A rational approach for predicting the minimum composition of anti-parasite sub-unit vaccines: a multiple target vaccine hypothesis

The present article introduces a new concept, termed a multiple vaccine target hypothesis (MVTH) for determining the minimum number of vaccine targets (epitopes/antigens) necessary to construct a highly efficacious (greater than 90%) anti-parasite vaccine. Drawing inspiration from the Metabolic Control Analysis (MCA) and immunological reasoning it is proposed that for a multi-stage parasite an effective anti-parasite vaccine will necessarily act on more than one stage of the parasite in the definitive host. It is argued that the minimum number of sub-unit targets for a highly efficacious anti-parasite vaccine will vary from one parasite to the other and will be equal to twice the number of major parasite stages occurring in the human host. Quantitatively stated, Cv=2n where Cv the number of required targets is, and n represents the number of major parasite stages in the definitive host. Conditions when the value of Cv may deviate from what is predicted by the formula given above are discussed. Extensive literature search on malaria, onchocerciasis and schistosomiasis sub-unit vaccine development suggests that subunit vaccines constructed from single components and directed to just one parasite stage are less efficacious that multivariate sub-unit vaccines, and obviously whole parasite vaccines. MVTH therefore provides a rational framework for constituting a sub-unit anti-parasite vaccine.Keywords: Vaccine, malaria, Onchocerca volvulus, schistosomiasis, parasite, equatio

Analysis of the Role of TpUB05 Antigen from Theileria parva in Immune Responses to Malaria in Humans Compared to Its Homologue in Plasmodium falciparum the UB05 Antigen

Despite the amount of resources deployed and the technological advancements in molecular biology, vaccinology, immunology, genetics, and biotechnology, there are still no effective vaccines against malaria. Immunity to malaria is usually seen to be species- and/or strain-specific. However, there is a growing body of evidence suggesting the possibility of the existence of cross-strain, cross-species, and cross-genus immune responses in apicomplexans. The principle of gene conservation indicates that homologues play a similar role in closely related organisms. The homologue of UB05 in Theileria parva is TpUB05 (XP_763711.1), which has been tested and shown to be associated with protective immunity in East Coast fever. In a bid to identify potent markers of protective immunity to aid malaria vaccine development, TpUB05 was tested in malaria caused by Plasmodium falciparum. It was observed that TpUB05 was better at detecting antigen-specific antibodies in plasma compared to UB05 when tested by ELISA. The total IgG raised against TpUB05 was able to block parasitic growth in vitro more effectively than that raised against UB05. However, there was no significant difference between the two study antigens in recalling peripheral blood mononuclear cell (PBMC) memory through IFN-γ production. This study suggests, for the first time, that TpUB05 from T. parva cross-reacts with UB05 from P. falciparum and is a marker of protective immunity in malaria. Hence, TpUB05 should be considered for possible development as a potential subunit vaccine candidate against malaria

Comparative performance evaluation of blood film microscopy for the diagnosis of bovine trypanosomosis by some laboratories in North-central Nigeria

Background: Due to its affordability in disease-affected communities and suitability for field application, microscopy has historically been considered the gold standard for field diagnosis of trypanosomosis in rural settings. Aim: This works aims to compare the performance of microscopists on bovine trypanosome microscopy by organizing the first comparative assessment on a correct reading of slides by laboratory professionals using the read slide results and a structured interviewer-administered questionnaire in North-central Nigeria. Methods: Ten participants were addressed, as they were sent a panel of two slides (Slide 1: No Trypanosome present; Slide 2: Trypanosome present) and a questionnaire. Results: All participants greater than 41 years old reported correctly the presence and absence of parasites on slides. Only 3/8 of microscopists from routine diagnostic laboratories reported correctly the presence of the parasite. Conclusion: Our study confirmed errors in reading slides. Therefore, training of microscopists besides a nationwide quality assessment is recommended

Commentary on COVID-19 Vaccine Hesitancy in sub-Saharan Africa

This research was funded in part by the Bill and Melinda Gates Foundation (Grant number: OPP1075938-PEARL Program Support) awarded to Jerome Nyhalah Dinga.Peer reviewedPublisher PD

Assessment of Vaccine Hesitancy to a COVID-19 Vaccine in Cameroonian Adults and Its Global Implication

Since the outbreak of COVID-19 in December 2019, no global consensus treatment has been developed and generally accepted for the disease. However, eradicating the disease will require a safe and efficacious vaccine. In order to prepare for the eventual development of a safe and efficacious COVID-19 vaccine and to enhance its uptake, it is imperative to assess vaccine hesitancy in Cameroonians. After obtaining ethical clearance from the Institutional Review Board of the University of Buea, a questionnaire was administered (May–August 2020) to consenting adults either online or in person. A qualitative thematic analysis was done to analyze the participants’ answers to the open questions. A deductive approach was used, that is, the codes and patterns according to the World Health Organization (WHO) Strategic Advisory Group of Experts (SAGE) Working Group Matrix of Determinants of vaccine hesitancy. The number of consenting adult Cameroonians who completed the questionnaire were 2512 (Two thousand five hundred and twelve). Vaccine hesitancy to a COVID-19 vaccine was 84.6% in Cameroonians. Using the WHO recommended Matrix of Determinant of Vaccine hesitancy, the most prominent determinants observed in this study were: Communication and Media Environment, Perception of pharmaceutical industry, Reliability and/or source of vaccine and cost. Most Cameroonians agree that even though there are benefits of a clinical trial, they will prefer it should be done out of the continent and involving African scientists for eventual acceptance and uptake. The concerns of safety, efficacy and confidence has to be addressed using a Public Engagement approach if a COVID-19 vaccine has to be administered successfully in Africa or Cameroon specifically. Since this study was carried out following WHO standards, its result can be compared to those of other studies carried out in different cultural settings using similar standards

Factors Driving COVID-19 Vaccine Hesitancy in Cameroon and Their Implications for Africa: A Comparison of Two Cross-Sectional Studies Conducted 19 Months Apart in 2020 and 2022

Many efficacious COVID-19 vaccines have been approved for general use but their ability to control the disease is being undermined by slow uptake. Resources are needed to persuade people to obtain a COVID-19 vaccine. Here we compare this present study and a previous one to assess the impact of the Cameroon government’s policy and efforts to reduce COVID-19 vaccine hesitancy after one year of implementation. After obtaining ethical clearance and informed consent, 6732 participants completed a questionnaire about COVID-19 vaccine hesitancy and acceptance. It was observed that the government’s policies and efforts reduced COVID-19 vaccine hesitancy significantly, but this was not enough to ensure the herd immunity necessary to control the disease. The risk factors associated with vaccine hesitancy were the consumption of traditional herbal remedies; living in an urban setting; being female, jobless or a student; working in the education sector; being a politician/policy maker/administrator, engineer or technician; medium income; no education/primary school/secondary/high school/professional training; and working in the informal sector. In contrast, people who were male, healthcare personnel, high-income earners, participants who do not consume traditional herbal remedies, infected or knowing someone who has been infected by COVID-19, and having a chronic illness or comorbidity, were associated with COVID-19 vaccine acceptance. Participants also gave several reasons they were either hesitant or willing to take the vaccine. A more rigorous surveillance system is needed to systematically monitor drivers of vaccine hesitancy, establish tailored interventions promoting vaccine acceptance, and evaluate the impact of these interventions

Antimicrobial Activities of a Plethora of Medicinal Plant Extracts and Hydrolates against Human Pathogens and Their Potential to Reverse Antibiotic Resistance

Microbial infections till date remain a scourge of humanity due to lack of vaccine against some infections, emergence of drug resistant phenotypes, and the resurgence of infections amongst others. Continuous quest for novel therapeutic approaches remains imperative. Here we (i) assessed the effects of extracts/hydrolates of some medicinal plants on pathogenic microorganisms and (ii) evaluated the inhibitory potential of the most active ones in combination with antibiotics. Extract E03 had the highest DZI (25 mm). Extracts E05 and E06 were active against all microorganisms tested. The MICs and MBCs of the methanol extracts ranged from 16.667 × 103 μg/mL to 2 μg/mL and hydrolates from 0.028 to 333333 ppm. Extract E30 had the highest activity especially against S. saprophyticus (MIC of 6 ppm) and E. coli (MIC of 17 ppm). Combination with conventional antibiotics was shown to overcome resistance especially with E30. Analyses of the extracts revealed the presence of alkaloids, flavonoids, triterpenes, steroids, phenols, and saponins. These results justify the use of these plants in traditional medicine and the practice of supplementing decoctions/concoctions with conventional antibiotics. Nauclea pobeguinii (E30), the most active and synergistic of all these extracts, and some hydrolates with antimicrobial activity need further exploration for the development of novel antimicrobials

African Vaccinology Network (AfVANET) : an African network by African scientists

We write to introduce the African Vaccinology Network (AfVANET) as a new network of African research scientists involved in vaccine research and development (R&D) for human and animal diseases. The goal of this network is to promote and build capacity for early phase vaccine R&D in Africa in order to stimulate the development of innovative solutions to combat diseases that affect the continent. This will be achieved by bringing together different stakeholders in vaccinology and related sciences in Africa to identify and prioritise gaps in vaccine development for both human and animal diseases and to promote sound ethics, biosafety, biosecurity and animal welfare practices, facilitate the mobility of students and early career researcher between research institutions and universities in Africa through south-south collaborations and address the gender imbalance in the scientific workforce. The African continent has for decades suffered the social and economic consequences of several infectious diseases. Examples include the recent spate of infectious disease outbreaks as seen with the Ebola outbreak in the Democratic Republic of Congo (DRC) [1], Lassa fever in Nigeria and Liberia [2,3], cholera in some parts of Nigeria [4], yellow fever in Angola, the DRC, South Sudan and Nigeria [5-7] and measles and Rift Valley fever in some African countries [8,9]. In addition, there are continual loses in livestock productivity due to, e.g. African trypanosomiasis, ticks and tick-borne diseases and lack of access to global markets due to the presence of trans-boundary diseases such as contagious bovine pleuropneumonia, foot-andmouth disease and African swine fever. Hence, there is an urgent need for a sound framework for R&D towards developing novel and effective vaccines for human and animal diseases.The International Veterinary Vaccinology Network (IVVN) and the Bill and Melinda Gates Foundation.http://www.panafrican-med-journal.comam2021Production Animal Studie

ELISpot assay to assess subset of PBMCs stimulated by TpUB05 to produce interferon-gamma.

<p>CD4+ and CD8+ T-cells were separated from three (3) animals and stimulated with r-TpUB05 using bovine ELISpot assay. The CD4+ subpopulations of BH055 and BA219 appear to be significantly stimulated by TpUB05 (<i>p</i> = 0.013) compared to their CD8+ subpopulations. The CD4+ T-cells of BB007 did not significantly produce a higher amount of IFN-γ compared to its CD8+ T-cells subset. Comparing the response of all three animals tested, CD4+ T-cells produced a higher amount of IFN-γ (<i>p</i> = 0.046) compared to the CD8+ T-cells. An SI>2 is considered positive. The experiment was run in triplicates.</p