We have identified and functionally characterized a novel Plasmodium falciparum surface-related antigen (PfSRA) as a potential multistage vaccine candidate. The antigen is localized on both merozoites and gametocytes with high anti-PfSRA growth inhibition assay activity in laboratory strains and clinical isolates.
BackgroundCholera has been endemic in Ghana since its detection in 1970. It has been shown that long-term survival of the bacteria may be attained in aquatic environments. Consequently, cholera outbreaks may be triggered predominantly in densely populated urban areas. We investigated clinical and environmental isolates of Vibrio cholerae O1 in Accra to determine their virulence genes, antibiotic susceptibility patterns and environmental factors maintaining their persistence in the environment.MethodsWater samples from various sources were analyzed for the presence of V. cholerae O1 using culture methods. Forty clinical isolates from a previous cholera outbreak were included in the study for comparison. Antibiotic susceptibility patterns of the bacteria were determined by disc diffusion. Virulence genes were identified by analyzing genes for ctx, tcpA (tcpAEl Tor tcpACl), zot, ompW, rbfO1 and attRS using PCR. Physicochemical characteristics of water were investigated using standard methods. One-way ANOVA and student t - test were employed to analyze the relationship between physicochemical factors and the occurrence of V. cholerae O1.ResultsEleven V. cholerae O1 strains were successfully isolated from streams, storage tanks and wells during the study period. All isolates were resistant to one or more of the eight antibiotics used. Multidrug resistance was observed in over 97% of the isolates. All isolates had genes for at least one virulence factor. Vibrio cholerae toxin gene was detected in 82.4% of the isolates. Approximately 81.8% of the isolates were positive for tcpAEl Tor gene, but also harbored the tcpAcl gene. Isolates were grouped into thirteen genotypes based on the genes analyzed. High temperature, salinity, total dissolved solids and conductivity was found to significantly correlate positively with isolation of V. cholerae O1. V. cholerae serotype Ogawa biotype El tor is the main biotype circulating in Ghana with the emergence of a hybrid strain.ConclusionsMultidrug resistant V. cholerae O1 with different genotypes and pathogenicity are present in water sources and co-exist with non O1/O139 in the study area.Electronic supplementary materialThe online version of this article (10.1186/s12879-019-3714-z) contains supplementary material, which is available to authorized users.
Nearly half of the genes in the Plasmodium falciparum genome have not yet been functionally investigated. We used homology-based structural modeling to identify multiple copies of Armadillo repeats within one uncharacterized gene expressed during the intraerythrocytic stages, PF3D7_0410600, subsequently referred to as P. falciparum Armadillo-Type Repeat Protein (PfATRP). Soluble recombinant PfATRP was expressed in a bacterial expression system, purified to apparent homogeneity and the identity of the recombinant PfATRP was confirmed by mass spectrometry. Affinity-purified α-PfATRP rabbit antibodies specifically recognized the recombinant protein. Immunofluorescence assays revealed that α-PfATRP rabbit antibodies reacted with P. falciparum schizonts. Anti-PfATRP antibody exhibited peripheral staining patterns around the merozoites. Given the localization of PfATRP in merozoites, we tested for an egress phenotype during schizont arrest assays and demonstrated that native PfATRP is inaccessible on the surface of merozoites in intact schizonts. Dual immunofluorescence assays with markers for the inner membrane complex (IMC) and microtubules suggest partial colocalization in both asexual and sexual stage parasites. Using the soluble recombinant PfATRP in a screen of plasma samples revealed that malaria-infected children have naturally acquired PfATRP-specific antibodies.
Problem International students are an important part of higher education institutions because they bring in funds, they enhance the diversity, and increase the knowledge being shared (Srivastava et al., 2010; Luo & Jamieson-Drake, 2013; Ongo, 2019; Knight, 2007; Pandit, K., 2007; Baklashova & Kazakov, 2016). Therefore, if retention is not monitored and maintained, the United States could soon lose this important group to other countries with more competitive retention plans (Srivastava, 2010, p. 1561). Andrews University is one school in the U.S. that already shows signs of retention issues among international students, including African international students. There are several challenges that contribute to retention issues in higher education including lack of inclusion, financial issues, lack of support from faculty, and lack of familiarity with the learning expectations (Gao, 2021; Haverila et al., 2020; Heyman, 2010; Mamiseishvili, 2012; Unruh, 2015). These challenges can also lead to students remaining in their programs much longer than the expected time of completion. Exceeding completion times not only negatively impacts the goals and aspirations of the student, but it also negatively reflects on the effectiveness of the university’s education and learning process. This research explored the issues of students exceeding their expected time of completion is explored as it pertained to African graduate students at Andrews University. Purpose of the Study The purpose of this qualitative study was to understand the factors contributing to the time of completion for African graduate students at Andrews University by exploring the challenges that affect their persistence. Additionally, the perspectives of African graduate students about these factors were explored to better understand what contributed to their persistence in their programs or if adequate support was provided from Andrews University to address any issues hindering their graduation. Method This research used a phenomenological qualitative approach to understand the phenomenon of students exceeding the expected time of completion in the graduate program at Andrews University. A hermeneutical phenomenological approach was utilized to explore the lived experience of students from their perspective. A research sample of 10 African graduate students was chosen; 5 male students and 5 female students. All participants had to be international students who travelled on a F1 visa, and they had to be still on campus at Andrews university having studied for more than the expected number of years in their graduate programs. Information was gathered through interviews with participants recorded digitally which were then transcribed and analyzed by hand. Findings External factors play a much larger role than internal factors for African graduate students at Andrews University. There are many challenges that they face due to transitioning to a new environment and trying to adapt to a new education system. However, challenges related to being self-sponsored were the most significant. Without substantial funds, students are forced to balance working hours, raising a family, and doing coursework on their own. The support provided through scholarships, donors, and work-studies are crucial forms of aid for African graduate students. More programs such as the Aspire scholarship with Ghana, God’s Abundant Pantry, and Neighbor to Neighbor can help Andrews University become a place where African students go with assurance of support. Because most participants were enrolled during the height of the COVID-19 pandemic, changes to travel, education, and access to resources also impacted the time they spent in their programs. Although the university did not cause many of the problems related to prolonged time of completion, the action they take to help alleviate these problems can determine whether they will have a steady intake of African students in the future.
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