Prenatal immunity to

Malaria parasites reside inside erythrocytes and the disease manifestations are linked to the growth inside infected erythrocytes (IE). The growth of the parasite is mostly confined to the trophozoite stage during which nuclear division occurs followed by the formation of cell bodies (schizogony). The mechanism and regulation of schizogony are poorly understood. Here we show a novel role for a Plasmodium falciparum 60S stalk ribosomal acidic protein P2 (PfP2) (PFC0400w), which gets exported to the IE surface for 6–8 hrs during early schizogony, starting around 26–28 hrs post-merozoite invasion. The surface exposure is demonstrated using multiple PfP2-specific monoclonal antibodies, and is confirmed through transfection using PfP2-GFP. The IE surface-exposed PfP2-protein occurs mainly as SDS-resistant P2-homo-tetramers. Treatment with anti-PfP2 monoclonals causes arrest of IEs at the first nuclear division. Upon removal of the antibodies, about 80–85% of synchronized parasites can be released even after 24 hrs of antibody treatment. It has been reported that a tubovesicular network (TVN) is set up in early trophozoites which is used for nutrient import. Anti-P2 monoclonal antibodies cause a complete fragmentation of TVN by 36 hrs, and impairs lipid import in IEs. These may be downstream causes for the cell-cycle arrest. Upon antibody removal, the TVN is reconstituted, and the cell division progresses. Each of the above properties is observed in the rodent malaria parasite species P. yoelii and P. berghei. The translocation of the P2 protein to the IE surface is therefore likely to be of fundamental importance in Plasmodium cell division.

Background: The “Wide Awake Local Anesthesia No Tourniquet” (WALANT) technique is gaining popularity in hand surgery owing to its benefits of reduced cost, shorter hospital stay, improved safety, and the ability to perform active intraoperative examinations. The aim of this study is to analyze the cost savings and efficiency of performing A1 pulley release for treatment of trigger finger using the WALANT technique in a major city hospital procedure room (PR) as compared with the standard tourniquet, operating room (OR) approach. Methods: Patients who underwent trigger finger release between 2012 and 2017 were identified. Demographic and procedural information were obtained. Patients were followed for an average of 82 and 242 days in the PR and OR groups, respectively. Results: Thirty-nine PR and 37 OR patients were identified. Case length and turnover time were shorter in the PR group [21.4 ± 7 versus 23.5 ± 14.3 min (P = 0.942) and 31.1 ± 11.1 and 65.3 ± 17.7 min (P < 0.001), respectively). The cost of the instrument tray utilized was calculated as $3,304.25 in the main OR and $993.79 in the PR. Cost per minute for all personal services in the OR was calculated to be $44/min, a cost that was virtually absent in the PR. Complication rates did not differ between both groups. Conclusion: Performing A1 pulley release for treatment of trigger finger using the WALANT technique is both cost effective and time efficient compared to performing the same procedure in the main OR of a major city public hospital.

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The enolase protein of the human malarial parasite Plasmodium falciparum has recently been characterized. Apart from its glycolytic function, enolase has also been shown to possess antigenic properties and to be present on the cell wall of certain invasive organisms, such as Candida albicans. In order to assess whether enolase of P. falciparum is also antigenic, sera from residents of a region of Eastern India where malaria is endemic were tested against the recombinant P. falciparum enolase (r-Pfen) protein. About 96% of immune adult sera samples reacted with r-Pfen over and above the seronegative controls. Rabbit anti-r-Pfen antibodies inhibited the growth of in vitro cultures of P. falciparum. Mice immunized with r-Pfen showed protection against a challenge with the 17XL lethal strain of the mouse malarial parasite Plasmodium yoelii. The antibodies raised against r-Pfen were specific for Plasmodium and did not react to the host tissues. Immunofluorescence as well as electron microscopic examinations revealed localization of the enolase protein on the merozoite cell surface. These observations establish malaria enolase to be a potential protective antigen.Malaria continues to be a life-threatening infectious disease in the tropical world. Despite tremendous efforts to control the malaria epidemic, current prophylaxis and drug treatments are proving insufficient. The extensive spreading of drug-resistant Plasmodium strains as well as insecticide-resistant mosquitoes makes it urgent to develop an effective malaria vaccine. Long years of antigen identification and characterization have yielded many potential vaccine candidates, but developing an effective malaria vaccine has remained an incredibly difficult challenge (17). It has been observed that immunity to the disease develops gradually, after many attacks and over many years, in adults living in areas where malaria is endemic (2). The successful passive transfer of this immunity by injecting antibodies from malaria-immune persons to children susceptible to malaria has demonstrated that antibodies alone can trigger protection (5, 9, 58). These experiments have worked across geographical borders, as immunoglobulin G (IgG) from malaria-immune West Africans have cured East Africans as well as Thai malaria patients (5). The nature of this immunity is poorly understood at the molecular level. However, attempts have been made to identify antigens, the humoral response against which leads to protection. Seroepidemiological studies have identified several specific malarial blood-stage antigens including ring-infected erythrocyte surface antigen (10), apical membrane antigen (53), and PfP0, a conserved ribosomal protein (7,18,24), as protective antigens.Enolase has been reported to be present on the cell surface of several organisms (38). It is also considered to be a major immunostimulatory protein in the case of visceral leishmaniasis (19). Enolase has been demonstrated to play a protective role in Candida albicans infection (31, 41, 55). Recently, it has also been ...

The erythrocytic stages of the malaria parasite depend on anaerobic glycolysis for energy. Using [2-13 C]glucose and nuclear magnetic resonance, the glucose utilization rate and 2,3-diphosphoglycerate (2,3-DPG) level produced in normal RBCs and Plasmodium falciparum infected red blood cell populations (IRBCs, with <4% parasite infected red cells), were measured. The glucose flux in IRBCs was several-folds greater, was proportional to parasitemia, and maximal at trophozoite stage. The 2,3-DPG levels were disproportionately lower in IRBCs, indicating a downregulation of 2,3-DPG flux in non-parasitized RBCs. This may be due to lowered pH leading to selective differential inhibition of the regulatory glycolytic enzyme phosphofructokinase. This downregulation of the glucose utilization rate in the majority (>96%) of uninfected RBCs in an IRBC population may have physiological implications in malaria patients.

BackgroundIn an earlier study, it was observed that the vaccination with Plasmodium falciparum enolase can confer partial protection against malaria in mice. Evidence has also build up to indicate that enolases may perform several non-glycolytic functions in pathogens. Investigating the stage-specific expression and sub-cellular localization of a protein may provide insights into its moonlighting functions.MethodsSub-cellular localization of P. falciparum enolase was examined using immunofluorescence assay, immuno-gold electron microscopy and western blotting.ResultsEnolase protein was detected at every stage in parasite life cycle examined. In asexual stages, enolase was predominantly (≥85–90%) present in soluble fraction, while in sexual stages it was mostly associated with particulate fraction. Apart from cytosol, enolase was found to be associated with nucleus, food vacuole, cytoskeleton and plasma membrane.ConclusionDiverse localization of enolase suggests that apart from catalyzing the conversion of 2-phosphoglycericacid into phosphoenolpyruvate in glycolysis, enolase may be involved in a host of other biological functions. For instance, enolase localized on the merozoite surface may be involved in red blood cell invasion; vacuolar enolase may be involved in food vacuole formation and/or development; nuclear enolase may play a role in transcription.