Study on Anatomical Structures of the Dromedary Udder.

The objectives of the present study were to describe specific anatomical structures of the dromedary udder. Eighty-six dromedary udders were examined, taking morphological measurements and producing injection casts using resin, gelatin, and paraffin. The udder of the dromedaries consists of four quarters. The shape of the udders and teats varies considerably between animals and is influenced by age, breeding, and lactation status. The most frequently found udder form was the globular udder (48.8%) and the most common teat form in this study was the funnel teat (44.2%). The most common teat tip shape was a smooth or a slightly rough ring teat (61.6%). Injection casts showed a complete separation of the teat canals. There is also no communication between tributary mammary complexes. Resin injections of the glandular tissue adjacent to the teat cistern showed an extensive branching into large, medium, and small milk ducts. Frozen sections of the udder revealed complete separation of the right and left mammary complex through the Sulcus intermammarius. The teat sections showed longitudinal folds from the tip of the teat to the base of the teat. A ring fold at the transition from the Ductus papillaris to the teat cistern was present. The results of this study increase the knowledge of the anatomical structures of the dromedary udder, which may be useful for breeding a selection of dairy dromedaries.

Usefulness of Next-Generation Sequencing in Excluding Bovine Leukemia Virus as a Cause of Adult Camel Leukosis in Dromedaries.

Adult camel leukosis is an emerging hematological and neoplastic disease in dromedaries. It has been hypothesized that bovine leukemia virus (BLV) or its genetic variants may be associated with adult camel leukosis. In this study, we used next-generation sequencing (NGS) to detect all possible viruses in five lung samples from five dromedaries with histopathological evidence of adult camel leukosis and four tissue samples from two control dromedaries. A total throughput of 114.7 Gb was achieved, with an average of 12.7 Gb/sample. For each sample, all the pair-end 151-bp reads were filtered to remove rRNA sequences, bacterial genomes and redundant sequences, resulting in 1-7 Gb clean reads, of which <3% matched to viruses. The largest portion of these viral sequences was composed of bacterial phages. About 100-300 reads in each sample matched "multiple sclerosis-associated retrovirus", but manual analysis showed that they were only repetitive sequences commonly present in mammalian genomes. All viral reads were also extracted for analysis, confirming that no BLV or its genetic variants or any other virus was detected in the nine tissue samples. NGS is not only useful for detecting microorganisms associated with infectious diseases, but also important for excluding an infective cause in scenarios where such a possibility is suspected.

DISEASE PROCESSES IDENTIFIED IN CAPTIVE ARABIAN SAND CATS (FELIS MARGARITA HARRISONI).

The objective of this retrospective study is to identify common and significant causes of mortality and disease processes in the Arabian sand cat (Felis margarita harrisoni) captive population at Al Ain Zoo (Abu Dhabi, United Arab Emirates). Complete postmortem records of 25 Arabian sand cats, dead between 2009 and 2022, were reviewed retrospectively. A complete postmortem examination was done in all cases, and information was recorded in the Al Ain Zoo database and files. Out of 25 animals dead, 11 were adults (4-12 yr) and 12 were classified as geriatric animals (>12 yr), with only two neonatal (0-4 mon) deaths and no recorded deaths in juveniles (4 mon to 4 yr). Interestingly, but also expected because of the age range, 24% of the cases had concurrent pathologies at the time of death. As expected in adult and geriatric felines, more than half of the cases (60%) developed nephropathies that were either one of the most important contributors or the main cause of death of the animal. Different neoplastic lesions were described in four cases and reported for the first time in this subspecies: benign peripheral nerve sheath tumor, hepatobiliary carcinoma, and two different thyroid neoplasia. A vasculoproliferative disorder of the liver, peliosis hepatis, was described in one of the cases. Additionally, in at least four cases, hyperthyroidism was strongly suspected in connection with thyroid neoplasia and hyperplasia, clinical signs, and other observed postmortem lesions. Traumatic causes of death also were reported in six cases, including the only two neonates recorded dead. This information will contribute to Arabian sand cat improved veterinary care by identifying common pathologies in this species, potentially allowing earlier diagnosis and, ultimately, improving their management and husbandry in the captive breeding populations.

The Experimental Infection of Goats with Small Ruminant Morbillivirus Originated from Barbary Sheep.

Peste des Petits Ruminants (PPR) is a transboundary contagious disease in domestic small ruminants. Infections with the small ruminant morbillivirus (SRMV) were regularly found in wildlife, with unknown roles in PPR epidemiology. In order to access infection dynamics and virulence, we infected German Edelziege goats intranasally with a SRMV isolate that originated from Barbary sheep from an outbreak in the United Arab Emirates. Six goats were infected with cell culture-isolated SRMV, and two goats were kept in contact. Goats were daily monitored, and clinical score was recorded. EDTA blood, nasal, conjunctival and rectal swab samples were collected for the detection of SRMV genome load and serum for serological analysis. Short incubation period in infected (4 to 5 dpi) as well as in contact goats (9 dpi) was followed by typical clinical signs related to PPR. The highest viral load was detectable in conjunctival and nasal swab samples with RT-qPCR and rapid pen-side test. Specific antibodies were detected at 7 dpi in infected and 14 dpi in contact goats. In general, high virulence and easy transmission of the virus originated from wildlife in domestic goats was observed. The virus isolate belongs to Asian lineage IV, genetically related to Chinese and Mongolian strains.

Genetic diversity and spatial distribution of Burkholderia mallei by core genome-based multilocus sequence typing analysis.

Burkholderia mallei is the etiological agent of glanders, a highly contagious and often fatal disease in equids. Due to the high genetic clonality of B. mallei, high-resolution typing assays are necessary to differentiate between individual strains. Here we report on the development and validation of a robust and reproducible core genome-based Multi Locus Sequence Typing Assay (cgMLST) for B. mallei, which is based on 3328 gene targets and enables high-resolution typing at the strain level. The assay was validated using a set of 120 B. mallei genomes from public databases and 23 newly sequenced outbreak strains from in-house strain collections. In this cgMLST analysis, strains from different geographic regions were clearly distinguished by at least 70 allele differences, allowing spatial clustering while closely related and epidemiologically related strains were separated by only zero to three alleles. Neither the different sequencing technologies nor the assembly strategies had an influence on the cgMLST results. The developed cgMLST is highly robust, reproducible and can be used for outbreak investigations, source tracking and molecular characterization of new B. mallei isolates.

Outbreak of a Systemic Form of Camelpox in a Dromedary Herd (Camelus dromedarius) in the United Arab Emirates.

Camelpox virus (CMLV) is the causative agent of camelpox, which frequently occurs in the Old World camelids-rearing countries except for Australia. It has also been described in experimentally inoculated New World camelids. Camelpox outbreaks are often experienced shortly after the rainy season, which occurs twice a year on the Arabian Peninsula because of the increased density of the insect population, particularly mosquitos. A systemic form of camelpox outbreak in seven dromedary camels was diagnosed by histology, virus isolation, and PCR. A phylogenetic analysis using full length CMLV genomes of the isolated CMLV strains showed a single phylogenetic unit without any distinctive differences between them. The United Arab Emirates (UAE) isolate sequences showed phylogenetical relatedness with CMLV isolates from Israel with only minor sequence differences. Although the sequences of viruses from both countries were closely related, the disease manifestation was vastly different. Our study shows that the virulence is not only determined by genetic features of CMLV alone but may also depend on other factors such as unknown aspects of the host (e.g., age, overall fitness), management, and the environment.

First Isolation and Rapid Identification of Newcastle Disease Virus from Aborted Fetus of Dromedary Camel Using Next-Generation Sequencing.

Newcastle disease virus (NDV) causes morbidities and mortalities in wild and domestic birds globally. For humans, exposure to infected birds can cause conjunctivitis and influenza-like symptoms. NDV infections in mammals are rarely reported. In this study, using next-generation sequencing, an NDV was identified and isolated from Vero cells inoculated with the nasal swab of an aborted dromedary fetus in Dubai, during the time when an NDV outbreak occurred in a pigeon farm located in close proximity to the dairy camel farm where the mother of the aborted dromedary fetus resided, and there were a lot of pigeons in the camel farm. Genome analysis revealed that the structurally and functionally important features of other NDVs were also present in this dromedary NDV genome. Phylogenetic analysis based on the nucleotide sequences of fusion protein (F), hemagglutinin-neuraminidase protein (HN) and complete polyprotein showed that the virus belonged to sub-genotype VIg of class II NDV and is most closely related to pigeon NDVs in Egypt in the same year. The present study is the first that demonstrated isolation of NDV in dromedaries. Further study is warranted to investigate the relationship between NDV infection and abortion.

Gametogony of Eimeria cameli in the small intestine of one-humped camel (Camelus dromedarius).

Domesticated Old World camels (Camelus dromedarius and Camelus bactrianus) are important for the economy of several countries in Asia, Africa, and the Arabian Peninsula, and coccidiosis is an important disease in camels. There is confusion concerning the species of coccidian parasites in camels and their life cycles. Although five species of Eimeria (E. cameli, E. rajasthani, E. dromedarii, E. bactriani, and E. pellerdyi) were named from camels, E. cameli is considered the most pathogenic. Here, development of gametogonic stages and oocysts of E. cameli are described in the lamina propria of the small intestines of naturally infected camels. Only sexual stages have been confirmed.

Polyphyletic origin of MERS coronaviruses and isolation of a novel clade A strain from dromedary camels in the United Arab Emirates.

Little is known regarding the molecular epidemiology of Middle East respiratory syndrome coronavirus (MERS-CoV) circulating in dromedaries outside Saudi Arabia. To address this knowledge gap, we sequenced 10 complete genomes of MERS-CoVs isolated from 2 live and 8 dead dromedaries from different regions in the United Arab Emirates (UAE). Phylogenetic analysis revealed one novel clade A strain, the first detected in the UAE, and nine clade B strains. Strain D998/15 had a distinct phylogenetic position within clade A, being more closely related to the dromedary isolate NRCE-HKU205 from Egypt than to the human isolates EMC/2012 and Jordan-N3/2012. A comparison of predicted protein sequences also demonstrated the existence of two clade A lineages with unique amino acid substitutions, A1 (EMC/2012 and Jordan-N3/2012) and A2 (D998/15 and NRCE-HKU205), circulating in humans and camels, respectively. The nine clade B isolates belong to three distinct lineages: B1, B3 and B5. Two B3 strains, D1271/15 and D1189.1/15, showed evidence of recombination between lineages B4 and B5 in ORF1ab. Molecular clock analysis dated the time of the most recent common ancestor (tMRCA) of clade A to March 2011 and that of clade B to November 2011. Our data support a polyphyletic origin of MERS-CoV in dromedaries and the co-circulation of diverse MERS-CoVs including recombinant strains in the UAE.

Complete Genome Sequence of Influenza Virus H9N2 Associated with a Fatal Outbreak among Chickens in Dubai.

We report the complete genome sequence of influenza virus H9N2 associated with a fatal outbreak among chickens in Dubai. All segments are clustered with avian H9N2 viruses circulating in the Middle East but distinct from those in southeast Asia. It is not a reassortant virus or transmitted from other regions.

A RARE CASE OF HEPATOCELLULAR CARCINOMA IN THE ARABIAN SAND CAT (FELIS MARGARITA HARRISONI).

Primary liver cancer is uncommon and is generally classified as hepatocellular carcinoma (HCC), bile duct carcinoma, neuroendocrine (or carcinoid) tumor, and mesenchymal tumor (sarcoma). Here we describe the gross and histopathology characteristics of a rare HCC in a captive Arabian sand cat (Felis margarita harrisoni) held at Al Ain Zoo, United Arab Emirates. The description of this case in the Arabian sand cat adds to the current knowledge of hepatocellular carcinoma in captive nondomestic felids.

Genotyping of Burkholderia mallei from an outbreak of glanders in Bahrain suggests multiple introduction events.

BACKGROUND: Glanders, caused by the gram-negative bacterium Burkholderia mallei, is a highly infectious zoonotic disease of solipeds causing severe disease in animals and men. Although eradicated from many Western countries, it recently emerged in Asia, the Middle-East, Africa, and South America. Due to its rareness, little is known about outbreak dynamics of the disease and its epidemiology. METHODOLOGY/PRINCIPAL FINDINGS: We investigated a recent outbreak of glanders in Bahrain by applying high resolution genotyping (multiple locus variable number of tandem repeats, MLVA) and comparative whole genome sequencing to B. mallei isolated from infected horses and a camel. These results were compared to samples obtained from an outbreak in the United Arab Emirates in 2004, and further placed into a broader phylogeographic context based on previously published B. mallei data. The samples from the outbreak in Bahrain separated into two distinct clusters, suggesting a complex epidemiological background and evidence for the involvement of multiple B. mallei strains. Additionally, the samples from Bahrain were more closely related to B. mallei isolated from horses in the United Arab Emirates in 2004 than other B. mallei which is suggestive of repeated importation to the region from similar geographic sources. CONCLUSION/SIGNIFICANCE: High-resolution genotyping and comparative whole genome analysis revealed the same phylogenetic patterns among our samples. The close relationship of the Dubai/UAE B. mallei populations to each other may be indicative of a similar geographic origin that has yet to be identified for the infecting strains. The recent emergence of glanders in combination with worldwide horse trading might pose a new risk for human infections.

Host species restriction of Middle East respiratory syndrome coronavirus through its receptor, dipeptidyl peptidase 4.

UNLABELLED: Middle East respiratory syndrome coronavirus (MERS-CoV) emerged in 2012. Recently, the MERS-CoV receptor dipeptidyl peptidase 4 (DPP4) was identified and the specific interaction of the receptor-binding domain (RBD) of MERS-CoV spike protein and DPP4 was determined by crystallography. Animal studies identified rhesus macaques but not hamsters, ferrets, or mice to be susceptible for MERS-CoV. Here, we investigated the role of DPP4 in this observed species tropism. Cell lines of human and nonhuman primate origin were permissive of MERS-CoV, whereas hamster, ferret, or mouse cell lines were not, despite the presence of DPP4. Expression of human DPP4 in nonsusceptible BHK and ferret cells enabled MERS-CoV replication, whereas expression of hamster or ferret DPP4 did not. Modeling the binding energies of MERS-CoV spike protein RBD to DPP4 of human (susceptible) or hamster (nonsusceptible) identified five amino acid residues involved in the DPP4-RBD interaction. Expression of hamster DPP4 containing the five human DPP4 amino acids rendered BHK cells susceptible to MERS-CoV, whereas expression of human DPP4 containing the five hamster DPP4 amino acids did not. Using the same approach, the potential of MERS-CoV to utilize the DPP4s of common Middle Eastern livestock was investigated. Modeling of the DPP4 and MERS-CoV RBD interaction predicted the ability of MERS-CoV to bind the DPP4s of camel, goat, cow, and sheep. Expression of the DPP4s of these species on BHK cells supported MERS-CoV replication. This suggests, together with the abundant DPP4 presence in the respiratory tract, that these species might be able to function as a MERS-CoV intermediate reservoir. IMPORTANCE: The ongoing outbreak of Middle East respiratory syndrome coronavirus (MERS-CoV) has caused 701 laboratory-confirmed cases to date, with 249 fatalities. Although bats and dromedary camels have been identified as potential MERS-CoV hosts, the virus has so far not been isolated from any species other than humans. The inability of MERS-CoV to infect commonly used animal models, such as hamster, mice, and ferrets, indicates the presence of a species barrier. We show that the MERS-CoV receptor DPP4 plays a pivotal role in the observed species tropism of MERS-CoV and subsequently identified the amino acids in DPP4 responsible for this restriction. Using a combined modeling and experimental approach, we predict that, based on the ability of MERS-CoV to utilize the DPP4 of common Middle East livestock species, such as camels, goats, sheep, and cows, these form a potential MERS-CoV intermediate host reservoir species.

Serum amyloid A as an indicator of health status in falcons.

Serum amyloid A (SAA) is used as an indicator of health status in many species. To investigate the possible use of SAA as a health indicator in falcons, SAA levels were measured in 259 falcons of varying species and health status. A significant increase (P < .001) in SAA concentrations was observed in falcons affected by inflammatory disease compared with healthy birds and birds with noninflammatory disease. Serum amyloid A concentrations ranged from 0.1 to 6.8 mg/L (mean [SD], 3.4 +/- 1.4 mg/L) in the healthy group, from 0.8 to 8.5 mg/L (mean [SD], 4.0 +/- 3.1 mg/L) in the group with noninflammatory disease, and from 2.3 to 137.5 mg/L (mean [SD], 47.7 +/- 29.7 mg/L) in the group with inflammatory disease. In birds with chronic pododermatitis or fungal pneumonia/airsacculitis, SAA levels remained significantly increased throughout the study period. These results indicate that SAA concentrations can be used in avian medicine to assess the health status of falcons and as a prognostic indicator of certain pathologic disease processes.

Opportunistic infection of Aspergillus and bacteria in captive Cape vultures (Gyps coprotheres).

OBJECTIVE: To describe clinical signs, pathology, diagnosis and treatment of Cape vultures in which Aspergillus fumigatus (A. fumigatus) and mixed species of bacteria were isolated. METHODS: Six Cape vultures sourced from South Africa for exhibition at Al Ain Zoo developed illness manifesting as anorexia, dyspnea, polyuria and lethargy. Three vultures died manifesting "pneumonia-like syndrome". These three vultures were necropsied and gross lesions recorded, while organ tissues were collected for histopathology. Internal organs were swabbed for bacteriology and mycology. From live vultures, blood was collected for hematology and biochemistry, oropharyngeal and cloacal swabs were collected for mycology and bacteriology. RESULTS: A. fumigatus was isolated from the three dead vultures and two live ones that eventually survived. One of the dead vulture and two live vultures were co-infected with A. fumigatus and mixed species of bacteria that included Clostridium perfringens, Pseudomonas, Staphylococcus, Escherichia, Proteus, Enterococcus and Enterbacter. One of the Cape vulture and a Lappet-faced vulture, however, were free of Aspergillus or bacterial infections. At necropsy, intestinal hemorrhages were observed and the lungs were overtly congested with granulomas present on caudal air sac. Histopathological examinations demonstrated granulomatous lesions that were infiltrated by mononuclear cells and giant cells. CONCLUSIONS: Aspergillosis is a persistent threat to captive birds and we recommend routine health assessments so that early diagnosis may prompt early treatment. It is likely that prompt prophylaxis by broad spectrum antibiotics and antifungals medication contributed to the survival of some of the vultures.

Opportunistic infection of Aspergillus and bacteria in captive Cape vultures (Gyps coprotheres)

Objective: To describe clinical signs, pathology, diagnosis and treatment of Cape vultures in which Aspergillus fumigatus (A. fumigatus) and mixed species of bacteria were isolated. Methods: Six Cape vultures sourced from South Africa for exhibition at Al Ain Zoo developed illness manifesting as anorexia, dyspnea, polyuria and lethargy. Three vultures died manifesting‘‘pneumonia-like syndrome’’. These three vultures were necropsied and gross lesions recorded, while organ tissues were collected for histopathology. Internal organs were swabbed for bacteriology and mycology. From live vultures, blood was collected for hematology and biochemistry, oropharyngeal and cloacal swabs were collected for mycology and bacteriology. Results: A. fumigatus was isolated from the three dead vultures and two live ones that eventually survived. One of the dead vulture and two live vultures were co-infected with A. fumigatus and mixed species of bacteria that included Clostridium perfringens, Pseudomonas, Staphylococcus, Escherichia, Proteus, Enterococcus and Enterbacter. One of the Cape vulture and a Lappet-faced vulture, however, were free of Aspergillus or bacterial infections. At necropsy, intestinal hemorrhages were observed and the lungs were overtly congested with granulomas present on caudal air sac. Histopathological examinations demonstrated granulomatous lesions that were infiltrated by mononuclear cells and giant cells. Conclusions: Aspergillosis is a persistent threat to captive birds and we recommend routine health assessments so that early diagnosis may prompt early treatment. It is likely that prompt prophylaxis by broad spectrum antibiotics and antifungals medication contributed to the survival of some of the vultures.

A bacterial-two-hybrid selection system for one-step isolation of intracellularly functional Nanobodies.

Camel single-domain antibody fragments or Nanobodies, are practical in a wide range of applications. Their unique biochemical and biophysical properties permit an intracellular expression and antigen targeting. The availability of an efficient intracellular selection step would immediately identify the best intracellularly performing functional antibody fragments. Therefore, we assessed a bacterial-two-hybrid system to retrieve such Nanobodies. With GFP as an antigen we demonstrate that antigen-specific Nanobodies of sub-micromolar affinity and stability above 30 kJ/mol, at a titer of 10(-4) can be retrieved in a single-step selection. This was further proven practically by the successful recovery from an 'immune' library of multiple stable, antigen-specific Nanobodies of good affinity for HIV-1 integrase or nucleoside hydrolase. The sequence diversity, intrinsic domain stability, antigen-specificity and affinity of these binders compare favorably to those that were retrieved in parallel by phage display pannings.

Production of chicken progeny (Gallus gallus domesticus) from interspecies germline chimeric duck (Anas domesticus) by primordial germ cell transfer.

The present study aimed to investigate the differentiation of chicken (Gallus gallus domesticus) primordial germ cells (PGCs) in duck (Anas domesticus) gonads. Chimeric ducks were produced by transferring chicken PGCs into duck embryos. Transfer of 200 and 400 PGCs resulted in the detection of a total number of 63.0 ± 54.3 and 116.8 ± 47.1 chicken PGCs in the gonads of 7-day-old duck embryos, respectively. The chimeric rate of ducks prior to hatching was 52.9% and 90.9%, respectively. Chicken germ cells were assessed in the gonad of chimeric ducks with chicken-specific DNA probes. Chicken spermatogonia were detected in the seminiferous tubules of duck testis. Chicken oogonia, primitive and primary follicles, and chicken-derived oocytes were also found in the ovaries of chimeric ducks, indicating that chicken PGCs are able to migrate, proliferate, and differentiate in duck ovaries and participate in the progression of duck ovarian folliculogenesis. Chicken DNA was detected using PCR from the semen of chimeric ducks. A total number of 1057 chicken eggs were laid by Barred Rock hens after they were inseminated with chimeric duck semen, of which four chicken offspring hatched and one chicken embryo did not hatch. Female chimeric ducks were inseminated with chicken semen; however, no fertile eggs were obtained. In conclusion, these results demonstrated that chicken PGCs could interact with duck germinal epithelium and complete spermatogenesis and eventually give rise to functional sperm. The PGC-mediated germline chimera technology may provide a novel system for conserving endangered avian species.

Natural Burkholderia mallei infection in Dromedary, Bahrain.

We confirm a natural infection of dromedaries with glanders. Multilocus variable number tandem repeat analysis of a Burkholderia mallei strain isolated from a diseased dromedary in Bahrain revealed close genetic proximity to strain Dubai 7, which caused an outbreak of glanders in horses in the United Arab Emirates in 2004.

The pleural curtain of the camel (Camelus dromedarius).

The visceral pleura of the camel (Camelus dromedarius) possesses a fibrous curtain of pleural threads or extensions along its basal margins, which extends into the pleural cavity of the costophrenic recesses. These threads are lined by mesothelium and have a core or stroma, which is largely collagenous. Small threads are avascular and nearly acellular. In larger proximal threads, blood vessels in the stroma are often arranged in a branching network, with irregular endothelia surrounded by several incomplete basal laminae. Lymphocytes and other inflammatory cell types aggregate in the stroma near blood vessels. The threads are lined by typical mesothelium except in patches close to the main pleural surface. These patches consist of layers of loosely applied cells with numerous cellular processes and features suggestive of phagocytosis. The position of the pleural curtain in the costophrenic recess and the presence of possibly phagocytotic cells suggest that the pleural curtain stirs, samples, and cleans the pleural fluid. The pleural curtain appears to be a feature of camelids and has also been seen in giraffes.