody responses in mice. Mol Biochem Parasitol 2001; 118:75-82. [PMID: 11704275 DOI: 10.1016/s0166-6851(01)00369-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The circumsporozoite protein is a predominant surface antigen present on Plasmodium sporozoites. In Plasmodium falciparum circumsporozoite protein (PfCSP), two cysteine residues (396 and 401) are present adjacent to two overlapping cytotoxic T-lymphocyte epitopes of the protein and are involved in the formation of disulfide bridges. We investigated the role of these cysteines on the cellular and antibody responses towards the CS protein because disruption of disulfide linkages and the presence of cysteine residues in the flanking region of an epitope has been shown to significantly alter the immune responses to various proteins. Mice were immunized with variant forms of PfCSP DNA vaccine plasmids where these cysteine residues were individually mutated to alanine. The plasmid vaccines induced antigen specific antibody and cytotoxic T lymphocyte responses. While no alterations of cysteine influenced the CTL responses to P. falciparum CS protein, vaccine pVRCS4, containing an altered cysteine at position 401, dramatically improved the antibody response to the carboxyl-terminal region of the protein. This work indicates that sequence alterations of genes in an anti-malarial vaccine could enhance the response towards the native protein. Given the fact that long term natural immunity to the pathogen has not been documented, it may be important to challenge the immune system with non-native proteins.
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Affiliation(s)
- D Rathore
- Growth and Development Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Room 126, Building 4, 4 Center Drive, MSC, 0425, Bethesda, MD 20892-0425, USA
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Perlmann P, Björkman A. Malaria research: host-parasite interactions and new developments in chemotherapy, immunology and vaccinology. Curr Opin Infect Dis 2000; 13:431-443. [PMID: 11964811 DOI: 10.1097/00001432-200010000-00002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Malaria remains the major parasitic disease, with 300-500 million new infections each year. This survey covers recent advances in the field of parasite-host interactions, focusing on Plasmodium falciparum, the most virulent of the human parasites. Rapid progress in genomic research is creating a basis for the development of new drugs and vaccines. Identification of drug-resistance mutations facilitates evaluation of improved drug policies, and attempts are being made to develop new compounds that inhibit metabolic pathways that are specific to the parasite. Cytoadherence of parasitized erythrocytes to microvascular endothelium is responsible for the sequestration of parasites, causing pathology and severe disease. Newly identified molecular fine structures that mediate cytoadherence may provide new targets for specific therapies. Humoral and cell-mediated immunity induced by the parasite may be protective, but may also be harmful by generating imbalance in cytokine responses. Efforts are made to determine the pathways that give rise to protection, with vaccination being the principal goal for achieving malaria control. Different vaccine constructs are being evaluated in preclinical and clinical trials, including modified viral vectors, synthetic peptides, DNA and new adjuvants.
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Affiliation(s)
- Peter Perlmann
- aDepartment of Immunology, Stockholm University, and bKarolinska Institute, Infectious Diseases Unit, Karolinska Hospital, Stockholm, Sweden
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Rathore D, McCutchan TF. Role of cysteines in Plasmodium falciparum circumsporozoite protein: interactions with heparin can rejuvenate inactive protein mutants. Proc Natl Acad Sci U S A 2000; 97:8530-5. [PMID: 10890903 PMCID: PMC26982 DOI: 10.1073/pnas.140224597] [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: 11/18/2022] Open
Abstract
Various pathogenic bacteria, viruses, and protozoan bind to glycosaminoglycan-based receptors on host cells and initiate an infection. Sporozoites of Plasmodium predominantly express circumsporozoite (CS) protein on their surface, which binds to heparan sulfate proteoglycans on liver cell surface that subsequently leads to malaria. Here we show that the interaction of free heparin with this parasite ligand has the potential to be a critical component of invasion. CS protein of P. falciparum contains four cysteines at positions 361, 365, 396, and 401. In this study, all four cysteine residues were mutagenized to alanine both individually and in different combinations. Conversion of cysteine 396 to alanine (protein CS3) led to a 10-fold increase in the binding activity of the protein to HepG2 cells. Replacement of cysteines at positions 361, 365, and 401 either alone or in different combinations led to a near total loss of binding. Surprisingly, activity in these inactive mutants could be effectively restored in the presence of submolar concentrations of heparin. Heparin also up-regulated binding of CS3 at submolar concentrations with respect to the protein but down-regulated binding when present in excess. Given the significantly different concentrations of heparin in different organs of the host and the in vitro results described here one can consider in vivo ramifications of this phenomenon for pathogen targeting of specific organs and for the functional effects of antigenic variation on receptor ligand interaction.
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Affiliation(s)
- D Rathore
- Growth and Development Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD 20892-0425, USA
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Rathore D, McCutchan TF. Heparin can regulate the binding of Plasmodium falciparum circumsporozoite protein. Mol Biochem Parasitol 2000; 108:253-6. [PMID: 10838228 DOI: 10.1016/s0166-6851(00)00214-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Affiliation(s)
- D Rathore
- Growth and Development Section, Laboratory of Parasitic Diseases, Room 126, Building 4, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 4 Centre Drive MSC 0425, 9000 Rockville Pike, Bethesda, MD 20892-0425, USA
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