Veterinary Research Forum

Abstract The bovine leukemia virus (BLV) is an important infectious agent transmitted from cattle to humans. It is considered one of the oncogenic viruses in breast cancer, so an accurate detection of this virus is important. The study aimed to design a specific and sensitive method based on TaqMan^® real-time polymerase chain reaction (RT-PCR) for BLV detection. Probes and primers were designed using bioinformatics software for a 108 pairs region of the BLV tax gene. Criteria employed for determining analytical sensitivity were prepared using in-vitro RNA transcriptions. The National Center for Biotechnology Information (NCBI), basic local alignment search tool (BLAST) databases various viral panels and genomic samples from healthy individuals (Qom Province, Iran in 2023) were used to verify analytical specificity and clinical specificity, respectively. This method can measure a minimum of 10 copies of DNA and RNA mL^-1. Moreover, the assay is linear in the range of 10⁰ - 10⁹ copies mL^-1. By testing negative specimens, the method specificity was 100%. The reproducibility results of the reaction were examined at the intra- and inter-assay comparison. In fact, 10 technical replicates of each concentration of the control sample were analyzed in each working reaction. Due to the locally made kit, exact sensitivity and specificity, rapid analysis, and relatively low cost, as compared to commercial kits of other countries, the method introduced in the present study could be suitable for accurate detection of the BLV. Also, the TaqMan^® real-time PCR method could be detected in cattle and human and before malignant changes of breast cancer which could reduce infection and breast cancer.

Abstract In addition to the fifty years since the test-and-slaughter program began in Iran and despite a significant reduction in the disease prevalence, positive tuberculosis cases are still being isolated from livestock farms across the country. Tests with 100% sensitivity and specificity are essential features for bovine tuberculosis diagnosis. The relationship between real-time PCR and immunohistochemistry (IHC) as two essential laboratory methods in the diagnosis of bacterial infections were aimed to evaluate single intradermal comparative tuberculin test (SICTT) results. One hundred thirty-eight cows in two groups were examined: Reactors (108 cows) and clean (as a control group; 30 cows). In the reactor group, 58(54.00%) cows were Mycobacterium bovis positive, 46(43.00%) were Mycobacterium avium subsp. paratuberculosis (MAP) positive, and 11(10.00%) were Mycobacterium tuberculosis positive. 32(55.00%) cows were co-infected with M. bovis and MAP and 5(4.55%) cows were co-infected with Mycobacterium tuberculosis and MAP in this group. Of 50 M. bovis negative cows of reactor group were 14(28.00%) MAP positive and 36(72.00%) negative, as well. Concurrent infection with all was observed in one reactor case. Comparing IHC and real-time PCR for the detection of bovine tuberculosis and Johne’s disease showed very good agreement (Kappa values 0.81 - 1.00). The results also provided further confirmation on IHC and real-time PCR as a sensitive and reliable diagnostic screening approach for detection of bovine tuberculosis. The use of one laboratory method to detect bovine tuberculosis is not sufficient alone.

Abstract This study was conducted to investigate the effects of recycled poultry bedding (RPB) treated with different levels of pomegranate peel extract (PPE) as a tannin source on cellulolytic bacterial population and rumen fermentation parameters of fattening lambs. For this purpose, twenty-eight Arabian lambs (19.70 ± 2.45 kg body weight, 90 ± 12 days of age) were randomly assigned to four dietary treatments. Recycled poultry bedding was treated with PPE at four levels of 0 (control), 20.00, 25.00 and 30.00% on DM basis. Bacterial populations were enumerated by DNA extraction of samples of rumen liquor followed by real-time polymerase chain reaction analysis. Also, rumen samples were evaluated for pH, volatile fatty acid (VFA) and ammonia nitrogen (AN) concentrations. The populations of total bacteria, Ruminococcusalbus and Fibrobacter succinogenes were decreased significantly as the level of PPE in the diet increased, however, the population of Ruminococcus flavefaciens was not affected. Dietary treatments did not have effect on ruminal pH, while AN concentration was decreased in the diets containing RPB treated with PPE compared to the control. Concentrations of total VFA and individual VFA remained unchanged by PPE-treated RPB inclusion in the diet. In conclusion, supplementing RPB with PPE improved nitrogen metabolism of fattening lambs, however, it decreased population of rumen cellulolytic bacteria R. flavefaciens.

Abstract Avian infectious bronchitis (IB) is a major cause of economic losses in poultry industry. The IB virus primarily affects respiratory tract, but various strains differ in their tropism for other target organs such as kidney and alimentary tract. The objective of this study was to estimate the pathogenicity of Iranian IBV variant (IR-1), which is limited exclusively to Iran. Specific pathogen free chicks were inoculated intranasally. Sera, fecal swabs and different tissue samples were collected on different days post infection (DPI). Clinical signs, gross pathology and histological changes were recorded. The viral load was quantified in the RNA extractions from different tissue samples using real-time PCR. Anti-IBV antibodies were detected in serum samples. The IgG antibody were found on 21 and 28 DPI. Severe histological lesions were observed in the trachea and lung while the lesions in kidney were appeared to be milder. Viral RNA was detected in all tested tissues from 1 DPI to the last day of the experiment. The highest viral load was measured in the trachea and feces on 1^st and 5^th DPI, respectively. It can be concluded the IR-1 had broad tropism for respiratory tract, digestive system, and renal tissue, reflecting its epitheliotropic nature, but it caused the most severe lesions in the respiratory tract. This was the first pathogenicity study of Iranian IR-1 IBV. Further knowledge of IBV pathogenesis provides the groundwork to inform more effective prevention practices.