151
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Lombardo F, Nolan T, Lycett G, Lanfrancotti A, Stich N, Catteruccia F, Louis C, Coluzzi M, Arcà B. An Anopheles gambiae salivary gland promoter analysis in Drosophila melanogaster and Anopheles stephensi. INSECT MOLECULAR BIOLOGY 2005; 14:207-216. [PMID: 15796754 DOI: 10.1111/j.1365-2583.2004.00549.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Regulatory regions driving gene expression in specific target organs of the African malaria vector Anopheles gambiae are of critical relevance for studies on Plasmodium-Anopheles interactions as well as to devise strategies for blocking malaria parasite development in the mosquito. In order to identify an appropriate salivary gland promoter we analysed the transactivation properties of genomic fragments located just upstream of the An. gambiae female salivary gland-specific genes AgApy and D7r4. An 800 bp fragment from the AgApy gene directed specific expression of the LacZ reporter gene in the salivary glands of transgenic Anopheles stephensi. However, expression levels were lower than expected and the transgene was expressed in the proximal-rather than in the distal-lateral lobes of female glands. Surprisingly, a promoter fragment from the D7r4 gene conferred strong tissue-specific expression in Drosophila melanogaster but only low transcription levels in transgenic An. stephensi. These results imply a certain conservation of gland-specific control elements between the fruit fly and the mosquito suggesting that an increased degree of complexity, probably connected to the evolution of haematophagy, underlies the regulation of tissue-specific expression in mosquito female salivary glands.
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Affiliation(s)
- F Lombardo
- Dipartimento di Scienze di Sanità Pubblica - Sezione di Parassitologia, Università di Roma La Sapienza, Rome, Italy
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152
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Adam I, Osman ME, Elghzali G, Ahmed GI, Gustafssons LL, Elbashir MI. Efficacies of chloroquine, sulfadoxine-pyrimethamine and quinine in the treatment of uncomplicated, Plasmodium falciparum malaria in eastern Sudan. ANNALS OF TROPICAL MEDICINE AND PARASITOLOGY 2005; 98:661-6. [PMID: 15509420 DOI: 10.1179/000349804225021514] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The efficacies of several antimalarial drugs in the treatment of uncomplicated Plasmodium falciparum malaria were compared, during an open, randomized trial, in New Halfa, eastern Sudan. The 96 patients who completed the 28 days of follow-up were treated with chloroquine (N = 26), sulfadoxine-pyrimethamine (N = 38) or quinine (N = 32). No treatment failures were observed among the patients given sulfadoxine-pyrimethamine. Only 23.1% of the patients given chloroquine showed adequate clinical response, however, the rest showing early (15.4%) or, more frequently, late (61.5%) treatment failure. In terms of parasitological failure, 54.1% of the patients given chloroquine showed early RI resistance, 7.7% showed late RI, and 15.1% showed RIII. Most (90.6%) of the patients treated with quinine had adequate treatment responses, the rest having late treatment failures (and late RI). The frequency of treatment failure was significantly higher, however, among the patients given chloroquine than in the quinine-treatment arm. The present results and those of earlier investigations indicate that the problem of chloroquine resistance is worsening in eastern Sudan, and that the use of chloroquine as the first-line drug for the treatment of uncomplicated malaria in this area is now compromised. The response to quinine may also be faltering.
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Affiliation(s)
- I Adam
- New Halfa Teaching Hospital, P.O. Box 61, New Halfa, Sudan.
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153
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Cifuentes G, Salazar LM, Vargas LE, Parra CA, Vanegas M, Cortes J, Patarroyo ME. Evidence supporting the hypothesis that specifically modifying a malaria peptide to fit into HLA-DRβ1*03 molecules induces antibody production and protection. Vaccine 2005; 23:1579-87. [PMID: 15694510 DOI: 10.1016/j.vaccine.2004.08.052] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2004] [Accepted: 08/10/2004] [Indexed: 11/26/2022]
Abstract
EBA-175 protein is used as ligand in Plasmodium falciparum binding to erythrocytes. Evidence shows that conserved peptide 1815 from this protein having high red blood cell binding ability plays an important role in the invasion process. This peptide is neither immunogenic nor protective. Residues were substituted by amino acids having similar volume or mass but different polarity in 1815 analogues had to make them fit into HLA-DRbeta1*03 molecules; these were synthesised and inoculated into Aotus monkeys, generating different immunogenic and/or protective immune responses. A shortening in alpha-helix structure was found in the immunogenic and protective ones when their secondary structure was analyzed by NMR to correlate their structure with their immunological properties. This data, together with results from previous studies, suggests that this shortening in high-activity binding peptide (HABP) helical configuration may lead to better fitting into immune system molecules as shown by binding to purified HLA-DRbeta1* molecules rendering them immunogenic and protective and therefore, excellent candidates for consideration as components of a subunit based multi-component synthetic vaccine against malaria.
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Affiliation(s)
- Gladys Cifuentes
- Fundación Instituto de Inmunología de Colombia (FIDIC), Cra. 50, No. 26-00, Bogotá, Colombia
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154
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Pearce JA, Mills K, Triglia T, Cowman AF, Anders RF. Characterisation of two novel proteins from the asexual stage of Plasmodium falciparum, H101 and H103. Mol Biochem Parasitol 2005; 139:141-51. [PMID: 15664649 DOI: 10.1016/j.molbiopara.2004.09.012] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2004] [Revised: 09/22/2004] [Accepted: 09/23/2004] [Indexed: 10/26/2022]
Abstract
The merozoite surface of the pathogenic malaria parasite Plasmodium falciparum is comprised of proteins that are important for the identification and invasion of human red cells. Merozoite surface protein (MSP)3 is a polymorphic protein associated with the surface of merozoites and is also a vaccine candidate. A distinct feature of the MSP3 sequence is three blocks of alanine-rich heptad repeats that are predicted to form an intramolecular coiled-coil. Three orthologues of MSP3 that also contain alanine-rich heptad repeats have been described in P. vivax and we therefore searched the P. falciparum genome database for MSP3 paralogues. We have identified two genes, H101 and H103 related to MSP3, however like another MSP3 paralogue, MSP6, H101 and H103 do not contain heptad repeats. H101 and H103 are expressed during the asexual cycle and immunofluorescence indicates H103 localises to the merozoite surface as a peripheral membrane protein. Transfected parasite lines that express truncated forms of H101 or H103 were viable and grew at the same rate as the parental parasite line. This result may reflect redundancy in function among members of the MSP3/MSP6 gene family as has been described for other families of paralogue genes in P. falciparum.
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Affiliation(s)
- J Andrew Pearce
- Infection and Immunity Division, The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Melbourne, Vic. 3050, Australia.
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155
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Blake DP, Hesketh P, Archer A, Carroll F, Smith AL, Shirley MW. Parasite genetics and the immune host: recombination between antigenic types of Eimeria maxima as an entrée to the identification of protective antigens. Mol Biochem Parasitol 2004; 138:143-52. [PMID: 15500925 DOI: 10.1016/j.molbiopara.2004.08.006] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2004] [Revised: 08/02/2004] [Accepted: 08/14/2004] [Indexed: 10/26/2022]
Abstract
The genomes of protozoan parasites encode thousands of gene products and identification of the subset that stimulates a protective immune response is a daunting task. Most screens for vaccine candidates identify molecules by capacity to induce immune responses rather than protection. This paper describes the core findings of a strategy developed with the coccidial parasite Eimeria maxima to rationally identify loci within its genome that encode immunoprotective antigens. Our strategy uses a novel combination of parasite genetics, DNA fingerprinting, drug-resistance and strain-specific immunity and centres on two strains of E. maxima that each induce a lethal strain-specific protective immune response in the host and show a differential response to anti-Eimeria chemotherapy. Through classical mating studies with these strains we have demonstrated that loci encoding molecules stimulating strain-specific protective immunity or resistance to the anti-coccidial drug robenidine segregate independently. Furthermore, passage of populations of recombinant parasites in the face of killing in the immune host was accompanied by the elimination of some polymorphic DNA markers defining the parent strain used to immunise the host. Consideration of the numbers of parasites recombinant for the two traits implicates very few antigen-encoding loci. Our data provide a potential strategy to identify putative antigen-encoding loci in other parasites.
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Affiliation(s)
- Damer P Blake
- Eimerian Genomics Group, Institute for Animal Health, Compton, Nr. Newbury, Berkshire RG20 7NN, UK
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156
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Patarroyo ME, Cifuentes G, Vargas LE, Rosas J. Structural Modifications Enable Conserved Peptides to Fit into MHC Molecules thus Inducing Protection against Malaria. Chembiochem 2004; 5:1588-93. [PMID: 15515079 DOI: 10.1002/cbic.200400116] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Manuel Elkin Patarroyo
- Fundación Instituto de Inmunologia de Colombia (FIDIC), Cra. 50 No. 26-00 Bogotá, Colombia.
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157
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Burns JM, Flaherty PR, Nanavati P, Weidanz WP. Protection against Plasmodium chabaudi malaria induced by immunization with apical membrane antigen 1 and merozoite surface protein 1 in the absence of gamma interferon or interleukin-4. Infect Immun 2004; 72:5605-12. [PMID: 15385457 PMCID: PMC517570 DOI: 10.1128/iai.72.10.5605-5612.2004] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Strategies to optimize formulations of multisubunit malaria vaccines require a basic knowledge of underlying protective immune mechanisms induced by each vaccine component. In the present study, we evaluated the contribution of antibody-mediated and cell-mediated immune mechanisms to the protection induced by immunization with two blood-stage malaria vaccine candidate antigens, apical membrane antigen 1 (AMA-1) and merozoite surface protein 1 (MSP-1). Immunologically intact or selected immunologic knockout mice were immunized with purified recombinant Plasmodium chabaudi AMA-1 (PcAMA-1) and/or the 42-kDa C-terminal processing fragment of P. chabaudi MSP-1 (MSP-1(42)). The efficacy of immunization in each animal model was measured as protection against blood-stage P. chabaudi malaria. Immunization of B-cell-deficient JH(-/-) mice indicated that PcAMA-1 vaccine-induced immunity is largely antibody dependent. In contrast, JH(-/-) mice immunized with PcMSP-1(42) were partially protected against P. chabaudi malaria, indicating a role for protective antibody-dependent and antibody-independent mechanisms of immunity. The involvement of gammadelta T cells in vaccine-induced PcAMA-1 and/or PcMSP-1(42) protection was minor. Analysis of the isotypic profile of antigen-specific antibodies induced by immunization of immunologically intact mice revealed a dominant IgG1 response. However, neither interleukin-4 and the production of IgG1 antibodies nor gamma interferon and the production of IgG2a/c antibodies were essential for PcAMA-1 and/or PcMSP-1(42) vaccine-induced protection. Therefore, for protective antibody-mediated immunity, vaccine adjuvants and delivery systems for AMA-1- and MSP-1-based vaccines can be selected for their ability to maximize responses irrespective of IgG isotype or any Th1 versus Th2 bias in the CD4(+)-T-cell response.
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Affiliation(s)
- James M Burns
- Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, Pennsylvania 19129, USA.
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158
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Rummel T, Batchelder J, Flaherty P, LaFleur G, Nanavati P, Burns JM, Weidanz WP. CD28 costimulation is required for the expression of T-cell-dependent cell-mediated immunity against blood-stage Plasmodium chabaudi malaria parasites. Infect Immun 2004; 72:5768-74. [PMID: 15385476 PMCID: PMC517583 DOI: 10.1128/iai.72.10.5768-5774.2004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Mice suppress the parasitemia of acute blood-stage Plasmodium chabaudi malaria by an antibody- or T-cell-dependent cell-mediated mechanism of immunity (AMI and CMI, respectively) or by both mechanisms. To determine whether CD28 costimulation is required for expression of these polar immune responses, we first compared the time courses of P. chabaudi malaria in CD28-deficient (CD28(-/-)) and CD28-intact (CD28(+/+)) mice. Acute infections in both knockout (KO) and control mice followed similar time courses, with the period of descending parasitemia being prolonged approximately 2 weeks in KO mice followed by intermittent low-grade chronic parasitemia. Infected CD28(-/-) mice produced primarily the immunoglobulin M antibody, which upon passive transfer provided partial protection against P. chabaudi challenge, suggesting that the elimination of blood-stage parasites by CD28(-/-) mice was achieved by AMI. To determine whether CD28(-/-) costimulation is required for the expression of CMI against the parasite, we compared the time courses of parasitemia in B-cell-deficient double-KO (J(H)(-/-) x CD28(-/-)) mice and control (J(H)(-/-) x CD28(+/+)) mice. Whereas control mice suppressed parasitemia to subpatent levels within approximately 2 weeks postinoculation, double-KO mice developed high levels of parasitemia of long-lasting duration. Although not required for the suppression of acute P. chabaudi parasitemia by AMI, CD28 costimulation is essential for the elimination of blood-stage parasites by CMI.
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Affiliation(s)
- Thomas Rummel
- Department of Medical Microbiology and Immunology, University of Wisconsin Medical School, Madison, Wisconsin 53706, USA
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159
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Gazzinelli RT, Ropert C, Campos MA. Role of the Toll/interleukin-1 receptor signaling pathway in host resistance and pathogenesis during infection with protozoan parasites. Immunol Rev 2004; 201:9-25. [PMID: 15361229 DOI: 10.1111/j.0105-2896.2004.00174.x] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Different studies have illustrated the activation of the innate immune system during infection with protozoan parasites. Experiments performed in vivo also support the notion that innate immunity has a crucial role in resistance as well as pathogenesis observed during protozoan infections such as malaria, leishmaniasis, toxoplasmosis, and trypanosomiasis. While major advances have been made in the assignment of bacterial molecules as Toll-like receptors (TLRs) agonists as well as defining the role of the Toll/interleukin-1 receptor (TIR) signaling pathway in host resistance to bacterial infection, this research area is now emerging in the field of protozoan parasites. In this review, we discuss the recent studies describing parasite molecules as TLR agonists and those studies indicating the essential role of the TIR-domain bearing molecule named myeloid differentiation factor 88 in host resistance to infection with protozoan parasites. Together, these studies support the hypothesis that the TIR signaling pathway is involved in the initial recognition of protozoan parasites by the immune system of the vertebrate host, early resistance to infection, development of acquired immunity, as well as pathology observed during acute infection with this class of pathogens.
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Affiliation(s)
- Ricardo T Gazzinelli
- Department of Biochemistry and Immunology, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil.
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160
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Good MF, Stanisic D, Xu H, Elliott S, Wykes M. The immunological challenge to developing a vaccine to the blood stages of malaria parasites. Immunol Rev 2004; 201:254-67. [PMID: 15361246 DOI: 10.1111/j.0105-2896.2004.00178.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Twenty-one years after malaria antigens were first cloned, a vaccine still appears to be a long way off. There have been periods of great excitement, and in model systems, subunit vaccine homologs can induce robust protection. However, significant challenges exist concerning antigenic variation and polymorphism, immunological non-responsiveness to individual vaccine antigens, parasite-induced apoptosis of immune effector and memory cells, and immune deviation as a result of maternal immunity and alterations of dendritic cell function. Novel approaches will be required. This review addresses some of the approaches that might present malaria antigens in a way designed to induce superior immune responses or that target novel conserved epitopes. Cell-mediated immunity, acting independently of antibody, may exert potent anti-parasite effects, and identification of multiple target antigens/epitopes could lead to the development of vaccines with profound efficacy.
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Affiliation(s)
- Michael F Good
- Queensland Institute of Medical Research, Brisbane, Australia.
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161
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Mackinnon MJ, Read AF. Virulence in malaria: an evolutionary viewpoint. Philos Trans R Soc Lond B Biol Sci 2004; 359:965-86. [PMID: 15306410 PMCID: PMC1693375 DOI: 10.1098/rstb.2003.1414] [Citation(s) in RCA: 171] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Malaria parasites cause much morbidity and mortality to their human hosts. From our evolutionary perspective, this is because virulence is positively associated with parasite transmission rate. Natural selection therefore drives virulence upwards, but only to the point where the cost to transmission caused by host death begins to outweigh the transmission benefits. In this review, we summarize data from the laboratory rodent malaria model, Plasmodium chabaudi, and field data on the human malaria parasite, P. falciparum, in relation to this virulence trade-off hypothesis. The data from both species show strong positive correlations between asexual multiplication, transmission rate, infection length, morbidity and mortality, and therefore support the underlying assumptions of the hypothesis. Moreover, the P. falciparum data show that expected total lifetime transmission of the parasite is maximized in young children in whom the fitness cost of host mortality balances the fitness benefits of higher transmission rates and slower clearance rates, thus exhibiting the hypothesized virulence trade-off. This evolutionary explanation of virulence appears to accord well with the clinical and molecular explanations of pathogenesis that involve cytoadherence, red cell invasion and immune evasion, although direct evidence of the fitness advantages of these mechanisms is scarce. One implication of this evolutionary view of virulence is that parasite populations are expected to evolve new levels of virulence in response to medical interventions such as vaccines and drugs.
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Affiliation(s)
- Margaret J Mackinnon
- School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3JT, Scotland, UK.
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162
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Charoenvit Y, Brice GT, Bacon D, Majam V, Williams J, Abot E, Ganeshan H, Sedegah M, Doolan DL, Carucci DJ, Zimmerman DH. A small peptide (CEL-1000) derived from the beta-chain of the human major histocompatibility complex class II molecule induces complete protection against malaria in an antigen-independent manner. Antimicrob Agents Chemother 2004; 48:2455-63. [PMID: 15215094 PMCID: PMC434180 DOI: 10.1128/aac.48.7.2455-2463.2004] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
CEL-1000 (DGQEEKAGVVSTGLIGGG) is a novel potential preventative and therapeutic agent. We report that CEL-1000 confers a high degree of protection against Plasmodium sporozoite challenge in a murine model of malaria, as shown by the total absence of blood stage infection following challenge with 100 sporozoites (100% protection) and by a substantial reduction (400-fold) of liver stage parasite RNA following challenge with 50,000 sporozoites. CEL-1000 protection was demonstrated in A/J (H-2(a)) and C3H/HeJ (H-2(k)) mice but not in BALB/c (H-2(d)) or CAF1 (A/J x BALB/c F(1) hybrid) mice. In CEL-1000-treated and protected mice, high levels of gamma interferon (IFN-gamma) in serum and elevated frequencies of hepatic and splenic CD4+ IFN-gamma-positive T cells were detected 24 h after administration of an additional dose of CEL-1000. Treatment of A/J mice that received CEL-1000 with antibodies against IFN-gamma just prior to challenge abolished the protection, and a similar treatment with antibodies against CD4+ T cells partially reduced the level of protection, while treatment with control antibodies or antibodies specific for interleukin-12 (IL-12), CD8+ T cells, or NK cells had no effect. Our data establish that the protection induced by CEL-1000 is dependent on IFN-gamma and is partially dependent on CD4+ T cells but is independent of CD8+ T cells, NK cells, and IL-12 at the effector phase and does not induce a detectable antibody response.
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Affiliation(s)
- Yupin Charoenvit
- CEL-SCI Corporation, 8229 Boone Blvd., Suite 802, Vienna, VA 22182, USA
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163
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Zimmerman PA, Mehlotra RK, Kasehagen LJ, Kazura JW. Why do we need to know more about mixed Plasmodium species infections in humans? Trends Parasitol 2004; 20:440-7. [PMID: 15324735 PMCID: PMC3728821 DOI: 10.1016/j.pt.2004.07.004] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Four Plasmodium species cause malaria in humans. Most malaria-endemic regions feature mixed infections involving two or more of these species. Factors contributing to heterogeneous parasite species and disease distribution include differences in genetic polymorphisms underlying parasite drug resistance and host susceptibility, mosquito vector ecology and transmission seasonality. It is suggested that unknown factors limit mixed Plasmodium species infections, and that mixed-species infections protect against severe Plasmodium falciparum malaria. Careful examination of methods used to detect these parasites and interpretation of individual- and population-based data are necessary to understand the influence of mixed Plasmodium species infections on malarial disease. This should ensure that deployment of future antimalarial vaccines and drugs will be conducted in a safe and timely manner.
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Affiliation(s)
- Peter A Zimmerman
- The Center for Global Health and Diseases, Case Western Reserve University, 2103 Cornell Road, Wolstein Research Building, Cleveland, OH 44106-7286, USA.
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164
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Osta MA, Christophides GK, Vlachou D, Kafatos FC. Innate immunity in the malaria vector Anopheles gambiae:comparative and functional genomics. J Exp Biol 2004; 207:2551-63. [PMID: 15201288 DOI: 10.1242/jeb.01066] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
SUMMARY
The resurgence of malaria is at least partly attributed to the absence of an effective vaccine, parasite resistance to antimalarial drugs and resistance to insecticides of the anopheline mosquito vectors. Novel strategies are needed to combat the disease on three fronts: protection (vaccines),prophylaxis/treatment (antimalarial drugs) and transmission blocking. The latter entails either killing the mosquitoes (insecticides), preventing mosquito biting (bednets and repellents), blocking parasite development in the vector (transmission blocking vaccines), genetic manipulation or chemical incapacitation of the vector. During the past decade, mosquito research has been energized by several breakthroughs, including the successful transformation of anopheline vectors, analysis of gene function by RNAi,genome-wide expression profiling using DNA microarrays and, most importantly,sequencing of the Anopheles gambiae genome. These breakthroughs helped unravel some of the mechanisms underlying the dynamic interactions between the parasite and the vector and shed light on the mosquito innate immune system as a set of potential targets to block parasite development. In this context, putative pattern recognition receptors of the mosquito that act as positive and negative regulators of parasite development have been identified recently. Characterizing these molecules and others of similar function, and identifying their ligands on the parasite surface, will provide clues on the nature of the interactions that define an efficient parasite–vector system and open up unprecedented opportunities to control the vectorial capacity of anopheline mosquitoes.
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Affiliation(s)
- Mike A Osta
- European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany
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165
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Kaur A, Kinhikar AG, Singh PP. Bioimmunotherapy of rodent malaria: co-treatment with recombinant mouse granulocyte-macrophage colony-stimulating factor and an enkephalin fragment peptide Tyr-Gly-Gly. Acta Trop 2004; 91:27-41. [PMID: 15158686 DOI: 10.1016/j.actatropica.2004.02.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2002] [Revised: 10/21/2003] [Accepted: 02/03/2004] [Indexed: 11/19/2022]
Abstract
We have earlier shown that recombinant mouse granulocyte-macrophage colony-stimulating factor (rmGM-CSF) and methionine-enkephalin co-treatment can protect mice from malaria. We now report the bioimmunotherapeutic effect of rmGM-CSF and a synthetic enkephalin fragment peptide Tyr-Gly-Gly (TGG) co-treatment on blood-induced Plasmodium berghei infection in Swiss mice. Mice were completely aparasitimic following co-treatment with rmGM-CSF (10.0 microg/kg) and TGG (2.0 mg/kg x 3 per day, intraperitoneally (i.p.)) starting from day -1 to day +4; however, in monotherapy, neither of these agents showed any detectable bioimmunotherapeutic effect. Curiously, similar co-treatment with rmGM-CSF (10.0 microg/kg) and higher doses of TGG (10.0 mg/kg) did not protect the mice. The combined bioimmunotherapeutic effect of these agents was abrogated by the separate administration each of rabbit neutralizing anti-rmGM-CSF antibody, non-selective opioid receptor antagonist naltrexone (10.0 mg/kg x 6 per day, i.p.), and silica (3.0 mg per mouse, intravenously (i.v.)). The peritoneal and splenic macrophages from the protected mice showed a significant (P<0.05) increase in their pool-size and the phagocytic activity, ex vivo. Furthermore, the protected mice, as compared to the unprotected ones, showed a significant (P<0.05) maximum increase in their serum nitrate and nitrite, interferon-gamma (IFN-gamma), and tumor necrosis factor-alpha (TNF-alpha) levels in their splenic homogenates, on the day before the beginning of the resolution of parasitaemia. Selective inhibitors of both inducible (aminoguanidine) and all forms (L-N(G)-monomethyl arginine) of nitric oxide (NO) synthase, significantly (P<0.05) augmented the mortality of co-treated mice, suggesting the role of NO in protection. These data show that, in P. berghei-infected mice, co-treatment with rmGM-CSF and conditional doses of TGG can impart protection, apparently through partly NO-dependent and macrophage-mediated mechanism(s).
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Affiliation(s)
- A Kaur
- National Institute of Pharmaceutical Education and Research, S.A.S. Nagar 160062, India
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166
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Alba MP, Salazar LM, Purmova J, Vanegas M, Rodriguez R, Patarroyo ME. Induction and displacement of an helix in the 6725 SERA peptide analogue confers protection against P. falciparum malaria. Vaccine 2004; 22:1281-9. [PMID: 15003658 DOI: 10.1016/j.vaccine.2003.08.046] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2003] [Accepted: 08/28/2003] [Indexed: 11/18/2022]
Abstract
The protein called serine repeat antigen (SERA) is a Plasmodium falciparum malaria antigen; high activity erythrocyte binding peptides have been identified in this protein. One of these, the 6725 peptide (non-immunogenic and non-protective), was analyzed for immunogenicity and protective activity in Aotus monkeys, together with several of its analogues. These peptides were studied by 1H NMR to try to correlate their structure with their biological function. These peptides showed helical regions having differences in their position, except for randomly structured 6725. It is shown that replacing some amino acids induced immunogenicity and protectivity against experimental malaria and changed their three-dimensional (3D) structure, suggesting that such modifications may allow a better fit with immune system molecules.
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Affiliation(s)
- Martha Patricia Alba
- Fundación Instituto de Inmunología de Colombia (FIDIC), Cra. 50, No. 26-00, Bogotá, Colombia
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167
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Nuttall SD, Humberstone KS, Krishnan UV, Carmichael JA, Doughty L, Hattarki M, Coley AM, Casey JL, Anders RF, Foley M, Irving RA, Hudson PJ. Selection and affinity maturation of IgNAR variable domains targeting Plasmodium falciparum AMA1. Proteins 2004; 55:187-97. [PMID: 14997552 DOI: 10.1002/prot.20005] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The new antigen receptor (IgNAR) is an antibody unique to sharks and consists of a disulphide-bonded dimer of two protein chains, each containing a single variable and five constant domains. The individual variable (V(NAR)) domains bind antigen independently, and are candidates for the smallest antibody-based immune recognition units. We have previously produced a library of V(NAR) domains with extensive variability in the CDR1 and CDR3 loops displayed on the surface of bacteriophage. Now, to test the efficacy of this library, and further explore the dynamics of V(NAR) antigen binding we have performed selection experiments against an infectious disease target, the malarial Apical Membrane Antigen-1 (AMA1) from Plasmodium falciparum. Two related V(NAR) clones were selected, characterized by long (16- and 18-residue) CDR3 loops. These recombinant V(NAR)s could be harvested at yields approaching 5mg/L of monomeric protein from the E. coli periplasm, and bound AMA1 with nanomolar affinities (K(D)= approximately 2 x 10(-7) M). One clone, designated 12Y-2, was affinity-matured by error prone PCR, resulting in several variants with mutations mapping to the CDR1 and CDR3 loops. The best of these variants showed approximately 10-fold enhanced affinity over 12Y-2 and was Plasmodium falciparum strain-specific. Importantly, we demonstrated that this monovalent V(NAR) co-localized with rabbit anti-AMA1 antisera on the surface of malarial parasites and thus may have utility in diagnostic applications.
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Affiliation(s)
- Stewart D Nuttall
- CSIRO Health Sciences and Nutrition, Parkville, Victoria, Australia.
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168
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Arai M, Alavi YIH, Mendoza J, Billker O, Sinden RE. Isonicotinic acid hydrazide: an anti-tuberculosis drug inhibits malarial transmission in the mosquito gut. Exp Parasitol 2004; 106:30-6. [PMID: 15013786 DOI: 10.1016/j.exppara.2004.01.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2003] [Revised: 12/24/2003] [Accepted: 01/05/2004] [Indexed: 11/26/2022]
Abstract
We studied the transmission-blocking effect of isonicotinic acid hydrazide (INH), a widely used anti-tuberculosis drug, against Plasmodium gallinaceum and Plasmodium berghei. INH-treatment of infected animals did not inhibit parasite development in the blood of the vertebrate host, but did inhibit exflagellation, ookinete formation, and oocyst development in the mosquito. Oocyst development was inhibited in a dose-dependent manner. The ED(50) in the P. gallinaceum/chicken/Aedes aegypti model and P. berghei/mouse/Anopheles stephensi model was 72 and 109 mg/kg, respectively. In marked contrast, in vitro exflagellation and ookinete development were not directly affected by physiological concentrations of INH. We suggest that INH exerts its inhibitory effects on the mosquito stages of the malaria parasite by an indirect, and at present undefined mechanism. Further elucidation of the mechanism how INH inhibits parasite development specifically on mosquito stages may allow us to identify new targets for malaria control strategy.
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Affiliation(s)
- Meiji Arai
- Department of Biological Sciences, Imperial College of Science, Technology, and Medicine, London SW7 2AZ, UK.
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169
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Epstein JE, Charoenvit Y, Kester KE, Wang R, Newcomer R, Fitzpatrick S, Richie TL, Tornieporth N, Heppner DG, Ockenhouse C, Majam V, Holland C, Abot E, Ganeshan H, Berzins M, Jones T, Freydberg CN, Ng J, Norman J, Carucci DJ, Cohen J, Hoffman SL. Safety, tolerability, and antibody responses in humans after sequential immunization with a PfCSP DNA vaccine followed by the recombinant protein vaccine RTS,S/AS02A. Vaccine 2004; 22:1592-603. [PMID: 15068840 DOI: 10.1016/j.vaccine.2004.01.031] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Optimal protection against malaria may require induction of high levels of protective antibody and CD8(+) and CD4(+) T cell responses. In humans, malaria DNA vaccines elicit CD8(+) cytotoxic T cells (CTL) and IFNgamma responses as measured by short-term (ex vivo) ELISPOT assays, and recombinant proteins elicit antibodies and excellent T cell responses, but no CD8(+) CTL or CD8(+) IFNgamma-producing cells as measured by ex vivo ELISPOT. Priming with DNA and boosting with recombinant pox virus elicits much better T cell responses than DNA alone, but not antibody responses. In an attempt to elicit antibodies and enhanced T cell responses, we administered RTS,S/AS02A, a partially protective Plasmodium falciparum recombinant circumsporozoite protein (CSP) vaccine in adjuvant, to volunteers previously immunized with a P. falciparum CSP DNA vaccine (VCL-2510) and to naïve volunteers. This vaccine regimen was well tolerated and safe. The volunteers who received RTS,S/AS02A alone had, as expected, antibody and CD4(+) T cell responses, but no CD8(+) T cell responses. Volunteers who received PfCSP DNA followed by RTS,S/AS02A had antibody and CD8(+) and CD4(+) T cell responses (Wang et al., submitted). Sequential immunization with DNA and recombinant protein, also called heterologous prime-boost, led to enhanced immune responses as compared to DNA or recombinant protein alone, suggesting that it might provide enhanced protective immunity.
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Affiliation(s)
- Judith E Epstein
- Malaria Program, Naval Medical Research Center, 503 Robert Grant Ave, Silver Spring, MD 20910, USA
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170
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Maestre A, Sunil S, Ahmad G, Mohmmed A, Echeverri M, Corredor M, Blair S, Chauhan VS, Malhotra P. Inter-allelic recombination in the Plasmodium vivax merozoite surface protein 1 gene among Indian and Colombian isolates. Malar J 2004; 3:4. [PMID: 15003129 PMCID: PMC385245 DOI: 10.1186/1475-2875-3-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2003] [Accepted: 03/05/2004] [Indexed: 11/10/2022] Open
Abstract
Background A major concern in malaria vaccine development is the polymorphism observed among different Plasmodium isolates in different geographical areas across the globe. The merozoite surface protein 1 (MSP-1) is a leading vaccine candidate antigen against asexual blood stages of malaria parasite. To date, little is known about the extent of sequence variation in the Plasmodium vivax MSP-1 gene (Pvmsp-1) among Indian isolates. Since P. vivax accounts for >50% of malaria cases in India and in Colombia, it is essential to know the Pvmsp-1 gene variability in these two countries to sustain it as a vaccine candidate. The extent of polymorphism in Pvmsp-1 gene among Indian and Colombian isolates is described. Methods The sequence variation in the region encompassing the inter-species conserved blocks (ICBs) five and six of Pvmsp-1 gene was examined. PCR was carried out to amplify the polymorphic region of Pvmsp-1 and the PCR products from twenty (nine Indian and 11 Colombian) isolates were sequenced and aligned with Belem and Salvador-1 sequences. Results Results revealed three distinct types of sequences among these isolates, namely, Salvador-like, Belem-like and a third type sequence which was generated due to interallelic recombination between Salvador-like sequences and Belem-like sequences. Existence of the third type in majority (44%) showed that allelic recombinations play an important role in PvMSP1 diversity in natural parasite population. Micro-heterogeneity was also seen in a few of these isolates due to nucleotide substitutions, insertions as well as deletions. Conclusions Intergenic recombination in the Pvmsp-1 gene was found and suggest that this is the main cause for genetic diversity of the Pvmsp-1 gene.
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Affiliation(s)
- Amanda Maestre
- International Centre for Genetic Engineering and Biotechnology, New Delhi. India
- Grupo Malaria, Facultad de Medicina, Universidad de Antioquia. Medellin. Colombia
| | - Sujatha Sunil
- International Centre for Genetic Engineering and Biotechnology, New Delhi. India
- Malaria Research Centre, Delhi, India
| | - Gul Ahmad
- International Centre for Genetic Engineering and Biotechnology, New Delhi. India
| | - Asif Mohmmed
- International Centre for Genetic Engineering and Biotechnology, New Delhi. India
| | - Marcela Echeverri
- Grupo Malaria, Facultad de Medicina, Universidad de Antioquia. Medellin. Colombia
| | - Mauricio Corredor
- Universidad de Pamplona, Corporación para Investigaciones Biológicas, Medellín. Colombia
| | - Silvia Blair
- Grupo Malaria, Facultad de Medicina, Universidad de Antioquia. Medellin. Colombia
| | - Virander S Chauhan
- International Centre for Genetic Engineering and Biotechnology, New Delhi. India
| | - Pawan Malhotra
- International Centre for Genetic Engineering and Biotechnology, New Delhi. India
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171
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Carcaboso AM, Hernández RM, Igartua M, Rosas JE, Patarroyo ME, Pedraz JL. Potent, long lasting systemic antibody levels and mixed Th1/Th2 immune response after nasal immunization with malaria antigen loaded PLGA microparticles. Vaccine 2004; 22:1423-32. [PMID: 15063565 DOI: 10.1016/j.vaccine.2003.10.020] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2003] [Accepted: 10/27/2003] [Indexed: 10/26/2022]
Abstract
The immunogenicity of the synthetic malaria vaccine SPf66 has been recently improved by the application of new adjuvants as QS-21 saponin or poly-D,L-lactide-co-glycolide (PLGA) polymers. The search for less invasive administration routes made us test the immunogenicity of SPf66-loaded microparticles by the nasal route in Balb/c mice. We report here that the intranasal administration of the adequate PLGA vaccine formulations greatly improves and maintains higher antibody levels compared to the conventional alum adjuvant and to the administration of the particles by other routes (subcutaneous, oral). Systemic immune responses were characterized as mixed Th1/Th2-type: IFN-gamma and IgG2a isotype were found as signs of Th1 activation, whilst IgE and IgG1 secretions indicate Th2 response. Since both types of response have been associated to protective immunity in malaria, we postulate that this new approach supposes an advantage over the traditional adjuvants and routes.
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Affiliation(s)
- A M Carcaboso
- Pharmacy and Pharmaceutical Technology Laboratory, Universidad del País Vasco (UPV-EHU), Paseo de la Universidad 7, 01006 Vitoria-Gasteiz, Spain
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172
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Iwasa Y, Michor F, Nowak MA. Evolutionary dynamics of escape from biomedical intervention. Proc Biol Sci 2004; 270:2573-8. [PMID: 14728779 PMCID: PMC1691545 DOI: 10.1098/rspb.2003.2539] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Viruses, bacteria, eukaryotic parasites, cancer cells, agricultural pests and other inconvenient animates have an unfortunate tendency to escape from selection pressures that are meant to control them. Chemotherapy, anti-viral drugs or antibiotics fail because their targets do not hold still, but evolve resistance. A major problem in developing vaccines is that microbes evolve and escape from immune responses. The fundamental question is the following: if a genetically diverse population of replicating organisms is challenged with a selection pressure that has the potential to eradicate it, what is the probability that this population will produce escape mutants? Here, we use multi-type branching processes to describe the accumulation of mutants in independent lineages. We calculate escape dynamics for arbitrary mutation networks and fitness landscapes. Our theory shows how to estimate the probability of success or failure of biomedical intervention, such as drug treatment and vaccination, against rapidly evolving organisms.
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Affiliation(s)
- Yoh Iwasa
- Department of Biology, Kyushu University, Fukuoka 812-8581, Japan
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173
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Mitchell GH, Thomas AW, Margos G, Dluzewski AR, Bannister LH. Apical membrane antigen 1, a major malaria vaccine candidate, mediates the close attachment of invasive merozoites to host red blood cells. Infect Immun 2004; 72:154-8. [PMID: 14688092 PMCID: PMC343990 DOI: 10.1128/iai.72.1.154-158.2004] [Citation(s) in RCA: 159] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Apical membrane antigen 1 (AMA-1) of Plasmodium merozoites is established as a candidate molecule for inclusion in a human malaria vaccine and is strongly conserved in the genus. We have investigated its function in merozoite invasion by incubating Plasmodium knowlesi merozoites with red cells in the presence of a previously described rat monoclonal antibody (MAb R31C2) raised against an invasion-inhibitory epitope of P. knowlesi AMA-1 and then fixing the material for ultrastructural analysis. We have found that the random, initial, long-range (12 nm) contact between merozoites and red cells occurs normally in the presence of the antibody, showing that AMA-1 plays no part in this stage of attachment. Instead, inhibited merozoites fail to reorientate, so they do not bring their apices to bear on the red cell surface and do not make close junctional apical contact. We conclude that AMA-1 may be directly responsible for reorientation or that the molecule may initiate the junctional contact, which is then presumably dependent on Duffy binding proteins for its completion.
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Affiliation(s)
- G H Mitchell
- Department of Immunobiology, Guy's, King's and St Thomas' School of Medicine, Guy's Hospital, London SE1 9RT, United Kingdom.
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174
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Singh S, Kennedy MC, Long CA, Saul AJ, Miller LH, Stowers AW. Biochemical and immunological characterization of bacterially expressed and refolded Plasmodium falciparum 42-kilodalton C-terminal merozoite surface protein 1. Infect Immun 2004; 71:6766-74. [PMID: 14638762 PMCID: PMC308882 DOI: 10.1128/iai.71.12.6766-6774.2003] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Protection against Plasmodium falciparum can be induced by vaccination in animal models with merozoite surface protein 1 (MSP1), which makes this protein an attractive vaccine candidate for malaria. In an attempt to produce a product that is easily scaleable and inexpensive, we expressed the C-terminal 42 kDa of MSP1 (MSP1(42)) in Escherichia coli, refolded the protein to its native form from insoluble inclusion bodies, and tested its ability to elicit antibodies with in vitro and in vivo activities. Biochemical, biophysical, and immunological characterization confirmed that refolded E. coli MSP1(42) was homogeneous and highly immunogenic. In a formulation suitable for human use, rabbit antibodies were raised against refolded E. coli MSP1(42) and tested in vitro in a P. falciparum growth invasion assay. The antibodies inhibited the growth of parasites expressing either homologous or heterologous forms of P. falciparum MSP1(42). However, the inhibitory activity was primarily a consequence of antibodies directed against the C- terminal 19 kDa of MSP1 (MSP1(19)). Vaccination of nonhuman primates with E. coli MSP1(42) in Freund's adjuvant protected six of seven Aotus monkeys from virulent infection with P. falciparum. The protection correlated with antibody-dependent mechanisms. Thus, this new construct, E. coli MSP1(42), is a viable candidate for human vaccine trials.
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Affiliation(s)
- Sanjay Singh
- Malaria Vaccine Development Unit, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland 20852, USA.
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175
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Abstract
Global change includes climate change and climate variability, land use, water storage and irrigation, human population growth and urbanization, trade and travel, and chemical pollution. Impacts on vector-borne diseases, including malaria, dengue fever, infections by other arboviruses, schistosomiasis, trypanosomiasis, onchocerciasis, and leishmaniasis are reviewed. While climate change is global in nature and poses unknown future risks to humans and natural ecosystems, other local changes are occurring more rapidly on a global scale and are having significant effects on vector-borne diseases. History is invaluable as a pointer to future risks, but direct extrapolation is no longer possible because the climate is changing. Researchers are therefore embracing computer simulation models and global change scenarios to explore the risks. Credible ranking of the extent to which different vector-borne diseases will be affected awaits a rigorous analysis. Adaptation to the changes is threatened by the ongoing loss of drugs and pesticides due to the selection of resistant strains of pathogens and vectors. The vulnerability of communities to the changes in impacts depends on their adaptive capacity, which requires both appropriate technology and responsive public health systems. The availability of resources in turn depends on social stability, economic wealth, and priority allocation of resources to public health.
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176
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Hisaeda H, Maekawa Y, Iwakawa D, Okada H, Himeno K, Kishihara K, Tsukumo SI, Yasutomo K. Escape of malaria parasites from host immunity requires CD4+ CD25+ regulatory T cells. Nat Med 2003; 10:29-30. [PMID: 14702631 DOI: 10.1038/nm975] [Citation(s) in RCA: 281] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2003] [Accepted: 12/03/2003] [Indexed: 11/08/2022]
Abstract
Infection with malaria parasites frequently induces total immune suppression, which makes it difficult for the host to maintain long-lasting immunity. Here we show that depletion of CD4(+)CD25(+) regulatory T cells (T(reg)) protects mice from death when infected with a lethal strain of Plasmodium yoelii, and that this protection is associated with an increased T-cell responsiveness against parasite-derived antigens. These results suggest that activation of T(reg) cells contributes to immune suppression during malaria infection, and helps malaria parasites to escape from host immune responses.
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Affiliation(s)
- Hajime Hisaeda
- Department of Immunology & Parasitology, School of Medicine, The University of Tokushima, 3-18-15 Kuramoto, Tokushima, 770-8503, Japan
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177
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Torres MH, Salazar LM, Vanegas M, Guzman F, Rodriguez R, Silva Y, Rosas J, Patarroyo ME. Modified merozoite surface protein-1 peptides with short alpha helical regions are associated with inducing protection against malaria. ACTA ACUST UNITED AC 2003; 270:3946-52. [PMID: 14511376 DOI: 10.1046/j.1432-1033.2003.03780.x] [Citation(s) in RCA: 27] [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 merozoite surface protein-1 represents a prime candidate for development of a malaria vaccine. Merozoite surface protein-1 has been shown to demonstrate high-activity peptide binding to human red blood cells. One of the high-activity binding peptides, named 5501, located in the N-terminus (amino acid sequence MLNISQHQCVKKQCPQNS) of the 19-kDa molecular mass fragment of merozoite surface protein-1, is conserved, nonimmunogenic and nonprotective. Its critical binding residues were identified and replaced with amino acids of similar mass but different charge, in order to modify their immunogenic and protective characteristics. Three analogues with positive or negative immunological results were studied by nuclear magnetic resonance to correlate their three-dimensional structure with their biological functions. The studied peptides presented alpha-helical fragments, but in different peptide regions and extensions, except for randomly structured 5501. We show that altering a few amino acids induced immunogenicity and protectivity against experimental malaria and changed the peptide three-dimensional structure, suggesting a better fit with immune-system molecules.
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Affiliation(s)
- Mary H Torres
- Fundacion Instituto de Inmunología de Colombia, Bogotá, Colombia
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178
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Doolan DL, Aguiar JC, Weiss WR, Sette A, Felgner PL, Regis DP, Quinones-Casas P, Yates JR, Blair PL, Richie TL, Hoffman SL, Carucci DJ. Utilization of genomic sequence information to develop malaria vaccines. J Exp Biol 2003; 206:3789-802. [PMID: 14506214 DOI: 10.1242/jeb.00615] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
SUMMARYRecent advances in the fields of genomics, proteomics and molecular immunology offer tremendous opportunities for the development of novel interventions against public health threats, including malaria. However, there is currently no algorithm that can effectively identify the targets of protective T cell or antibody responses from genomic data. Furthermore, the identification of antigens that will stimulate the most effective immunity against the target pathogen is problematic, particularly if the genome is large. Malaria is an attractive model for the development and validation of approaches to translate genomic information to vaccine development because of the critical need for effective anti-malarial interventions and because the Plasmodium parasite is a complex multistage pathogen targeted by multiple immune responses. Sterile protective immunity can be achieved by immunization with radiation-attenuated sporozoites, and anti-disease immunity can be induced in residents in malaria-endemic areas. However, the 23 Mb Plasmodium falciparum genome encodes more than 5300 proteins, each of which is a potential target of protective immune responses. The current generation of subunit vaccines is based on a single or few antigens and therefore might elicit too narrow a breadth of response. We are working towards the development of a new generation vaccine based on the presumption that duplicating the protection induced by the whole organism may require a vaccine nearly as complex as the organism itself. Here, we present our strategy to exploit the genomic sequence of P. falciparum for malaria vaccine development.
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Affiliation(s)
- D L Doolan
- Malaria Program, Naval Medical Research Center, Silver Spring, MD 20910-7500, USA.
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179
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Mahanty S, Saul A, Miller LH. Progress in the development of recombinant and synthetic blood-stage malaria vaccines. J Exp Biol 2003; 206:3781-8. [PMID: 14506213 DOI: 10.1242/jeb.00646] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
SUMMARYThe use of asexual blood-stage proteins as malaria vaccines is strongly supported by experimental data directly implicating antibodies induced by these antigens in parasite clearance and protection from re-challenge. The selection of blood-stage antigens is based on their ability to interfere with the pathogenesis of clinical malaria by reducing parasitemias. These vaccines could complement other vaccines aimed at preventing infection, such as those targeted at pre-erythrocytic or mosquito stages of the parasite. Asexual blood-stage vaccines may reduce disease by blockade of red blood cell invasion, inhibition of parasite growth in red cells or interference in cytoadherence of infected red cells. Clearance of blood-stage parasites is dependent primarily on antibody-mediated mechanisms, but CD4 T cells may also play an important role in help for B cells and probably have a direct effector function in the clearance of blood-stage parasites. Since asexual blood-stage parasites reside within erythrocytes, they are accessible to immune clearance mechanisms only for a short time, which imposes special requirements on vaccines. For example, immunity that induces high titers of antibody will be required. Antigenic variation and extensive polymorphism of malarial proteins also needs to be addressed. Several recombinant antigens derived from blood-stage proteins have moved beyond basic research and are now poised for phase I trials in endemic countries. In this review we discuss the state of asexual blood-stage vaccines, focusing on recombinant antigens from Plasmodium falciparum. The significance of polymorphism and antigenic variation, the relevance of parasite immune evasion mechanisms, the need for reliable measures of successful intervention and new adjuvants are reviewed. Results from trials of asexual blood stage vaccine that support the continued effort to develop these antigens as key ingredients of multicomponent,multistage malaria vaccines are documented.
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Affiliation(s)
- Siddhartha Mahanty
- Malaria Vaccine Development Unit, NIAID, NIH, Twin Brook I, 5640 Fishers Lane, Rockville, MD 20852, USA.
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180
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de Koning-Ward TF, O'Donnell RA, Drew DR, Thomson R, Speed TP, Crabb BS. A new rodent model to assess blood stage immunity to the Plasmodium falciparum antigen merozoite surface protein 119 reveals a protective role for invasion inhibitory antibodies. J Exp Med 2003; 198:869-75. [PMID: 12963693 PMCID: PMC2194199 DOI: 10.1084/jem.20030085] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Antibodies capable of inhibiting the invasion of Plasmodium merozoites into erythrocytes are present in individuals that are clinically immune to the malaria parasite. Those targeting the 19-kD COOH-terminal domain of the major merozoite surface protein (MSP)-119 are a major component of this inhibitory activity. However, it has been difficult to assess the overall relevance of such antibodies to antiparasite immunity. Here we use an allelic replacement approach to generate a rodent malaria parasite (Plasmodium berghei) that expresses a human malaria (Plasmodium falciparum) form of MSP-119. We show that mice made semi-immune to this parasite line generate high levels of merozoite inhibitory antibodies that are specific for P. falciparum MSP-119. Importantly, protection from homologous blood stage challenge in these mice correlated with levels of P. falciparum MSP-119-specific inhibitory antibodies, but not with titres of total MSP-119-specific immunoglobulins. We conclude that merozoite inhibitory antibodies generated in response to infection can play a significant role in suppressing parasitemia in vivo. This study provides a strong impetus for the development of blood stage vaccines designed to generate invasion inhibitory antibodies and offers a new animal model to trial P. falciparum MSP-119 vaccines.
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Affiliation(s)
- Tania F de Koning-Ward
- The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville Victoria 3050, Australia
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181
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Doolan DL, Southwood S, Freilich DA, Sidney J, Graber NL, Shatney L, Bebris L, Florens L, Dobano C, Witney AA, Appella E, Hoffman SL, Yates JR, Carucci DJ, Sette A. Identification of Plasmodium falciparum antigens by antigenic analysis of genomic and proteomic data. Proc Natl Acad Sci U S A 2003; 100:9952-7. [PMID: 12886016 PMCID: PMC187898 DOI: 10.1073/pnas.1633254100] [Citation(s) in RCA: 190] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2003] [Indexed: 11/18/2022] Open
Abstract
The recent explosion in genomic sequencing has made available a wealth of data that can now be analyzed to identify protein antigens, potential targets for vaccine development. Here we present, in the context of Plasmodium falciparum, a strategy that rapidly identifies target antigens from large and complex genomes. Sixteen antigenic proteins recognized by volunteers immunized with radiation-attenuated P. falciparum sporozoites, but not by mock immunized controls, were identified. Several of these were more antigenic than previously identified and well characterized P. falciparum-derived protein antigens. The data suggest that immune responses to Plasmodium are dispersed on a relatively large number of parasite antigens. These studies have implications for our understanding of immunodominance and breadth of responses to complex pathogens.
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Affiliation(s)
- Denise L Doolan
- Malaria Program, Naval Medical Research Center, Silver Spring, MD 20910-7500, USA
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182
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Walker KR, Ricciardone MD, Jensen J. Developing an international consensus on DDT: a balance of environmental protection and disease control. Int J Hyg Environ Health 2003; 206:423-35. [PMID: 12971698 DOI: 10.1078/1438-4639-00239] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The Stockholm Convention on Persistent Organic Pollutants provides a framework for international action on 12 persistent, bioaccumulative and toxic chemicals of global concern. While production and use of most of the listed chemicals will shortly be eliminated, there is widespread agreement that DDT will continue to be needed for disease vector control. Science played a key role in informing policy makers from developed and developing countries who drafted the DDT provision of the convention. This paper examines both the science and the politics that contributed to an international consensus on DDT.
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183
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Mueller MS, Renard A, Boato F, Vogel D, Naegeli M, Zurbriggen R, Robinson JA, Pluschke G. Induction of parasite growth-inhibitory antibodies by a virosomal formulation of a peptidomimetic of loop I from domain III of Plasmodium falciparum apical membrane antigen 1. Infect Immun 2003; 71:4749-58. [PMID: 12874357 PMCID: PMC166038 DOI: 10.1128/iai.71.8.4749-4758.2003] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Apical membrane antigen 1 (AMA-1) of Plasmodium falciparum is a leading candidate antigen for inclusion in a malaria subunit vaccine. Its ectodomain can be divided into three subdomains, each with disulfide bond-stabilized structures. Since the majority of antibodies raised against the ectodomain appear to recognize strain-specific epitopes in domain I, we attempted to develop a vaccine formulation which directs the immune response to a region that contains more conserved epitopes. Here we demonstrate that a virosomal formulation of a peptide that mimics the semiconserved loop I of domain III elicits parasite growth-inhibitory antibodies. A synthetic peptide comprising residues 446 to 490 of AMA-1 (AMA-1(446-490)) was conjugated through the N terminus to a derivative of phosphatidylethanolamine and the phosphatidylethanolamine-peptide conjugate was incorporated into immunopotentiating reconstituted influenza virosomes as a human-compatible antigen delivery system. Both cyclized and linear versions of the peptide antigen elicited antibodies which specifically bound to parasite-expressed AMA-1 in Western blotting with parasite lysates as well as in immunofluorescence assays with blood stage parasites. All 11 peptidomimetic-specific monoclonal antibodies generated were cross-reactive with parasite-expressed AMA-1. Antigen binding assays with a library of overlapping cyclic peptides covering the target sequence revealed differences in the fine specificity of these monoclonal antibodies and provided evidence that at least some of them recognized discontinuous epitopes. The two immunodominant epitopes comprised the conserved linear sequences K(459)RIKLN(464) and D(467)DEGNKKII(475). A key feature of the synthetic vaccine formulation proposed here is the display of the peptide antigen in a native-like state on the surface of the virosome.
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Affiliation(s)
- Markus S Mueller
- Molecular Immunology, Swiss Tropical Institute, CH-4002 Basel, Switzerland
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184
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Carcaboso AM, Hernández RM, Igartua M, Gascón AR, Rosas JE, Patarroyo ME, Pedraz JL. Immune response after oral administration of the encapsulated malaria synthetic peptide SPf66. Int J Pharm 2003; 260:273-82. [PMID: 12842346 DOI: 10.1016/s0378-5173(03)00266-7] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The synthetic peptide SPf66 adsorbed on alum is one of the few Plasmodium falciparum vaccines which have been tested in field trials. We previously reported that subcutaneous administration of SPf66 loaded PLGA microparticles (MP) enhances the antibody response to this antigen compared to the conventional alum formulation. We now evaluate the suitability of polymeric formulations to obtain systemic immune responses by gastric intubation of Balb/c mice. Formulations composed of 1:1 mixtures of PLGA 50:50 and 75:25 (lactic:glycolic) microparticles were administered by the oral route, and when animals were boosted 3 weeks later significant systemic IgG antibody responses were elicited, comparable to alum triple shot and superior to the aqueous vaccine given by the oral route. The finding of IgG2a isotype for PLGA-vaccinated mice compared to the absent levels of this isotype for the alum-vaccinated group could be interpreted as a sign of Th1-like immune response and cellular immune response activation. Our results confirm that using the appropriate schedule the oral administration of PLGA particles is suitable to obtain systemic immune responses to the carried antigen.
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Affiliation(s)
- A M Carcaboso
- Pharmacy and Pharmaceutical Technology Laboratory, Pharmacy Faculty, University of the Basque Country (UPV-EHU), Paseo de la Universidad no 7, 01006 Vitoria-Gasteiz, Spain
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185
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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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186
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Dessens JT, Sidén-Kiamos I, Mendoza J, Mahairaki V, Khater E, Vlachou D, Xu XJ, Kafatos FC, Louis C, Dimopoulos G, Sinden RE. SOAP, a novel malaria ookinete protein involved in mosquito midgut invasion and oocyst development. Mol Microbiol 2003; 49:319-29. [PMID: 12828632 DOI: 10.1046/j.1365-2958.2003.03566.x] [Citation(s) in RCA: 114] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
An essential, but poorly understood part of malaria transmission by mosquitoes is the development of the ookinetes into the sporozoite-producing oocysts on the mosquito midgut wall. For successful oocyst formation newly formed ookinetes in the midgut lumen must enter, traverse, and exit the midgut epithelium to reach the midgut basal lamina, processes collectively known as midgut invasion. After invasion ookinete-to-oocyst transition must occur, a process believed to require ookinete interactions with basal lamina components. Here, we report on a novel extracellular malaria protein expressed in ookinetes and young oocysts, named secreted ookinete adhesive protein (SOAP). The SOAP gene is highly conserved amongst Plasmodium species and appears to be unique to this genus. It encodes a predicted secreted and soluble protein with a modular structure composed of two unique cysteine-rich domains. Using the rodent malaria parasite Plasmodium berghei we show that SOAP is targeted to the micronemes and forms high molecular mass complexes via disulphide bonds. Moreover, SOAP interacts strongly with mosquito laminin in yeast-two-hybrid assays. Targeted disruption of the SOAP gene gives rise to ookinetes that are markedly impaired in their ability to invade the mosquito midgut and form oocysts. These results identify SOAP as a key molecule for ookinete-to-oocyst differentiation in mosquitoes.
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Affiliation(s)
- Johannes T Dessens
- Department of Biological Sciences, Sir Alexander Fleming Building, Imperial College London, South Kensington Campus, SW7 2AZ, UK.
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187
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Alba MP, Salazar LM, Puentes A, Pinto M, Torres E, Patarroyo ME. 6746 SERA peptide analogues immunogenicity and protective efficacy against malaria is associated with short alpha helix formation: malaria protection associated with peptides alpha helix shortening. Peptides 2003; 24:999-1006. [PMID: 14499278 DOI: 10.1016/s0196-9781(03)00187-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Erythrocyte high activity binding peptides (HABPs) have been identified for the Plasmodium falciparum serine repeat antigen (SERA). HABP 6746, located in this protein's 50 kDa fragment had its critical binding residues replaced by amino acids having similar mass but different charge to change their immunologic properties. This peptide analogues were used to immunize Aotus monkeys that were challenged later on with a virulent P. falciparum strain to determine their protective efficacy. A shortening in alpha helix structure was found in the immunogenic and protective ones when their secondary structure was analyzed by NMR, to correlate their structure with their immunologic properties. These data, together with results from previous studies, suggest that this shortening in HABP helical configuration may lead to better fitting with immune system molecules, rendering them immunogenic and protective and therefore making them excellent candidates for consideration as components of a subunit based multicomponent synthetic vaccine against malaria.
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MESH Headings
- Amino Acid Sequence
- Animals
- Antigens/immunology
- Antigens, Protozoan/chemistry
- Antigens, Protozoan/immunology
- Aotidae
- Blotting, Western
- Chromatography, High Pressure Liquid
- Fluorescent Antibody Technique, Indirect
- Magnetic Resonance Spectroscopy
- Malaria Vaccines/chemistry
- Malaria Vaccines/immunology
- Malaria Vaccines/pharmacology
- Malaria, Falciparum/immunology
- Models, Molecular
- Molecular Sequence Data
- Molecular Weight
- Plasmodium falciparum/immunology
- Polymers/chemistry
- Polymers/pharmacology
- Protein Structure, Secondary
- Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
- Structure-Activity Relationship
- Vaccination
- Vaccines, Subunit/chemistry
- Vaccines, Subunit/immunology
- Vaccines, Subunit/pharmacology
- Vaccines, Synthetic/chemistry
- Vaccines, Synthetic/immunology
- Vaccines, Synthetic/pharmacology
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Affiliation(s)
- Martha Patricia Alba
- Fundación Instituto de Inmunología de Colombia, Cra. 50 No. 26-00, Bogota, Colombia
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188
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Stauffer WM, Kamat D, Magill AJ. Traveling with infants and children. Part IV: insect avoidance and malaria prevention. J Travel Med 2003; 10:225-40. [PMID: 12946301 DOI: 10.2310/7060.2003.40594] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Affiliation(s)
- William M Stauffer
- Regions Hospital Center for International Health and International Travel Clinic, 640 Jackson Street, St Paul, Minnesota 55101, USA
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189
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Genton B, Anders RF, Alpers MP, Reeder JC. The malaria vaccine development program in Papua New Guinea. Trends Parasitol 2003; 19:264-70. [PMID: 12798084 DOI: 10.1016/s1471-4922(03)00111-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Through a collaborative project led by the Papua New Guinea Institute of Medical Research (PNGIMR), Papua New Guinea has a significant role in the global effort to develop a malaria vaccine, ensuring that the malaria patterns in Asia and the Pacific region are considered in vaccine development strategies. Some of the major perspectives and achievements of the program are discussed here, one of the most successful being the trial of Combination B, a vaccine comprising three asexual blood-stage proteins [merozoite surface protein (MSP)1, MSP2 and ring-infected erythrocyte surface antigen (RESA)], which led to a considerable reduction of parasite density in the immunized children.
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Affiliation(s)
- Blaise Genton
- Swiss Tropical Institute, Socinstrasse 57, 4002 Basel, Switzerland.
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190
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Cifuentes G, Patarroyo ME, Urquiza M, Ramirez LE, Reyes C, Rodriguez R. Distorting malaria peptide backbone structure to enable fitting into MHC class II molecules renders modified peptides immunogenic and protective. J Med Chem 2003; 46:2250-3. [PMID: 12747797 DOI: 10.1021/jm020440w] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The conserved, nonantigenic, nonimmunogenic malaria Merozoite Surface Protein-2 peptide 1, having high affinity for red blood cells, was rendered immunogenic and protective in Aotus monkeys by specifically changing some critical residues. The NMR structure revealed a switch from classical type III' into distorted III' and III beta turns in the protective peptides. These changes may lead to a better fit into the Aotus MHC class II human HLA-DRbeta1 12 molecule equivalent, thus activating the immune system.
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Affiliation(s)
- Gladys Cifuentes
- Fundación Instituto de Inmunología de Colombia, Carrera 50 No. 26-00 Bogotá, Colombia
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191
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Helg A, Mueller MS, Joss A, Pöltl-Frank F, Stuart F, Robinson JA, Pluschke G. Comparison of analytical methods for the evaluation of antibody responses against epitopes of polymorphic protein antigens. J Immunol Methods 2003; 276:19-31. [PMID: 12738356 DOI: 10.1016/s0022-1759(03)00075-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Surface exposed protein antigens of the malaria parasite Plasmodium falciparum frequently harbor multiple dimorphic amino acid positions. These are associated with parasite immune evasion and represent a major obstacle for subunit vaccine design. Here, we have analyzed the flexibility of the humoral immune response against a semiconserved sequence (YX(44)LFX(47)KEKMX(52)L) of the key malaria blood stage vaccine candidate merozoite surface protein-1 (MSP-1). Monoclonal antibodies (mAbs) raised against one of the six described natural sequence variants of MSP-1(43-53) were analyzed for cross-reactivity with the other allelic forms, which differ in one to three positions from the immunizing sequence. Enzyme-linked immunosorbent assay (ELISA) and surface plasmon resonance (SPR) spectroscopy demonstrated marked differences in mAb binding avidity to the variant sequences and isothermal titration calorimetry (ITC) provided evidence for a very low affinity of some of the interactions. In immunofluorescence analysis (IFA) and Western blotting analysis, the mAbs nevertheless stained all analyzed parasite clones expressing MSP-1(43-53) variant sequences. When used for the evaluation of humoral immune responses in clinical malaria vaccine trials, these two commonly used methods may thus not be suitable to distinguish biologically functional high affinity antibody responses from irrelevant low-affinity cross-reactivities.
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Affiliation(s)
- A Helg
- Swiss Tropical Institute, Socinstrasse 57, CH 4002, Basel, Switzerland
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192
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Buddle BM, Pollock JM, Skinner MA, Wedlock DN. Development of vaccines to control bovine tuberculosis in cattle and relationship to vaccine development for other intracellular pathogens. Int J Parasitol 2003; 33:555-66. [PMID: 12782055 DOI: 10.1016/s0020-7519(03)00060-2] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Vaccination of cattle against bovine tuberculosis could be an important strategy for the control of disease either where there is a wildlife reservoir of Mycobacterium bovis infection or in developing countries where it is not economically feasible to implement a 'test and slaughter' control program. Advances in the understanding of protective immune responses to M. bovis infection in cattle and the advent of new molecular biological techniques, coupled with the sequencing of the M. bovis genome have provided opportunities for the rational development of improved tuberculosis vaccines. A number of new tuberculosis vaccines including attenuated M. bovis strains, killed mycobacteria, protein and DNA vaccines are under development and many are being assessed in cattle. Recent results have revealed several promising vaccine candidates and vaccination strategies. Ways of distinguishing between vaccinated and infected cattle are becoming available and the possibility of new approaches to the eradication of tuberculosis from domestic livestock is discussed. Similarities between the mechanisms of protective immunity against M. bovis and against other intracellular parasites continue to be found and discoveries from vaccine studies on bovine tuberculosis may provide helpful insights into requirements for vaccines against other intracellular pathogens.
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MESH Headings
- Animals
- Animals, Newborn/immunology
- Animals, Wild/immunology
- BCG Vaccine/immunology
- BCG Vaccine/therapeutic use
- Bacterial Proteins/immunology
- Cattle
- Developing Countries
- Genome, Bacterial
- Immunity, Cellular/immunology
- Mycobacterium bovis/genetics
- Mycobacterium bovis/immunology
- Mycobacterium bovis/pathogenicity
- Tuberculosis Vaccines/immunology
- Tuberculosis Vaccines/therapeutic use
- Tuberculosis, Bovine/diagnosis
- Tuberculosis, Bovine/immunology
- Tuberculosis, Bovine/prevention & control
- Vaccination/methods
- Vaccines, Attenuated/immunology
- Vaccines, Attenuated/therapeutic use
- Vaccines, DNA/immunology
- Vaccines, DNA/therapeutic use
- Virulence
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Affiliation(s)
- Bryce M Buddle
- AgResearch, Wallaceville Animal Research Centre, P.O. Box 40063, Upper Hutt, New Zealand.
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193
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Baum J, Pinder M, Conway DJ. Erythrocyte invasion phenotypes of Plasmodium falciparum in The Gambia. Infect Immun 2003; 71:1856-63. [PMID: 12654801 PMCID: PMC152018 DOI: 10.1128/iai.71.4.1856-1863.2003] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In vitro experimentation with Plasmodium falciparum has determined that a number of different receptor-ligand interactions are involved in the invasion of erythrocytes. Most culture-adapted parasite isolates use a mechanism of invasion that depends primarily on the erythrocyte sialoglycoprotein glycophorin A (GYPA) and erythrocyte-binding antigen 175 (EBA-175) of the parasite blood-stage merozoite. However, a minority of culture-adapted parasites and a majority of Indian field isolates can apparently invade by other means. Here, erythrocyte invasion phenotypes of P. falciparum field isolates in Africa were studied. For 38 Gambian isolates, invasion of neuraminidase-treated and trypsin-treated erythrocytes was inhibited, on average, by more than 60 and 85%, respectively, indicating a high level of dependence on sialic acid and trypsin-sensitive proteins on the erythrocyte surface. These results support the hypothesis that African P. falciparum parasites use GYPA as a primary receptor for invasion. However, the considerable variation among isolates confirms the idea that alternative receptors are also used by many parasites. Three amino acid polymorphisms in the GYPA-binding region of EBA-175 (region II) were not significantly associated with invasion phenotype. There was variation among isolates in the selectivity index (i.e., a statistical tendency toward aggregation or multiple invasions of host erythrocytes), but this variation did not correlate with enzyme-determined invasion phenotype or with eba-175 alleles. Overall, these invasion phenotypes in Africa support a vaccine strategy of inhibiting EBA-175 binding to GYPA but suggest that parasites with alternative phenotypes would be selected for if this strategy were used alone.
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Affiliation(s)
- Jake Baum
- Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK.
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194
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Daubenberger CA, Diaz D, Curcic M, Mueller MS, Spielmann T, Certa U, Lipp J, Pluschke G. Identification and characterization of a conserved, stage-specific gene product of Plasmodium falciparum recognized by parasite growth inhibitory antibodies. Infect Immun 2003; 71:2173-81. [PMID: 12654839 PMCID: PMC152076 DOI: 10.1128/iai.71.4.2173-2181.2003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We have identified a novel conserved protein of Plasmodium falciparum, designated D13, that is stage-specifically expressed in asexual blood stages of the parasite. The predicted open reading frame (ORF) D13 contains 863 amino acids with a calculated molecular mass of 99.7 kDa and displays a repeat region composed of pentapeptide motives. Northern blot analysis with lysates of synchronized blood stage parasites showed that D13 is highly expressed at the mRNA level during schizogony. The first N'-terminal 138 amino acids of D13 were expressed in Escherichia coli and the purified protein was used to generate anti-D13 monoclonal antibodies (MAbs). Using total lysates of blood stage parasites and Western blot analysis, these MAbs stained one single band of approximately 100 kDa, corresponding to the predicted molecular mass of ORF D13. Western blot analysis demonstrated further that D13 is expressed during schizogony, declines rapidly in early ring stages and is undetectable in trophozoites. D13 protein is localized in individual merozoites in a distinct area, as demonstrated by indirect immunofluorescence analysis. After subcellular fractionation, D13 was confined to the pelleted fraction of the parasite lysate and its extraction by alkaline carbonate buffer treatment indicated that D13 is not a membrane-integral protein. Inclusion of certain anti-D13 MAbs into in vitro cultures of blood stage parasites resulted in considerable reduction in parasite growth. The N'-terminal domain encompassing 158 amino acids is 94 and 95%, respectively, identical at the amino acid level between Plasmodium knowlesi, Plasmodium yoelii, and P. falciparum. In summary, we describe a novel stage-specifically expressed, highly conserved gene product of P. falciparum that is recognized by parasite growth inhibitory antibodies.
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Affiliation(s)
- Claudia A Daubenberger
- Molecular Immunology, Swiss Tropical Institute, Socinstrasse 57, 4002 Basel, Switzerland.
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195
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Riddell A, Pollard AJ. Tropical disease vaccines. Expert Rev Vaccines 2003; 2:105-12. [PMID: 12901602 DOI: 10.1586/14760584.2.1.105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Infectious diseases remain a key cause of morbidity and mortality in the Tropics. Many of these diseases are already preventable by effective vaccines. The Extended Program of Immunization provides protection against six serious infections. However, this program is still not optimally implemented in all developing countries. The Extended Program of Immunization could benefit from the addition of several vaccines, but unfortunately the cost is prohibitive in many areas of the Tropics. For some of the most important infections, such as malaria and HIV, vaccines are not yet available. Novel strategies for vaccine development and policy implementation offer the best hope to combat the infections targeted by the World Health Organization as causing the highest annual death toll worldwide.
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Affiliation(s)
- Anna Riddell
- Oxford Vaccine Group, John Radcliffe Hospital, Headington, UK.
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196
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Cifuentes G, Guzmán F, Alba MP, Salazar LM, Patarroyo ME. Analysis of a Plasmodium falciparum EBA-175 peptide with high binding capacity to erythrocytes and their analogues using 1H NMR. J Struct Biol 2003; 141:115-21. [PMID: 12615537 DOI: 10.1016/s1047-8477(02)00584-1] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
A 175-erythrocyte-binding protein (EBA-175) conserved high-activity binding peptide (HABP), called 1783 (nonimmunogenic, nonprotective against Plasmodium falciparum malaria), was analyzed for antigenic and protective activity in Aotus monkeys, together with several of its analogues. 1H NMR studies of peptides 17912, 14016, and 22814 allowed their structure to be related to their biological function. These peptides showed helical regions having differences in their position and length. Nonimmunogenic, nonprotective peptides 1783 and 17912 showed an extensive helical region, while the 22814 immunogenic protective peptide's alpha-helix was found in the N-terminal region. This suggests that the more flexible C-terminal region will allow better interaction between these peptides and immune system molecules as well as relating these peptides' three-dimensional structure to their immunogenicity and protective activity, thus leading to a more rational development of the new malaria multicomponent vaccine.
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Affiliation(s)
- Gladys Cifuentes
- Fundación Instituto de Inmunología de Colombia (FIDIC), Universidad Nacional de Colombia, Carrera 50 No. 26-00, Santa fe de Bogota, Colombia
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197
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Miles MA. Malaria--there could be a third way. Nature 2003; 421:13. [PMID: 12511928 DOI: 10.1038/421013b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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198
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Bell E. A new tool for testing malaria vaccines. Nat Rev Immunol 2003. [DOI: 10.1038/nri990] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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199
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Gil de Miguel A, Carrasco Garrido P. [Immunisation: leaps into the future: a new concept: therapeutic immunisation]. Aten Primaria 2003; 31:198-201. [PMID: 12622989 PMCID: PMC7684252 DOI: 10.1016/s0212-6567(03)70684-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
Affiliation(s)
- A Gil de Miguel
- Facultad de Ciencias de la Salud. Universidad Rey Juan Carlos. Madrid. España.
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200
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Abstract
BACKGROUND Four types of malaria vaccine, SPf66 and MSP/RESA vaccines (against the asexual stages of the Plasmodium parasite) and CS-NANP and RTS,S vaccines (against the sporozoite stages), have been tested in randomized controlled trials in endemic areas. OBJECTIVES To assess malaria vaccines against Plasmodium falciparum, P. vivax, P. malariae and P ovale in preventing infection, disease and death. SEARCH STRATEGY We searched the Cochrane Infectious Diseases Group trials register (July 2002), the Cochrane Controlled Trials Register (The Cochrane Library Issue 2, 2002), MEDLINE (1966 to July 2002), EMBASE (1980 to May 2002), Science Citation Index (1981 to July 2002), and reference lists of articles. We also contacted organizations and researchers in the field. SELECTION CRITERIA Randomized controlled trials comparing vaccines against Plasmodium falciparum, P. vivax, P. malariae or P. ovale with placebo or routine antimalarial control measures in people of any age receiving a challenge malaria infection. DATA COLLECTION AND ANALYSIS Two reviewers independently assessed trial quality and extracted data. MAIN RESULTS Eighteen efficacy trials involving 10,971 participants were included. There were ten trials of SPf66 vaccine, four trials of CS-NANP vaccines, two trials of RTS,S vaccine, and two of MSP/RESA vaccine. Results with SPf66 in reducing new malaria infections (P. falciparum) were heterogeneous: it was not effective in four African trials (Peto odds ratio (OR) 0.96, 95% confidence interval (CI) 0.81 to 1.14), but in five trials outside Africa the number of first attacks was reduced (Peto OR 0.77, 95% CI 0.67 to 0.88). Trials to date have not indicated any serious adverse events with SPf66 vaccine. In three trials of CS-NANP vaccines, there was no evidence for protection by these vaccines against P. falciparum malaria (Peto OR 1.12, 95% CI 0.64 to 1.93). In a small trial in non-immune adults in the USA, RTS,S gave strong protection against experimental infection with P. falciparum. In a trial in an endemic area of the Gambia in semi-immune people, there was a reduction in clinical malaria episodes in the second year of follow up, corresponding to a vaccine efficacy of 66% (CI 14% to 85%). In a trial in Papua New Guinea, MSP/RESA had no protective effect against episodes of clinical malaria. There was evidence of an effect on parasite density, but this differed according to whether the participants had been pretreated with sulfadoxine/pyrimethamine or not. The prevalence of infections with the parasite subtype of MSP2 in the vaccine was reduced compared with the other subtype (Peto OR 0.35, CI 0.23 to 0.53). REVIEWER'S CONCLUSIONS There is no evidence for protection by SPf66 vaccines against P. falciparum in Africa. There is a modest reduction in attacks of P. falciparum malaria following vaccination with SPf66 in other regions. Further research with SPf66 vaccines in South America or with new formulations of SPf66 may be justified. There was not enough evidence to evaluate the use of CS-NANP vaccines. The RTS,S vaccine showed promising result, as did the MSP/RESA vaccine, but it should include the other main allelic form of MSP2. The MSP/RESA trial demonstrated that chemotherapy during a vaccine trial may reduce vaccine efficacy, and trials should consider very carefully whether this practice is justified.
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Affiliation(s)
- P Graves
- 1400 W. Oak Street, Fort Collins, CO 80521, USA.
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