Comparison of biotinylated monoclonal and polyclonal antibodies in an evaluation of a direct rapid immunohistochemical test for the routine diagnosis of rabies in southern Africa

The etiological agent of rabies, rabies virus, is a member of the fatal Lyssavirus genus that accounts for the death of more than 55 000 humans per annum, with the number of infected animals far exceeding that number. The process of post-mortem diagnosis of rabies plays a crucial role in general disease surveillance as well as in the implementing and monitoring of disease control programs in animal populations. Although post mortem diagnostic techniques play a crucial role in impeding disease spread, the routine diagnosis of rabies in resource-limited developing countries remains limited due to a lack of stable infrastructures, power supplies, technical expertise and general resources required to perform the routine gold standard fluorescent antibody test (FAT) diagnosis. Based on the aforementioned facts, the development of diagnostic assays that are suitable for application in the resource-limited developing countries has recently gained a lot of consideration, with numerous novel assays being developed and applied in small-scale investigations. Of all the novel diagnostic assays, the direct rapid immunohistochemical test (dRIT) has, to date, shown the most promise in terms of applicability because of its diagnostic sensitivity and specificity, which has been shown to be equal to that of the FAT in five pilot studies. The main drawback with the current application of the dRIT diagnostic assay is that the Centres for Disease Control and Prevention (CDC) are the only supplier of the required cocktail of two-biotinylated monoclonal antibodies. The singular source of biotinylated antibody thus limits the widespread application of the dRIT diagnostic assay because of the limited availability of the cocktail of biotinylated antibodies. This study endeavoured to ascertain whether an alternative antibody preparation could be biotinylated and applied to the dRIT diagnostic assay in order to act as a routine replacement for the cocktail of biotinylated monoclonal antibodies supplied by the CDC. In order to gain comparative data pertaining to the diagnostic efficacy and versatility of the dRIT diagnostic test relying on the locally produced biotinylated polyclonal antibody, the research involved a multi-faceted investigation. The investigated facets included the comparison of the dRIT test relying on the locally produced biotinylated polyclonal antibody to the FAT test. Apart from the comparison to the gold standard FAT, the three versions of the dRIT test, each relying on one of three-biotinylated antibodies used in the study was performed. The antibodies involved in the comparison included the locally produced biotinylated polyclonal antibody preparation as well as the two-biotinylated monoclonal antibodies (monoclonal antibody 1 and monoclonal antibody 2) that make up the antibody cocktail supplied by the CDC. Apart from the said investigation into the diagnostic efficacy of the dRIT diagnostic assay, the versatility of the given assay was also investigated by adapting the standard operating procedure to accommodate an acetone fixation step. The sample set used for the study included a significant number of central nervous system (CNS) tissues samples (n=250) derived from five of the major mammalian reservoir species in southern Africa as well as a subset of CNS tissue samples derived from mice inoculated with seven representative African rabies-related lyssavirus isolates. The results indicated that the dRIT diagnostic assay, relying on the biotinylated polyclonal antibody preparation, had a diagnostic sensitivity (100%) and specificity (100%) that was marginally higher than that of the widely recognised gold standard FAT diagnostic test that had produced a single false negative result (diagnostic sensitivity of 99,5%) once applied to the known true positive and negative samples included in the study. The dRIT diagnostic test, relying on either of the two-biotinylated monoclonal antibodies, had reduced levels of diagnostic efficacy compared to the FAT assay in terms of the sensitivity of the given assays (monoclonal antibody 1: 83,08% and monoclonal antibody 2: 90,55%) once applied to the known true positive and negative samples included in the study. Monoclonal antibody 2, once applied to the dRIT assay in this study, was the only antibody to produce a single false positive result (diagnostic specificity of 97,96%). The adaptation of the dRIT protocol to include the acetone fixation step had no influence on the diagnostic efficacy of the dRIT test, while the results of the study were indicative of the fact that the dRIT diagnostic assay could be used to detect the viral antigen of all the representative rabies-related viruses, irrespective of the biotinylated antibody used. While the data obtained from the study was used to interpret the diagnostic efficacy of the various biotinylated antibodies applied to the dRIT diagnostic assay, a simulation framework was also developed to analyse the costs involved in performing routine rabies diagnosis with either the FAT or dRIT diagnostic tests in order to broaden the scope of the research. The only cost in the simulation framework that resulted in a significant difference between the two assays was the capital expenditure required to set up a new diagnostic facility, with the costs indicating that five dRIT diagnostic facilities could be established for the price of one FAT diagnostic facility. In summary, the work presented in this study has shown that not only is it indeed possible to apply alternative biotinylated antibody preparations to the dRIT diagnostic assay, but that it is also necessary to optimize the concentration of the biotinylated antibody preparation of the dRIT diagnostic assay before routine application can occur. In the case of this specific study, the dRIT diagnostic assay relying on the biotinylated polyclonal antibody preparation was shown to be an ideal complimentary diagnostic assay to the FAT due to its high diagnostic efficacy, adaptability and calculated costs.Dissertation (MSc)--University of Pretoria, 2013.Microbiology and Plant PathologyMScUnrestricte

Description of Pressure Fluctuations in a Circulating Fluidized Bed by Statistical Analysis

In this paper we evaluate different methods for statistically analyzing the variability in pressure fluctuations measured at three locations in an 80-mm-ID, 5-m-tall CFB model operated with natural rutile particles and air at ambient conditions. The methods evaluated are the Shannon entropy, Fischer information matrix together with kernel density estimation, and an estimation of the magnitude of the pressure amplitudes. The accuracy of the different methods is estimated by the bootstrap method. We illustrate how informative statistics from these methods can be used to quantify the effect of the process variables on fluidization at different bed locations. Depending on the interest of the experimenter, the method and statistic can be selected which explains fluidization operation most accurately

A novel integrated and Labile eHealth system for monitoring dog rabies vaccination campaigns

The elimination of canine rabies through the implementation of high coverage mass dog vaccination campaigns is a complex task, particularly in the resource-limited countries of the rabies endemic world. Here we demonstrated the feasibility of applying targeted rabies vaccination campaigns to deliver more impactful intervention campaigns in resource-limited settings using evidence and lessons learnt from other diseases. With the use of strategic rabies intervention programs, we demonstrate the noteworthy reduction of rabies cases in two very di erent African settings. The strategic intervention was most significantly aided by the use of a custom-developed vaccination tracking device (the Global Alliance for Rabies Control (GARC) Data Logger) and an integrated rabies surveillance system (the Rabies Epidemiological Bulletin). Our first case study, an island-wide strategic dog vaccination on Tanzania’s Unguja island, reduced the incidence of rabies by 71% in the first 16 months of implementation. In the second case study, a similar approach was applied in the metropolitan capital city of Zimbabwe and the incidence of rabies declined by 13% during the first 13 months of implementation. The methodologies and results presented here suggest that, in resource-limited settings, an optimal approach towards the elimination of dog rabies would revolve around strategic interventions, subject to the use of appropriate planning, surveillance, and vaccination tools.World Animal Protection, grant number “WAP/AF/CA/GR/2017-03 and the APC was funded by the Global Alliance for Rabies Control, US.http://www.mdpi.com/journal/vaccinesam2020BiochemistryGeneticsMicrobiology and Plant Patholog

The Pan-African Rabies Control Network (PARACON) : a unified approach to eliminating canine rabies in Africa

Even though Africa has the highest per capita death rate from rabies of any continent, and the disease is almost entirely transmitted by the bites of rabid dogs, there has been no coordinated pan-African approach to controlling canine rabies. In order to attain an inclusive and unified network, the Pan- African Rabies Control Network (PARACON) was established in 2014. By following the ‘One Health’ concept, which involves close coordination between animal and human health sectors across national, regional and continental levels, PARACON will provide a platform to facilitate and promote coordinated and sustainable control strategies and programmes. Meetings will take place at regular intervals and will be centred on the involvement by key focal persons from the medical and veterinary sectors. The inaugural meeting was held in South Africa in June, 2015 and was focused around interactive discussions and workshops, whilst updating country representatives on the tools available to aid them in developing and implementing sustainable rabies intervention strategies. Experts from various global organizations, institutions and industry participated in the discussions and shared their experience and expertise. The workshops focused on the latest format of the Rabies Blueprint platform (www.rabiesblueprint.com), which in the broadest sense assists with control and elimination campaigns, including educational and advocacy drives, improvement of surveillance and diagnosis and the systematic monitoring of progress. Together with the Stepwise Approach towards Rabies Elimination, the Blueprint is a planning tool to help countries free themselves from caninetransmitted rabies.http://www.elsevier.com/locate/antiviral2016-12-31hb2016Microbiology and Plant Patholog

Comparison of biotinylated monoclonal and polyclonal antibodies in an evaluation of a direct rapid immunohistochemical test for the routine diagnosis of rabies in southern Africa

The major etiological agent of rabies, rabies virus (RABV), accounts for tens of thousands of human deaths per annum. The majority of these deaths are associated with rabies cycles in dogs in resource-limited countries of Africa and Asia. Although routine rabies diagnosis plays an integral role in disease surveillance and management, the application of the currently recommended direct fluorescent antibody (DFA) test in countries on the African and Asian continents remains quite limited. A novel diagnostic assay, the direct rapid immunohistochemical test (dRIT), has been reported to have a diagnostic sensitivity and specificity equal to that of the DFA test while offering advantages in cost, time and interpretation. Prior studies used the dRIT utilized monoclonal antibody (MAb) cocktails. The objective of this study was to test the hypothesis that a biotinylated polyclonal antibody (PAb) preparation, applied in the dRIT protocol, would yield equal or improved results compared to the use of dRIT with MAbs. We also wanted to compare the PAb dRIT with the DFA test, utilizing the same PAb preparation with a fluorescent label. The PAb dRIT had a diagnostic sensitivity and specificity of 100%, which was shown to be marginally higher than the diagnostic efficacy observed for the PAb DFA test. The classical dRIT, relying on two-biotinylated MAbs, was applied to the same panel of samples and a reduced diagnostic sensitivity (83.50% and 90.78% respectively) was observed. Antigenic typing of the false negative samples indicated all of these to be mongoose RABV variants. Our results provided evidence that a dRIT with alternative antibody preparations, conjugated to a biotin moiety, has a diagnostic efficacy equal to that of a DFA relying on the same antibody and that the antibody preparation should be optimized for virus variants specific to the geographical area of focus.National Research Foundation (NRF; Grant number: 66187), Poliomyelitis Research Foundation (PRF; Grant number: 12/38 [MSc]) and the European Virus Archive project (EVA; Grant number: 04/17/c215).http://www.plosntds.orghb201

Epidemiology of Rabies in Lesotho : the importance of routine surveillance and virus characterization

Rabies is widespread throughout Africa and Asia, despite the fact that the control and elimination of this disease has been proven to be feasible. Lesotho, a small landlocked country surrounded by South Africa, has been known to be endemic for rabies since the 1980s but the epidemiology of the disease remains poorly understood due to limited sample submission, constrained diagnostic capabilities, and a lack of molecular epidemiological data. Considering the existing challenges experienced in Lesotho, we aimed to evaluate the direct, rapid immunohistochemical test (DRIT) as an alternative to the direct fluorescent antibody (DFA) test for rabies diagnosis in Lesotho. Towards this aim, extensive training on the implementation and interpretation of the DRIT was hosted in Lesotho in April 2016 before both tests were applied to all samples subjected to routine rabies diagnosis at the Central Veterinary Laboratory (CVL). We found agreement between the DFA and DRIT assays in 90/96 samples (93.75%). The samples that produced inconsistent results (n = 6) were re-tested a further two times with both assays before being subjected to a real-time qPCR to confirm the diagnosis. Additionally, a statistically significant three-fold increase in the average number of samples submitted per month was observed after the DRIT implementation started, following continuous rabies awareness initiatives amongst the animal health professionals in the country over a 12-month period (p = 0.0279). Partial G-L intergenic regions of selected rabies-positive samples (n = 21) were amplified, sequenced, and subjected to phylogenetic analyses. Molecular epidemiological analyses, which included viruses from neighbouring provinces in South Africa, suggested that at least three independent rabies cycles within Lesotho were implicated in instances of cross-border transmission. This study has evaluated alternative methods for diagnosing and improving rabies surveillance in Lesotho, as well as providing new information that would be of importance in the planning of future disease intervention campaigns, not only in Lesotho, but also in neighbouring South Africa.Table S1. Panel of rabies viruses from Lesotho and neighbouring South African provinces included in the phylogenetic analysis performed in this study.This work is based on the research supported in part by grants from the World Animal Protection (WAP) (grant number: WAP/AF/IHC/GR/2016-01), the National Research Foundation (NRF) of South Africa (grant number 78566, NRF Research Infrastructure Support Programmes (RISP) grant for the ABI3500), and the Cooperative Agreement Number, [93.318 5 NU2GGH001874-02-00], funded by the Centers for Disease Control and Prevention. Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the Centres for Disease Control and Prevention.http://www.mdpi.com/journal/tropicalmedam2018Forestry and Agricultural Biotechnology Institute (FABI)Medical VirologyMicrobiology and Plant Patholog

Roles of traditional medicine and traditional healers for rabies prevention and potential impacts on post-exposure prophylaxis : a literature review

INTRODUCTION : Globally, traditional medicine is widely used to treat a variety of injuries and illnesses, including dog bites, and exposures that are risky for rabies. However, efficacy of most traditional remedies used for rabies prevention or treatment has not been demonstrated in controlled trials or proven in community-based surveys. METHODS : Six databases were searched including the terms rabies, traditional treatment, traditional remedy, traditional therapy, traditional medicine, and medicinal treatment to review traditional remedies used in the prevention and treatment of rabies. In addition, published literature of rabies transmission dynamics was used to estimate statistical likelihood of dog bite victims developing rabies to provide clarity as to why traditional healers have a high apparent success rate when preventing death from rabies in victims bitten by suspected rabid dogs. RESULTS : Literature review yielded 50 articles, including three controlled experiments, that described use of traditional remedies for rabies prevention and treatment. Traditional remedies for rabies ranged from plant- or animal-based products to spiritual rituals; however, only a few controlled mice trials were conducted, and none of these trials demonstrated efficacy in preventing or treating rabies. Risk of dying from rabies after a bite from a dog with unknown rabies status is low, 1.90% (0.05%-29.60%). Therefore, traditional healers had a 98.10% (70.40%-99.95%) apparent success rate in preventing death from suspected rabid dog bites despite inefficaciousness of herbal remedies. CONCLUSION : There was no universal plant species or route of administration that was consistently used for rabies prevention or treatment across countries. No traditional remedy was efficacious in the prevention or treatment of rabies in randomized controlled experiments. Understanding the cultural context under which traditional remedies are used may facilitate collaboration of traditional healers with the modern medical system to ensure timely and appropriate use of proven therapies for prevention and clinical management of rabies.https://journals.plos.org/plosntdsdm2022BiochemistryGeneticsMicrobiology and Plant Patholog

Enhanced diagnosis of rabies and molecular evidence for the transboundary spread of the disease in Mozambique

Rabies is a neglected zoonotic disease with veterinary and public health significance, particularly in Africa and Asia. The current knowledge of the epidemiology of rabies in Mozambique is limited because of inadequate sample submission, constrained diagnostic capabilities and a lack of molecular epidemiological research. We wanted to consider the direct, rapid immunohistochemical test (DRIT) as an alternative to the direct fluorescent antibody (DFA) for rabies diagnosis at the diagnostic laboratory of the Central Veterinary Laboratory (CVL), Directorate of Animal Science, Maputo, Mozambique. Towards this aim, as a training exercise at the World Organisation for Animal Health (OIE) Rabies Reference Laboratory in South Africa, we performed the DRIT on 29 rabies samples from across Mozambique. With the use of the DRIT, we found 15 of the 29 samples (52%) to be negative. The DRIT-negative samples were retested by DFA at the OIE Rabies Reference Laboratory, as well as with an established real-time Polymerase chain reaction, confirming the DRIT-negative results. The DRIT-positive results (14/29) were retested with the DFA and subsequently amplified, sequenced and subjected to phylogenetic analyses, confirming the presence of rabies RNA. Molecular epidemiological analyses that included viruses from neighbouring countries suggested that rabies cycles within Mozambique might be implicated in multiple instances of cross-border transmission. In this regard, our study has provided new insights that should be helpful in informing the next steps required to better diagnose, control and hopefully eliminate rabies in Mozambique.The National Research Foundation (NRF) of South Africahttp://www.jsava.co.zaam2017Microbiology and Plant Patholog

The use of dog collars offers significant benefits to rabies vaccination campaigns : the case of Zanzibar, Tanzania

SUPPLEMENTARY MATERIAL : FILE S1: Questionnaire used during the KAP survey in Zanzibar. FILE S2: Overview of the vaccination date and survey date for each ward included in the study. FILE S3: Supplementary tables derived from the data collected in this study.DATA AVAILABILITY STATEMENT : The survey data file is available from the Open Science Framework database (https://osf.io/56wkj/) (accessed on 27 July 2023).Tools and resources that could increase dog vaccination coverage have become increasingly critical towards progressing the goal to eliminate dog-mediated human rabies by 2030. In this regard, dog collars that are fitted during vaccination campaigns could potentially enhance owner participation. The use of dog collars will, however, increase the cost per dog vaccinated and the impact and benefit of this practice should be elucidated. This study evaluated the impact of dog collars by testing the perception and related behavioural influences in communities in Zanzibar. In this cross-sectional investigation—conducted approximately two months after the implementation of a mass dog vaccination (MDV) where dog collars were provided to vaccinated dogs—data were collected from 600 respondents in 56 municipal wards in Zanzibar. Descriptive analyses and logistic regressions were undertaken to determine the impact the collars had on respondents with regards to (i) engaging with the community dogs, (ii) health seeking behaviour after exposure, and (iii) overall participation during dog vaccination campaigns. From the data, it was evident that the collars had a positive impact on the community’s perception of dogs, with 57% of the respondents feeling safer around a dog with a collar, while 66% of the respondents felt less safe around a dog without a collar. Furthermore, the collars had a positive impact on participation during dog vaccination campaigns. Of the 142 respondents who owned dogs, 64% reported that the collars made them more likely to take their dogs for vaccination, and 95% felt that the collar was an important sign of the dog’s vaccination status. This study demonstrated that dog collars could not only improve participation during dog vaccination campaigns, but that they could also play a significant role in the community’s perception of rabies vaccination campaigns and vaccinated dogs in general.Boehringer Ingelheim.https://www.mdpi.com/journal/tropicalmedam2023BiochemistryGeneticsMicrobiology and Plant PathologySDG-03:Good heatlh and well-bein

The formation of the Eastern Africa rabies network : a sub-regional approach to rabies elimination

International rabies networks have been formed in many of the canine-rabies endemic regions around the world to create unified and directed regional approaches towards elimination. The aim of the first sub-regional Eastern Africa rabies network meeting, which included Kenya, Ethiopia, Tanzania, Rwanda, and Uganda, was to discuss how individual country strategies could be coordinated to address the unique challenges that are faced within the network. The Stepwise Approach towards Rabies Elimination and the Global Dog Rabies Elimination Pathway tool were used to stimulate discussion and planning to achieve the elimination of canine-mediated human rabies by 2030. Our analysis estimated a total dog population of 18.3 million dogs in the Eastern Africa region. The current dog vaccination coverage was estimated to be approximately 5% (915,000 dogs), with an estimated 4910 vaccinators available. Assuming that every vaccinator performs rabies vaccination, this equated to each vaccinator currently vaccinating 186 dogs per year, whilst the target would be to vaccinate 2609 dogs every year for the community to reach 70% coverage. In order to achieve the World Health Organization-recommended 70% vaccination coverage, an additional 11 million dogs need to be vaccinated each year, pointing to an average annual shortfall of $ 23 million USD in current spending to achieve elimination by 2030 across the region. Improved vaccination efficiency within the region could be achieved by improving logistics and/or incorporating multiple vaccination methods to increase vaccinator efficiency, and could serve to reduce the financial burden associated with rabies elimination. Regional approaches to rabies control are of value, as neighboring countries can share their unique challenges while, at the same time, common approaches can be developed and resource-saving strategies can be implemented.http://www.mdpi.com/journal/tropicalmedam2018Microbiology and Plant Patholog