Malaria infection by sporozoite challenge induces high functional antibody titres against blood stage antigens after a DNA prime, poxvirus boost vaccination strategy in Rhesus macaques

<p>Abstract</p> <p>Background</p> <p>A DNA prime, poxvirus (COPAK) boost vaccination regime with four antigens, i.e. a combination of two <it>Plasmodium knowlesi </it>sporozoite (<it>csp/ssp2</it>) and two blood stage (<it>ama1/msp1</it>_<it>42</it>) genes, leads to self-limited parasitaemia in 60% of rhesus monkeys and survival from an otherwise lethal infection with <it>P. knowlesi</it>. In the present study, the role of the blood stage antigens in protection was studied in depth, focusing on antibody formation against the blood stage antigens and the functionality thereof.</p> <p>Methods</p> <p>Rhesus macaques were immunized with the four-component vaccine and subsequently challenged i.v. with 100 <it>P. knowlesi </it>sporozoites. During immunization and challenge, antibody titres against the two blood stage antigens were determined, as well as the <it>in vitro </it>growth inhibition capacity of those antibodies. Antigen reversal experiments were performed to determine the relative contribution of antibodies against each of the two blood stage antigens to the inhibition.</p> <p>Results</p> <p>After vaccination, PkAMA1 and PkMSP1₁₉antibody titres in vaccinated animals were low, which was reflected in low levels of inhibition by these antibodies as determined by <it>in vitro </it>inhibition assays. Interestingly, after sporozoite challenge antibody titres against blood stage antigens were boosted over 30-fold in both protected and not protected animals. The <it>in vitro </it>inhibition levels increased to high levels (median inhibitions of 59% and 56% at 6 mg/mL total IgG, respectively). As growth inhibition levels were not significantly different between protected and not protected animals, the ability to control infection appeared cannot be explained by GIA levels. Judged by <it>in vitro </it>antigen reversal growth inhibition assays, over 85% of the inhibitory activity of these antibodies was directed against PkAMA1.</p> <p>Conclusions</p> <p>This is the first report that demonstrates that a DNA prime/poxvirus boost vaccination regimen induces low levels of malaria parasite growth inhibitory antibodies, which are boosted to high levels upon challenge. No association could, however, be established between the levels of inhibitory capacity <it>in vitro </it>and protection, either after vaccination or after challenge.</p

Exploration of pathomechanisms triggered by a single-nucleotide polymorphism in titin\u27s I-band: the cardiomyopathy-linked mutation T2580I

Missense single-nucleotide polymorphisms (mSNPs) in titin are emerging as a main causative factor of heart failure. However, distinguishing between benign and disease-causing mSNPs is a substantial challenge. Here, we research the question of whether a single mSNP in a generic domain of titin can affect heart function as a whole and, if so, how. For this, we studied the mSNP T2850I, seemingly linked to arrhythmogenic right ventricular cardiomyopathy (ARVC). We used structural biology, computational simulations and transgenic muscle in vivo methods to track the effect of the mutation from the molecular to the organismal level. The data show that the T2850I exchange is compatible with the domain three-dimensional fold, but that it strongly destabilizes it. Further, it induces a change in the conformational dynamics of the titin chain that alters its reactivity, causing the formation of aberrant interactions in the sarcomere. Echocardiography of knock-in mice indicated a mild diastolic dysfunction arising from increased myocardial stiffness. In conclusion, our data provide evidence that single mSNPs in titin\u27s I-band can alter overall muscle behaviour. Our suggested mechanisms of disease are the development of non-native sarcomeric interactions and titin instability leading to a reduced I-band compliance. However, understanding the T2850I-induced ARVC pathology mechanistically remains a complex problem and will require a deeper understanding of the sarcomeric context of the titin region affected

A pandemic within a pandemic? Admission to COVID-19 wards in hospitals is associated with increased prevalence of antimicrobial resistance in two African settings

BACKGROUND: Patients who develop severe illness due to COVID-19 are more likely to be admitted to hospital and acquire bacterial co-infections, therefore the WHO recommends empiric treatment with antibiotics. Few reports have addressed the impact of COVID-19 management on emergence of nosocomial antimicrobial resistance (AMR) in resource constrained settings. This study aimed to ascertain whether being admitted to a COVID-19 ward (with COVID-19 infection) compared to a non-COVID-19 ward (as a COVID-19 negative patient) was associated with a change in the prevalence of bacterial hospital acquired infection (HAI) species or resistance patterns, and whether there were differences in antimicrobial stewardship (AMS) and infection prevention and control (IPC) guidelines between COVID-19 and non-COVID-19 wards. The study was conducted in Sudan and Zambia, two resource constrained settings with differing country-wide responses to COVID-19. METHODS: Patients suspected of having hospital acquired infections were recruited from COVID-19 wards and non-COVID-19 wards. Bacteria were isolated from clinical samples using culture and molecular methods and species identified. Phenotypic and genotypic resistance patterns were determined by antibiotic disc diffusion and whole genome sequencing. Infection prevention and control guidelines were analysed for COVID-19 and non-COVID-19 wards to identify potential differences. RESULTS: 109 and 66 isolates were collected from Sudan and Zambia respectively. Phenotypic testing revealed significantly more multi-drug resistant isolates on COVID-19 wards in both countries (Sudan p = 0.0087, Zambia p = 0.0154). The total number of patients with hospital acquired infections (both susceptible and resistant) increased significantly on COVID-19 wards in Sudan, but the opposite was observed in Zambia (both p = ≤ 0.0001). Genotypic analysis showed significantly more β-lactam genes per isolate on COVID-19 wards (Sudan p = 0.0192, Zambia p = ≤ 0.0001). CONCLUSIONS: Changes in hospital acquired infections and AMR patterns were seen in COVID-19 patients on COVID-19 wards compared to COVID-19 negative patients on non-COVID-19 wards in Sudan and Zambia. These are likely due to a potentially complex combination of causes, including patient factors, but differing emphases on infection prevention and control, and antimicrobial stewardship policies on COVID-19 wards were highlighted

Married women's decision making power on modern contraceptive use in urban and rural southern Ethiopia

<p>Abstract</p> <p>Background</p> <p>Women in developing countries are either under collective decision making with their partners or completely rely on the male partner's decision on issues that affect their reproductive live. Identifying the major barriers of married women's decision making power on contraceptive use has significant relevance for planning contextually appropriate family planning interventions. The objective of this study was to determine current modern contraceptive practices and decision making power among married women in Tercha Town and surrounding rural areas of Dawro zone, Southern Ethiopia.</p> <p>Methods</p> <p>Community based comparative cross-sectional design with both quantitative and Qualitative study has been employed in March and April 2010. The respondents were 699 married women of child bearing age from urban and rural parts of Dawro zone. After conducting census, we took the sample using simple random sampling technique.</p> <p>Results</p> <p>Current modern contraceptive use among married women in the urban was 293 (87.5%) and 243 (72.8%) in rural. Married women who reside in urban area were more likely to decide on the use of modern contraceptive method than rural women. Having better knowledge about modern contraceptive methods, gender equitable attitude, better involvement in decisions related to children, socio-cultural and family relations were statistically significant factors for decision making power of women on the use of modern contraceptive methods in the urban setting. Better knowledge, fear of partner's opposition or negligence, involvement in decisions about child and economic affairs were statistically significant factors for better decision making power of women on the use of modern contraceptive methods in the rural part.</p> <p>Conclusions</p> <p>High level of current modern contraceptive practice with reduced urban-rural difference was found as compared to regional and national figures. Urban women had better power to make decisions on modern contraceptive than rural women. Modern family planning interventions in the area should be promoted by considering empowering of women on modern contraceptive use decision making.</p

Vaccination with Plasmodium knowlesi AMA1 Formulated in the Novel Adjuvant Co-Vaccine HT™ Protects against Blood-Stage Challenge in Rhesus Macaques

Plasmodium falciparum apical membrane antigen 1 (PfAMA1) is a leading blood stage vaccine candidate. Plasmodium knowlesi AMA1 (PkAMA1) was produced and purified using similar methodology as for clinical grade PfAMA1 yielding a pure, conformational intact protein. Combined with the adjuvant CoVaccine HT™, PkAMA1 was found to be highly immunogenic in rabbits and the efficacy of the PkAMA1 was subsequently tested in a rhesus macaque blood-stage challenge model. Six rhesus monkeys were vaccinated with PkAMA1 and a control group of 6 were vaccinated with PfAMA1. A total of 50 µg AMA1 was administered intramuscularly three times at 4 week intervals. One of six rhesus monkeys vaccinated with PkAMA1 was able to control parasitaemia, upon blood stage challenge with P. knowlesi H-strain. Four out of the remaining five showed a delay in parasite onset that correlated with functional antibody titres. In the PfAMA1 vaccinated control group, five out of six animals had to be treated with antimalarials 8 days after challenge; one animal did not become patent during the challenge period. Following a rest period, animals were boosted and challenged again. Four of the six rhesus monkeys vaccinated with PkAMA1 were able to control the parasitaemia, one had a delayed onset of parasitaemia and one animal was not protected, while all control animals required treatment. To confirm that the control of parasitaemia was AMA1-related, animals were allowed to recover, boosted and re-challenged with P. knowlesi Nuri strain. All control animals had to be treated with antimalarials by day 8, while five out of six PkAMA1 vaccinated animals were able to control parasitaemia. This study shows that: i) Yeast-expressed PkAMA1 can protect against blood stage challenge; ii) Functional antibody levels as measured by GIA correlated inversely with the day of onset and iii) GIA IC50 values correlated with estimated in vivo growth rates

Geographical Variation in the Response of Visceral Leishmaniasis to Paromomycin in East Africa: A Multicentre, Open-Label, Randomized Trial

Visceral leishmaniasis (VL) is a fatal parasitic disease with 500,000 new cases each year according to WHO estimates. New and better treatment options are urgently needed in disease endemic areas due to the long courses, toxicity and development of resistance to current treatments. Recently, the antibiotic paromomycin was tested and registered in India to treat this disease. The current study describes a clinical trial to test the effectiveness of injectable paromomycin, either alone or in combination with the standard drug sodium stibogluconate in three East African countries—Sudan, Kenya and Ethiopia. The study showed that at the same paromomycin dose that was successfully used and registered in India, a far poorer outcome was obtained, particularly in Sudan, suggesting that there are either differences in the patients ability to respond to the drug or in the susceptibility of parasites in East Africa compared with those in India. However, no major safety concerns were noted with the treatment. Further research was initiated to see if a higher dose of paromomycin would perform better, especially in Sudan. The results of this and the performance of the combination arm will be reported later. Our study highlights the importance of considering geographical differences to treatment responses

Elevated intracranial pressure and cerebral edema following permanent MCA occlusion in an ovine model

INTRODUCTION: Malignant middle cerebral artery (MCA) stroke has a disproportionately high mortality due to the rapid development of refractory space-occupying cerebral edema. Animal models are essential in developing successful anti-edema therapies; however to date poor clinical translation has been associated with the predominately used rodent models. As such, large animal gyrencephalic models of stroke are urgently needed. The aim of the study was to characterize the intracranial pressure (ICP) response to MCA occlusion in our recently developed ovine stroke model. MATERIALS AND METHODS: 30 adult female Merino sheep (n = 8-12/gp) were randomized to sham surgery, temporary or permanent proximal MCA occlusion. ICP and brain tissue oxygen were monitored for 24 hours under general anesthesia. MRI, infarct volume with triphenyltetrazolium chloride (TTC) staining and histology were performed. RESULTS: No increase in ICP, radiological evidence of ischemia within the MCA territory but without space-occupying edema, and TTC infarct volumes of 7.9+/-5.1% were seen with temporary MCAO. Permanent MCAO resulted in significantly elevated ICP, accompanied by 30% mortality, radiological evidence of space-occupying cerebral edema and TTC infarct volumes of 27.4+/-6.4%. CONCLUSIONS: Permanent proximal MCAO in the sheep results in space-occupying cerebral edema, raised ICP and mortality similar to human malignant MCA stroke. This animal model may prove useful for pre-clinical testing of anti-edema therapies that have shown promise in rodent studies.Adam J. Wells, Robert Vink, Stephen C. Helps, Steven J. Knox, Peter C. Blumbergs, Renée J. Turne