مجله تحقیقات دامپزشکی
سال هفتاد و نهم شماره 1 (بهار 1403)

BACKGROUND:

 Honey bee venom contains complex compounds such as polypeptides, enzymes, and amines. One of the important components of bee venom is the phospholipase A2 enzyme, which is considered an important honey bee venom allergen and is also used to treat some diseases. This enzyme is found in other insects, arachnids, snakes, and mammalian cells, and its function is the hydrolysis of the second ester bond of glycerophospholipids and the release of fatty acids and lysophospholipids. Although transient transfection can produce recombinant proteins, stable cells are more suitable for high-scale production with economic efficiency.

The present study created a stable cell line to produce recombinant phospholipase A2 from honey bee (Apis mellifera) venom.

Plasmid cloning DNA vector containing phospholipase A2 gene was prepared by Macrogen Company. The recombinant plasmid was transferred to Chinese hamster ovary cells by heat shock method, and gene expression was carried out in a HamsF12 culture medium containing neomycin antibiotic. After increasing polyclonal strains containing plasmid, monoclonal clones were selected by limiting dilution. Then, monoclonal clones were propagated, the soup of the selected cells was collected and concentrated, and the protein expression was checked by sodium dodecyl-sulfate polyacrylamide gel electrophoresis test.

The results of electrophoresis, which was performed to confirm the expression of the phospholipase A2 gene in the cell soup, showed a band with a molecular weight of 20 kilodaltons, which confirms the creation of a stable cell line for the production of recombinant phospholipase A2 honey bee venom.

After the transient transfection of the plasmid containing this gene, several cells undergo recombination due to having repair mechanisms and putting the desired gene along with the antibiotic resistance gene in their genome. These cells can be selected and propagated by adding antibiotics to the culture medium.

Toxocara canis is a zoonotic disease that commonly infects canids. Mammals and birds are sometimes infected with this disease as paratenic hosts. It can also cause accidental infection in humans. The increase in the number of stray dogs, the expansion of urban gardens, and the proximity of dogs to humans increase the risk of human infection with Toxocara canis.

This study aims to determine the prevalence of Toxocara canis infection in dogs and foxes in Zanjan province, Iran.

A total of 484 fecal samples of stray dogs (n=355), rescue dogs (n=49), guard dogs (n=50), and foxes (n=30) in Zanjan were randomly collected from June 2021 to February 2022. The microscopic examination was done following formalin-ethyl acetate sedimentation procedures. Finally, the PCR method was used to confirm the presence of Toxocara canis in positive samples.

Microscopic study revealed that, out of 484 samples, 21 (4.3%) were positive for Toxocara/ Toxascaris eggs. Between these positive samples of dogs and foxes, only 6 samples from dog feces were confirmed as a Toxocara canis infection by the PCR method.

There is an increase in the prevalence of Toxocara canis infection in stray dogs in Zanjan, Iran. Given the presence of dogs in parks and residential areas, there is a risk of human infection with Toxocara canis, emphasizing the importance of adhering to treatment and prevention protocols in dealing with stray dogs.

Pre-purchase radiographic examinations of horses are very important for the diagnosis of possible disorders.

This study aims to determine the variation and frequency of common disorders of the tarsus in pre-purchase radiographic examinations of horses and assess the effect of age, sex, and type of hind limb (right or left) on the occurrence of these disorders.

In this study, we used the radiographs taken from the tarsal joints of the right and left hind limbs in 110 horses for a two-year period which were requested for pre-purchase radiographic examinations. Among these radiographs, the cases that included the standard position of the tarsal joint were evaluated for the existing disorders and the effect of age, sex, and type of involved hind limb.

The most frequent disorders were osteoarthrosis (32.27 %), osteochondritis dissecans (5.91 %), and soft tissue swelling (1.36 %). The least common disorders were calcification, desmopathy, and tenosynovitis, each with a prevalence of 0.45%. Also, most of the tarsal ​​joint disorders had a mild degree of severity (80 %). The prevalence of disorders was 100 % for horses aged <4 years (4 out of 4) and 49.1 % for horses aged >4 years (52 out of 106). No significant difference was observed in terms of gender (P=0.65) and type of involved hind limb (P=0.17).

Considering the prevalence of tarsal joint disorders in horses, pre-purchase radiographic examination can be very important for predicting the future health and performance of the horse. Therefore, radiographic evaluation of the tarsal joint should always be a part of pre-purchase examinations in horses.

In free stalls, factors related to the surface and dimensions of the stall affect how the cows rest and comfort. The brisket board and the neck rail are the most controversial parts of the free stall in Iran's dairy farms, that can affect the stability of the stall and its lifespan, while improper use of these structures has led to significant discomfort for cows, causing substantial issues including lameness and hock, knee and withers lesions.

This study aims to investigate Brisket boards and neck rails usage and measures in freestall barns and assess its possible impact on some comfort indices in dairy cows.

Nine dairy farms with over 100 milk cows and freestall barns were selected using the Dairy Farmers of Canada protocols by a convenience sampling method. Horizontal, vertical, and diagonal distances of the neck rail, the presence or absence of brisket boards, and the brisket board height from the bedding were measured. The locomotion score based on a five-point scale as well as hygiene, knees, hocks, and withers scores were recorded. The correlation was evaluated using the Spearman correlation test and Pearson’s correlation test.

In 68.3 % of the freestall barns, the brisket boards were at the bedding level or were not used at all; however, the mean brisket board height (11.2±10.8) was not significantly different from the standard height value of 10 cm (P>0.05). The vertical distance of the neck rail (120.4±10.4 cm) was significantly different from the standard values. The median of withers and locomotion scores were consistent among all farms. At the farm level, the median knee, hygiene, and hock scores did not show a significant correlation with the mean of neck rail measures and brisket board height (P>0.05). Also, the median locomotion score did not show a significant correlation with the mean horizontal distance of the neck rail at the individual freestall barn level (P>0.05). However, a significant correlation between the mean of knee scores and vertical distance of the neck rail at the farm level, and between the mean of locomotion score and horizontal distance of the neck rail at the individual freestall barn level were reported.

An increase in the mean vertical distance of the neck rail is associated with an increase in the median knee scores, while an increase in the mean horizontal distance in each barn was associated with an increase in the median locomotion score, indicating the potential impact of these measurements on cow comfort. However, further research using a larger sample size is needed.

Corynebacterium pseudotuberculosis is the etiological agent of caseous lymphadenitis (CLA), a chronic and very common disease in sheep and goats, which can lead to severe economic losses in the livestock industry.

This study aims to investigate the prevalence of CLA in sheep in Kurdistan province of Iran using phenotypic and molecular methods, and assess the antibiotic resistance of isolated Corynebacterium pseudotuberculosis.

In this study, from September to March 2022, 270 samples of skin abscesses were collected from sheep in livestock farms of Kurdistan province. Immediately, using the cold chain system, the samples were transferred to the microbiology laboratory of the Faculty of Medicine at Kurdistan University of Medical Sciences. Identification of isolates was done using biochemical tests and polymerase chain reaction (PCR) method. The antibiotic resistance of the isolates was examined using the Kirby-Bauer disk diffusion method.

Based on biochemical tests, out of 270 samples, 82 suspected to have Corynebacterium pseudotuberculosis. Out 82 samples, the presence of bacteria was confirmed in 76 samples by the PCR. The antibiotic sensitivity test showed that the isolates had high sensitivity to doxycycline and ceftriaxone and high resistance to streptomycin and kanamycin.

The CLA has a high prevalence in sheep in Kurdistan province. According to high resistance rate of Corynebacterium pseudotuberculosis to streptomycin and kanamycin, it recommended to avoid treatment of CLA cases with these antibiotics.

The bacterium Capnocytophaga canimorsus is a relatively newly recognized gram-negative, facultative, slow-growing bacillus that forms part of the normal oral flora of dogs and cats. Considering the pathogenicity of this bacterium in humans, determining its prevalence is very important for public health as well as the health of dog owners.

This study aims to investigate the prevalence of Capnocytophaga canimorsus in the normal oral flora of healthy dogs.

After taking samples from the saliva of 32 healthy dogs without oral, dental or digestive diseases at different ages, breeds, and sexes, they were placed in a test tube containing 10 mL of sterile peptone water with sterile plastic brushes, and immediately sent to the bacteriology laboratory under sterile conditions. The samples were cultured on a chocolate agar medium containing 5 % defibrinated sheep blood. Then, all the samples were kept in a greenhouse for 48 hours at a temperature of 37 °C and under anaerobic conditions. Using a loop, the grown pink colonies were isolated and to confirm the identification of the isolates, polymerase chain reaction (PCR) test was used in three main steps: Gene extraction, PCR reaction, and electrophoresis.

Out of 32 saliva samples, four positive cases of Capnocytophaga canimorsus bacteria were identified by PCR diagnostic method.

Given that Capnocytophaga canimorsus bacterium is present in the oral flora of healthy ​​dogs, dog owners should have sufficient and favorable knowledge about this bacterium and related diseases. The PCR method can be used to detect this bacterium.