Immunology Department
Permanent URI for this collectionhttp://197.255.125.131:4000/handle/123456789/24485
Browse
242 results
Search Results
Item Advancing hypertensive disorders of pregnancy management: insights from the 5th preeclampsia scientifc symposium in Ghana(BMC Proceedings, 2024) Koi‑Larbi, K.; Obiri, D.; Browne, J. L.; et al.The 5th Preeclampsia Scientific Symposium (PSS2023) organized by Action on Preeclampsia (APEC) Ghana was themed: ‘Realign, Refocus: Improving outcomes of Hypertensive Disorders of Pregnancy through Shared Decision Making, Research & Quality of Care’. It took place on the 18th and 19th of May 2023 at the Ghana College of Physicians and Surgeons (GCPS), Accra Ghana. This transdisciplinary symposium brought together a national representation of experts, policy makers, scientists, and healthcare professionals to discuss key priorities, opportunities, approaches, and strategies to improve the maternal and perinatal outcomes of hypertensive disorders of pregnancy (HDP) in Ghana and the sub-region. The symposium centered around three key themes: realigning/refocusing patient-doc‑ tor decision making processes to improve outcomes of HDP; realigning/refocusing clinical care to improve outcomes of HDP; and leveraging on research to predict, recognize and manage high-risk women. This report summarizes insights from the diverse presentations and discussions held at the #PSS2023. This will form a roadmap for future research, policy, and interventions to improve outcomes of HDP in Ghana and the sub region. The symposium provided a wealth of evidence and knowledge from various experts, highlighting the need for women-centered care, equitable re-allocation of resources, multi-sectoral and innovative approaches, capacity strengthening. Other highlights include knowledge base development and increased stakeholder and community engagement with an overall aim of improving outcomes of HDP. The symposium also fostered inclusivity, welcoming survivors of HDP and their families at a scientific platform. They provided invaluable insights into the challenges faced and the lived experiences of those affected by the disease. Trainees and students also benefited from the symposium as it provided networking opportunities with fellow researchers, and a front row to gaining insights into cutting-edge research in GhanaItem Atypical memory B cell frequency correlates with antibody breadth and function in malaria immune adults(Scientific Reports, 2024) Partey, F.D.; Dowuona, J.N.; Pobee, A.N.; et.alClinical immunity to malaria develops slowly after repeated episodes of infection and antibodies are essential in naturally acquired immunity against malaria. However, chronic exposure to malaria has been linked to perturbation in B-cell homeostasis with the accumulation of atypical memory B cells. It is unclear how perturbations in B cell subsets influence antibody breadth, avidity, and function in individuals naturally exposed to malaria. We show that individuals living in high malaria transmission regions in Ghana have higher Plasmodium falciparum merozoite antigen-specific antibodies and an increased antibody breadth score but lower antibody avidities relative to low transmission regions. The frequency of circulating atypical memory B cells is positively associated with an individual’s antibody breadth. In vitro growth inhibition is independent of the ability to bind to free merozoites but associated with the breadth of antibody reactivity in an individual. Taken together, our data shows that repeated malaria episodes hamper the development of high avid antibodies which is compensated for by an increase in antibody breadth. Our results provide evidence to reinforce the idea that in regions with high malaria prevalence, repeated malaria infections lead to the broadening of antibody diversity and the continued presence of atypical memory B cell populations.Item In vitro assessment of crude oil degradation by Acinetobacter junii and Alcanivorax xenomutans isolated from the coast of Ghana(Heliyon, 2024) Gyasi, S. F.; Adu, B.; Appiah, A. S.; et alThis study was aimed at using in vitro microcosm experiments to assess crude oil degradation efficiency of Acinetobacter junii and Alcanivorax xenomutans isolated along Ghana’s coast. Un contaminated seawater from selected locations along the coast was used to isolate bacterial species by employing enrichment culture procedures with crude oil as the only carbon source. The isolates were identified by means of the extended direct colony transfer method of the Matrix Assisted Laser Desorption Ionization Time of Flight Mass Spectroscopy (MALDI-TOF MS), as Acinetobacter junii, and Alcanivorax xenomutans. Remediation tests showed that Acinetobacter junii yielded degradation efficiencies of 27.59 %, 41.38 % and 57.47 %. Whereas efficiencies of 21.14 %, 32.18 % and 43.68 % were recorded by Alcanivorax xenomutans representing 15, 30 and 45 days respectively. Consortia of Acinetobacter junii, and Alcanivorax xenomutans also yielded 32.18 %, 48.28 % and 62.07 % for the selected days respectively. Phylogenetic characterization using ClustalW and BLAST of sequences generated from the Oxford Nanopore Sequencing technique, showed that the Ghanaian isolates clustered with Alcanivorax xenomutans and Acinetobacter junii species respectively. An analysis of the sequenced data for the 1394-bp portion of the 16S rRNA gene of the isolates revealed >99 % sequence identity with the isolates present on the GenBank database. The isolates of closest identity were Alcanivorax xenomutans and Acinetobacter junii with accession numbers, NR_133958.1 and KJ147060.1 respectively. Acinetobacter junii and Alcani vorax xenomutans isolated from Ghana’s coast under pristine seawater conditions have therefore demonstrated their capacity to be used for the remediation of crude oil spills.Item High Prevalence Of Impaired Glucose Metabolism Among Children And Adolescents Living With HIV In Ghana(HIV Medicine, 2023) Ayanful-Torgby, R.; Shabanova, V.; Essuman, A.A.; et al.Background: Antiretroviral therapy (ART)-associated metabolic abnormalities, including impairment of glucose metabolism, are prevalent in adults living with HIV. However, the prevalence and pathogenesis of impaired glucose The metabolism of children and adolescents living with HIV, particularly in sub-Saharan Africa, is not well characterized. We investigated the prevalence of impaired glucose metabolism among children and adolescents living with perinatally infected HIV in Ghana. Methods: In this multicenter, cross-sectional study, we recruited participants from 10 paediatric antiretroviral treatment clinics from January to June 2022 in 10 facilities in the Greater Accra and Eastern regions of Ghana. We determined impaired glucose metabolism in the study sample by assessing fasting blood sugar (FBS), insulin resistance as defined by the homeostatic model assessment for insulin resistance (HOMA-IR) index and glycated haemoglobin (HbA1c) levels. The prevalence of impaired glucose metabolism using each criterion was stratified by age and sex. The phenotypic correlates of glucose metabolism Markers were also assessed among age, sex, body mass index (BMI), and waist-to-hip ratio (WHR). Results: We analysed data from 393 children and adolescents living with HIV aged 6–18 years. A little over half (205/393 or 52.25%) of the children were female. The mean age of the participants was 11.60 years (SD = 3.50), with 122/393 (31.00%) aged 6–9 years, 207/393 (52.67%) aged 10–15 years, and 62/393 (15.78%) were aged 16–18 years. The prevalence rates of glucose impairment in the study population, 15.52% [95% confidence interval (CI): 12.26– 19.45], 22.39% (95% CI: 18.54–26.78), and 26.21% (95% CI: 22.10–30.78) using HbA1c, HOMA-IR, and FBS criteria, respectively. Impaired glucose metabolism detected by FBS and HOMA-IR was higher in the older age group, whereas the prevalence of abnormal HbA1c levels was highest among the youngest age group. Age and BMI were positively associated with FBS and HOMA-IR (p < 0.001). However, there was negative correlation of WHR and HOMA-IR (p < 0.01) and HbA1c (p = 0.01).Conclusion: The high prevalence of impaired glucose metabolism observed among the children and adolescents living with HIV in sub-Saharan Africa is of concern as this could contribute to the development of metabolic syndrome in adulthood.Item Prevalence of Leucocytozoon infection in domestic birds in Ghana(PLOS Neglected Tropical Diseases, 2023) Agbemelo-Tsomafo, C.; AdjeiI, S.; Kusi, K.A.; et al.Leucocytozoon is a haemosporidian parasite known to cause leucocytozoonosis in domes tic and wild birds in most parts of the world. It is an important pathogen, as some species can be pathogenic, especially in domestic birds. One of the factors affecting poultry health management worldwide is parasitism. However, the study of haemosporidian parasites in Ghana is still lacking. This study sought to assess the prevalence and diversity of Leucocy tozoon parasites in domestic birds in Ghana. Blood samples were collected from domestic birds in Ghana’s Bono and Eastern regions to screen for Leucocytozoon parasites. Thin blood smears were prepared for microscopy and DNA was extracted from whole blood kept in ethylenediaminetetraacetic acid (EDTA) tubes for PCR. Due to the large number of sam ples, real-time PCR was performed to amplify the conserved rDNA gene. Two different nested PCR protocols were performed on the positive samples obtained from real-time PCR results, to amplify a partial region of the mitochondrial cytochrome b gene and the amplicons were sequenced. Sequencing revealed six new lineages of Leucocytozoon sp. recovered in 976 individual domestic birds and these sequences were deposited in the National Center for Biotechnology Information (NCBI) GenBank. An overall Leucocytozoon prevalence of 11.6% was reported in all birds sampled. The most prevalent lineage LGHA146 (GenBank accession no. OM643346) (93.8%) was found infecting 3 bird species, Gallus gallus, Meleagris gallopavo, and Anas platyrhynchos. Phylogenetic analysis revealed that the new lineages (GenBank accession nos. OM643342, OM643343, OM643344, OM643345, OM643346, and OM643347), reported in this study were closely related to Leucocytozoon schoutedeni. We suggest that further studies be conducted to evaluate the effect of these parasite species on the general well-being of poultry in Ghana.Item Distribution of Plasmodium falciparum K13 gene polymorphisms across transmission settings in Ghana(BMC Infectious Diseases, 2023) Dieng, C.C.; Morrison, V.; Donu, D.; Cui, L.; Amoah, L.; Afrane, Y.; Lo, E.Malaria is a signifcant global health concern, with a majority of cases in Sub-Saharan African nations. Numerous anti malarial drugs have been developed to counter the rampant prevalence of Plasmodium falciparum malaria. Arte misinin-based Combination Therapy (ACT) has served as the primary treatment of uncomplicated malaria in Ghana since 2005. However, a growing concern has emerged due to the escalating reports of ACT resistance, particularly in Southeast Asia, and its encroachment into Africa. Specifcally, mutations in the Kelch propeller domain on chromo some 13 (Pfk13) have been linked to ACT resistance. Yet, our understanding of mutation prevalence in Africa remains largely uncharted. In this study, we compared Pfk13 sequences obtained from 172 P. falciparum samples across three ecological and transmission zones in Ghana. We identifed 27 non-synonymous mutations among these sequences, of which two of the mutations, C580Y (found in two samples from the central region) and Y493H (found in one sam ple from the north), had previously been validated for their association with artemisinin resistance, a phenomenon widespread in Southeast Asia. The Pfk13 gene diversity was most pronounced in the northern savannah than the cen tral forest and south coastal regions, where transmission rates are lower. The observed mutations were not signif cantly associated with geographical regions, suggesting a frequent spread of mutations across the country. The ongo ing global surveillance of artemisinin resistance remains pivotal, and our fndings provides insights into the potential spread of resistant parasites in West Africa. Furthermore, the identifcation of novel codon mutations in this study raises their potential association to ACT resistance, warranting further investigation through in vitro assays to ascertain their functional signifcance.Item Biomarker of Anopheles exposure in Ghanaian children with hemoglobin S and C(Acta Tropica, 2024) Londono-Renteria, B.; Seidu, Z.; Lamptey, H.; Ofori, M.F.; Hviid, L.; Lopez-Perez, M.Heterozygous carriers of hemoglobin S and C (HbAS and HbAC) have a reduced risk of severe malaria but are not protected from Plasmodium falciparum infection, suggesting that the protection involves acquired immunity. During a blood meal, female Anopheles mosquitoes inject saliva that can elicit a host antibody response, which can serve as a proxy for exposure to Plasmodium infection. Previous studies have shown that the peptide gSG6-P1 of An. gambiae saliva is antigenic and highly Anopheles specific. Here, we used plasma samples from 201 Gha naian children with wild-type hemoglobin (HbAA), HbAS, and HbAC to evaluate antibody levels against gSG6-P1 as a serological biomarker of Anopheles exposure and, therefore of P. falciparum infection risk. Malaria antigen (PfCSP, GLURP, Pfs230, and HB3VAR06)-specific IgG levels, demographic data, and data regarding P. falciparum infection and malaria control practices were also analyzed. Children with active P. falciparum infection had higher antibody levels against all antigens, and those with HbAS and HbAC had significantly higher antibody levels against Pfs230. Pfs230-specific IgG correlated negatively with gSG6-P1-specific IgG in children with HbAC. Our results highlight the importance of studying the role of hemoglobinopathies in malaria transmission to improve control interventions.Item Background malaria incidence and parasitemia during the three-dose RTS,S/AS01 vaccination series do not reduce magnitude of antibody response nor efficacy against the first case of malaria(BMC Infectious Diseases, 2023) Bell, G.J.; Gyaase, S.; Adu, B.; et al.Background RTS,S/AS01 has been recommended by WHO for widespread implementation in medium to high malaria transmission settings. Previous analyses have noted lower vaccine efficacies in higher transmission settings, possibly due to the more rapid development of naturally acquired immunity in the control group. Methods To investigate a reduced immune response to vaccination as a potential mechanism behind lower efficacy in high transmission areas, we examine initial vaccine antibody (anti-CSP IgG) response and vaccine efficacy against the first case of malaria (to exclude the effect of naturally acquired immunity) using data from three study areas (Kintampo, Ghana; Lilongwe, Malawi; Lambaréné, Gabon) from the 2009–2014 phase III trial (NCT00866619). Our key exposures are parasitemia during the vaccination series and background malaria incidence. We calculate vaccine efficacy (one minus hazard ratio) using a cox-proportional hazards model and allowing for the time-varying effect of RTS,S/AS01. Results We find that antibody responses to the primary three-dose vaccination series were higher in Ghana than in Malawi and Gabon, but that neither antibody levels nor vaccine efficacy against the first case of malaria varied by background incidence or parasitemia during the primary vaccination series. Conclusions We find that vaccine efficacy is unrelated to infections during vaccination. Contributing to a conflicting literature, our results suggest that vaccine efficacy is also unrelated to infections before vaccination, meaning that control-group immunity is likely a major reason for lower efficacy in high transmission settings, not reduced immune responses to RTS,S/AS01. This may be reassuring for implementation in high transmission settings, though further studies are needed.Item Macrophage susceptibility to infection by Ghanaian Mycobacterium tuberculosis complex lineages 4 and 5 varies with self-reported ethnicity(Frontiers in Cellular and Infection Microbiology, 2023) Osei-Wusu, S.; Tetteh, J.K.A.; Arthur, N.; et al.Background: The epidemiology of Mycobacterium tuberculosis complex (MTBC) lineage 5 (L5) infections in Ghana revealed a significantly increased prevalence in Ewes compared to other self-reported ethnic groups. In that context, we sought to investigate the early phase of tuberculosis (TB) infection using ex vivo infection of macrophages derived from the blood of Ewe and Akan ethnic group volunteers with MTBC L4 and L5 strains. Methods: The study participants consisted of 16 controls, among which self reported Akan and Ewe ethnicity was equally represented, as well as 20 cured TB cases consisting of 11 Akans and 9 Ewes. Peripheral blood mononuclear cells were isolated from both healthy controls and cured TB cases. CD14+ monocytes were isolated and differentiated into monocyte-derived macrophages (MDMs) before infection with L4 or L5 endemic strains. The bacterial load was assessed after 2 hours (uptake) as well as 3 and 7 days post-infection. Results: We observed a higher capacity of MDMs from Ewes to phagocytose L4 strains (p < 0.001), translating into a higher bacillary load on day 7 (p < 0.001) compared to L5, despite the higher replication rate of L5 in Ewe MDMs (fold change: 1.4 vs. 1.2, p = 0.03) among the controls. On the contrary, within macrophages from Akans, we observed a significantly higher phagocytic uptake of L5 (p < 0.001) compared to L4, also translating into a higher load on day 7 (p = 0.04). However, the replication rate of L4 in Akan MDMs was higher than that of L5 (fold change: L4 = 1.2, L4 = 1.1, p = 0.04). Although there was no significant difference in the uptake of L4 and L5 among cured TB cases, there was a higher bacterial load of both L4 (p = 0.02) and L5 (p = 0.02) on day 7 in Ewe MDMs. Conclusion: Our results suggest that host ethnicity (driven by host genetic diversity), MTBC genetic diversity, and individual TB infection history are all acting together to modulate the outcome of macrophage infections by MTBC.Item The Rapid and Spontaneous Postpartum Clearance of Plasmodium falciparum Is Related to Expulsion of the Placenta(The Journal of Infectious Diseases, 2023) Anabire, N.G.; Quintana, M.D.P.; Ofori, M.F,; Hviid, L.Parasitemia among pregnant women with protective immunity to Plasmodium falciparum malaria is often dominated by VAR2CSA-positive infected erythrocytes (IEs). VAR2CSA mediates sequestration of IEs in the placenta. We hypothesized that the previously observed spontaneous postpartum clearance of parasitemia in such women is related to the expulsion of the placenta, which removes the sequestration focus of VAR2CSA-positive IEs. We assessed parasitemias and gene transcription before and shortly after delivery in 17 Ghanaian women. The precipitous decline in parasitemia postpartum was accompanied by selective reduction in transcription of the gene encoding VAR2CSA. Our findings provide a mechanistic explanation for the earlier observation.