Antimicrobial activities of essential oils from Southern Africa against selected bacterial and fungal organisms

In the present study, essential oils from four plants including Melissa officinalis, Mentha piperita,  Pelargonium graveolens and Leucosidea sericea, traditionally used to treat infectious diseases were  tested for antimicrobial activity against seven Gram-positive bacteria, eight Gram-negative bacteria and six yeast species (Candida spp. and Cryptococcus neoformans) using the agar diffusion method. The  minimum inhibitory concentrations (MIC) of the oils were determined by the microdilution technique. The killing kinetics of the oils was further evaluated against specific bacterial and fungal organisms. Both  antifungal and antibacterial activities were observed from the essential oil of P. graveolens and M.  peripeta against bacterial and fungal strains tested in the present study with the MIC values ranging from 0.95 to 7.5 mg/ml against the bacterial isolates and 0.24 to 7.50 mg/ml 'against the fungal isolates. The oils of P. graveolens were fungicidal to all the yeast isolates tested in the present study with minimum fungicidal concentration (MFC) values ranging from 0.12 to 7.50 mg/ml while the essential oil from M. piperita was fungicidal to one of the six yeast isolates tested with the smallest MFC of 0.48 mg/ml against Candida tropicalis. Essential oils from P. graveolens were able to kill 90% of the P. aeruginosa cells within three hours. The present study has revealed the antimicrobial activity of P. graveolens and M. piperita and indicated that essential oils are promising sources of natural products with potential antimicrobial activity. These results will guide the selection of some plant species for further pharmacological and phytochemical analysis. These results also support the use of essential oils to treat microbial infections and could be used as pharmaceuticals as well as preservatives in the food industry.Key words: Medicinal plants, essential oils, antibacterial activity, antifungal activity, time-kill activity

Screening for immune biomarkers associated with infection or protection against Ehrlichia ruminantium by RNA-sequencing analysis

DATA AVAILABILITY : The data that has been used is confidential.Heartwater is one of the most economically important tick-borne fatal diseases of livestock. The disease is caused by the bacteria Ehrlichia ruminantium transmitted by Amblyomma ticks. Although there is evidence that interferon-gamma controls E. ruminantium growth and that cellular immune responses are protective, an effective recombinant vaccine for this disease is lacking. Analyses of markers associated with infection as well as protection will lead to a better understanding of the E. ruminantium immune response and corresponding pathways induced in sheep peripheral blood mononuclear cells (PBMC) will assist in development of such a vaccine. In this study, Biomarkers of infection (BMI) were identified as uniquely expressed genes during primary infection and biomarkers of protection (BMP) associated with immune to heartwater were identified post challenge. Sheep were experimentally infected and challenged with E. ruminantium infected ticks. The immune phenotypic and transcriptome profile of their PBMC were compared to their own naïve PBMC collected before infection. The study revealed 305 differentially expressed genes (DEGs) as BMI, of these 17 were upregulated at all three time-points investigated. These DEGs, form part of the bacterial invasion of epithelial cells Kyoto Encyclopaedia of Genes and Genomes (KEGG) pathway, and others detected from day 1 post infection and are considered predictive markers for early heartwater infection in ruminants. Similarly, a total of 332 DEGs were identified as BMP, of these 100 were upregulated and 75 were downregulated at all three time-points investigated. However, at D1PC most DEGs were downregulated (n = 1312) that correlated with a reduction in the % CD4 and CD8 T cells detected with flow cytometry. KEGG pathway analyses showed complete down regulation of T cell specific pathways possibly due to homing of immune cells to the site of infection after acquired immunity developed. At D4PC, expression levels of most of these downregulated genes increased and by D6PC they were upregulated. This indicates that the sampling time-point for biomarker analyses is important when results for acquired immune responses are inferred. This data identified DEGs that could be considered as biomarkers of protective immunity that can be used for identification of vaccine antigens and provides a strong foundation to further development of heartwater recombinant vaccines.The ARC-OVR; Economic Competitiveness Support Programme (ECSP) V0/11 grant and the National Research Foundation (NRF) of South Africa.https://www.elsevier.com/locate/micpathhj2024Veterinary Tropical DiseasesSDG-03:Good heatlh and well-bein

Protection of cattle elicited using a bivalent lumpy skin disease virus-vectored recombinant Rift Valley fever vaccine

Lumpy skin disease and Rift Valley fever are two high-priority livestock diseases which have the potential to spread into previously free regions through animalmovement and/or vectors, as well as intentional release by bioterrorists. Since the distribution range of both diseases is similar in Africa, it makes sense to use a bivalent vaccine to control them. This may lead to the more consistent and sustainable use of vaccination against Rift Valley fever through a more cost-effective vaccine. In this study, a recombinant lumpy skin disease virus was constructed in which the thymidine kinase gene was used as the insertion site for the Gn and Gc protective glycoprotein genes of Rift Valley fever virus using homologous recombination. Selection markers, the enhanced green fluorescent protein and Escherichia coli guanidine phosphoribosyl transferase (gpt), were used for selection of recombinant virus and in amanner enabling a second recombination event to occur upon removal of the gpt selection-pressure allowing the removal of both marker genes in the final product. This recombinant virus, LSD-RVF.mf, was selected to homogeneity, characterized and evaluated in cattle as a vaccine to show protection against both lumpy skin disease and Rift Valley fever in cattle. The results demonstrate that the LSD-RVF.mf is safe, immunogenic and can protect cattle against both diseases.This work was generously supported by the GALVmed organization (recombinant virus construction, selection, and characterization) (under grant no. 710/CAP/07/003) and the Canadian International Development Research Centre in collaboration with Global Affairs Canada, within the Canadian International Food Security Research Fund (CIFSRF) Grant no. 107848-002 (cattle trial). IDRC have also kindly agreed to pay the APF.https://www.frontiersin.org/journals/veterinary-science#am2020Veterinary Tropical Disease

The application of omics in ruminant production: a review in the tropical and sub-tropical animal production context

The demand for animal products (e.g. dairy and beef) in tropical regions is expected to increase in parallel with the public demand for sustainable practices, due to factors such as population growth and climate change. The necessity to increase animal production output must be achieved with better management and production technologies. For this to happen, novel research methodologies, animal selection and postgenomic tools play a pivotal role. Indeed, improving breeder selection programs, the quality of meat and dairy products as well as animal health will contribute to higher sustainability and productivity. This would surely benefit regions where resource quality and quantity are increasingly unstable, and research is still very incipient, which is the case of many regions in the tropics. The purpose of this review is to demonstrate how omics-based approaches play a major role in animal science, particularly concerning ruminant production systems and research associated to the tropics and developing countriesinfo:eu-repo/semantics/acceptedVersio