scholarly journals Monoclonal Antibodies Specific for Immunorecessive Epitopes of Glucuronoxylomannan, the Major Capsular Polysaccharide of Cryptococcus neoformans, Reduce Serotype Bias in an Immunoassay for Cryptococcal Antigen

2011 ◽  
Vol 18 (8) ◽  
pp. 1292-1296 ◽  
Author(s):  
Ann Percival ◽  
Peter Thorkildson ◽  
Thomas R. Kozel
Keyword(s):  
Monoclonal Antibodies ◽  
Cryptococcus Neoformans ◽  
Capsular Polysaccharide ◽  
Polyclonal Antibodies ◽  
Sub Saharan Africa ◽  
Enzyme Linked Immunosorbent Assay ◽  
Content Type ◽  
Screening Strategies ◽  
Sub Saharan ◽  
High Degree

ABSTRACTImmunoassay for detection of glucuronoxylomannan (GXM), the major capsular polysaccharide ofCryptococcus neoformans, is an important tool for diagnosis of cryptococcosis. However, immunoassays that are based solely or in part on detection with polyclonal antibodies may show serotype bias in detection of GXM, particularly limited sensitivity for serotype C. In this study, we describe detection of GXM in an antigen capture sandwich enzyme-linked immunosorbent assay (ELISA) that used a cocktail of two monoclonal antibodies (MAbs). MAb F12D2 was previously produced by immunization with GXM that had been treated to removeO-acetyl groups, a major source of serotype specificity. MAb F12D2 has a high degree of reactivity with GXM of serotypes A, B, C, and D, but the reactivity with serotype D was less than was found with other MAbs. MAb 339 is highly reactive with GXM of serotypes A and D. Use of a combination of the two MAbs produced an immunoassay that had the best properties of both MAbs, including good reactivity with serotype C, which is an emerging threat in sub-Saharan Africa. These results suggest that next-generation immunoassays for diagnosis of cryptococcosis may be formulated by (i) use of immunization and hybridoma screening strategies that are designed to prospectively meet the needs of immunoassay performance and (ii) careful selection of MAbs that span the expected polysaccharide serotypes in the subject patient population.

scholarly journals Development of Opsonic Mouse Monoclonal Antibodies against Multidrug-Resistant Enterococci

2019 ◽  
Vol 87 (9) ◽  
Author(s):  
Ermioni Kalfopoulou ◽  
Diana Laverde ◽  
Karmela Miklic ◽  
Felipe Romero-Saavedra ◽  
Suzana Malic ◽  
...  
Keyword(s):  
Monoclonal Antibodies ◽  
Capsular Polysaccharide ◽  
Selection Process ◽  
Multidrug Resistant ◽  
Expression Vectors ◽  
Hybridoma Cells ◽  
Enzyme Linked Immunosorbent Assay ◽  
Bacterial Strains ◽  
Variable Regions ◽  
Content Type

ABSTRACTMultidrug-resistant enterococci are major causes of hospital-acquired infections. Immunotherapy with monoclonal antibodies (MAbs) targeting bacterial antigens would be a valuable treatment option in this setting. Here, we describe the development of two MAbs through hybridoma technology that target antigens from the most clinically relevant enterococcal species. Diheteroglycan (DHG), a well-characterized capsular polysaccharide ofEnterococcus faecalis, and the secreted antigen A (SagA), an immunogenic protein fromEnterococcus faecium, are both immunogens that have been proven to raise opsonic and cross-reactive antibodies against enterococcal strains. For this purpose, a conjugated form of the native DHG with SagA was used to raise the antibodies in mice, while enzyme-linked immunosorbent assay and opsonophagocytic assay were combined in the selection process of hybridoma cells producing immunoreactive and opsonic antibodies targeting the selected antigens. From this process, two highly specific IgG1(κ) MAbs were obtained, one against the polysaccharide (DHG.01) and one against the protein (SagA.01). Both MAbs exhibited good opsonic killing against the target bacterial strains: DHG.01 showed 90% killing againstE. faecalistype 2, and SagA.01 showed 40% killing againstE. faecium11231/6. In addition, both MAbs showed cross-reactivity toward otherE. faecalisandE. faeciumstrains. The sequences from the variable regions of the heavy and light chains were reconstructed in expression vectors, and the activity of the MAbs upon expression in eukaryotic cells was confirmed with the same immunological assays. In summary, we identified two opsonic MAbs against enterococci which could be used for therapeutic or prophylactic approaches against enterococcal infections.

scholarly journals Development of a Novel Cocktail Enzyme-Linked Immunosorbent Assay and a Field-Applicable Lateral-Flow Rapid Test for Diagnosis of Contagious Bovine Pleuropneumonia

2016 ◽  
Vol 54 (6) ◽  
pp. 1557-1565 ◽  
Author(s):  
Martin Heller ◽  
Nimmo Gicheru ◽  
Georgina Tjipura-Zaire ◽  
Cecilia Muriuki ◽  
Mingyan Yu ◽  
...  
Keyword(s):  
Immunosorbent Assay ◽  
Rapid Test ◽  
Lateral Flow ◽  
Sub Saharan Africa ◽  
Enzyme Linked Immunosorbent Assay ◽  
Contagious Bovine Pleuropneumonia ◽  
Serum Samples ◽  
Content Type ◽  
Mycoplasma Mycoides ◽  
Sub Saharan

Contagious bovine pleuropneumonia (CBPP) is a severe respiratory disease that is widespread in sub-Saharan Africa. It is caused byMycoplasma mycoidessubsp.mycoides, a bacterium belonging to theMycoplasma mycoidescluster. In the absence of an efficient CBPP vaccine, improved and easy-to-use diagnostic assays for recurrent testing combined with isolation and treatment of positive animals represent an option for CBPP control in Africa. Here we describe the comprehensive screening of 17 immunogenicMycoplasma mycoidessubsp.mycoidesproteins using well-characterized bovine sera for the development of a novel cocktail enzyme-linked immunosorbent assay (ELISA) for laboratory use. Two recombinantMycoplasmaimmunogens, MSC_0136 and MSC_0636, were used to set up a standardized cocktail ELISA protocol. According to the results from more than 100 serum samples tested, the sensitivity and specificity of the novel cocktail ELISA were 85.6% and 96.4%, respectively, with an overall diagnostic accuracy comparable to that of the Office International des Epizooties (OIE)-prescribed serological assays. In addition, we provide a proof of principle for a field-applicable, easy-to-use commercially produced prototype lateral-flow test for rapid (<30-min) diagnosis of CBPP.

scholarly journals Physiological Differences in Cryptococcus neoformans Strains In Vitro versus In Vivo and Their Effects on Antifungal Susceptibility

2016 ◽  
Vol 61 (3) ◽  
Author(s):  
Nina T. Grossman ◽  
Arturo Casadevall
Keyword(s):  
Cryptococcus Neoformans ◽  
Cryptococcal Meningitis ◽  
Antifungal Susceptibility ◽  
Sub Saharan Africa ◽  
Content Type ◽  
Laboratory Conditions ◽  
Physiological Differences ◽  
Sub Saharan

ABSTRACT Cryptococcus neoformans is an environmentally ubiquitous fungal pathogen that primarily causes disease in people with compromised immune systems, particularly those with advanced AIDS. There are estimated to be almost 1 million cases per year of cryptococcal meningitis in patients infected with human immunodeficiency virus, leading to over 600,000 annual deaths, with a particular burden in sub-Saharan Africa. Amphotericin B (AMB) and fluconazole (FLC) are key components of cryptococcal meningitis treatment: AMB is used for induction, and FLC is for consolidation, maintenance and, for occasional individuals, prophylaxis. However, the results of standard antifungal susceptibility testing (AFST) for AMB and FLC do not correlate well with therapeutic outcomes and, consequently, no clinical breakpoints have been established. While a number of explanations for this absence of correlation have been proffered, one potential reason that has not been adequately explored is the possibility that the physiological differences between the in vivo infection environment and the in vitro AFST environment lead to disparate drug susceptibilities. These susceptibility-influencing factors include melanization, which does not occur during AFST, the size of the polysaccharide capsule, which is larger in infecting cells than in those grown under normal laboratory conditions, and the presence of large polyploid “titan cells,” which rarely occur under laboratory conditions. Understanding whether and how C. neoformans differentially expresses mechanisms of resistance to AMB and FLC in the AFST environment compared to the in vivo environment could enhance our ability to interpret AFST results and possibly lead to the development of more applicable testing methods.

scholarly journals Contribution of Epitope Specificity to the Binding of Monoclonal Antibodies to the Capsule of Cryptococcus neoformans and the Soluble Form of Its Major Polysaccharide, Glucuronoxylomannan

2003 ◽  
Vol 10 (2) ◽  
pp. 252-258 ◽  
Author(s):  
Raymond M. Duro ◽  
Dale Netski ◽  
Peter Thorkildson ◽  
Thomas R. Kozel
Keyword(s):  
Monoclonal Antibodies ◽  
Cryptococcus Neoformans ◽  
Capsular Polysaccharide ◽  
Protective Efficacy ◽  
Biological Activities ◽  
Qualitative Assessment ◽  
Soluble Form ◽  
Enzyme Linked Immunosorbent Assay ◽  
Serological Assay ◽  
Epitope Specificity

ABSTRACT Incubation of encapsulated cryptococci with monoclonal antibodies (MAbs) specific for glucuronoxylomannan (GXM), the major capsular polysaccharide of Cryptococcus neoformans, produces two distinct capsular quellung-type reactions termed rim and puffy. The type of capsular reaction that occurs is determined by the epitope specificity of the MAb and the serotype of the yeast cell. Several biological activities, including opsonic activity, complement activation, and protective efficacy, are associated with the type of capsular reaction produced by a MAb. The goal of this study was to examine the reactivities of two families of anti-GXM MAbs with serotype A and D capsular polysaccharides in several immunochemical assays, including agglutination, immunofluorescence, quantitative precipitation, and enzyme-linked immunosorbent assay, in an effort to identify serological assays that are predictive of the capsular quellung reaction. The results showed that the type of capsular reaction (rim versus puffy) is a qualitative assessment of antibody-capsule interaction that cannot be predicted on the basis of a serological assay. The results further showed that antibody reactivity demonstrated in one serological assay is not necessarily predictive of results in another assay, particularly in cases where one assay examines antibody-capsule interactions, e.g., agglutination, and another assay examines interaction of antibody with soluble GXM. Taken together, the results suggest caution in interpretation of immunochemical assays for anti-GXM antibodies and recommend the use of multiple assays formats when studying anticryptococcal antibodies.

scholarly journals Preparation and Characterization of Group A Meningococcal Capsular Polysaccharide Conjugates and Evaluation of Their Immunogenicity in Mice

2003 ◽  
Vol 71 (9) ◽  
pp. 5115-5120 ◽  
Author(s):  
Zhigang Jin ◽  
Chiayung Chu ◽  
John B. Robbins ◽  
Rachel Schneerson
Keyword(s):  
Capsular Polysaccharide ◽  
Geometric Mean ◽  
Sub Saharan Africa ◽  
World Health ◽  
Enzyme Linked Immunosorbent Assay ◽  
Group A ◽  
Low Levels ◽  
The Difference ◽  
Sub Saharan

ABSTRACT Epidemic and endemic meningitis caused by group A Neisseria meningitidis remains a problem in sub-Saharan Africa. Although group A meningococcal capsular polysaccharide (GAMP) vaccine confers immunity at all ages, the improved immunogenicity of a conjugate and its compatibility with the World Health Organization's Extended Program on Immunization offers advantages over GAMP alone. Conjugates of GAMP bound to bovine serum albumin (BSA) were synthesized, characterized, and evaluated for their immunogenicities in mice. Two methods, involving adipic acid dihydrazide (ADH) as a linker, were used. First, ADH was bound to GAMP activated with cyanogen bromide (CNBr) or with 1-cyano-4(dimethylamino)-pyridinium tetrafluoroborate (CDAP) to form GAMPCNBr AH and GAMPCDAP AH. These derivatives were bound to BSA by 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) to form GAMPCNBr AH-BSA and GAMPCDAP AH-BSA. Second, ADH was bound to BSA with EDC to form AHBSA. AHBSA was bound to activated GAMP to form GAMPCNBr-AHBSA and GAMPCDAP-AHBSA. The yield of GAMPCDAP-AHBSA (35 to 40%) was higher than those of the other conjugates (5 to 20%). GAMP conjugates elicited immunoglobulin G (IgG) anti-GAMP in all mice after three injections of 2.5 or 5.0 μg of GAMP: the geometric mean (GM) was highest in recipients of GAMPCDAP-AHBSA (11.40 enzyme-linked immunosorbent assay units). Although the difference was not statistically significant, the 5.0-μg dose elicited a higher GM IgG anti-GAMP than the 2.5-μg dose. Low levels of anti-GAMP were elicited by GAMP alone. GAMPCDAP-AHBSA elicited bactericidal activity roughly proportional to the level of IgG anti-GAMP.

scholarly journals Antibodies to Streptococcus pneumoniae Capsular Polysaccharide Enhance Pneumococcal Quorum Sensing

mBio ◽  
2011 ◽  
Vol 2 (5) ◽  
Author(s):  
Masahide Yano ◽  
Shruti Gohil ◽  
J. Robert Coleman ◽  
Catherine Manix ◽  
Liise-anne Pirofski
Keyword(s):  
Monoclonal Antibodies ◽  
Streptococcus Pneumoniae ◽  
Quorum Sensing ◽  
Direct Effect ◽  
Pneumococcal Disease ◽  
Effector Cell ◽  
Capsular Polysaccharide ◽  
Genetic Exchange ◽  
Content Type ◽  
Specific Antibodies

ABSTRACTThe use of pneumococcal capsular polysaccharide (PPS)-based vaccines has resulted in a substantial reduction in invasive pneumococcal disease. However, much remains to be learned about vaccine-mediated immunity, as seven-valent PPS-protein conjugate vaccine use in children has been associated with nonvaccine serotype replacement and 23-valent vaccine use in adults has not prevented pneumococcal pneumonia. In this report, we demonstrate that certain PPS-specific monoclonal antibodies (MAbs) enhance the transformation frequency of two differentStreptococcus pneumoniaeserotypes. This phenomenon was mediated by PPS-specific MAbs that agglutinate but do not promote opsonic effector cell killing of the homologous serotypeinvitro. Compared to the autoinducer, competence-stimulating peptide (CSP) alone, transcriptional profiling of pneumococcal gene expression after incubation with CSP and one such MAb to the PPS of serotype 3 revealed changes in the expression of competence (com)-related and bacteriocin-like peptide (blp) genes involved in pneumococcal quorum sensing. This MAb was also found to induce a nearly 2-fold increase in CSP2-mediated bacterial killing or fratricide. These observations reveal a novel, direct effect of PPS-binding MAbs on pneumococcal biology that has important implications for antibody immunity to pneumococcus in the pneumococcal vaccine era. Taken together, our data suggest heretofore unsuspected mechanisms by which PPS-specific antibodies could affect genetic exchange and bacterial viability in the absence of host cells.IMPORTANCECurrent thought holds that pneumococcal capsular polysaccharide (PPS)-binding antibodies protect against pneumococcus by inducing effector cell opsonic killing of the homologous serotype. While such antibodies are an important part of how pneumococcal vaccines protect against pneumococcal disease, PPS-specific antibodies that do not exhibit this activity but are highly protective against pneumococcus in mice have been identified. This article examines the effect of nonopsonic PPS-specific monoclonal antibodies (MAbs) on the biology ofStreptococcus pneumoniae. The results showed that in the presence of a competence-stimulating peptide (CSP), such MAbs increase the frequency of pneumococcal transformation. Further studies with one such MAb showed that it altered the expression of genes involved in quorum sensing and increased competence-induced killing or fratricide. These findings reveal a novel, previously unsuspected mechanism by which certain PPS-specific antibodies exert a direct effect on pneumococcal biology that has broad implications for bacterial clearance, genetic exchange, and antibody immunity to pneumococcus.

scholarly journals A Case for Regular Aflatoxin Monitoring in Peanut Butter in Sub-Saharan Africa: Lessons from a 3-Year Survey in Zambia

2016 ◽  
Vol 79 (5) ◽  
pp. 795-800 ◽  
Author(s):  
SAMUEL M. C. NJOROGE ◽  
LIMBIKANI MATUMBA ◽  
KENNEDY KANENGA ◽  
MOSES SIAMBI ◽  
FARID WALIYAR ◽  
...  
Keyword(s):  
South Africa ◽  
Aflatoxin B1 ◽  
Peanut Butter ◽  
Aflatoxin Contamination ◽  
Comprehensive Analysis ◽  
Sub Saharan Africa ◽  
Enzyme Linked Immunosorbent Assay ◽  
Contamination Level ◽  
Batch Number ◽  
Sub Saharan

ABSTRACT A 3-year comprehensive analysis of aflatoxin contamination in peanut butter was conducted in Zambia, sub-Saharan Africa. The study analyzed 954 containers of 24 local and imported peanut butter brands collected from shops in Chipata, Mambwe, Petauke, Katete, and Nyimba districts and also in Lusaka from 2012 to 2014. For analysis, a sample included six containers of a single brand, from the same processing batch number and the same shop. Each container was quantitatively analyzed for aflatoxin B1 (AFB1) in six replicates by using competitive enzyme-linked immunosorbent assay; thus, aflatoxin contamination level of a given sample was derived from an average of 36 test values. Results showed that 73% of the brands tested in 2012 were contaminated with AFB1 levels &gt;20 μg/kg and ranged up to 130 μg/kg. In 2013, 80% of the brands were contaminated with AFB1 levels &gt;20 μg/kg and ranged up to 10,740 μg/kg. Compared with brand data from 2012 and 2013, fewer brands in 2014, i.e., 53%, had aflatoxin B1 levels &gt;20 μg/kg and ranged up to 1,000 μg/kg. Of the eight brands tested repeatedly across the 3-year period, none consistently averaged ≤20 μg/kg. Our survey clearly demonstrates the regular occurrence of high levels of AF B1 in peanut butter in Zambia. Considering that some of the brands tested originated from neighboring countries such as Malawi, Zimbabwe, and South Africa, the current findings provide a sub-Saharan regional perspective regarding the safety of peanut butter.

Cross-cultural communication imperatives

2018 ◽  
Vol 14 (2/3) ◽  
pp. 170-187 ◽  
Author(s):  
James Baba Abugre
Keyword(s):  
Business Environment ◽  
Cross Cultural ◽  
Sub Saharan Africa ◽  
Work Outcomes ◽  
Cultural Communication ◽  
Global Business ◽  
Content Type ◽  
Local Staff ◽  
Cross Cultural Communication ◽  
Sub Saharan

Purpose Given the rising expansion of Western multinational companies (MNCs) to the African contexts, the development of expatriates and local employees has become increasingly important to the human resource management of these MNCs. This paper aims to provide critical lessons on cross-cultural communication competences for Western expatriates working in the sub-Saharan Africa business environment. Design/methodology/approach This paper is a qualitative phenomenology that makes use of lived experiences of senior expatriate staff working in Ghana in the form of direct interviews. Findings Results showed that cross-cultural communication competence is very important for Western expatriates’ functioning in sub-Saharan Africa. The findings also established a plethora of cross-cultural communication skills that are essential for Western expatriates’ successful adaptation and work outcomes in Africa. Practical implications This research argues that there is the need for the appreciations of the differing cultural patterns of expatriates and local staff, and this provides the underlying assumptions of intercultural and cross-cultural communication in global business. Originality/value A critical perspective of international business that has scarcely been studied offers lessons for Western expatriates working in sub-Saharan Africa.

A comparison of global suicide terrorism by region before and after 9/11 terrorist attacks

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Ahmet Guler ◽  
Mustafa Demir
Keyword(s):  
Time Series ◽  
Interrupted Time Series ◽  
Sub Saharan Africa ◽  
Terrorist Attacks ◽  
Suicide Terrorism ◽  
Content Type ◽  
The World ◽  
Before And After ◽  
Sub Saharan ◽  
Global Terrorism Database

Purpose This study aims to examine the effect of the 9/11 terrorist attacks on suicide terrorism in different regions of the world and changes in the trends in suicide terrorism according to regions before and after 9/11. Design/methodology/approach Using the data obtained from the Global Terrorism Database from 1981 to 2019, the descriptive statistics were computed first and then, independent samples t-tests were run to compare the monthly mean percentage of suicide-terrorism incidents that occurred in each region between the pre-9/11 and the post-9/11 periods. Finally, to statistically assess the effect of the 9/11 attacks and changes in the trends for the dependent variables over time, monthly interrupted time-series analyzes were conducted. Findings The results of monthly interrupted time series analyzes showed that after the 9/11 attacks, the trends for suicide-terrorism rates decreased significantly in three regions including South Asia, the Middle East and North Africa and Europe, while the trend for suicide-terrorism rates increased significantly in Sub-Saharan Africa. However, no statistically significant changes in the trends in suicide-terrorism rates occurred in three regions including North America, East Asia and Central Asia and Southeast Asia before 9/11, during November 2001 or after 9/11. Originality/value This study indicates the critical importance of the 9/11 terrorist attacks in suicide terrorism and its impact on these events in different regions of the world. The research also provides some recommendations concerning the effectiveness of defensive and offensive counterterrorism policies against suicide terrorism.

Factors limiting the adoption of hemp as an alternative sustainable material for green building delivery in Ghana

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Kofi Agyekum ◽  
Emmanuel Adinyira ◽  
James Anthony Oppon
Keyword(s):  
Building Materials ◽  
Green Building ◽  
Sub Saharan Africa ◽  
Content Type ◽  
Sustainable Material ◽  
Environmental Threats ◽  
Additional Information ◽  
Comparative Review ◽  
Sub Saharan ◽  
The Government

PurposeThe increased awareness of global environmental threats like climate change has created an upsurge of interest in low embodied carbon building materials for green building delivery. Though the literature advocates for the use of hemp-based building materials, there is no evidence of studies to explore its potential use in Ghana. Therefore, this study explores the potential factors that limit the adoption of hemp as an alternative sustainable material for green building delivery in Ghana.Design/methodology/approachA structured questionnaire was used to solicit the views of built environment professionals operating in construction, consulting and developer firms. The questions were developed through a comparative review of the related literature and complemented with a pilot review. Data were analysed via descriptive and inferential statistics.FindingsOn the average, the majority of the respondents showed a moderate level of awareness of hemp and its related uses in the construction industry. Also, certain key factors like the perceived association of hemp with marijuana, lack of expertise in the production of hemp-related building materials, farmers not getting the needed clearance for the cultivation of hemp, lack of legislation by the government in the legalisation of hemp and the inadequate knowledge of consumers on the benefits of hemp-based building materials were identified as potential limitations to the adoption of hemp as an alternative sustainable material for green building delivery.Originality/valueThe findings from this study provide insights into a less investigated area in sub-Saharan Africa and further provide new and additional information to the current state-of-the-art on the potential for the use of hemp in the building construction sector.

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