Louis Miller - Academia.edu (original) (raw)

Papers by Louis Miller

NPJ Vaccines, 2017

The Plasmodium falciparum protein, apical membrane antigen 1 forms a complex with another parasit... more The Plasmodium falciparum protein, apical membrane antigen 1 forms a complex with another parasite protein, rhoptry neck protein 2, to initiate junction formation with the erythrocyte and is essential for merozoite invasion during the blood stage of infection. Consequently, apical membrane antigen 1 has been a target of vaccine development but vaccination with apical membrane antigen 1 alone in controlled human malaria infections failed to protect and showed limited efficacy in field trials. Here we show that vaccination with AMA1-RON2L complex in Freund's adjuvant protects Aotus monkeys against a virulent Plasmodium falciparum infection. Vaccination with AMA1 alone gave only partial protection, delaying infection in one of eight animals. However, the AMA1-RON2L complex vaccine completely protected four of eight monkeys and substantially delayed infection (>25 days) in three of the other four animals. Interestingly, antibodies from monkeys vaccinated with the AMA1-RON2L compl...

Molecular and Biochemical Parasitology, 1998

The A4VAR is a variant antigen expressed by a clonal line that binds CD36 and intercellular adhes... more The A4VAR is a variant antigen expressed by a clonal line that binds CD36 and intercellular adhesion molecule-1, ICAM-1. We have cloned and sequenced the extracellular domain coded by the A4var gene. To probe the relationship between A4var expression and parasite adhesion to ICAM-1, var mRNA and protein expression were analyzed in an enriched population of A4 parasites that displayed higher ICAM-1 binding. By Northern analyses, A4var was the predominant var message and antisera raised against a recombinant A4VAR protein reacted with the majority of infected erythrocytes, reinforcing previous conclusions that A4VAR binds ICAM-1. A4VAR contains five Duffy-binding like (DBL) domains, and two cysteine-rich interdomain regions (CIDR) domains. DBL and CIDR domains from A4VAR were expressed in mammalian cells to determine which regions mediate binding to CD36 and ICAM-1. Using several different binding assays, the A4VAR CIDR1 was the only domain found to bind CD36. In contrast, the same assays were unable to identify the ICAM-1 binding domain in A4VAR. This is the first time that each of the DBL and CIDR domains from a Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) have been systematically expressed and tested for binding. These results confirm that CIDR1 is sufficient to bind CD36 without any apparent contribution from other domains.

Experimental Parasitology, Nov 30, 1995

Int J Parasitol, 2004

Malaria parasites must recognise and invade different cells during their life cycle. The efficien... more Malaria parasites must recognise and invade different cells during their life cycle. The efficiency with which Plasmodium falciparum invades erythrocytes of all ages is an important virulence factor, since the ability of the parasite to reach high levels of parasitemia is often associated with severe pathology and morbidity. The merozoite invasion of erythrocytes is a highly complex, multi-step process that is dependent on a cascade of specific molecular interactions. Although many proteins are known to play an important role in invasion, their functional characteristics remain unclear. Therefore, a complete understanding of the molecular interactions that are the basis of the invasion process is absolutely crucial, not only in improving our knowledge about the basic biology of the malarial parasite, but also for the development of intervention strategies to counter the disease. Here we review the current state of knowledge about the receptor-ligand interactions that mediate merozoite invasion of erythrocytes. q

Proceedings of the National Academy of Sciences of the United States of America, 2005

Experimental Parasitology, Sep 1, 1976

Http Dx Doi Org 10 4161 Hv 7 0 14588, 2011

Malaria is a serious and sometimes fatal mosquito-borne disease caused by a protozoan parasite. E... more Malaria is a serious and sometimes fatal mosquito-borne disease caused by a protozoan parasite. Each year, it is estimated that over one million people are killed by malaria, yet the disease is preventable and treatable. Developing vaccines against the parasite is a critical component in the fight against malaria and these vaccines can target different stages of the pathogen's life cycle. We are targeting sexual stage proteins of P. falciparum which are found on the surface of the parasite reproductive cells present in the mosquito gut. Antibodies against these proteins block the progression of the parasite's life cycle in the mosquito, and thus block transmission to the next human host. Transmission blocking vaccines are essential to the malaria eradication program to ease the disease burden at the population level. We have successfully produced multiple versions of the Pfs25 antigen in a plant virus-based transient expression system and have evaluated these vaccine candidates in an animal model. The targets are expressed in plants at a high level, are soluble and most importantly, generate strong transmission blocking activity as determined by a standard membrane feeding assay. These data demonstrate the feasibility of expressing Plasmodium antigens in a plant-based system for the economic production of a transmission blocking vaccine against malaria.

Vaccine, Sep 10, 2009

Aluminum based adjuvants (alum), including aluminum hydroxide (Alhydrogel ® ) and aluminum phosph... more Aluminum based adjuvants (alum), including aluminum hydroxide (Alhydrogel ® ) and aluminum phosphate are the most commonly used adjuvant in the US. In order to ensure quality of vaccines, regulatory authorities require evaluation of antigen content in final vaccine products. Currently, there are no generic methods available for the determination of protein content in alum-based vaccines. Aluminum hydroxide gels exist as particles in solution, which interfere with direct quantitation of protein content in formulations using assays such as Lowry, BCA or Bradford protein assay. The present study adapts a simple fluorescent assay to directly (without the need for antigen extraction) determine antigen content on Alhydrogel ® with accuracy and sensitivity using the o-phthalaldehyde (OPA) reagent. Malaria vaccine candidates AMA1-C1/Alhydrogel, AMA1-C2/Alhydrogel, MSP1 42 -3D7/Alhydrogel, MSP1 42 -C1/Alhydrogel or BSAM-2/Alhydrogel were used as model formulations. The results of the present study show that the OPA assay is highly accurate (87-100%), reproducible, and simple with a linear detection range of 25-400 g/mL for Alhydrogel ® vaccines (except for MSP1 42 -C1, which has a linear detection range of 31.25-500 g/mL). This assay has proven to be highly useful in our laboratory and been used in routine vaccine quality control processes.

The American Journal of Tropical Medicine and Hygiene, Nov 1, 2005

Aotus monkeys were used to determine the immunogenicity of Pvs25 protein expressed in the zygote/... more Aotus monkeys were used to determine the immunogenicity of Pvs25 protein expressed in the zygote/ ookinete surface. Animals were immunized in three times with 100 g of Pvs25 formulated in Montanide ISA-720. Antibodies to Pvs25 detected by an enzyme-linked immunosorbent assay appeared by day 30 after the first immunization, with a peak of antibodies levels on day 150. These antibodies were still detectable on day 300. Plasma samples on day 150 from experimental group were able to completely block the development of the parasite in Anopheles albimanus mosquitoes artificially fed with human isolates of Plasmodium vivax. Immunized Aotus monkeys were infected with blood forms of the P. vivax Salvador I strain and no boosting effect of blood infection on titers of antibodies to Pvs25 was observed despite the presence of infective gametocytes. In conclusion, Pvs25 protein formulated in Montanide ISA-720 induces efficient and long-lasting transmission-blocking antibodies that cannot be boosted by parasite infection.

Past observations on serologic cross-reactions between malarias of different species indicated th... more Past observations on serologic cross-reactions between malarias of different species indicated that malaria parasites have common antigenic determinants (interspecies antigens) (I, 2). However, the molecular nature and subcellular localization of interspecies antigens have never been determined. Such an analysis is complicated by the fact that the malaria parasite has morphologically distinct stages in its life cycle (i.e., sporozoites, asexual erythrocytic parasites, and gametes). Furthermore, antigens of a particular stage may be on the surface or located internally. Even asexual erythrocytic parasites, the focus of this study, have developmental stages. On invasion of an erythrocyte, the merozoite rapidly transforms into a ring form. Developmental stages include the trophozoite and the schizont, the latter stage being a dividing parasite that contains, at full maturation, individual merozoites. When the infected erythrocyte ruptures, the released merozoites have a short extracellular life in the plasma before invading other erythrocytes. New antigens are expressed as the parasite develops from its ring form to the schizont stage (3). Parasite antigens also appear on the erythrocyte membrane as the intraerythrocytic parasite matures (4). Extracellular merozoites are antigenically similar to schizont-infected erythrocytes (3).

The American journal of tropical medicine and hygiene, 2005

Aotus monkeys were used to determine the immunogenicity of Pvs25 protein expressed in the zygote/... more Aotus monkeys were used to determine the immunogenicity of Pvs25 protein expressed in the zygote/ookinete surface. Animals were immunized in three times with 100 microg of Pvs25 formulated in Montanide ISA-720. Antibodies to Pvs25 detected by an enzyme-linked immunosorbent assay appeared by day 30 after the first immunization, with a peak of antibodies levels on day 150. These antibodies were still detectable on day 300. Plasma samples on day 150 from experimental group were able to completely block the development of the parasite in Anopheles albimanus mosquitoes artificially fed with human isolates of Plasmodium vivax. Immunized Aotus monkeys were infected with blood forms of the P. vivax Salvador I strain and no boosting effect of blood infection on titers of antibodies to Pvs25 was observed despite the presence of infective gametocytes. In conclusion, Pvs25 protein formulated in Montanide ISA-720 induces efficient and long-lasting transmission-blocking antibodies that cannot be ...

Transactions of the Royal Society of Tropical Medicine and Hygiene, 1979

The frequencies of the following blood group antigens: A, B, O, M, N, S, s, U, Fya, FyB, Lea, Jsa... more The frequencies of the following blood group antigens: A, B, O, M, N, S, s, U, Fya, FyB, Lea, Jsa and K have been determined in Nigerian children with severe falciparum malaria. The frequency distribution of M, N, S, s, U, Fya and Fyb were not significantly different in children with life-threatening falciparum malaria and controls. The frequencies of A, B, O, Lea, Jsa and K found in the children with severe malaria were similar to those previously reported for healthy adults in this population. The Duffy blood group antigens Fya and Fyb were virtually absent from both infected and control children. This finding is in variance with a Fya frequency of 23% reported by Worlledge et al. (1974) for healthy adults in this population.

National Institute of Allergy and Infectious Diseases, NIH, 2010

Despite recent advances, malaria remains a major cause of morbidity and mortality in children in ... more Despite recent advances, malaria remains a major cause of morbidity and mortality in children in sub-Saharan Africa. An estimated 881,000 malaria deaths occurred in 2006, of which 91% were in Africa and 85% were in children under five years of age [1]. Morbidity ...

Plos One, 2008

Pfs25 and Pvs25, surface proteins of mosquito stage of the malaria parasites P. falciparum and P.... more Pfs25 and Pvs25, surface proteins of mosquito stage of the malaria parasites P. falciparum and P. vivax, respectively, are leading candidates for vaccines preventing malaria transmission by mosquitoes. This single blinded, dose escalating, controlled Phase 1 study assessed the safety and immunogenicity of recombinant Pfs25 and Pvs25 formulated with Montanide ISA 51, a water-in-oil emulsion. The trial was conducted at The Johns Hopkins Center for Immunization Research, Washington DC, USA, between May 16, 2005-April 30, 2007. The trial was designed to enroll 72 healthy male and non-pregnant female volunteers into 1 group to receive adjuvant control and 6 groups to receive escalating doses of the vaccines. Due to unexpected reactogenicity, the vaccination was halted and only 36 volunteers were enrolled into 4 groups: 3 groups of 10 volunteers each were immunized with 5 microg of Pfs25/ISA 51, 5 microg of Pvs25/ISA 51, or 20 microg of Pvs25/ISA 51, respectively. A fourth group of 6 volunteers received adjuvant control (PBS/ISA 51). Frequent local reactogenicity was observed. Systemic adverse events included two cases of erythema nodosum considered to be probably related to the combination of the antigen and the adjuvant. Significant antibody responses were detected in volunteers who completed the lowest scheduled doses of Pfs25/ISA 51. Serum anti-Pfs25 levels correlated with transmission blocking activity. It is feasible to induce transmission blocking immunity in humans using the Pfs25/ISA 51 vaccine, but these vaccines are unexpectedly reactogenic for further development. This is the first report that the formulation is associated with systemic adverse events including erythema nodosum. ClinicalTrials.gov NCT00295581.

Plos One, 2008

Background: Apical Membrane Antigen 1 (AMA1), a polymorphic merozoite surface protein, is a leadi... more Background: Apical Membrane Antigen 1 (AMA1), a polymorphic merozoite surface protein, is a leading blood-stage malaria vaccine candidate. This is the first reported use in humans of an investigational vaccine, AMA1-C1/Alhydrogel, with the novel adjuvant CPG 7909.

Molecular and Biochemical Parasitology, 2009

Immunization with a recombinant yeast-expressed Plasmodium falciparum merozoite surface protein 3... more Immunization with a recombinant yeast-expressed Plasmodium falciparum merozoite surface protein 3 (MSP3) protected Aotus nancymai monkeys against a virulent challenge infection. Unfortunately, the production process for this yeast-expressed material was not optimal for human trials. In an effort to produce a recombinant MSP3 protein in a scaleable manner, we expressed and purified near-full-length MSP3 in Escherichia coli (EcMSP3). Purified EcMSP3 formed nonglobular dimers as determined by analytical size-exclusion HPLC with in-line multi-angle light scatter and quasi-elastic light scatter detection and velocity sedimentation (R h 7.6 ± 0.2 nm and 6.9 nm, respectively). Evaluation by high-resolution atomic force microscopy revealed non-linear asymmetric structures, with beaded domains and flexible loops that were recognized predominantly as dimers, although monomers and larger multimers were observed. The beaded substructure corresponds to predicted structural domains, which explains the velocity sedimentation results and improves the conceptual model of the protein. Vaccination with EcMSP3 in Freund's adjuvant-induced antibodies that recognized native MSP3 in parasitized erythrocytes by an immunofluorescence assay and gave delayed time to treatment in a group of Aotus monkeys in a virulent challenge infection with the FVO strain of P. falciparum. Three of the seven monkeys vaccinated with EcMSP3 had low peak parasitemias. EcMSP3, which likely mimics the native MSP3 structure located on the merozoite surface, is a viable candidate for inclusion in a multi-component malaria vaccine.

Chemical Immunology and Allergy, 1988

ABSTRACT

The Journal of Protozoology, 1981

ABSTRACT

NPJ Vaccines, 2017

The Plasmodium falciparum protein, apical membrane antigen 1 forms a complex with another parasit... more The Plasmodium falciparum protein, apical membrane antigen 1 forms a complex with another parasite protein, rhoptry neck protein 2, to initiate junction formation with the erythrocyte and is essential for merozoite invasion during the blood stage of infection. Consequently, apical membrane antigen 1 has been a target of vaccine development but vaccination with apical membrane antigen 1 alone in controlled human malaria infections failed to protect and showed limited efficacy in field trials. Here we show that vaccination with AMA1-RON2L complex in Freund's adjuvant protects Aotus monkeys against a virulent Plasmodium falciparum infection. Vaccination with AMA1 alone gave only partial protection, delaying infection in one of eight animals. However, the AMA1-RON2L complex vaccine completely protected four of eight monkeys and substantially delayed infection (>25 days) in three of the other four animals. Interestingly, antibodies from monkeys vaccinated with the AMA1-RON2L compl...

Molecular and Biochemical Parasitology, 1998

The A4VAR is a variant antigen expressed by a clonal line that binds CD36 and intercellular adhes... more The A4VAR is a variant antigen expressed by a clonal line that binds CD36 and intercellular adhesion molecule-1, ICAM-1. We have cloned and sequenced the extracellular domain coded by the A4var gene. To probe the relationship between A4var expression and parasite adhesion to ICAM-1, var mRNA and protein expression were analyzed in an enriched population of A4 parasites that displayed higher ICAM-1 binding. By Northern analyses, A4var was the predominant var message and antisera raised against a recombinant A4VAR protein reacted with the majority of infected erythrocytes, reinforcing previous conclusions that A4VAR binds ICAM-1. A4VAR contains five Duffy-binding like (DBL) domains, and two cysteine-rich interdomain regions (CIDR) domains. DBL and CIDR domains from A4VAR were expressed in mammalian cells to determine which regions mediate binding to CD36 and ICAM-1. Using several different binding assays, the A4VAR CIDR1 was the only domain found to bind CD36. In contrast, the same assays were unable to identify the ICAM-1 binding domain in A4VAR. This is the first time that each of the DBL and CIDR domains from a Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) have been systematically expressed and tested for binding. These results confirm that CIDR1 is sufficient to bind CD36 without any apparent contribution from other domains.

Experimental Parasitology, Nov 30, 1995

Int J Parasitol, 2004

Malaria parasites must recognise and invade different cells during their life cycle. The efficien... more Malaria parasites must recognise and invade different cells during their life cycle. The efficiency with which Plasmodium falciparum invades erythrocytes of all ages is an important virulence factor, since the ability of the parasite to reach high levels of parasitemia is often associated with severe pathology and morbidity. The merozoite invasion of erythrocytes is a highly complex, multi-step process that is dependent on a cascade of specific molecular interactions. Although many proteins are known to play an important role in invasion, their functional characteristics remain unclear. Therefore, a complete understanding of the molecular interactions that are the basis of the invasion process is absolutely crucial, not only in improving our knowledge about the basic biology of the malarial parasite, but also for the development of intervention strategies to counter the disease. Here we review the current state of knowledge about the receptor-ligand interactions that mediate merozoite invasion of erythrocytes. q

Proceedings of the National Academy of Sciences of the United States of America, 2005

Experimental Parasitology, Sep 1, 1976

Http Dx Doi Org 10 4161 Hv 7 0 14588, 2011

Malaria is a serious and sometimes fatal mosquito-borne disease caused by a protozoan parasite. E... more Malaria is a serious and sometimes fatal mosquito-borne disease caused by a protozoan parasite. Each year, it is estimated that over one million people are killed by malaria, yet the disease is preventable and treatable. Developing vaccines against the parasite is a critical component in the fight against malaria and these vaccines can target different stages of the pathogen's life cycle. We are targeting sexual stage proteins of P. falciparum which are found on the surface of the parasite reproductive cells present in the mosquito gut. Antibodies against these proteins block the progression of the parasite's life cycle in the mosquito, and thus block transmission to the next human host. Transmission blocking vaccines are essential to the malaria eradication program to ease the disease burden at the population level. We have successfully produced multiple versions of the Pfs25 antigen in a plant virus-based transient expression system and have evaluated these vaccine candidates in an animal model. The targets are expressed in plants at a high level, are soluble and most importantly, generate strong transmission blocking activity as determined by a standard membrane feeding assay. These data demonstrate the feasibility of expressing Plasmodium antigens in a plant-based system for the economic production of a transmission blocking vaccine against malaria.

Vaccine, Sep 10, 2009

Aluminum based adjuvants (alum), including aluminum hydroxide (Alhydrogel ® ) and aluminum phosph... more Aluminum based adjuvants (alum), including aluminum hydroxide (Alhydrogel ® ) and aluminum phosphate are the most commonly used adjuvant in the US. In order to ensure quality of vaccines, regulatory authorities require evaluation of antigen content in final vaccine products. Currently, there are no generic methods available for the determination of protein content in alum-based vaccines. Aluminum hydroxide gels exist as particles in solution, which interfere with direct quantitation of protein content in formulations using assays such as Lowry, BCA or Bradford protein assay. The present study adapts a simple fluorescent assay to directly (without the need for antigen extraction) determine antigen content on Alhydrogel ® with accuracy and sensitivity using the o-phthalaldehyde (OPA) reagent. Malaria vaccine candidates AMA1-C1/Alhydrogel, AMA1-C2/Alhydrogel, MSP1 42 -3D7/Alhydrogel, MSP1 42 -C1/Alhydrogel or BSAM-2/Alhydrogel were used as model formulations. The results of the present study show that the OPA assay is highly accurate (87-100%), reproducible, and simple with a linear detection range of 25-400 g/mL for Alhydrogel ® vaccines (except for MSP1 42 -C1, which has a linear detection range of 31.25-500 g/mL). This assay has proven to be highly useful in our laboratory and been used in routine vaccine quality control processes.

The American Journal of Tropical Medicine and Hygiene, Nov 1, 2005

Aotus monkeys were used to determine the immunogenicity of Pvs25 protein expressed in the zygote/... more Aotus monkeys were used to determine the immunogenicity of Pvs25 protein expressed in the zygote/ ookinete surface. Animals were immunized in three times with 100 g of Pvs25 formulated in Montanide ISA-720. Antibodies to Pvs25 detected by an enzyme-linked immunosorbent assay appeared by day 30 after the first immunization, with a peak of antibodies levels on day 150. These antibodies were still detectable on day 300. Plasma samples on day 150 from experimental group were able to completely block the development of the parasite in Anopheles albimanus mosquitoes artificially fed with human isolates of Plasmodium vivax. Immunized Aotus monkeys were infected with blood forms of the P. vivax Salvador I strain and no boosting effect of blood infection on titers of antibodies to Pvs25 was observed despite the presence of infective gametocytes. In conclusion, Pvs25 protein formulated in Montanide ISA-720 induces efficient and long-lasting transmission-blocking antibodies that cannot be boosted by parasite infection.

Past observations on serologic cross-reactions between malarias of different species indicated th... more Past observations on serologic cross-reactions between malarias of different species indicated that malaria parasites have common antigenic determinants (interspecies antigens) (I, 2). However, the molecular nature and subcellular localization of interspecies antigens have never been determined. Such an analysis is complicated by the fact that the malaria parasite has morphologically distinct stages in its life cycle (i.e., sporozoites, asexual erythrocytic parasites, and gametes). Furthermore, antigens of a particular stage may be on the surface or located internally. Even asexual erythrocytic parasites, the focus of this study, have developmental stages. On invasion of an erythrocyte, the merozoite rapidly transforms into a ring form. Developmental stages include the trophozoite and the schizont, the latter stage being a dividing parasite that contains, at full maturation, individual merozoites. When the infected erythrocyte ruptures, the released merozoites have a short extracellular life in the plasma before invading other erythrocytes. New antigens are expressed as the parasite develops from its ring form to the schizont stage (3). Parasite antigens also appear on the erythrocyte membrane as the intraerythrocytic parasite matures (4). Extracellular merozoites are antigenically similar to schizont-infected erythrocytes (3).

The American journal of tropical medicine and hygiene, 2005

Aotus monkeys were used to determine the immunogenicity of Pvs25 protein expressed in the zygote/... more Aotus monkeys were used to determine the immunogenicity of Pvs25 protein expressed in the zygote/ookinete surface. Animals were immunized in three times with 100 microg of Pvs25 formulated in Montanide ISA-720. Antibodies to Pvs25 detected by an enzyme-linked immunosorbent assay appeared by day 30 after the first immunization, with a peak of antibodies levels on day 150. These antibodies were still detectable on day 300. Plasma samples on day 150 from experimental group were able to completely block the development of the parasite in Anopheles albimanus mosquitoes artificially fed with human isolates of Plasmodium vivax. Immunized Aotus monkeys were infected with blood forms of the P. vivax Salvador I strain and no boosting effect of blood infection on titers of antibodies to Pvs25 was observed despite the presence of infective gametocytes. In conclusion, Pvs25 protein formulated in Montanide ISA-720 induces efficient and long-lasting transmission-blocking antibodies that cannot be ...

Transactions of the Royal Society of Tropical Medicine and Hygiene, 1979

The frequencies of the following blood group antigens: A, B, O, M, N, S, s, U, Fya, FyB, Lea, Jsa... more The frequencies of the following blood group antigens: A, B, O, M, N, S, s, U, Fya, FyB, Lea, Jsa and K have been determined in Nigerian children with severe falciparum malaria. The frequency distribution of M, N, S, s, U, Fya and Fyb were not significantly different in children with life-threatening falciparum malaria and controls. The frequencies of A, B, O, Lea, Jsa and K found in the children with severe malaria were similar to those previously reported for healthy adults in this population. The Duffy blood group antigens Fya and Fyb were virtually absent from both infected and control children. This finding is in variance with a Fya frequency of 23% reported by Worlledge et al. (1974) for healthy adults in this population.

National Institute of Allergy and Infectious Diseases, NIH, 2010

Despite recent advances, malaria remains a major cause of morbidity and mortality in children in ... more Despite recent advances, malaria remains a major cause of morbidity and mortality in children in sub-Saharan Africa. An estimated 881,000 malaria deaths occurred in 2006, of which 91% were in Africa and 85% were in children under five years of age [1]. Morbidity ...

Plos One, 2008

Pfs25 and Pvs25, surface proteins of mosquito stage of the malaria parasites P. falciparum and P.... more Pfs25 and Pvs25, surface proteins of mosquito stage of the malaria parasites P. falciparum and P. vivax, respectively, are leading candidates for vaccines preventing malaria transmission by mosquitoes. This single blinded, dose escalating, controlled Phase 1 study assessed the safety and immunogenicity of recombinant Pfs25 and Pvs25 formulated with Montanide ISA 51, a water-in-oil emulsion. The trial was conducted at The Johns Hopkins Center for Immunization Research, Washington DC, USA, between May 16, 2005-April 30, 2007. The trial was designed to enroll 72 healthy male and non-pregnant female volunteers into 1 group to receive adjuvant control and 6 groups to receive escalating doses of the vaccines. Due to unexpected reactogenicity, the vaccination was halted and only 36 volunteers were enrolled into 4 groups: 3 groups of 10 volunteers each were immunized with 5 microg of Pfs25/ISA 51, 5 microg of Pvs25/ISA 51, or 20 microg of Pvs25/ISA 51, respectively. A fourth group of 6 volunteers received adjuvant control (PBS/ISA 51). Frequent local reactogenicity was observed. Systemic adverse events included two cases of erythema nodosum considered to be probably related to the combination of the antigen and the adjuvant. Significant antibody responses were detected in volunteers who completed the lowest scheduled doses of Pfs25/ISA 51. Serum anti-Pfs25 levels correlated with transmission blocking activity. It is feasible to induce transmission blocking immunity in humans using the Pfs25/ISA 51 vaccine, but these vaccines are unexpectedly reactogenic for further development. This is the first report that the formulation is associated with systemic adverse events including erythema nodosum. ClinicalTrials.gov NCT00295581.

Plos One, 2008

Background: Apical Membrane Antigen 1 (AMA1), a polymorphic merozoite surface protein, is a leadi... more Background: Apical Membrane Antigen 1 (AMA1), a polymorphic merozoite surface protein, is a leading blood-stage malaria vaccine candidate. This is the first reported use in humans of an investigational vaccine, AMA1-C1/Alhydrogel, with the novel adjuvant CPG 7909.

Molecular and Biochemical Parasitology, 2009

Immunization with a recombinant yeast-expressed Plasmodium falciparum merozoite surface protein 3... more Immunization with a recombinant yeast-expressed Plasmodium falciparum merozoite surface protein 3 (MSP3) protected Aotus nancymai monkeys against a virulent challenge infection. Unfortunately, the production process for this yeast-expressed material was not optimal for human trials. In an effort to produce a recombinant MSP3 protein in a scaleable manner, we expressed and purified near-full-length MSP3 in Escherichia coli (EcMSP3). Purified EcMSP3 formed nonglobular dimers as determined by analytical size-exclusion HPLC with in-line multi-angle light scatter and quasi-elastic light scatter detection and velocity sedimentation (R h 7.6 ± 0.2 nm and 6.9 nm, respectively). Evaluation by high-resolution atomic force microscopy revealed non-linear asymmetric structures, with beaded domains and flexible loops that were recognized predominantly as dimers, although monomers and larger multimers were observed. The beaded substructure corresponds to predicted structural domains, which explains the velocity sedimentation results and improves the conceptual model of the protein. Vaccination with EcMSP3 in Freund's adjuvant-induced antibodies that recognized native MSP3 in parasitized erythrocytes by an immunofluorescence assay and gave delayed time to treatment in a group of Aotus monkeys in a virulent challenge infection with the FVO strain of P. falciparum. Three of the seven monkeys vaccinated with EcMSP3 had low peak parasitemias. EcMSP3, which likely mimics the native MSP3 structure located on the merozoite surface, is a viable candidate for inclusion in a multi-component malaria vaccine.

Chemical Immunology and Allergy, 1988

ABSTRACT

The Journal of Protozoology, 1981

ABSTRACT