Baraa Falemban

Taenia hydatigena is a widely distributed taeniid tapeworm of veterinary significance that circulates in transmission cycles among canid definitive hosts and various domestic and wild ungulates. Mitochondrial studies have shown significant genetic variation within this species; however, the geographical and host restrictions of these mitochondrial lineages are not yet fully understood. In this study, we analyzed the global mitochondrial diversity and phylogeographic distribution of T. hydatigena lineages in geographic and host groups based on a cytochrome c oxidase subunit 1 (cox1) sequence dataset obtained from the GenBank database. A total of 406 sequences were assembled, and were used for the population genetic analyses. Mitochondrial diversity and lineage distribution were characterized using haplotype and nucleotide diversity, neutrality statistics, country- and host-associated variation, median-joining networks, and maximum-likelihood phylogenetic reconstruction. The global dataset included 123 haplotypes, with high levels of haplotype diversity (Hd = 0.897) and comparatively low levels of nucleotide diversity (π = 0.00898). Haplotype frequencies were highly skewed, with 79 of them represented by a single sequence, whereas the most common haplotype, Hap-3, contained 124 sequences. Country-based analyses showed significant mitochondrial diversity, as well as geographically widespread and geographically restricted haplotypes, but no country-specific clustering pattern. There were eight different host categories for 364 sequences for which host information was available, and the haplotype diversity (Hd) was high (0.907), whereas the nucleotide diversity (π) was low (0.00926). Major haplotypes were common among several host species, especially sheep and goats, and mitochondrial variants within major haplotypes were shared with dogs and other wild animals. The maximum-likelihood phylogeny identified a monophyletic group of T. hydatigena and showed high levels of intraspecific mitochondrial variation but no obvious geographical structure in the largest mitochondrial subclades. All Tajima’s D, Fu’s Fs, Fu and Li’s D, and Fu and Li’s F statistics were negative for the pooled dataset. These are results that show a departure from the expectations of neutral models, but should not be interpreted as evidence for demographic expansion, as they represent a mixture of geographically and biologically heterogeneous GenBank records with unequal sampling and potentially non-independent sequences. In conclusion, the available GenBank data indicated a high mitochondrial haplotype richness, as well as the presence of widespread and geographically restricted cox1 haplotypes and haplotype sharing between recorded host and geographic categories. Unbalanced host and country representation, possible non-independence of sequence records, and host and geographic origin are each potential sources of confounding that reduce the power to make inferences concerning population connectivity and host-associated structure. These results offer a comparative model to understand the distribution of mitochondrial variation in T. hydatigena and point to the need for a sampling methodology that is both geographically distributed and standardized, as well as longer mitochondrial and nuclear sequence data, for sympatric hosts.

Surra, a wasting disease caused by Trypanosoma evansi, is one of the major animal health burdens in camel-rearing countries, imposing significant economic losses due to reduced fertility and high mortality rates. The present study used inactivated T. evansi (from the Card Agglutination Test for Trypanosomes/Trypanosoma evansi; CATT/T. evansi) and flow cytometry to investigate their binding and activation potential toward camel leukocyte subsets. Labeling T. evansi with propidium iodide (PI) enabled their flow cytometric enumeration and identification with forward scatter (FSC; indicative for cell size) and side scatter (SSC; indicative for cell internal complexity) characteristics that are comparable with values reported for Trypanosoma cruzi. The incubation of PI-labeled non-opsonized T. evansi with camel leukocyte populations revealed that camel monocytes have the highest potential to bind T. evansi, followed by granulocytes and lymphocytes. The identification of pattern recognition receptors (PRRs) on camel immune cells and the pathogen-associated molecular patterns (PAMPs) in T. evansi that are responsible for this different binding capacity requires further studies. Stimulation of camel neutrophils with Trypanosoma evansi induced shape change, reactive oxygen species (ROS) production, and neutrophil extracellular traps (NET)-formation. To ensure that T. evansi, in the parasite concentration used in this study, is not apoptotic or necrotic to camel leukocytes, we evaluated cell apoptosis and necrosis after stimulation with T. evansi. The results revealed no impact of T. evansi stimulation for 2 h on the cell viability of camel leukocytes. Subsequent work may focus on the diagnostic employment of labeled T. evansi and flow cytometry for the detection of anti-Trypanosoma antibodies in camel serum. In addition, more efforts should be deployed to investigate the host–pathogen interaction mechanisms and the escape mechanisms of T. evansi in camels. To complete these data, further studies using the living or freshly killed parasites could also be implemented in camels and/or horses.

Background and Aim: Avian viral diseases usually cause high economic losses because of high morbidity and mortality and poor growth. The rearing of chickens in backyards could have an important role in the spread of certain diseases, particularly those of viral origin. Infected birds might be prone to many viral infections for several reasons, including a lack of vaccination programs, the mixing of different bird species in the same location, and the close interactions of these birds with wild and migratory birds carrying various pathogens. This study aimed to conduct serological surveillance of avian encephalomyelitis virus (AEV) in some backyard chickens in the eastern region of Saudi Arabia. Materials and Methods: Serum samples (n = 368) were collected from domestic chickens reared in 10 backyards in the Eastern Province of Saudi Arabia. None of the domestic birds in these 10 backyards were vaccinated against the virus. In addition, 78 serum samples were collected from free-ranging birds belonging to Columbidae, such as pigeons and doves, in common areas near the domestic backyards. We tested these sera for specific antibodies against AEV. Results: Our results revealed seroconversion to AEV among the examined chickens (14.6%). None of the tested pigeons and doves displayed seroconversion to AEV. Conclusion: Seroconversion of these non-vaccinated birds against AEV was suggestive of a recent natural infection by this virus. Further studies with a large number of birds are required to molecularly characterize the circulating strains of this virus in this area. Keywords: antibody, avian encephalomyelitis virus, backyard, chicken, encephalomyelitis virus, enzyme-linked immunosorbent assay, seroprevalence, the prevalence, wild birds.

Background and Aim: Avian metapneumovirus (aMPV) is a recently discovered respiratory virus in chickens. Avian metapneumovirus has been linked to respiratory syndromes, reproductive failure in affected chickens and turkeys, swollen head syndrome in chickens, and rhinotracheitis in turkeys. Wild birds are considered potential reservoirs of aMPV, particularly aMPV-C. However, little is known about the prevalence of aMPV in Saudi Arabia. Considering the relevance of backyard chickens in the transmission and sustainability of certain avian viral diseases, this study aimed to assess aMPV exposure in backyard chickens and wild birds circulating near selected locations. Materials and Methods: We collected 368 serum samples from unvaccinated backyard chickens in ten locations in Eastern Saudi Arabia. Furthermore, we collected 78 serum samples from species of free-ranging birds belonging to the Columbidae family, such as pigeons and doves, captured from the same areas. Using commercial enzyme-linked immunosorbent assay kits, we tested the sera of domestic backyard chickens and wild birds for antibodies against aMPV. Results: Our results showed that 74/368 birds were positive for aMPV-related antibodies. Conversely, none of the tested wild birds seroconverted to aMPV. Conclusion: The antibody titers detected in the backyard chickens suggested recent exposure to aMPV. Considering these results, further large-scale serological and molecular studies are needed to evaluate the prevalence of aMPV in these birds and characterize the circulating strains of aMPV in this region. Keywords: antibodies, chickens, pigeons, Saudi Arabia.

Neutrophilic granulocytes are vital immune cells of the early response to pathogens. They contribute to the antimicrobial response through phagocytosis, production of reactive oxygen species, cytokine production, degranulation, and NET-formation. Neutrophil extracellular traps (NETs), also known as NETosis, are a critical antibacterial effector mechanism of cells of myeloid effector cells, including neutrophils and macrophages. Toll-like receptors (TLRs) are pattern recognition receptors (PRRs) that mediate pathogen sensing through the recognition of microbial structures known as pathogen-associated molecular patterns (PAMPs). The present study aimed to investigate the potential of several TLR ligands that mimic the sensing of bacterial and viral pathogens to stimulate NET-formation or Ca2+ influx in camel neutrophils. Neutrophils were purified from blood and were stimulated in vitro with ligands to TLR4, TLR2/1, TLR7/8, or TLR3. Net-formation was analyzed using the DNA-sensitive dye SYTOX™ Green and staining with antibodies to the neutrophil's granular enzyme myeloperoxidase. Real-time stimulation-induced Ca2+ influx was measured using the Ca2+-sensitive dye Flou-4 and flow cytometry. Only the TLR4-ligand lipopolysaccharide (LPS) could induce NET-formation in camel neutrophils, while none of the investigated TLR agonists showed a Ca2+ influx-inducing effect in camel neutrophils. The current study represents the first report on the impact of direct activation of TLR on NET-formation and Ca2+ influx in camel neutrophils with a selective effect of LPS on NET-formation induction. Future studies may investigate the molecular mechanisms behind the different responsiveness of bovine and camel neutrophils to TLR stimulation.

Innate recognition of pathogens depends on the interaction between microbial structures known as pathogen-associated molecular patterns (PAMPs) and pattern recognition receptors (PRRs) in host cells. Toll-like receptors (TLR) are among the most important PRRs being expressed on and in a wide range of immune cell types. Studies on the interaction mechanisms between different pathogen species and the immune system of the dromedary camel are still scarce. The present study aimed to investigate the immunomodulatory effect of synthetic bacterial and viral TLR ligands on some phenotypic properties and selected functions of neutrophils purified from dromedary camel blood. Neutrophils were separated from camel blood (n = five animals) and were stimulated in vitro with the TLR ligands LPS, Pam3CSK4, R848 (Resiquimod), and Poly IC or were left without stimulation. Stimulation with the protein kinase C activator phorbol 12-myristate 13-acetate (PMA) was used as a positive control stimulation. Shape change, phagocytosis activity, ROS production, the expression of cell surface markers, and cell vitality were compared between stimulated and non-stimulated cells. With exception of the TLR3 agonist Poly IC, all TLR ligands used showed the potential to stimulate camel neutrophils resulting in increased cell size and the upregulation of CD18 and CD14 on their surface. Similarly, the phagocytosis activity of camel neutrophils was significantly improved after priming with all TLR ligands, except Poly IC, which, in contrast, resulted in a reduced percentage of phagocytosis-positive cells. In contrast to stimulation with PMA, which induced a significant ROS production in camel neutrophils, none of the TLR ligands used stimulated ROS generation in neutrophils. Only stimulation with Pam3CSK4 increased the expression of MHCII molecules on camel neutrophils, resulting in an expanded MHCII^high fraction within camel neutrophils. Our study indicates selective immunomodulating effects of TLR agonists on purified camel neutrophils without affecting their vitality.

(1) Toll-like receptors (TLR) are a family of pattern recognition receptors that sense distinct molecular patterns of microbial origin. Although the immune cell composition of camel milk has been recently described, host–pathogen interaction studies in the camel mammary gland are still scarce. The present study aimed to use a whole milk stimulation assay for investigating the modulatory effect of selected Toll-like receptor (TLR) ligands on the phenotype and function of milk immune cells. (2) Methods—camel milk samples (n = 7) were stimulated in vitro with the TLR4 ligand LPS or the TLR2/1 ligand Pam3CSK4, and separated milk cells were evaluated for stimulation-induced shape change, the expression of cell surface markers, phagocytosis, apoptosis, ROS production, and NETosis. Stimulation with PMA was used as a control stimulation. (3) Results—all stimulants induced shape change in milk cells, change in the expression of several cell markers, and increased cell apoptosis and NETosis. In addition, stimulation with Pam3CSK4 and PMA was associated with enhanced ROS production, while only PMA stimulation resulted in enhanced bacterial phagocytosis by milk immune cells. (4) Conclusions—our data indicates selective modulating effects of the TLR ligands LPS and Pam3CSK4 on camel milk phagocytes. These results may have implications for the use of synthetic TLR agonists as immunomodulatory adjuvants of the immune response to intra-mammary vaccines against mastitis pathogens.

Background and Aim: Bovine viral diarrhea virus (BVDV) is one of the most important viral pathogens causing high economic losses in cattle of all ages. Despite the active vaccination campaigns against BVDV, many outbreaks are still detected in various populations of cattle worldwide. Other species of animals such as dromedary camels, sheep, and goats may harbor BVDV infection and cause variable clinical syndromes. Thus, they may act as a source of infection to the cattle population around them. However, little is still known about the roles of these animals in the viral transmission and sustainability of BVDV in the environment. This study aimed to explore if the dromedary camels, sheep, and goats may seroconvert against BVDV and to study some associated risk factors for BVDV in these species of animals. Materials and Methods: We tested 1012 serum samples from dromedary camels, 84 from goats, and 21 from sheep for BVDV antibodies using commercial enzyme-linked immunosorbent assay (ELISA) kits. Meanwhile, we selected 211 serum samples from dromedary camels to be tested for the BVDV antigen using the commercial ELISA kits. Results: Our results show that 49/1117 serum samples were positive for the BVDV antibodies in dromedary camels (46/1012), goats (3/84), and none of the tested sheep samples were positive. However, none of the collected serum samples tested positive for the BVDV antigen. Conclusion: Seroconversion of some dromedary camels, sheep, and goats to the BVDV with no history of vaccination against BVDV strongly suggests the potential roles of these species of animals in the virus transmission cycle. The main limitations of the current study are (1) the lack of samples from other species of animals that lived close by these animals, particularly cattle. (2) lack of follow-up samples from the same animal over a long period. We believe the long-term longitudinal study of BVDV in various species of animals, particularly dromedary camels, goats, and sheep, is one of our future research directions. This will provide more information about the dynamics of BVDV antibodies in these species of animals.