The exception that proves the rule: Virulence gene expression at the onset of Plasmodium falciparum blood stage infections.

Controlled human malaria infections (CHMI) are a valuable tool to study parasite gene expression in vivo under defined conditions. In previous studies, virulence gene expression was analyzed in samples from volunteers infected with the Plasmodium falciparum (Pf) NF54 isolate, which is of African origin. Here, we provide an in-depth investigation of parasite virulence gene expression in malaria-naïve European volunteers undergoing CHMI with the genetically distinct Pf 7G8 clone, originating in Brazil. Differential expression of var genes, encoding major virulence factors of Pf, PfEMP1s, was assessed in ex vivo parasite samples as well as in parasites from the in vitro cell bank culture that was used to generate the sporozoites (SPZ) for CHMI (Sanaria PfSPZ Challenge (7G8)). We report broad activation of mainly B-type subtelomeric located var genes at the onset of a 7G8 blood stage infection in naïve volunteers, mirroring the NF54 expression study and suggesting that the expression of virulence-associated genes is generally reset during transmission from the mosquito to the human host. However, in 7G8 parasites, we additionally detected a continuously expressed single C-type variant, Pf7G8_040025600, that was most highly expressed in both pre-mosquito cell bank and volunteer samples, suggesting that 7G8, unlike NF54, maintains expression of some previously expressed var variants during transmission. This suggests that in a new host, the parasite may preferentially express the variants that previously allowed successful infection and transmission. Trial registration: ClinicalTrials.gov - NCT02704533; 2018-004523-36.

A PfSPZ vaccine immunization regimen equally protective against homologous and heterologous controlled human malaria infection.

Immunization with radiation-attenuated Plasmodium falciparum (Pf) sporozoites (SPZ) in PfSPZ Vaccine, has provided better vaccine efficacy (VE) against controlled human malaria infection (CHMI) with the same parasites as in the vaccine (homologous) than with genetically distant parasites (heterologous). We sought to identify an immunization regimen that provided similar VE against CHMI with homologous and heterologous Pf for at least 9 weeks in malaria-naïve adults. Such a regimen was identified in part 1 (optimization), an open label study, and confirmed in part 2 (verification), a randomized, double-blind, placebo-controlled study in which VE was assessed by cross-over repeat CHMI with homologous (PfNF54) and heterologous (Pf7G8) PfSPZ at 3 and 9-10 weeks. VE was calculated using Bayesian generalized linear regression. In part 1, vaccination with 9 × 105 PfSPZ on days 1, 8, and 29 protected 5/5 (100%) subjects against homologous CHMI at 3 weeks after the last immunization. In part 2, the same 3-dose regimen protected 5/6 subjects (83%) against heterologous CHMI at both 3 and 9-10 weeks after the last immunization. Overall VE was 78% (95% predictive interval: 57-92%), and against heterologous and homologous was 79% (95% PI: 54-95%) and 77% (95% PI: 50-95%) respectively. PfSPZ Vaccine was safe and well tolerated. A 4-week, 3-dose regimen of PfSPZ Vaccine provided similar VE for 9-10 weeks against homologous and heterologous CHMI. The trial is registered with ClinicalTrials.gov, NCT02704533.

Efficacy, T cell activation and antibody responses in accelerated Plasmodium falciparum sporozoite chemoprophylaxis vaccine regimens.

Repeated direct venous inoculation of Plasmodium falciparum sporozoites (PfSPZ) together with antimalarial chemoprophylaxis (PfSPZ-CVac) is the most potent way to induce sterile immunity against P. falciparum infection in malaria-naive volunteers. However, established schedules are complex and long. Here, we tested two accelerated three-dose schedules (28- and 10-day regimen) assessing efficacy by controlled human malaria infection (CHMI) against placebo, comparing vaccine-specific T cell and antibody responses by antigen-reactive T cell enrichment (ARTE) and protein microarray, respectively. Both regimens were similarly efficacious (67 and 63% vaccine efficacy) but different in the induction of vaccine-specific T cells and antibodies. The 10-day regimen resulted in higher numbers of antigen-specific CD4+ effector memory pro-inflammatory T cells and a broader antibody response compared with the 28-day regimen. Usually in nature, P. falciparum liver stage lasts about 6.5 days. The short vaccination-interval of the 10-day regimen prolongs the time of continuous exposure to liver-stage parasites, which may explain the stronger response. Besides dose and number of vaccinations, duration of liver-stage exposure is a factor to optimize PfSPZ-CVac immunogenicity.

Heterologous protection against malaria by a simple chemoattenuated PfSPZ vaccine regimen in a randomized trial.

Immunization with Plasmodium falciparum (Pf) sporozoites under chemoprophylaxis (PfSPZ-CVac) is the most efficacious approach to malaria vaccination. Implementation is hampered by a complex chemoprophylaxis regimen and missing evidence for efficacy against heterologous infection. We report the results of a double-blinded, randomized, placebo-controlled trial of a simplified, condensed immunization regimen in malaria-naive volunteers (EudraCT-Nr: 2018-004523-36). Participants are immunized by direct venous inoculation of 1.1 × 105 aseptic, purified, cryopreserved PfSPZ (PfSPZ Challenge) of the PfNF54 strain or normal saline (placebo) on days 1, 6 and 29, with simultaneous oral administration of 10 mg/kg chloroquine base. Primary endpoints are vaccine efficacy tested by controlled human malaria infection (CHMI) using the highly divergent, heterologous strain Pf7G8 and safety. Twelve weeks following immunization, 10/13 participants in the vaccine group are sterilely protected against heterologous CHMI, while (5/5) participants receiving placebo develop parasitemia (risk difference: 77%, p = 0.004, Boschloo's test). Immunization is well tolerated with self-limiting grade 1-2 headaches, pyrexia and fatigue that diminish with each vaccination. Immunization induces 18-fold higher anti-Pf circumsporozoite protein (PfCSP) antibody levels in protected than in unprotected vaccinees (p = 0.028). In addition anti-PfMSP2 antibodies are strongly protection-associated by protein microarray assessment. This PfSPZ-CVac regimen is highly efficacious, simple, safe, well tolerated and highly immunogenic.

A call to caution when hydroxychloroquine is given to elderly patients with COVID-19.

INTRODUCTION: Use of hydroxychloroquine in patients with coronavirus disease 2019 (COVID-19) was widespread and uncontrolled until recently. Patients vulnerable to severe COVID-19 are at risk of hydroxychloroquine interactions with co-morbidities and co-medications contributing to detrimental, including fatal, adverse treatment effects. METHODS: A retrospective survey was undertaken of health conditions and co-medications of patients with COVID-19 who were pre-screened for enrolment in a randomized, double-blind, placebo-controlled hydroxychloroquine multi-centre trial. RESULTS: The survey involved 305 patients [median age 71 (interquartile range 59-81) years]. The majority of patients (n = 279, 92%) considered for inclusion in the clinical trial were not eligible, mainly due to safety concerns caused by health conditions or co-medications. The most common were QT-prolonging drugs (n = 188, 62%) and haematologic/haemato-oncologic diseases (n = 39, 13%) which prohibited the administration of hydroxychloroquine. In addition, 165 (54%) patients had health conditions and 167 (55%) patients were on co-medications that did not prohibit the use of hydroxychloroquine but had a risk of adverse interactions with hydroxychloroquine. The most common were diabetes (n = 86, 28%), renal insufficiency (n = 69, 23%) and heart failure (n = 58, 19%). CONCLUSION: The majority of hospitalized patients with COVID-19 had health conditions or took co-medications precluding safe treatment with hydroxychloroquine. Therefore, hydroxychloroquine should be administered with extreme caution in elderly patients with COVID-19, and only in clinical trials.

Forecasting tuberculosis using diabetes-related google trends data.

Online activity-based data can be used to aid infectious disease forecasting. Our aim was to exploit the converging nature of the tuberculosis (TB) and diabetes epidemics to forecast TB case numbers. Thus, we extended TB prediction models based on traditional data with diabetes-related Google searches. We obtained data on the weekly case numbers of TB in Germany from June 8th, 2014, to May 5th, 2019. Internet search data were obtained from a Google Trends (GTD) search for 'diabetes' to the corresponding interval. A seasonal autoregressive moving average (SARIMA) model (0,1,1) (1,0,0) [52] was selected to describe the weekly TB case numbers with and without GTD as an external regressor. We cross-validated the SARIMA models to obtain the root mean squared errors (RMSE). We repeated this procedure with autoregressive feed-forward neural network (NNAR) models using 5-fold cross-validation. To simulate a data-poor surveillance setting, we also tested traditional and GTD-extended models against a hold-out dataset using a decreased 52-week-long period with missing values for training. Cross-validation resulted in an RMSE of 20.83 for the traditional model and 18.56 for the GTD-extended model. Cross-validation of the NNAR models showed a mean RMSE of 19.49 for the traditional model and 18.99 for the GTD-extended model. When we tested the models trained on a decreased dataset with missing values, the GTD-extended models achieved significantly better prediction than the traditional models (p < 0.001). The GTD-extended models outperformed the traditional models in all assessed model evaluation parameters. Using online activity-based data regarding diabetes can improve TB forecasting, but further validation is warranted.

Ivermectin for causal malaria prophylaxis: a randomised controlled human infection trial.

OBJECTIVE: Ivermectin is safe and widely used for treating helminth infections. It also kills arthropods feeding on treated subjects, including malaria vectors. Thus, ivermectin mass drug administration as an additional tool for malaria control is being evaluated by WHO. As in vitro data, animal experiments and epidemiological observations suggest that ivermectin has a direct effect on the liver stages of the malaria parasite, this study was designed to assess the prophylactic effect of ivermectin on Plasmodium falciparum controlled human malaria infection. METHODS: A total of 4 volunteers were randomised to placebo, and 8 volunteers were randomised to receive ivermectin 0.4 mg/kg, orally, once 2 h before being experimentally infected intravenously with 3200 P. falciparum sporozoites. The primary endpoint was time to parasitaemia detected by positive thick blood smear; RT-qPCR was performed in parallel. RESULTS: All but one volunteer became thick blood smear positive between day 11 and day 12 after infection, and there was no significant effect of ivermectin on parasitaemia. CONCLUSION: Ivermectin - at the dose used - has no clinically relevant activity against the pre-erythrocytic stages of P. falciparum.

OBJECTIF: L'ivermectine est sûr et largement utilisé pour traiter les helminthiases. Il tue également les arthropodes se nourrissant sur les sujets traités, y compris les vecteurs du paludisme. Ainsi, l'administration en masse d'ivermectine en tant qu'outil supplémentaire de lutte contre le paludisme est actuellement évaluée par l'OMS. Comme les données in vitro, les expériences sur animaux et les observations épidémiologiques suggèrent que l'ivermectine a un effet direct sur les stades hépatiques du parasite du paludisme, cette étude a été conçue pour évaluer l'effet prophylactique de l'ivermectine sur l'infection paludéenne humaine par Plasmodium falciparum contrôlée. MÉTHODES: Quatre volontaires ont été randomisés pour un placebo et 8 volontaires ont été randomisés pour recevoir de l'ivermectine à 0,4 mg/kg en une fois par voie orale, 2 heures avant d'être expérimentalement infectés par voie intraveineuse avec 3.200 sporozoïtes de P. falciparum. Le critère d'évaluation principal était le temps à la parasitémie détectée par un frottis sanguin épais positif. Une RT-qPCR a été réalisée en parallèle. RÉSULTATS: Tous les volontaires sauf un sont devenus positifs pour les frottis sanguins épais entre le jour 11 et le jour 12 après l'infection et il n'y avait aucun effet significatif de l'ivermectine sur la parasitémie. CONCLUSION: L'ivermectine - à la dose utilisée - n'a aucune activité cliniquement pertinente contre les stades pré-érythrocytaires de P. falciparum.

[Development of malaria vaccines-state of the art]. / Entwicklung von Impfstoffen gegen Malaria ­ aktueller Stand.

Globally, 3.1 billion people live in areas endemic for malaria (the tropics and subtropics). Annually, around 200 million fall ill, and around 500,000 persons die as a result of this infection. Mainly children are the victims. In order to control and eventually prevent any new infection, the development of effective vaccines is pivotal. In this review, background information about the history of vaccine development and malaria disease as well as possibilities for therapy and control is given. In the main part of the article, an update on the development of vaccines against Plasmodium falciparum is provided followed by an extensive discussion.Malaria is a parasitic infectious disease caused by the single cell organism Plasmodium. Five different Plasmodium species can induce disease in humans with P. falciparum being the origin for more than 99% of infections in Africa. The vector is the Anopheles mosquito. The life cycle of Plasmodium offers several approaches for vaccines to have an impact. Out of around 70 candidates, pre-erythrocytic vaccine candidates interfering with the liver phase of the parasite are the most developed. However, a vaccine with more than 75% efficacy, as required by the World Health Organization (WHO), is not yet in sight.Currently, for the first time, a moderately efficacious vaccine (RTS,S/AS01) is being applied in large-scale operations. But it is obvious that malaria can only be controlled in combination with concurring measures. For example, the use of impregnated mosquito nets, indoor residual spraying, elimination of vector breeding sites, rapid diagnosis, and therapy of the infection as well as a functioning health system are important elements, which can hardly be guaranteed in areas characterized by poverty.

Predicting tick-borne encephalitis using Google Trends.

Data generated through public Internet searching offers a promising alternative source of information for monitoring and forecasting of infectious disease. Here future cases of tick-borne encephalitis (TBE) were predicted using traditional weekly case reports, both with and without Google Trends data (GTD). Data on the weekly number of acute, confirmed TBE cases in Germany were obtained from the Robert Koch Institute. Data relating to the volume of Internet searching on TBE was downloaded from the Google Trends website. Data were split into training and validation parts. A SARIMA (0,1,1) (1,1,1) [52] model was used to describe the weekly TBE case number time series. Google Trends Data was used as an external regressor in a second, as optimal identified SARIMA (4,1,1) (1,1,1) [52] model. Predictions for the number of future cases were made with both models and compared with the validation dataset. GTD showed a significant correlation with reported weekly case numbers of TBE (p < 0.0001). A comparison of forecasted values with reported ones resulted in an RMSE (residual mean squared error) of 0.71 for the model without Google search values, and an RMSE of 0.70 for the Google Trends values enhanced model. However, difference between predictive performances was not significant (Diebold Mariano test, p-value = 0.14).

Can Google Trends data improve forecasting of Lyme disease incidence?

BACKGROUND: Online activity-based epidemiological surveillance and forecasting is getting more and more attention. To date, Google search volumes have not been assessed for forecasting of tick-borne diseases. Thus, we performed an analysis of forecasting of the Lyme disease incidence based on the traditional data extended with Google Trends. METHODS: Data on the weekly incidence of Lyme disease in Germany from 16 June 2013 to 27 May 2018 were obtained from the database of the Robert Koch Institute. Data of Internet searches were obtained from Google Trends searching "Borreliose" in Germany for the "last 5 years" as a timespan category. Data were split into the training (from 16 June 2013 to 11 June 2017) and validation (from 12 June 2017, to 27 May 2018) data sets. A seasonal autoregressive moving average model, SARIMA (0,1,1) (0,1,1) [52] model was selected to describe the time series of the weekly Lyme incidence. After this, we added the Google Trends data as an external regressor and identified the SARIMA (0,1,1) (0,1,1) [52] model as optimal. We made predictions for the validation interval using these two models and compared predictions with the values of the validation data set. RESULTS: Forecasting for the validation timespan resulted in similar values for the models. Comparing the forecasted values with the reported ones resulted in an residual mean squared error (RMSE) of 0.3763; the mean absolute percentage error (MAPE) was 8.233 for the model without Google searches with an RMSE of 0.3732; and the MAPE was 8.17495 for the Google Trends values-expanded model. The difference between the predictive performances was insignificant (Diebold-Mariano Test, p-value = 0.4152). CONCLUSION: Google Trends data are a good correlate of the reported incidence of Lyme disease in Germany, but it failed to significantly improve the forecasting accuracy in models based on traditional data.

DSM265 for Plasmodium falciparum chemoprophylaxis: a randomised, double blinded, phase 1 trial with controlled human malaria infection.

BACKGROUND: A drug for causal (ie, pre-erythrocytic) prophylaxis of Plasmodium falciparum malaria with prolonged activity would substantially advance malaria control. DSM265 is an experimental antimalarial that selectively inhibits the parasite dihydroorotate dehydrogenase. DSM265 shows in vitro activity against liver and blood stages of P falciparum. We assessed the prophylactic activity of DSM265 against controlled human malaria infection (CHMI). METHODS: At the Institute of Tropical Medicine, Eberhard Karls University (Tübingen, Germany), healthy, malaria-naive adults were allocated to receive 400 mg DSM265 or placebo either 1 day (cohort 1A) or 7 days (cohort 2) before CHMI by direct venous inoculation (DVI) of 3200 aseptic, purified, cryopreserved P falciparum sporozoites (PfSPZ Challenge; Sanaria Inc, Rockville, MD, USA). An additional group received daily atovaquone-proguanil (250-100 mg) for 9 days, starting 1 day before CHMI (cohort 1B). Allocation to DSM265, atovaquone-proguanil, or placebo was randomised by an interactive web response system. Allocation to cohort 1A and 1B was open-label, within cohorts 1A and 2, allocation to DSM265 and placebo was double-blinded. All treatments were given orally. Volunteers were treated with an antimalarial on day 28, or when parasitaemic, as detected by thick blood smear (TBS) microscopy. The primary efficacy endpoint was time-to-parasitaemia, assessed by TBS. All participants receiving at least one dose of chemoprophylaxis or placebo were considered for safety, those receiving PfSPZ Challenge for efficacy analyses. Log-rank test was used to compare time-to-parasitemia between interventions. The trial was registered with ClinicalTrials.gov, number NCT02450578. FINDINGS: 22 participants were enrolled between Oct 23, 2015, and Jan 18, 2016. Five participants received 400 mg DSM265 and two participants received placebo 1 day before CHMI (cohort 1A), six participants received daily atovaquone-proguanil 1 day before CHMI (cohort 1B), and six participants received 400 mg DSM265 and two participants received placebo 7 days before CHMI (cohort 2). Five of five participants receiving DSM265 1 day before CHMI and six of six in the atovaquone-proguanil cohort were protected, whereas placebo recipients (two of two) developed malaria on days 11 and 14. When given 7 days before CHMI, three of six volunteers receiving DSM265 became TBS positive on days 11, 13, and 24. The remaining three DSM265-treated, TBS-negative participants of cohort 2 developed transient submicroscopic parasitaemia. Both participants receiving placebo 7 days before CHMI became TBS positive on day 11. The only possible DSM265-related adverse event was a moderate transient elevation in serum bilirubin in one participant. INTERPRETATION: A single dose of 400 mg DSM265 was well tolerated and had causal prophylactic activity when given 1 day before CHMI. Future trials are needed to investigate further the use of DSM265 for the prophylaxis of malaria. FUNDING: Global Health Innovative Technology Fund, Wellcome Trust, Bill & Melinda Gates Foundation through Medicines for Malaria Venture, and the German Center for Infection Research.

Hepatic fibrosis and factors associated with liver stiffness in HIV mono-infected individuals.

BACKGROUND: Liver disease has become an important cause of morbidity and mortality even in those HIV-infected individuals who are devoid of hepatitis virus co-infection. The aim of this study was to evaluate the degree of hepatic fibrosis and the role of associated factors using liver stiffness measurement in HIV mono-infected patients without significant alcohol intake. METHODS: We performed a cross-sectional study of 101 HIV mono-infected patients recruited prospectively from March 1, 2014 to October 30, 2014 at the Center for HIV, St István and St László Hospital, Budapest, Hungary. To determine hepatic fibrosis, liver stiffness was measured with transient elastography. Demographic, immunologic and other clinical parameters were collected to establish a multivariate model. Bayesian Model Averaging (BMA) was performed to identify predictors of liver stiffness. RESULTS: Liver stiffness ranged from 3.0-34.3 kPa, with a median value of 5.1 kPa (IQR 1.7). BMA provided a very high support for age (Posterior Effect Probability-PEP: 84.5%), moderate for BMI (PEP: 49.3%), CD4/8 ratio (PEP: 44.2%) and lipodystrophy (PEP: 44.0%). For all remaining variables, the model rather provides evidence against their effect. These results overall suggest that age and BMI have a positive association with LS, while CD4/8 ratio and lipodystrophy are negatively associated. DISCUSSION: Our findings shed light on the possible importance of ageing, overweight and HIV-induced immune dysregulation in the development of liver fibrosis in the HIV-infected population. Nonetheless, further controlled studies are warranted to clarify causal relations.

Successful treatment of HCV-associated cryoglobulinemia with ombitasvir/paritaprevir/ritonavir, dasabuvir and ribavirin: A case report.

Cryoglobulinemia is an important extrahepatic manifestation of chronic hepatitis C virus infection. Current treatments are suboptimal, resulting in relapse or refractoriness in 30-40% of patients. Hereby, we describe the case of a 40-year old man with severe hepatitis C virus-associated cryoglobulinemia, effectively treated with an interferon-free combination regimen. The patient was treated for 12 weeks with ombitasvir/paritaprevir/ritonavir, dasabuvir and ribavirin. Rapid clinical and immunological response, i.e., the resolution of symptoms and disappearance of serum cryoglobulins, ensued as early as 4 weeks after initiating direct acting antiviral therapy. Our reported case directs the attention to the possible consequences and importance of new, effective, interferon-free antiviral treatments in devastating lymphoproliferative and immunological manifestations of chronic hepatitis C virus infection.