Purification Methodology for Viable and Infective Plasmodium vivax Gametocytes That Is Compatible with Transmission-Blocking Assays.

Significant progress toward the control of malaria has been achieved, especially regarding Plasmodium falciparum infections. However, the unique biology of Plasmodium vivax hampers current control strategies. The early appearance of P. vivax gametocytes in the peripheral blood and the impossibility of culturing this parasite are major drawbacks. Using blood samples from 40 P. vivax-infected patients, we describe here a methodology to purify viable gametocytes and further infect anophelines. This method opens new avenues to validate transmission-blocking strategies.

Phase I safety and immunogenicity trial of Plasmodium vivax CS derived long synthetic peptides adjuvanted with montanide ISA 720 or montanide ISA 51.

We assessed the safety, tolerability, and immunogenicity of a mixture of three synthetic peptides derived from the Plasmodium vivax circumsporozoite protein formulated in Montanide ISA 720 or Montanide ISA 51. Forty healthy malaria-naive volunteers were allocated to five experimental groups (A-E): four groups (A-D) were immunized intramuscularly with 50 and 100 µg/dose injections of a mixture of N, R, and C peptides formulated in the two different adjuvants at 0, 2, and 4 months and one group was administered placebo. Vaccines were immunogenic, safe, well tolerated, and no serious adverse events related to the vaccine occurred. Seroconversion occurred in > 90% of the vaccines and antibodies recognized the sporozoite protein on immunofluorescent antibody test. Vaccines in Montanide ISA 51 showed a higher sporozoite protein recognition and interferon production. Results encourage further testing of the vaccine protective efficacy.

Antibody-mediated and cellular immune responses induced in naive volunteers by vaccination with long synthetic peptides derived from the Plasmodium vivax circumsporozoite protein.

Plasmodium vivax circumsporozoite (CS) protein is a leading malaria vaccine candidate. We describe the characterization of specific immune responses induced in 21 malaria-naive volunteers vaccinated with long synthetic peptides derived from the CS protein formulated in Montanide ISA 720. Both antibody- and cell-mediated immune responses were analyzed. Antibodies were predominantly of IgG1 and IgG3 isotypes, recognized parasite proteins on the immunofluorescent antibody test, and partially blocked sporozoite invasion of hepatoma cell lines in vitro. Peripheral blood mononuclear cells from most volunteers (94%) showed IFN-γ production in vitro upon stimulation with both long signal peptide and short peptides containing CD8+ T-cell epitopes. The relatively limited sample size did not allow conclusions about HLA associations with the immune responses observed. In summary, the inherent safety and tolerability together with strong antibody responses, invasion blocking activity, and the IFN-γ production induced by these vaccine candidates warrants further testing in a phase II clinical trial.

Preclinical vaccine study of Plasmodium vivax circumsporozoite protein derived-synthetic polypeptides formulated in montanide ISA 720 and montanide ISA 51 adjuvants.

Plasmodium vivax circumsporozoite (CS) protein is a leading malaria vaccine candidate previously assessed in animals and humans. Here, combinations of three synthetic polypeptides corresponding to amino (N), central repeat (R), and carboxyl (C) regions of the CS protein formulated in Montanide ISA 720 or Montanide ISA 51 adjuvants were assessed for immunogenicity in rodents and primates. BALB/c mice and Aotus monkeys were divided into test and control groups and were immunized three times with doses of 50 and 100 µg of vaccine or placebo. Antigen-specific antimalarial antibodies were determined by enzyme-linked immunosorbent assay, immunofluorescent antibody test, and IFN-γ responses by enzyme-linked immunosorbent spot (ELIspot). Both vaccine formulations were highly immunogenic in both species. Mice developed better antibody responses against C and R polypeptides, whereas the N polypeptide was more immunogenic in monkeys. Anti-peptide antibodies remained detectable for several months and recognized native proteins on sporozoites. Differences between Montanide ISA 720 and Montanide ISA 51 formulations were not significant.

Embolismo por polimetil-metacrilato posterior a inyección subcutánea en región glútea: a propósito de un caso / Polymethyl-methacrylate embolism after subcutaneous injection in gluteal region: report of a case

El polimetil-metacrilato es un polímero de alta resistencia al impacto, ampliamente utilizado en diferentes campos de la medicina, sin embargo, aún no está clara su indicación como relleno glúteo. A pesar de su aparente inocuidad, se han presentado complicaciones durante su uso como granulomas y nódulos palpables. Se han reportado casos de embolismo pulmonar por polimetil-metacrilato posterior a vertebroplastias. Sin embargo, no se encontró reporte bibliográfico de casos de embolismo pulmonar con su uso en procedimientos estéticos. Presentamos caso de paciente femenino de 31 años de edad, quien 4 horas luego de la inyección de 500 cm3 de polimetil-metacrilato en cada región glútea, presenta disnea en reposo de aparición súbita con tos seca y palpitaciones, disminución de agudeza visual y petequias generalizadas. Se diagnostica probable embolismo pulmonar por polimetil-metacrilato y retinopatía de Purtscher. Existe similitud clínica e imaginología del caso en estudio con embolismo por silicone, y las imágenes del fondo de ojo semejan la obstrucción de pequeñas arteriolas retinianas compatibles con este diagnóstico. Se sugieren nuevas investigaciones en el uso de polimetil-metacrilato como procedimiento estético en pro de la seguridad y en beneficio de los pacientes

Polymethyl-methacrylate is a high impact resistant polymer, widely used in different medicine fields, however its indication in buttock implants is still not clear. Even though its apparent innocuity, it has presented complications like granulomas and palpable nodules. There have been reported cases of pulmonary embolism caused by polimetil-metacrilato secondary to vertebroplasties. However, there have been no bibliographic cases of pulmonary embolism due to its use in aesthetic procedures. We present a case of a woman patient of 31 years old, who 4 hours after 500 cc injection of polymethyl- Methacrylate in each buttock, presents rest dyspnea with abrupt dry cough and palpitations, reduction in visual acuity and generalized petechiae. It is diagnosed probable pulmonary embolism by polimetil-metacrilato and Purtscher retinopathy. There is a clinical and imaginological similitude between this case and silicone embolism and the images of fondoscopy are similar to those of small retinian arteriole obstruction compatible with the diagnosis. Thereby, it is suggested new investigations in the use of polymethyl-methacrylate as esthetic procedure in favor of the patient’s security and benefit

Antibody response to Plasmodium vivax antigens in Fy-negative individuals from the Colombian Pacific coast.

The Duffy antigen (Fy) is necessary for Plasmodium vivax invasion of human erythrocytes. Some populations have a highly prevalent Fy-negative phenotype; such persons are naturally protected from P. vivax blood infection but are expected to completely support the P. vivax pre-erythrocytic cycle, representing a valuable model for studying the immune response during these parasitic stages. We typed 214 individuals, mostly Afro-Colombians, from a P. vivax-endemic area for Fy expression and determined the antibody response to P. vivax pre-erythrocytic (sporozoites and CS) and blood-stage antigens (blood forms, P. vivax merozoite surface protein 1, and P. vivax Duffy binding protein [PvDBP]). Antibody titers to P. vivax circumsporozoite protein, P11, and N-terminal peptides and the number of responders were similar in Fy-negative and Fy-positive individuals. The number of responders to sporozoites, blood forms, and PvDBP were different between these groups. Thus, Fy-negative individuals from malaria-endemic areas can be used to study the immune response to the P. vivax liver phase without interference of the erythrocytic cycle.

Immune responses to Plasmodium vivax pre-erythrocytic stage antigens in naturally exposed Duffy-negative humans: a potential model for identification of liver-stage antigens.

Duffy antigen is the receptor used by Plasmodium vivax to invade erythrocytes. Consequently, individuals lacking Duffy antigen [Fy(-)] do not develop blood-stage infections. We hypothesized that naturally exposed Fy(-) humans may develop immune responses mainly to pre-erythrocytic stages and could be used to study acquired immunity to P. vivax and to identify liver-stage antigens. We report here that antibody and IFN-gamma responses to known sporozoite antigens were significantly induced by natural exposure in Fy(-) humans, whereas responses to blood-stage antigens were significantly induced in Fy(+) humans. IFN-gamma responses to sporozoite antigens were lower in Fy(+) than in Fy(-) humans, indicating that in Fy(+) humans blood-stage infections may have suppressed T cell responses to pre-erythrocytic stages. We evaluated the immune responses to 18 novel P. vivax homologs of P. falciparum sporozoite proteins identified from the P. vivax genome sequence. Eight proteins recalled IFN-gamma responses in P. vivax-exposed but not in unexposed individuals. Of these, 3 antigens elicited IFN-gamma responses in Fy(-) but not in Fy(+) individuals. These results suggest that differential immune responses observed in naturally exposed Fy(-) and Fy(+) individuals can be exploited to identify P. vivax stage-specific antigens.