A Phase IIa Controlled Human Malaria Infection and Immunogenicity Study of RTS,S/AS01E and RTS,S/AS01B Delayed Fractional Dose Regimens in Malaria-Naive Adults.

Background: A previous RTS,S/AS01B vaccine challenge trial demonstrated that a 3-dose (0-1-7-month) regimen with a fractional third dose can produce high vaccine efficacy (VE) in adults challenged 3 weeks after vaccination. This study explored the VE of different delayed fractional dose regimens of adult and pediatric RTS,S/AS01 formulations.

Methods: A total of 130 participants were randomized into 5 groups.

Fractional Third and Fourth Dose of RTS,S/AS01 Malaria Candidate Vaccine: A Phase 2a Controlled Human Malaria Parasite Infection and Immunogenicity Study.

Background: Three full doses of RTS,S/AS01 malaria vaccine provides partial protection against controlled human malaria parasite infection (CHMI) and natural exposure. Immunization regimens, including a delayed fractional third dose, were assessed for potential increased protection against malaria and immunologic responses.

Methods: In a phase 2a, controlled, open-label, study of healthy malaria-naive adults, 16 subjects vaccinated with a 0-, 1-, and 2-month full-dose regimen (012M) and 30 subjects who received a 0-, 1-, and 7-month regimen, including a fractional third dose (Fx017M), underwent CHMI 3 weeks after the last dose.

Phase 1/2a Trial of Plasmodium vivax Malaria Vaccine Candidate VMP001/AS01B in Malaria-Naive Adults: Safety, Immunogenicity, and Efficacy.

Background: A vaccine to prevent infection and disease caused by Plasmodium vivax is needed both to reduce the morbidity caused by this parasite and as a key component in efforts to eradicate malaria worldwide. Vivax malaria protein 1 (VMP001), a novel chimeric protein that incorporates the amino- and carboxy- terminal regions of the circumsporozoite protein (CSP) and a truncated repeat region that contains repeat sequences from both the VK210 (type 1) and the VK247 (type 2) parasites, was developed as a vaccine candidate for global use.

Methods: We conducted a first-in-human Phase 1 dose escalation vaccine study with controlled human malaria infection (CHMI) of VMP001 formulated in the GSK Adjuvant System AS01B.

Ad35.CS.01-RTS,S/AS01 Heterologous Prime Boost Vaccine Efficacy against Sporozoite Challenge in Healthy Malaria-Naïve Adults.

Methods: In an observer blind, phase 2 trial, 55 adults were randomized to receive one dose of Ad35.CS.01 vaccine followed by two doses of RTS,S/AS01 (ARR-group) or three doses of RTS,S/AS01 (RRR-group) at months 0, 1, 2 followed by controlled human malaria infection.

Measurement of parasitological data by quantitative real-time PCR from controlled human malaria infection trials at the Walter Reed Army Institute of Research.

Background: The use of quantitative real-time PCR (qPCR) has allowed for precise quantification of parasites in the prepatent period and greatly improved the reproducibility and statistical power of controlled human malaria infection (CHMI) trials. Parasitological data presented here are from non-immunized, control-challenged subjects who participated in two CHMI trials conducted at the Walter Reed Army Institute of Research (WRAIR).

Methods: Standardized sporozoite challenge was achieved through the bite of five Anopheles stephensi mosquitoes infected with the 3D7clone of the NF54 strain of Plasmodium falciparum.

First-in-human evaluation of genetically attenuated Plasmodium falciparum sporozoites administered by bite of Anopheles mosquitoes to adult volunteers.

Background: Immunization with genetically engineered, attenuated malaria parasites (GAP) that arrest during liver infection confers sterile protection in mouse malaria models. A first generation Plasmodium falciparum GAP (Pf p52(-)/p36(-) GAP) was previously generated by deletion of two pre-erythrocytic stage-expressed genes (P52 and P36) in the NF54 strain.

Methods: A first-in-human, proof-of-concept, safety and immunogenicity clinical trial in six human volunteers was conducted.

Comparative evaluation of published real-time PCR assays for the detection of malaria following MIQE guidelines.

Background: The use of malaria-specific quantitative real-time PCR (qPCR) is increasing due to its high sensitivity, speciation and quantification of malaria parasites. However, due to the lack of consensus or standardized methods in performing qPCR, it is difficult to evaluate and/or compare the quality of work reported by different authors for a cross-study and/or cross-platform assay analysis.

Methods: The performances of seven published qPCR assays that detect Plasmodium spp or Plasmodium falciparum were compared using standard DNA and samples from a clinical trial.

Human adenovirus 5-vectored Plasmodium falciparum NMRC-M3V-Ad-PfCA vaccine encoding CSP and AMA1 is safe, well-tolerated and immunogenic but does not protect against controlled human malaria infection.

Background: In a prior study, a DNA prime / adenovirus boost vaccine (DNA/Ad) expressing P. falciparum circumsporozoite protein (CSP) and apical membrane antigen-1 (AMA1) (NMRC-M3V-D/Ad-PfCA Vaccine) induced 27% protection against controlled human malaria infection (CHMI). To investigate the contribution of DNA priming, we tested the efficacy of adenovirus vaccine alone (NMRC-M3V-Ad-PfCA ) in a Phase 1 clinical trial.

Use of qPCR and genomic sequencing to diagnose Plasmodium ovale wallikeri malaria in a returned soldier in the setting of a negative rapid diagnostic assay.

Plasmodium ovale is one of several clinically relevant malaria species known to cause disease in humans. However, in contrast to Plasmodium falciparum and Plasmodium vivax, which are responsible for most cases of human malaria, P. ovale has a wide distribution but low prevalence in tropical regions.

DNA prime/Adenovirus boost malaria vaccine encoding P. falciparum CSP and AMA1 induces sterile protection associated with cell-mediated immunity.

Background: Gene-based vaccination using prime/boost regimens protects animals and humans against malaria, inducing cell-mediated responses that in animal models target liver stage malaria parasites. We tested a DNA prime/adenovirus boost malaria vaccine in a Phase 1 clinical trial with controlled human malaria infection.

Methodology/principal Findings: The vaccine regimen was three monthly doses of two DNA plasmids (DNA) followed four months later by a single boost with two non-replicating human serotype 5 adenovirus vectors (Ad).

Plasmodium inui infection reduces the efficacy of a simian immunodeficiency virus DNA vaccine in a rhesus macaque model through alteration of the vaccine-induced immune response.

Human immunodeficiency virus type 1 and malaria are co-endemic in many areas. We evaluated the effects of Plasmodium inui infection on the performance of a simian immunodeficiency virus (SIV) DNA vaccine. Rhesus macaques were infected with P.

A consultation on the optimization of controlled human malaria infection by mosquito bite for evaluation of candidate malaria vaccines.

Early clinical investigations of candidate malaria vaccines and antimalarial medications increasingly employ an established model of controlled human malaria infection (CHMI). Study results are used to guide further clinical development of vaccines and antimalarial medications as CHMI results to date are generally predictive of efficacy in malaria-endemic areas. The urgency to rapidly develop an efficacious malaria vaccine has increased demand for efficacy studies that include CHMI and the need for comparability of study results among the different centres conducting CHMI.

Adenovirus-5-vectored P. falciparum vaccine expressing CSP and AMA1. Part B: safety, immunogenicity and protective efficacy of the CSP component.

Background: A protective malaria vaccine will likely need to elicit both cell-mediated and antibody responses. As adenovirus vaccine vectors induce both these responses in humans, a Phase 1/2a clinical trial was conducted to evaluate the efficacy of an adenovirus serotype 5-vectored malaria vaccine against sporozoite challenge.

Methodology/principal Findings: NMRC-MV-Ad-PfC is an adenovirus vector encoding the Plasmodium falciparum 3D7 circumsporozoite protein (CSP).

High antibody titer against apical membrane antigen-1 is required to protect against malaria in the Aotus model.

A Plasmodium falciparum 3D7 strain Apical Membrane Antigen-1 (AMA1) vaccine, formulated with AS02(A) adjuvant, slowed parasite growth in a recent Phase 1/2a trial, however sterile protection was not observed. We tested this AS02(A), and a Montanide ISA720 (ISA) formulation of 3D7 AMA1 in Aotus monkeys. The 3D7 parasite does not invade Aotus erythrocytes, hence two heterologous strains, FCH/4 and FVO, were used for challenge, FCH/4 AMA1 being more homologous to 3D7 than FVO AMA1.

Adenovirus 5 and 35 vectors expressing Plasmodium falciparum circumsporozoite surface protein elicit potent antigen-specific cellular IFN-gamma and antibody responses in mice.

Falciparum malaria vaccine candidates have been developed using recombinant, replication-deficient serotype 5 and 35 adenoviruses (Ad5, Ad35) encoding the Plasmodium falciparum circumsporozoite surface protein (CSP) (Ad5.CS, Ad35.CS) (Crucell Holland BV, Leiden, The Netherlands).

Malaria vaccines.

More than 120 years after Alphonse Laveran's discovery of the blood-stage malaria parasite, there is no licensed malaria vaccine and malaria remains the world's most serious parasitic disease. Efforts to develop a vaccine have been thwarted by the complexity of the parasite's life cycle and the ability of the parasite to suppress and evade the immune response. Currently, there are several candidate vaccines in clinical trials and many more candidate vaccines that have shown efficacy in animal models or are based on studies of the immune responses of people who are resistant to malaria.

Molecular cloning of the gyrA gene and characterization of its mutation in clinical isolates of quinolone-resistant Edwardsiella tarda.

Knowing the entire sequence of the gene encoding the DNA gyrase Subunit A (gyrA) of Edwardsiella tarda could be very useful for confirming the role of gyrA in quinolone resistance. Degenerate primers for the amplification of gyrA were designed from consensus nucleotide sequences of gyrA from 9 different Gram-negative bacteria, including Escherichia coli. With these primers, DNA segments of the predicted size were amplified from the genomic DNA of E.

Murine lethal toxic shock caused by intranasal administration of staphylococcal enterotoxin B.

Currently available murine staphylococcal enterotoxin B (SEB) shock models require pretreatment with various agents to increase mouse sensitivity to SEB. This study was performed to show that C3H/HeJ mice are highly susceptible to intranasal SEB inoculation, which caused toxic shock without using pretreatment agents. For this purpose, mice were injected intranasally with different doses of SEB and observed for up to 1 month.

Toxicity of the staphylococcal enterotoxin B mutants with histidine-to-tyrosine substitutions.

In this study we made a series of site-directed mutants of staphylococcal enterotoxin B (SEB), in which histidine residues in the molecule were replaced by tyrosine. The mutant genes were cloned and expressed, and the corresponding proteins were purified. These mutant proteins were tested for binding to human HLA-DR4 and for mitogenetic activity in mouse splenocyte culture.