Identifying targets of protective antibodies against severe malaria in Papua, Indonesia using locally expressed domains of Plasmodium falciparum Erythrocyte Membrane Protein 1.

Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1), a diverse family of multi-domain proteins expressed on the surface of malaria-infected erythrocytes, is an important target of protective immunity against malaria. Our group recently studied transcription of the var genes encoding PfEMP1 in individuals from Papua, Indonesia with severe or uncomplicated malaria. We cloned and expressed domains from 32 PfEMP1s including 22 that were upregulated in severe malaria and 10 that were upregulated in uncomplicated malaria, using a wheat germ cell-free expression system. We used Luminex technology to measure IgG antibodies to these 32 domains and control proteins in 63 individuals (11 children). At presentation to hospital, levels of antibodies to PfEMP1 domains were either higher in uncomplicated malaria or were not significantly different between groups. Using principal components analysis, antibodies to three of 32 domains were highly discriminatory between groups. These included two domains upregulated in severe malaria, a DBLβ13 domain and a CIDRα1.6 domain (which has been previously implicated in severe malaria pathogenesis), and a DBLδ domain that was upregulated in uncomplicated malaria. Antibody to control non-PfEMP1 antigens did not differ with disease severity. Antibodies to PfEMP1 domains differ with malaria severity. Lack of antibodies to locally expressed PfEMP1 types, including both domains previously associated with severe malaria and newly identified targets, may in part explain malaria severity in Papuan adults. Importance Severe Plasmodium falciparum malaria kills many African children, and lack of antibody immunity predisposes to severe disease. A critical antibody target is the P. falciparum erythrocyte membrane 1 (PfEMP1) family of multidomain proteins, which are expressed on the infected erythrocyte surface and mediate parasite sequestration in deep organs. We previously identified var genes encoding PfEMP1 that were differentially expressed between severe and uncomplicated malaria in Papua, Indonesia. Here, we have expressed domains from 32 of these PfEMP1s and measured IgG antibody responses to them in Papuan adults and children. Using Principal Component Analysis, IgG antibodies to three domains distinguished between severe and uncomplicated malaria and were higher in uncomplicated malaria. Domains included CIDRα1.6, implicated in severe malaria; a DBLβ13 domain; and a DBLδ domain of unknown function. Immunity to locally relevant PfEMP1 domains may protect from severe malaria. Targets of immunity show important overlap between Asian adults and African children.

C-reactive protein as an early biomarker for malaria infection and monitoring of malaria severity: a meta-analysis

This study investigated whether C-reactive protein (CRP) can be used as a marker for the early detection and monitoring of malaria severity. Potentially relevant studies were searched in Medline (PubMed), Scopus, and Web of Science. Differences in CRP between (1) severe malaria and uncomplicated malaria, (2) uncomplicated malaria and asymptomatic malaria, (3) uncomplicated malaria and febrile/healthy controls, and (4) asymptomatic malaria and febrile/healthy controls were estimated using random-effects models. Twenty-nine studies were included for meta-analysis. The results of meta-analysis demonstrated higher mean CRP levels in (1) patients with severe malaria compared with uncomplicated malaria (p < 0.001, standard mean difference [SMD]: 1.52, 95% confidence interval [CI]: 0.91–2.12, I2: 95.1%), (2) patients with uncomplicated malaria than in those with asymptomatic malaria (p: 0.001, SMD: 1.65, 95% CI: 0.67–2.62, I2: 96.7%), (3) patients with uncomplicated malaria compared with febrile/healthy controls (p < 0.001, SMD: 2.38, 95% CI: 1.37–3.40, I2: 98.5%), and (4) patients with asymptomatic malaria compared with febrile/healthy controls (p < 0.001, SMD: 2.55, 95% CI: 1.60–3.50, I2: 99.2%). This study demonstrated CRP levels are a biomarker for the early detection and monitoring of malaria severity.

Excreted Trypanosoma brucei proteins inhibit Plasmodium hepatic infection

Malaria, a disease caused by Plasmodium parasites, remains a major threat to public health globally. It is the most common disease in patients with sleeping sickness, another parasitic illness, caused by Trypanosoma brucei. We have previously shown that a T. brucei infection impairs a secondary P. berghei liver infection and decreases malaria severity in mice. However, whether this effect requires an active trypanosome infection remained unknown. Here, we show that Plasmodium liver infection can also be inhibited by the serum of a mouse previously infected by T. brucei and by total protein lysates of this kinetoplastid. Biochemical characterisation showed that the anti-Plasmodium activity of the total T. brucei lysates depends on its protein fraction, but is independent of the abundant variant surface glycoprotein. Finally, we found that the protein(s) responsible for the inhibition of Plasmodium infection is/are present within a fraction of ~350 proteins that are excreted to the bloodstream of the host. We conclude that the defence mechanism developed by trypanosomes against Plasmodium relies on protein excretion. This study opens the door to the identification of novel antiplasmodial intervention strategies.

Rural–urban dimensions of the perception of malaria severity and practice of malaria preventive measures: insight from the 2018 Nigeria Demographic and Health Survey

Morbidities and mortalities caused by malaria are still a serious issue in Nigeria, with the country accounting for 25% of malaria morbidities and 24% of malaria mortalities globally in 2018. Treated bed nets reduce the incidence of malaria, but not all Nigerians use them. This study aimed to examine the factors associated with treated bed net usage, including perceived severity of malaria, and the rural–urban differences in the relationship between socio-demographic factors and use of treated bed nets in Nigeria. The analytic sample size comprised 40,693 women aged 15–49 years. Poisson regression and bivariable and multivariable analyses were used to test the study hypothesis that women who agreed that malaria could potentially lead to death would be more likely to adopt malaria preventive measures, including treated bed net use. About 48% of the women slept under a treated mosquito net the night before the survey. Those who perceived that malaria could lead to death had a higher likelihood of using a treated bed net in the urban, rural and combined samples. However, in the multivariable model, the association between perceived malaria severity and use of a treated bed net was only significant for rural women (APR=0.964, 95% CI: 0.933, 0.996). The results unexpectedly suggest that rural Nigerian women who perceive malaria to be severe have a lower likelihood of using treated bed nets. Also, rural–urban variations in the relationship between the socio-demographic variables and use of treated bed nets were observed. Policies should consider the observed rural–urban dichotomy in the influence of perceived severity of malaria and other socio-demographic factors on women’s use of treated bed nets in Nigeria.

Role of Platelet Indices as a Potential Marker for Malaria Severity

Purpose. Platelet parameter alteration such as platelet count and platelet indices are more common than in other blood cell lines due to diverse causative pathophysiological mechanisms in severe malaria infection. In malaria patients, no more studies evaluated platelet indices in relation to disease severity and prognosis. Therefore, this review assessed the current scientific knowledge on the potential role of platelet indices for the diagnostic marker of severe malaria infection. Results. Hence, after reviewing recent literatures, elevation of mean platelet volume and platelet distribution width in addition to decreased plateletcrit and platelet counts is the known potential risk factor associated with warning signs of severe malaria. Thus, thrombocytopenia < 150 × 10 9 / L , MPV ≥ 9.05 fL , and PDW ≥ 14.550 % as well as significantly higher P-LCR and decrease in PCT are shown significant sensitivity and specificity as they are used as diagnostic and prognostic values in severe malaria infection. Conclusion. Platelet indices are useful predictors of malaria severity. Immature platelet fraction (IPF%) is raised in the case of severe malaria, and it was significantly more useful than MPV. Advanced research will further investigate the platelet index abnormality associated with specific age and gender among specific malaria species.

Malaria Severity Score in Malaria Patients Admitted in Critical Care Wards

Introduction: Prognostic scoring system in Intensive Care Unit (ICU) can be generic, which can be applied to any critical illness for which patients are admitted in critical wards or can be disease specific. Malaria Severity Score (MSS) is a disease specific prognostic scoring system. Aim: To study the role of MSS in patients having malaria who were critically ill having multi organ dysfunction and to correlate the score with risk of mortality. Materials and Methods: This longitudinal study was conducted at the Department of General Medicine, SBKSMI & RC, Sumandeep Vidyapeeth, Vadodara, Gujarat, India. Adult patients (>18 years) with falciparum as well as vivax malaria, who had positive peripheral smear malaria and were admitted in ICU/Casualty (Emergency) ward, were taken in the study. The score was calculated on day of admission, day 2 and day 7. The score was analysed between two groups: survivors and non-survivors. Appropriate statistical tests were applied (z-test for two population proportion and Chi-square test for categorical values). The p-value <0.05 was considered as significant. Results: Out of 60 patients, 41 survived and 19 died due to malaria. Mean age of survivors was 38.56±2.27 and of non-survivors 40.21±5.6 years (p=0.718). There were 27 patients of P.vivax, 30 of P. falciparum and three patients of mixed infection; mortality was in 09, 08, 02 patients, respectively. On admission, out of total 60 patients, 10 (16.67%) had 1+, 20 (33.33%) had 2+, 24 (40%) had 3+ and 6 (10%) had 4+ parasite count. There were no patients in 1+ parasite count group, two (10%) in 2+, eleven (45.8%) in 3+ and six (100%) in 4+ parasite count group. Mean MSS was not significantly different on day 0 and day 2 but was higher on day 7 in non-survivor group than in survivors group (p=0.005). Mortality prediction score cut-off was ≥9, which was obtained by plotting Receiver Operating Characteristic (ROC) curve. Mean MSS in non-survivor group was 7.37 on day 0, 6.58 on day 2 and 9.11 on day 7. Thus, MSS score of day 7 gave `prediction reaching cut-off value of ≥9. Conclusion: MSS was found to be a useful prognostic score in severe falciparum/vivax malaria who needs intensive care treatment as sequential score gives significant difference in survivors and non-survivors on seventh day.

Multiplexed quantitative proteomics provides mechanistic cues for malaria severity and complexity

Management of severe malaria remains a critical global challenge. In this study, using a multiplexed quantitative proteomics pipeline we systematically investigated the plasma proteome alterations in non-severe and severe malaria patients. We identified a few parasite proteins in severe malaria patients, which could be promising from a diagnostic perspective. Further, from host proteome analysis we observed substantial modulations in many crucial physiological pathways, including lipid metabolism, cytokine signaling, complement, and coagulation cascades in severe malaria. We propose that severe manifestations of malaria are possibly underpinned by modulations of the host physiology and defense machinery, which is evidently reflected in the plasma proteome alterations. Importantly, we identified multiple blood markers that can effectively define different complications of severe falciparum malaria, including cerebral syndromes and severe anemia. The ability of our identified blood markers to distinguish different severe complications of malaria may aid in developing new clinical tests for monitoring malaria severity.

Binding of human serum proteins to Plasmodium falciparum-infected erythrocytes and its association with malaria clinical presentation

Background The pathogenesis of Plasmodium falciparum malaria is related to the ability of parasite‑infected erythrocytes (IEs) to adhere to the vascular endothelium (cytoadhesion/sequestration) or to surrounding uninfected erythrocytes (rosetting). Both processes are mediated by the expression of members of the clonally variant PfEMP1 parasite protein family on the surface of the IEs. Recent evidence obtained with laboratory-adapted clones indicates that P. falciparum can exploit human serum factors, such as IgM and α2-macroglobulin (α2M), to increase the avidity of PfEMP1-mediated binding to erythrocyte receptors, as well as to evade host PfEMP1-specific immune responses. It has remained unclear whether PfEMP1 variants present in field isolates share these characteristics, and whether they are associated with clinical malaria severity. These issues were investigated here. Methods Children 1–12 years reporting with P. falciparum malaria to Hohoe Municipal Hospital, Ghana were enrolled in the study. Parasites from children with uncomplicated (UM) and severe malaria (SM) were collected. Binding of α2M and IgM from non-immune individuals to erythrocytes infected by P. falciparum isolates from 34 children (UM and SM) were analysed by flow cytometry. Rosetting in the presence of IgM or α2M was also evaluated. Experimental results were analysed according to the clinical presentation of the patients. Results Clinical data from 108 children classified as UM (n = 54) and SM cases (n = 54) were analysed. Prostration, severe malaria anaemia, and hyperparasitaemia were the most frequent complications. Three children were diagnosed with cerebral malaria, and one child died. Parasite isolates from UM (n = 14) and SM (n = 20) children were analysed. Most of the field isolates bound non-immune IgM (33/34), whereas the α2M-binding was less common (23/34). Binding of both non-immune IgM and α2M was higher but not significant in IEs from children with SM than from children with UM. In combination, IgM and α2M supported rosette formation at levels similar to that observed in the presence of 10% human serum. Conclusions The results support the hypothesis that binding of non-immune IgM and/or α2M to IEs facilitates rosette formation and perhaps contributes to P. falciparum malaria severity.