Novel antimalarial antibodies highlight the importance of the antibody Fc region in mediating protection

Blood ◽  
2003 ◽  
Vol 102 (13) ◽  
pp. 4424-4430 ◽  
Author(s):  
Richard J. Pleass ◽  
Solabomi A. Ogun ◽  
David H. McGuinness ◽  
Jan G. J. van de Winkel ◽  
Anthony A. Holder ◽  
...  

Abstract Parasite drug resistance and difficulties in developing effective vaccines have precipitated the search for alternative therapies for malaria. The success of passive immunization suggests that immunoglobulin (Ig)-based therapies are effective. To further explore the mechanism(s) by which antibody mediates its protective effect, we generated human chimeric IgG1 and IgA1 and a single-chain diabody specific for the C-terminal 19-kDa region of Plasmodium yoelii merozoite surface protein 1 (MSP119), a major target of protective immune responses. These novel human reagents triggered in vitro phagocytosis of merozoites but, unlike their parental mouse IgG2b, failed to protect against parasite challenge in vivo. Therefore, the Fc region appears critical for mediating protection in vivo, at least for this MSP119 epitope. Such antibodies may serve as prototype therapeutic agents, and as useful tools in the development of in vitro neutralization assays with Plasmodium parasites. (Blood. 2003;102:4424-4430)

1998 ◽  
Vol 66 (8) ◽  
pp. 3925-3930 ◽  
Author(s):  
Lilian M. Spencer Valero ◽  
Solabomi A. Ogun ◽  
Suzanne L. Fleck ◽  
Irene T. Ling ◽  
Terry J. Scott-Finnigan ◽  
...  

ABSTRACT We have produced monoclonal antibodies against Plasmodium yoelii merozoite surface protein 1 (MSP-1) and have assessed their ability to suppress blood stage parasitemia by passive immunization. Six immunoglobulin G antibodies were characterized in detail: three (B6, D3, and F5) were effective in suppressing a lethal blood stage challenge infection, two (B10 and G3) were partially effective, and one (B4) was ineffective. MSP-1 is the precursor to a complex of polypeptides on the merozoite surface; all of the antibodies bound to this precursor and to an ∼42-kDa fragment (MSP-142) that is derived from the C terminus of MSP-1. MSP-142 is further cleaved to an N-terminal ∼33-kDa polypeptide (MSP-133) and a C-terminal ∼19-kDa polypeptide (MSP-119) comprised of two epidermal growth factor (EGF)-like modules. D3 reacted with MSP-142 but not with either of the constituents MSP-133 and MSP-119, B4 recognized an epitope within the N terminus of MSP-133, and B6, B10, F5, and G3 bound to MSP-119. B10 and G3 bound to epitopes that required both C-terminal EGF-like modules for their formation, whereas B6 and F5 bound to epitopes in the first EGF-like module. These results indicate that at least three distinct epitopes on P. yoelii MSP-1 are recognized by antibodies that suppress parasitemia in vivo.


2008 ◽  
Vol 76 (8) ◽  
pp. 3817-3823 ◽  
Author(s):  
Solabomi A. Ogun ◽  
Laurence Dumon-Seignovert ◽  
Jean-Baptiste Marchand ◽  
Anthony A. Holder ◽  
Fergal Hill

ABSTRACT Highly purified protein antigens are usually poor immunogens; in practice, adjuvants are needed to obtain satisfactory immune responses. Plasmodium yoelii 19-kDa merozoite surface protein 1 (MSP119) is a weak antigen, but mice vaccinated with this antigen in strong adjuvants can survive an otherwise lethal parasite challenge. Fusion proteins comprising this antigen fused to the oligomerization domain of the murine complement inhibitor C4-binding protein (C4bp) and a series of homologues have been produced. These C4bp domains acted as adjuvants for the fused antigen; the MSP119-murine C4bp fusion protein induced protective immunity in BALB/c mice. Because this fusion protein also induced antibodies against circulating murine C4bp, distantly related C4bp oligomerization domains fused to the same antigen were tested. These homologous domains did not induce antibodies against murine C4bp and, surprisingly, induced higher antibody titers against the antigen than the murine C4bp domain induced. These results demonstrate a new adjuvantlike effect of C4bp oligomerization domains.


2007 ◽  
Vol 88 (1) ◽  
pp. 187-195 ◽  
Author(s):  
Marco Bestagno ◽  
Isabel Sola ◽  
Eliana Dallegno ◽  
Patricia Sabella ◽  
Monica Poggianella ◽  
...  

Small immunoproteins (SIPs) are single-chain molecules comprising the variable regions of an antibody assembled in a single polypeptide (scFv) and joined to the immunoglobulin heavy-chain dimerizing domain. To investigate the potential of these molecules to provide protection against enteric infections when supplied orally, SIPs were generated against Transmissible gastroenteritis virus (TGEV), a highly pathogenic porcine virus. Different variants of TGEV-specific SIPs were created, of ε and α isotypes, by exploiting the dimerizing domains εCH4 and αCH3 of human and swine origin. Transfected cells secreted these recombinant mini-antibodies efficiently, mainly as dimers stabilized covalently by inter-chain disulphide bridges. The specificity and functionality of the recombinant TGEV-specific SIPs were determined by in vitro binding, neutralization and infection-interference assays. The neutralization indices of the TGEV-specific SIPs were all very similar to that of the original TGEV-specific mAb, thus confirming that the immunological properties have been preserved in the recombinant SIPs. In vivo protection experiments on newborn piglets have, in addition, demonstrated a strong reduction of virus titre in infected tissues of animals treated orally with TGEV-specific SIPs. It has therefore been demonstrated that it is possible to confer passive immunization to newborn pigs by feeding them with recombinant SIPs.


2017 ◽  
Vol 24 (11) ◽  
Author(s):  
Anja Jäschke ◽  
Boubacar Coulibaly ◽  
Edmond J. Remarque ◽  
Hermann Bujard ◽  
Christian Epp

ABSTRACT Naturally acquired immunity against malaria is largely mediated by serum antibodies controlling levels of blood-stage parasites. A limited understanding of the antigenic targets and functional mechanisms of protective antibodies has hampered the development of efficient malaria vaccines. Besides directly inhibiting the growth of Plasmodium parasites, antibodies can opsonize merozoites and recruit immune effector cells such as monocytes and neutrophils. Antibodies against the vaccine candidate merozoite surface protein 1 (MSP-1) are acquired during natural infections and have been associated with protection against malaria in several epidemiological studies. Here we analyzed serum antibodies from semi-immune individuals from Burkina Faso for their potential (i) to directly inhibit the growth of P. falciparum blood stages in vitro and (ii) to opsonize merozoites and to induce the antibody-dependent respiratory burst (ADRB) activity of neutrophils. While a few sera that directly inhibited the growth of P. falciparum blood stages were identified, immunoglobulin G (IgG) from all individuals clearly mediated the activation of neutrophils. The level of neutrophil activation correlated with levels of antibodies to MSP-1, and affinity-purified MSP-1-specific antibodies elicited ADRB activity. Furthermore, immunization of nonhuman primates with recombinant full-size MSP-1 induced antibodies that efficiently opsonized P. falciparum merozoites. Reversing the function by preincubation with recombinant antigens allowed us to quantify the contribution of MSP-1 to the antiparasitic effect of serum antibodies. Our data suggest that MSP-1, especially the partially conserved subunit MSP-183, is a major target of opsonizing antibodies acquired during natural exposure to malaria. Induction of opsonizing antibodies might be a crucial effector mechanism for MSP-1-based malaria vaccines.


2003 ◽  
Vol 71 (12) ◽  
pp. 6766-6774 ◽  
Author(s):  
Sanjay Singh ◽  
Michael C. Kennedy ◽  
Carole A. Long ◽  
Allan J. Saul ◽  
Louis H. Miller ◽  
...  

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 (MSP142) 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 MSP142 was homogeneous and highly immunogenic. In a formulation suitable for human use, rabbit antibodies were raised against refolded E. coli MSP142 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 MSP142. However, the inhibitory activity was primarily a consequence of antibodies directed against the C- terminal 19 kDa of MSP1 (MSP119). Vaccination of nonhuman primates with E. coli MSP142 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 MSP142, is a viable candidate for human vaccine trials.


Blood ◽  
2005 ◽  
Vol 105 (1) ◽  
pp. 394-396 ◽  
Author(s):  
Rita Tewari ◽  
Solabomi A. Ogun ◽  
Ruwani S. Gunaratne ◽  
Andrea Crisanti ◽  
Anthony A. Holder

Abstract Merozoite invasion of red blood cells is crucial to the development of the parasite that causes malaria. Merozoite surface proteins (MSPs) mediate the first interaction between parasite and erythrocyte. In Plasmodium falciparum, they include a complex of products from at least 3 genes (msp1, msp6, and msp7), one of which, msp7, is part of a gene family containing 3 and 6 adjacent members in Plasmodium yoelii and Plasmodium falciparum, respectively. We have identified and disrupted msp7 in the Plasmodium berghei gene family. The protein is expressed in schizonts and colocalizes with MSP1. The synthesis and processing of MSP1 was unaffected in the parasite with the disrupted gene (MSP7ko). Disruption of msp7 was not lethal but affected blood-stage parasite growth. MSP7ko parasites initially grew more slowly than wild-type parasites. However, when reticulocytes were prevalent, the rate of increase in parasitemia was similar, suggesting that MSP7ko parasites prefer to invade and grow within reticulocytes. (Blood. 2005;105:394-396)


Vaccines ◽  
2021 ◽  
Vol 9 (11) ◽  
pp. 1308
Author(s):  
Ulrike S. Diesterbeck ◽  
Henrike P. Ahsendorf ◽  
André Frenzel ◽  
Ahmad Reza Sharifi ◽  
Thomas Schirrmann ◽  
...  

A panel of potent neutralizing antibodies are protective against orthopoxvirus (OPXV) infections. For the development of OPXV-specific recombinant human single-chain antibodies (scFvs), the IgG repertoire of four vaccinated donors was amplified from peripheral B-lymphocytes. The resulting library consisted of ≥4 × 108 independent colonies. The immuno-screening against vaccinia virus (VACV) Elstree revealed a predominant selection of scFv clones specifically binding to the D8 protein. The scFv-1.2.2.H9 was engineered into larger human scFv-Fc-1.2.2.H9 and IgG1-1.2.2.H9 formats to improve the binding affinity and to add effector functions within the human immune response. Similar binding kinetics were calculated for scFv-1.2.2.H9 and scFv-Fc-1.2.2.H9 (1.61 nM and 7.685 nM, respectively), whereas, for IgG1-1.2.2.H9, the Michaelis-Menten kinetics revealed an increased affinity of 43.8 pM. None of the purified recombinant 1.2.2.H9 formats were able to neutralize VACV Elstree in vitro. After addition of 1% human complement, the neutralization of ≥50% of VACV Elstree was achieved with 0.0776 µM scFv-Fc-1.2.2.H9 and 0.01324 µM IgG1-1.2.2.H9, respectively. In an in vivo passive immunization NMRI mouse model, 100 µg purified scFv-1.2.2.H9 and the IgG1-1.2.2.H9 partially protected against the challenge with 4 LD50 VACV Munich 1, as 3/6 mice survived. In contrast, in the scFv-Fc-1.2.2.H9 group, only one mouse survived the challenge.


2020 ◽  
Author(s):  
Md Ohedul Islam ◽  
Parag Palit ◽  
Jakaria Shawon ◽  
Md Kamrul Hasan ◽  
Mustafa Mahfuz ◽  
...  

AbstractMalaria represents a life-threatening disease caused by the obligate intra-erythrocytic protozoa of the Plasmodium genus, exerting a sinister global health burden and accounting for approximately 660,000 deaths annually. Additionally, 219 million new cases are reported each year, most of which result from the growing issue of artemisinin resistance shown by the Plasmodium parasite. Much of the research done for the purpose of development of therapeutics against malaria has traditionally been focused on Plasmodium falciparum, which is responsible for majority of the cases of mortality due to malaria, Plasmodium vivax is also known to contribute greatly towards the malaria relate morbidities particularly in vivax endemic areas. In this study, we have used two different computational approaches aimed at establishing newer concepts towards the development of advanced therapeutics against vivax malaria by targeting the surface antigen, merozoite surface protein-1 (MSP-1). In-silico approach involving computational siRNA designing against MSP-1 resulted in a total of four candidate siRNAs being rationally validated following corroboration with a plethora of algorithms. Additionally, molecular docking analysis unraveled a total of three anti-parasitic peptides. These peptides namely: AP02283, AP02285 and AP00101 were found to exhibit considerable binding affinity with MSP-1 of P.vivax, thus providing an apparent indication of their anti-malarial property and affirming their potency to be used as novel molecules for development of next generation anti-malarials. However, irrespective of the prospective magnitude of these in-silico findings, the results require extensive validation by further rigorous laboratory experiments involving both in-vitro and in-vivo approaches.


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