Biomedical subjects

P Perlmann

Publications and source records attributed to P Perlmann.

At least 73 records · Page 4Linked to original sources

PubMed1993

Immunogenicity in rabbits and monkeys of influenza ISCOMs conjugated with repeated sequences of the Plasmodium falciparum antigen Pf155/RESA.

Rabbits and monkeys were immunized with two fusion proteins, ZZ-M3 and ZZ-M5, coupled to pre-formed influenza virus membrane glycoprotein ISCOMs. The fusion proteins comprise two IgG-binding domains from staphylococcal protein A (ZZ) and repeated amino acid sequences from the C-terminal (M3) or central (M5) repeat regions of the Plasmodium falciparum antigen Pf155/RESA. The induced antibody responses were of long duration, could be efficiently boosted and were comparable to those obtained with Freund's Adjuvant. The produced antibodies reacted with M3, M5, protein A and the influenza glycoprotein, recognized Pf155/RESA and inhibited merozoite invasion in vitro. These results suggest that coupling of immunogens to pre-formed ISCOMs may be a basis for construction of multivalent subunit vaccines.

Amino Acid Sequence↗

PubMed1993

Epitope specificity and capacity to inhibit parasite growth in vitro of human antibodies to repeat sequences of the Plasmodium falciparum antigen Ag332.

It has earlier been shown that the Plasmodium falciparum-reactive human monoclonal antibody 33G2 inhibits parasite growth in vitro as well as cytoadherence of infected red blood cells to melanoma cells in vitro. MoAb 33G2 recognizes an epitope of the P. falciparum antigen Ag332 and cross-reactive determinants in Pf155/RESA and Pf11.1 located in repetitive regions containing sequences of regularly spaced pairs of glutamic acid. To study whether antibodies of this specificity frequently occur in human immune sera and if they could be of importance for protective immunity, antibodies were affinity purified on MoAb 33G2 reactive Ag332 peptides. The epitope specificity of the affinity purified antibodies, determined by the Pepscan method, resembled that of MoAb 33G2, but showed differences in fine specificity. The antibodies cross-reacted to some extent with Pf11.1 and Pf155/RESA repeat peptides as detected by peptide ELISA and Pepscan. In indirect immunofluorescence all purified antibodies displayed a dotted pattern of staining of late stage infected red blood cells of two lines of the P. falciparum strain FCR3, including a Pf155/RESA deficient line. The in vitro growth of these two lines was efficiently inhibited by the affinity purified antibodies, indicating that their inhibitory effect was mainly due to reactivity with antigens other than Pf155/RESA. This, and the fact that Pf11.1 has been shown not to be expressed by the asexual stages suggests that Ag332 may be an important target for potentially protective antibodies in vivo and that Ag332 based immunogens are of interest for development of malaria subunit vaccines.

Amino Acid Sequence↗

PubMed1992

Genetic regulation of human anti-malarial antibodies in twins.

Immune responses to defined antigens may differ between individuals in a population as the reflection of differences in genetic regulation. In experimental animals, variation in responsiveness to a given epitope may be due to major histocompatibility complex (HLA, in humans) class II restrictions, implying serious limitations for the development of subunit vaccines. For human populations, knowledge of the relative importance of genetic as opposed to environmental factors affecting the immune response is scarce. We have compared antibody levels after immunization through repeated infections to a major malarial antigen (Pf155/RESA) in monozygotic twins with those in dizygotic twins, siblings, or unrelated controls. Antibody responses to the intact antigen and to some of its immunodominant epitopes were found to be more concordant within monozygotic twin pairs than in dizygotic pairs or age- and sex-matched siblings living under similar environmental conditions. The results support the conclusion that the antibody responses were genetically regulated. When the responses were assessed for possible associations with different HLA class II DRB, DQA, and DQB alleles had haplotypes, no associations were found. This suggests that the regulation of the Pf155/RESA antibody responses seen in this study reflects the impact of factors encoded by genes outside the HLA class II regions.

Adolescent↗

PubMed1992

Involvement of Pf155/RESA and cross-reactive antigens in Plasmodium falciparum merozoite invasion in vitro.

Lines of Plasmodium falciparum FCR3 either expressing or not expressing the blood-stage antigen Pf155/RESA were used to analyze the possible involvement of this antigen in the merozoite invasion process in vitro. Antibodies from human sera, affinity purified on synthetic peptides corresponding to C-terminal repeated sequences in Pf155/RESA, were shown to inhibit merozoite invasion of both types of parasites with similar efficiency. Reversal of the invasion inhibition by fusion proteins containing repeated sequences of Pf155/RESA but not of the cross-reactive antigens Ag332 and Pf11.1 indicated that the inhibitory antibodies had similar target antigens in both Pf155/RESA+ and Pf155/RESA- parasites that involved cross-reacting epitopes present in Pf155/RESA. Rabbit antibodies specific for Pf155/RESA repeats inhibited merozoite invasion of Pf155/RESA expressing parasites efficiently but had no or very small effect on the invasion of Pf155/RESA-deficient parasites. In contrast, rabbit antibodies specific for Ag332 repeats as well as human antibodies affinity purified on synthetic Ag332 peptides inhibited merozoite invasion of both types of parasites with high efficiency. A similar inhibition pattern was seen with the human monoclonal antibody 33G2, which has specificity for Ag332 but also cross-reacts with Pf155/RESA and Pf11.1. Taken together, our data suggest that Pf155/RESA and related cross-reactive antigens as well as Ag332 are involved in the merozoite invasion process and may constitute targets for invasion inhibitory antibodies.

Animals↗

PubMed1992

Ultrastructural analysis of fresh Plasmodium falciparum-infected erythrocytes and their cytoadherence to human leukocytes.

Sixty fresh Plasmodium falciparum isolates obtained from Gambian children with mild or cerebral malaria were investigated by transmission electron microscopy for the expression of knob-like protrusions (K+) on the surface of the infected erythrocytes. More than six-hundred infected erythrocytes were analyzed. Knob-forming parasites were present in all 60 isolates. Although knobless parasites (K-) were found in 25 (42%) of the isolates, only 39 were K-, while 577 were K+. Nine of the 39 K- infected erythrocytes that were studied in greater detail appeared to be asexual parasites because they were either segmented or they lacked mitochondrial DNA-like filaments and cristae, which are abundant in immature gametocytes. No difference was observed in the relative frequency of K+K- infected erythrocytes in isolates from patients with mild or cerebral malaria. Binding of both knobby and knobless infected erythrocytes to autologous leukocytes including monocytes, neutrophils, lymphocytes and plasma cells was found in some of the primary in vitro cultures. By using P. falciparum laboratory strains of known phenotypes and leukocytes from healthy blood bank donors, it was established that this novel adherence phenomenon was related to that of cytoadherence to certain melanoma or endothelial cells. Cytoadherent infected erythrocytes that bind to leukocytes enhance antibody-independent phagocytosis and induce cellular aggregation, while non-cytoadherent or rosetting infected erythrocytes do not.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1992

Effect of different fractions of heparin on Plasmodium falciparum merozoite invasion of red blood cells in vitro.

Heparin and various heparin fractions were separated according to differences in molecular weight or affinity for antithrombin III and used for the inhibition of Plasmodium falciparum merozoite invasion of red blood cells in vitro. No variation in sensitivity to heparin was found among the four strains of P. falciparum tested; all required approximately 5 micrograms/ml (0.5 U/ml) of heparin for 50% inhibition of invasion. The most efficient fraction of heparin was the one with low affinity for antithrombin III. Its 50% inhibition concentration was 1 microgram/ml, indicating that it was more efficient than unfractionated heparin and other heparin fractions. The effect of heparin was reversible, since washing of heparin-treated cultures containing mainly schizonts showed no inhibition of merozoite invasion. The results suggest that a heparin fraction with no anticoagulant effect might be useful in the treatment of patients with falciparum malaria.

Animals↗

PubMed1992

Seroepidemiologic studies of humoral immune response to the Plasmodium falciparum antigens in Thailand.

We have investigated seroreactivity against Plasmodium falciparum crude parasite antigens, the P. falciparum ring-infected erythrocyte surface antigen (Pf155/RESA), as well as against two synthetic peptides (EENV)6 and (EENVEHDA)3 that represent important epitopes of Pf155/RESA. The study population consisted of 421 children and adult Thais living in an area with moderate malaria transmission. We related these serologic findings to some important epidemiologic baseline data collected in the study area. The parasite rate in study subjects was 18.76%. Sixty-two percent were seropositive to crude P. falciparum antigens, 30.3% to the Pf155/RESA antigen, 23.05% to (EENV)6, and 20.17% to (EENVEHDA)3. Antibody responses to crude P. falciparum antigens and to Pf155/RESA were age dependent and increased with exposure. There was evidence that Pf155/RESA antibodies might play a role in protective immunity in this population. Since Pf155/RESA is a potential vaccine candidate antigen, the information obtained from these field studies will provide some seroepidemiologic baseline data for subsequent vaccine trials.

Adolescent↗

PubMed1991

Human immune response in Plasmodium falciparum malaria. Synthetic peptides corresponding to known epitopes of the Pf155/RESA antigen induce production of parasite-specific antibodies in vitro.

Autologous cell mixtures containing T cells, B cells, and adherent accessory cells from individuals primed to the malaria parasite Plasmodium falciparum by repeated natural infections were investigated for induction of Ig and antibody secretion in vitro. In vitro activation of cell cultures with two synthetic peptides corresponding to immunodominant T cell epitopes of the merozoite Ag ring-infected erythrocyte surface Ag (Mr 155,000) (Pf155/RESA), one from its carboxyl-terminal repeat and one from its nonrepeated amino-terminal region, gave rise to significant IgG secretion. Supernatants from lymphocyte cultures activated with either one of these peptides contained antibodies reacting with P. falciparum Ag in immunofluorescence assays and with Pf155/RESA peptides in a slot blot assay. No anti-P. falciparum antibodies were induced in the medium controls by lymphocyte stimulation with either tetanus toxoid or PWM. Induction in vitro of anti-Pf155/RESA antibodies was correlated with the presence of such antibodies in the sera of the lymphocyte donors, suggesting that the induction of antibody secretion reflected a secondary response in vitro of in vivo primed cells. Inspection of antibody profiles in individual donors revealed that the peptide corresponding to a sequence in the 3' repeat region induced anti-Pf155/RESA peptide antibodies reacting with identical or related and cross-reacting sequences in the 3' or 5' repeat region of the molecule. In contrast, the peptide corresponding to a nonrepeated T cell epitope in the amino terminus of the molecule only induced antibodies to an immunodominant amino-terminal B cell epitope partly overlapping with the T cell reactive sequence. Similar findings were made in the lymphocyte donors' plasma, frequently displaying significant correlations between antibody reactivities to the repeat peptides but not between these reactivities and those to the amino-terminal peptide. The marked specificity of this antibody formation in vitro suggests an underlying process of cognate recognition involving Ag-specific T and B cells reacting with different segments of the inducer peptide. The present experimental system should be well suited for identification of Th epitopes capable of inducing the production of antibodies of defined specificity in the human system.

Adolescent↗

PubMed1991

Studies on Pf155/RESA and other soluble antigens from in vitro cultured Plasmodium falciparum.

Spent culture medium from in vitro cultures of Plasmodium falciparum was used as the source for immunoadsorbent enrichment of soluble parasite antigens. IgG obtained from P. falciparum-hyperimmune Liberian serum was used as the ligand in the immunoadsorbent. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of the immunoadsorbent isolated material revealed the presence of at least 15 antigenic and parasite-derived polypeptides. Immunoblotting after SDS-PAGE showed greater than 20 antigenic polypeptides in the molecular weight range of 15-250 kDa. Several of these were heat-stable (100 degrees C for 5 min), and six of them were detected even after heating for 60 min. Among the latter antigens was Pf155/RESA, a merozoite antigen deposited in the erythrocyte membrane at invasion. Pf155/RESA can be detected using a modified erythrocyte membrane immunofluorescence (EMIF) assay. Inhibition of EMIF with heated parasite material showed that the antigenic activity was intact after heating for up to 30 min. The immunofluorescence-inhibitory activity was separated into two fractions, one containing Pf155/RESA and one containing polypeptides with molecular weights of 135 and 120 kDa. All three of these antigenic polypeptides bound selectively, albeit nonspecifically, to aminoethyl-BioGel resins.

Animals↗

PubMed1991

Plasmodium falciparum: analysis of the interaction of antigen Pf155/RESA with the erythrocyte membrane.

The location of the Plasmodium falciparum vaccine candidate antigen Pf155/RESA in the membrane of infected erythrocytes was analzyed by means of selective surface radioiodination and immunofluorescence of surface-modified cells. The lack of radiolabel in Pf155/RESA as well as its localization by immunofluorescence similar to that of the N-terminal region of erythrocyte band 3 suggests that the antigen is associated with the cytoplasmic phase of the erythrocyte membrane. In concordance with this, Pf155/RESA was detected by immunofluorescence on the surface of inside out membrane vesicles from P. falciparum-infected erythrocytes. Pf155/RESA from spent culture medium also bound to inside out membrane vesicles of normal erythrocytes as well as to cytoskeletal shells of such vesicles, but failed to bind to sealed right-side out membrane vesicles. Depletion of spectrin from the vesicles abolished antigen binding, suggesting that Pf155/RESA association with the erythrocyte cytoskeleton is mediated by spectrin.

Amino Acid Sequence↗

PubMed1991

Plasmodium falciparum: an invasion inhibitory human monoclonal antibody is directed against a malarial glycolipid antigen.

A Plasmodium falciparum malaria blood stage antigen was detected using a human monoclonal antibody (MAb A52A6) obtained from a clinically immune donor. Immunofluorescence analysis showed that the MAb reacted with the intracellular parasite throughout the asexual blood stage cycle as well as with gametocytes. The MAb also reacted with the surface of erythrocytes containing late stage P. falciparum parasites. The antigen seen by the MAb was species- but not strain- or isolate-specific. At rupture of the infected erythrocytes, antigenic material was deposited on the membrane of uninfected cells surrounding the parasite. At merozoite invasion MAb reactive material was present on the invaginating erythrocyte membrane, indicating an involvement of the antigen in the invasion process. This was also indicated by the high capacity of the MAb to inhibit merozoite invasion in vitro. The antigen appears to be a phosphoglycolipid, sensitive to phospholipase and present in lipid extracts of P. falciparum-infected erythrocytes.

Animals↗

PubMed1991

Definition of the epitope recognized by the Plasmodium falciparum-reactive human monoclonal antibody 33G2.

The human monoclonal antibody 33G2 has earlier been shown to inhibit merozoite reinvasion of red blood cells in Plasmodium falciparum cultures in vitro and to inhibit cytoadherence of infected red blood cells to melanoma cells in vitro. 33G2 cross-reacts with a family of P. falciparum antigens, Ag332, Pf11.1 and Pf155/RESA, sharing a common feature of repeated sequences consisting of regularly spaced pairs of glutamic acid. Peptides corresponding to residues 2-19 of the known amino acid sequence of Ag332 have been shown earlier to have the highest inhibitory capacity of antibody binding to infected red blood cells. Using the PEPSCAN method, overlapping hepta-, hexa-, penta- and tetrapeptides corresponding to residues 1-19 of the known sequence of Ag332 were synthesized. Antibody fine specificity was examined by synthesizing an octapeptide (residues 1-8) and all possible single amino acid substitutions. The monoclonal antibody was shown to react with a linear 5-amino acid-long sequence corresponding to Ag332 residues 3-7: VTEEI. These amino acids were irreplaceable or only partially replaceable in the replacement set analysis. Furthermore, epitope analogs corresponding to sequences contained within the Pf11.1 repeats and overlapping heptapeptides corresponding to Pf155/RESA repeats were synthesized. Reactivity to epitope analogs and Pf155/RESA peptides provided information which may explain antibody cross-reactivity. The defined epitope of this monoclonal antibody is of interest as a potential B cell epitope for the development of a malaria subunit vaccine.

Amino Acid Sequence↗

PubMed1991

Cytoadherence of knobby and knobless Plasmodium falciparum-infected erythrocytes.

Cytoadherence of Plasmodium falciparum-infected erythrocytes to melanoma cells was analysed using strains or isolates of parasites expressing or not expressing knobs (K+ or K- phenotype) on the erythrocyte surface. Both K+ and K- parasites had the capacity to cytoadhere to melanoma cells. Using a panel of melanoma cell lines with different surface expression of the cytoadherence receptors CD36, thrombospondin and ICAM-1 indicated that CD36 was the major receptor for parasites of both K+ and K- phenotypes. Binding competition experiments between K+ and K- -infected erythrocytes suggested that K+ cytoadherence is of higher affinity than that of K- parasites. However, some K- cytoadherence was also found in isolates containing mixed populations of K+ and K- parasites. The interaction of the two types of infected erythrocytes with melanoma cells also differed ultrastructurally, erythrocytes of K+ phenotype showing intimate interdigitations with microvilli on the melanoma cells, while erythrocytes of K- phenotype displayed more separated interactions with fewer sites of contact and involving only a few melanoma cell microvilli. One and the same infected erythrocyte may co-express the ligand for CD36-mediated cytoadherence and the structures mediating binding of uninfected erythrocytes to form rosettes.

Animals↗

PubMed1991

Failure to detect MHC class II associations of the human immune response induced by repeated malaria infections to the Plasmodium falciparum antigen Pf155/RESA.

Available evidence suggests that human T and B cell responses to a major Plasmodium falciparum malaria antigen (Pf155/RESA) in individuals primed by repeated infections are genetically regulated. In the present study we have attempted to establish whether these regulations reflect genetic restrictions imposed on the immune response by class II molecules of the donor's MHC system. T cell activation (proliferation and IFN-gamma release in vitro) and antibody activity (ELISA) were assayed with synthetic peptides corresponding to major Pf155/RESA epitopes. To associate T cell and antibody responses with the donors' MHC class II genotypes, leukocytes from 145 donors living in holo- or hyperendemic regions of Africa (Liberia, Gambia, Madagascar) were used for genomic HLA class II typing of their DRB-DQA and DQB genes by means of restriction fragment length analysis (RFLP). No associations between T cell responses and HLA-DR or -DQ alleles or DRB-DQA-DQB haplotypes were seen among the West Africans even when the donors were divided into high, medium or low responders. This was also true for a small group of HLA class II identical Malagasy donors including three pairs of twins. However, while the T cell responses between the twin pairs varied, those within the pairs were similar. Very similar findings were made with antibodies binding to Pf155/RESA peptides. Our data imply that the impact of MHC class II gene products on specific immune responses to Pf155/RESA epitopes is weak and hard to demonstrate in outbred human populations naturally primed by infection. This may be due to genetic regulations by other, non-HLA class II coded factors superimposed on possible HLA class II restrictions.

Adult↗

PubMed1991

Epitopes of the Plasmodium falciparum clustered-asparagine-rich protein (CARP) recognized by human T-cells and antibodies.

Linear B- and T-cell epitopes have been identified in the Plasmodium falciparum clustered-asparagine-rich-protein (CARP). Twenty-six synthetic peptides, 15-25 amino acids in length, were assayed for their ability to stimulate purified, human T-cells primed to P.falciparum by natural infection to proliferate and/or secrete gamma-interferon (IFN gamma). The plasma of malaria exposed individuals were tested for antibody reactivity with peptides coupled to bovine serum albumin in a semiquantitative ELISA. Two of the peptides (NNFMNRNMKNKNMN/NAKNVNDMYRDGEMS) induced T-cells from many malaria exposed donors to proliferate and/or secrete-IFN gamma. Six peptides bound antibodies from a large number of the plasma samples, the amounts ranging from ten to more than 200 micrograms specific antibody/ml. T-cell activation was most pronounced when the T-cells were from highly immune donors. In contrast, high anti-peptide specific antibody levels were usually detected in the plasma of less immune donors, recently exposed to infection. One short sequence (NAKNVNDMYRDGEMS) was found to contain both T- and B-cell epitopes. Thus, CARP includes both T- and B-cell reactive elements recognized by the human immune system following exposure to the parasite by natural infection.

Amino Acid Sequence↗

PubMed1991

A longitudinal study of seroreactivities to Plasmodium falciparum antigens in infants and children living in a holoendemic area of Liberia.

Investigators studied 348 children age 0-10 years, living in a holoendemic area of Liberia, for parasitological, serological and clinical parameters. The age-specific parasite rate increased towards the 7-10 year-old age group in which it was 86.8%. The geometrical mean parasite density decreased from the 3-4 year-old age group, in which fewer episodes of clinical malaria were observed. Antibodies to crude Plasmodium falciparum parasite antigens were detected in all children. The (EENV)6 seropositive rate was a maximum of 67.9% in the 3-11 month-old age group. It declined to a minimum of 31.7% in the 5-6 years age group after which it increased slowly in the 7-10 years age group. Antibodies to the synthetic peptide (NANP)6 showed a steady seropositive rate after the age of 3 months, between 30.0% and 39.3% in all the age groups up to 10 years. No statistically significant correlation was found between seropositivity to (EENV)6 and malarial parasitemia. In contrast, a statistically significant positive correlation was found between seropositivity to (NANP)6 and parasite rates. The antibody response for the individual child was transient to both Pf155/RESA, measured by immunofluorescence, and to (EENV)6 and (NANP)6, measured by ELISA, especially in the younger age groups of this study population. Parasitological and clinical immunity developed before a stable antibody response to these defined malaria antigens was established. These antibodies may still contribute to the immune protection against malaria, but they were not reliable parameters for protective immunity in the population we studied.

Amino Acid Sequence↗

PubMed1991

Whole-blood microassay for immunodetection of antigen specific cell mediated immunity using bromodeoxyuridine incorporation.

The study evaluates a novel version of the bromodeoxyuridine (BrdU) incorporation assay for in vitro proliferative responses, which works with finger-prick blood specimens. It was developed primarily for field-work involving children in Africa and elsewhere. Heparinized blood specimens from healthy volunteers were diluted 1:15 and cultured with purified protein derivative, tetanus toxoid, concanavalin A or medium alone for four-seven days and pulsed during the last 24 hours with bromodeoxyuridine. Thereafter, white and red cells were separated by Ficoll-Pacque centrifugation. The white cells were made to adhere to Multitest slides pre-treated with poly-L-lysin. After fixation with paraformaldehyde, the cells were incubated with mouse monoclonal antibodies to a surface marker for activated T cells (CD25, interleukin-2 receptor) and the reaction visualized with anti-mouse alkaline phosphatase conjugated antibodies and a Fast Red substrate. After treatment with cold acetone, the cells were covered with formamide and heated to 70 degrees C, without loss of surface staining. The incorporation of bromodeoxyuridine was visualized in the UV-microscope with mouse anti-bromodeoxyuridine monoclonal antibodies and a rabbit anti-mouse fluorescein conjugate. Both the surface staining and the nuclear fluorescence can be seen in UV-light and the cells be classified as single- or double-positive or negative. Parallel experiments on the same blood-sample from seven donors allowed for at least 42 paired comparisons between the proportion of BrdU positive cells and thymidine incorporation stimulation indices. The latter assay was carried out both in the conventional version and in a whole-blood micro-version. The rank order correlations were 0.84 and 0.91 respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Bromodeoxyuridine↗

PubMed1990

Plasmodium falciparum: differential parasite reactivity of rabbit antibodies to repeated sequences in the antigen Pf155/RESA.

For selection of immunogens capable of inducing high levels of antibodies reactive with the Plasmodium falciparum antigen Pf155/RESA, rabbits were immunized with synthetic peptides corresponding to sequences based on the repeat subunits EENVEHDA and (EENV)2 from the C-terminus of this antigen. The antibodies obtained were analyzed with regard to binding to synthetic peptides in ELISA and to reactivity with parasite antigens by immunofluorescence or immunoblotting. All antisera reacted with both the peptides EENVEHDA and (EENV)2 as well as with Pf155/RESA. Antibody fractions specific for each of the two peptides were prepared by affinity chromatography on insolubilized peptides. Strong reactivity with antigens in the membrane of erythrocytes infected with early stages of the parasite as well as reactivity with Pf155/RESA in immunoblotting correlated with reactivity of antibody with (EENV)2. Antibody preparations reactive with EENVEHDA and depleted of (EENV)2 reactivity showed only a weak reactivity with Pf155/RESA but reacted also with P. falciparum polypeptides of 250, 210, and 88 kDa. In immunofluorescence, these antibodies stained mainly the intraerythrocytic parasite. Both EENVEHDA- and (EENV)2-specific antibodies inhibited merozoite reinvasion in P. falciparum in vitro cultures, the latter antibodies being the most efficient. This study defines the specificity and cross-reactivity with other P. falciparum antigens of antibodies to the C-terminal repeats of Pf155/RESA.

Amino Acid Sequence↗