Tackling protozoan parasites of cattle in sub-Saharan Africa

Structural and Kinetic Profiling of Leishmania braziliensis Trypanothione Reductase: A Molecular Model for the Development of Targeted Therapies

This study explores the recombinant protein expression, purification, and characterization of Leishmania braziliensis Trypanothione Reductase (LbTR), an essential enzyme implicated in cutaneous leishmaniasis. Using E. coli as the host organism, the synthetic gene encoding LbTR was successfully expressed and subsequently purified using Immobilized Metal Affinity Chromatography (IMAC) yielding 20 mg/L of highly pure LbTR, verified by SDS-PAGE and isoelectric focusing. Comprehensive biochemical analyses were conducted to determine the recombinant enzyme's kinetic properties and structural features. Enzymatic assays revealed that LbTR efficiently reduces its natural substrate, following Michaelis-Menten kinetics. Structural characterization, including dynamic light scattering and fluorescence spectroscopy, confirmed the protein's stability and homogeneity in solution under varying temperatures. Circular dichroism analysis corroborated the presence of significant α-helical and β-sheet content, aligning with the structural model generated with AlphaFold. Molecular dynamics simulations over one microsecond were employed to investigate the conformational dynamics of LbTR in its native homodimeric form, complexed with essential cofactors and substrates. The results from these simulations offer valuable insights into the enzyme's structural behavior and catalytic mechanism, underscoring its potential as a target for therapeutic development against leishmaniasis.

Comparative efficacy of imidocarb dipropionate with additive in naturally infected cattle against bovine babesiosis

Babesiosis is a tick borne disease prevalent worldwide. The present study was planned to evaluate the therapeutic efficacy of imidocarb dipropionate alone and with additive milk, cumin, and jetepar syrup in naturally Babesia-infected cattle. Blood samples (n = 300) were collected from the selected cattle. Age, breed, dung pile location, use of acaricides, temperature, health status, tick infestation and housing type were also considered during sample collection. Out of 90 samples that were found positive through staining procedures, 45 were confirmed through PCR. As per infection rate observed more in exotic breed, the treatment trials were conducted on these cattle. These cattle were divided into three groups, each consisting of 15 cattle. Group 1 was treated with imidocarb dipropionate. Group 2 was treated with imidocarb dipropionate and additives (milk, cumin, and jetepar syrup). Group 3 was the infected, non-medicated group, and group 4 consisted of healthy, non-infected cattle (n = 15).The cattle were subjected to liver function tests and recorded milk production before and after treatment. The afore-mentioned factorsi.e. age (<3 years), Holstein Friesian breed, with dung piles near their living area, without acaricides use, poor health status, tick infestation, and tethered housing system were found significant associated with babesiosis in the cattle. Cattle in G1 treated with imidocarb dipropionate showed an efficacy of 60 %. G2, on the other hand, showed 90 % efficacy. The cattle in G3, did not recover and two died. All cattle in G4, remained health. It was concluded that the cattle treated with imidiocarb dipropionate as well as additives showed better and rapid recovery.

A step forward to revolutionize the eimeriosis controlling strategies in cattle by using traditional medication

More than 10 species of Eimeria is found in cattle but Eimeria zuernii is one of the most pathogenic protozoan parasites affecting the global livestock industry. At the herd level, E. zuernii can cause illness in 10-80% of animals and reduce gross margins by 8-9%, leading to estimated annual losses of $731 million. This review highlights the economic impact, prevalence, and current control methods for E. zuernii infections, as well as the challenges associated with treatment and the development of alternative control methods. In the past two decades, 22 studies have examined synthetic drugs for managing eimeriosis in cattle. Various anticoccidial drugs (AcDs; Amprolium, decoquinate, ionophores, monensin, lasalocid, toltrazuril etc) have been used, but the efficacy of these drugs is no more consistent. Because of this, E. zuernii develops resistance to some of these anticoccidials. This trend highlights the urgent need for alternative treatments. The medicinal plants being enriched with various phytochemicals like flavonoids, tannins, alkaloids, terpenes etc have been reported as potential anticoccidial, anthelmintic and antimicrobial efficacy against the different parasites including Eimeria species in chicken, pig and rabbits. However, this review suggests the research community to treat the E. zuernii with a plant based medication (oils and extracts). This review critically emphasizes the need to acknowledge the significant role of medicinal plants in controlling eimeriosis and also the large-scale trials or standardization of plant-based therapies is required. By incorporating plant-based remedies into integrated treatment strategies alongside synthetic drugs and improved sanitation practices, we can effectively minimize financial losses and safeguard livestock health.

Multiplex reverse transcription recombinase polymerase amplification combined with lateral flow biosensor for simultaneous detection of three viral pathogens in cattle

Bovine viral diarrhea virus (BVDV), bovine epidemic fever virus (BEFV), and bovine respiratory syncytial virus (BRSV) cause respiratory symptoms in cattle. The absence of rapid, precise, and easily accessible diagnostic methods poses difficulties for herders and veterinary epidemiologists during outbreaks of major infectious animal diseases. Considering the mixed infection of viruses, a multiple-detection method, reverse transcription recombinase polymerase amplification (mRT-RPA) combined with a lateral flow biosensor (LFB), was established to simultaneously detect the three pathogens. This technique is based on the specific binding of three differently labeled RT-RPA products (DNA sequences) to antibodies on the three test lines of the LFB, achieving multiplex detection through the presence or absence of coloration on the LFB test lines. The fluorescence values of the LFB test lines are recorded by a test strip reader. The mRT-RPA-LFB assay completes detection at a constant temperature of 41 °C within 33 min. The limits of detection (LODs) for BVDV, BEFV and BRSV were 2.62 × 101, 2.42 × 101 and 2.56 × 101 copies/μL, respectively. No cross-reactivity was observed with the other six bovine viruses. The developed method showed satisfactory intra- and inter-assay precision, and the average coefficients of variation were ranged from 2.92 % to 3.99 %. The diagnostic sensitivity and specificity were 98.11 % and 100 %, respectively, which were highly consistent with the RT-qPCR assay, and the kappa value was 0.988 (95 % confidence interval, CI). In general, the mRT-RPA-LFB assay has the potential to become a powerful tool for rapid screening of cattle diseases because of its advantages such as fast detection speed, convenient operation, strong specificity, and high sensitivity.

Genome-wide local ancestry and the functional consequences of admixture in African and European cattle populations

Bos taurus (taurine) and Bos indicus (indicine) cattle diverged at least 150,000 years ago and, since that time, substantial genomic differences have evolved between the two lineages. During the last two millennia, genetic exchange in Africa has resulted in a complex tapestry of taurine-indicine ancestry, with most cattle populations exhibiting varying levels of admixture. Similarly, there are several Southern European cattle populations that also show evidence for historical gene flow from indicine cattle, the highest levels of which are found in the Central Italian White breeds. Here we use two different software tools (MOSAIC and ELAI) for local ancestry inference (LAI) with genome-wide high- and low-density SNP array data sets in hybrid African and residually admixed Southern European cattle populations and obtained broadly similar results despite critical differences in the two LAI methodologies used. Our analyses identified genomic regions with elevated levels of retained or introgressed ancestry from the African taurine, European taurine, and Asian indicine lineages. Functional enrichment of genes underlying these ancestry peaks highlighted biological processes relating to immunobiology and olfaction, some of which may relate to differing susceptibilities to infectious diseases, including bovine tuberculosis, East Coast fever, and tropical theileriosis. Notably, for retained African taurine ancestry in admixed trypanotolerant cattle we observed enrichment of genes associated with haemoglobin and oxygen transport. This may reflect positive selection of genomic variants that enhance control of severe anaemia, a debilitating feature of trypanosomiasis disease, which severely constrains cattle agriculture across much of sub-Saharan Africa.

Apical annuli are specialised sites of post-invasion secretion of dense granules in Toxoplasma

Apicomplexans are ubiquitous intracellular parasites of animals. These parasites use a programmed sequence of secretory events to find, invade, and then re-engineer their host cells to enable parasite growth and proliferation. The secretory organelles micronemes and rhoptries mediate the first steps of invasion. Both secrete their contents through the apical complex which provides an apical opening in the parasite's elaborate inner membrane complex (IMC) - an extensive subpellicular system of flattened membrane cisternae and proteinaceous meshwork that otherwise limits access of the cytoplasm to the plasma membrane for material exchange with the cell exterior. After invasion, a second secretion programme drives host cell remodelling and occurs from dense granules. The site(s) of dense granule exocytosis, however, has been unknown. In Toxoplasma gondii, small subapical annular structures that are embedded in the IMC have been observed, but the role or significance of these apical annuli to plasma membrane function has also been unknown. Here, we determined that integral membrane proteins of the plasma membrane occur specifically at these apical annular sites, that these proteins include SNARE proteins, and that the apical annuli are sites of vesicle fusion and exocytosis. Specifically, we show that dense granules require these structures for the secretion of their cargo proteins. When secretion is perturbed at the apical annuli, parasite growth is strongly impaired. The apical annuli, therefore, represent a second type of IMC-embedded structure to the apical complex that is specialised for protein secretion, and reveal that in Toxoplasma there is a physical separation of the processes of pre- and post-invasion secretion that mediate host-parasite interactions.

Eukaryotic Infections in Dairy Calves: Impacts, Diagnosis, and Strategies for Prevention and Control

Eukaryotic infections are common among dairy calves and can have significant impacts on their health and growth rates. Fungal infections caused by Aspergillus fumigatus, Trichophyton verrucosum, and Candida albicans can cause respiratory diseases, dermatophytosis, and diarrhea, respectively. Protozoan parasites, including Cryptosporidium parvum, Giardia duodenalis, and Eimeria spp., are also common in dairy calves. C. parvum is highly contagious and can cause severe diarrhea and dehydration, while Giardia duodenalis can lead to poor growth and is transmissible to humans through contaminated food or water. Eimeria spp. can cause coccidiosis and lead to reduced growth rates, poor feed conversion, and death. The common helminthic infections in dairy calves include Ostertagia ostertagi, Cooperia spp., Fasciola hepatica, and Strongyloides papillosus. These parasitic infections significantly impact calf health, growth, and dairy industry productivity. Diagnosis of these infections can be made through fecal samples using microscopy or molecular methods. However, diagnosis of the infections can be challenging and requires a combination of clinical signs and laboratory tests such as culture and PCR. Preventing and controlling eukaryotic infections in dairy calves requires several measures. Good hygiene and sanitation practices, proper management strategies, and timely treatment of affected animals are important. It is also necessary to avoid overcrowding and consider vaccination against ringworm. Further research is needed to better understand the epidemiology and characterization of eukaryotic infections in dairy calves, which will help in the development of more effective prevention and control strategies. In general, good hygiene practices, appropriate management strategies, and timely treatment of affected animals are crucial in preventing and controlling the infections, ensuring the health and well-being of dairy calves.

Epidemiology of free-living amoebae infections in Africa: a review

FLA-related conditions are a rare medical occurrence. Despite their rarity, they are considered a public health concern for two reasons: the absence of a regular treatment regimen in the case of central nervous system infections and the fast progression of the symptoms leading to fatal outcomes. A total of 358 articles were retrieved from different databases (91 from PubMed, 26 from NCBI, 138 from Academia, 102 from Science Direct, and one from IJMED). 7 (46.6%) clinical cases came from Egypt, 2 (13.3%) cases of FLA infection came from Nigeria, 3 (20%) cases came from the Gambia, and 1 (6.6%) case was reported from African countries like Algeria, Tunisia, South Africa, and Zambia. Medical conditions caused by free-living amoeba are considered significant public health concerns. These ubiquitous organisms can cause both fatal and debilitating health conditions. Immediate diagnosis of cases and proper hygienic practices are necessary to provide direct medical intervention. They may be the key to reducing the morbidity and mortality rates from FLA-acquired infections. Although several government-led initiatives have been implemented to mitigate a plethora of parasitic diseases, the case of FLA-related conditions in African countries has yet to be realized.

Stable endocytic structures navigate the complex pellicle of apicomplexan parasites

Apicomplexan parasites have immense impacts on humanity, but their basic cellular processes are often poorly understood. Where endocytosis occurs in these cells, how conserved this process is with other eukaryotes, and what the functions of endocytosis are across this phylum are major unanswered questions. Using the apicomplexan model Toxoplasma, we identified the molecular composition and behavior of unusual, fixed endocytic structures. Here, stable complexes of endocytic proteins differ markedly from the dynamic assembly/disassembly of these machineries in other eukaryotes. We identify that these endocytic structures correspond to the 'micropore' that has been observed throughout the Apicomplexa. Moreover, conserved molecular adaptation of this structure is seen in apicomplexans including the kelch-domain protein K13 that is central to malarial drug-resistance. We determine that a dominant function of endocytosis in Toxoplasma is plasma membrane homeostasis, rather than parasite nutrition, and that these specialized endocytic structures originated early in infrakingdom Alveolata likely in response to the complex cell pellicle that defines this medically and ecologically important ancient eukaryotic lineage.

Nisbet R. In silico identification of Theileria parva surface proteins

East Coast Fever is a devastating African cattle disease caused by the apicomplexan parasite, Theileria parva. Little is known about the cell surface, and few proteins have been identified. Here, we take an in silico approach to identify novel cell surface proteins, and predict the structure of four key proteins.