Veterinary Research Forum

Abstract Mycobacterium avium subsp. paratuberculosis (MAP), the causative agent of Johne’s disease and a potential contributor to Crohn’s disease, presents a significant challenge due to its resistance to conventional antibiotics. This necessitates the development of innovative strategies for prevention and treatment. This study aimed to evaluate the anti-bacterial activity of pathogen-specific antibodies derived from chicken egg yolks (immunoglobulin Y [IgY]) and the postbiotics from lactic acid bacteria against MAP. Immunoglobulin Y antibodies were produced by immunizing hens with formalin-killed MAP strain antigens. The IgY was extracted and purified, and the anti-MAP titers were quantified by indirect enzyme-linked immunosorbent assay. The minimum inhibitory concentration of different concentrations of specific anti-MAP IgY and the mixture of postbiotics (from four different probiotic strains, including Lactobacillus reuteri, Lactobacillus rhamnosus, Lactobacillus acidophilus, and Pediococcus acidilactici) individually and in combination against MAP was determined at various time intervals. Anti-MAP IgY titers in egg yolks increased within 2 weeks of immunization, reaching peak levels at 6 weeks. Growth inhibition assays revealed that postbiotics concentration as low as 6.25 mg mL^-1 effectively inhibited MAP growth. Anti-MAP IgY demonstrated anti-bacterial activity with a minimum inhibitory concentration of 50.00 mg mL^-1, while the combined IgY-posbiotics treatment achieved MAP growth inhibition at a minimum inhibitory concentration of 3.125 mg mL^-1. The findings of the study suggest that combination therapy with specific IgY and postbiotics may be a promising preventive strategy for controlling MAP infections. Further in vivo studies are needed to elucidate the underlying mechanisms and optimize the application of this approach for broader use in veterinary and human medicine.

Abstract Brucellosis is considered as one of the important global zoonotic diseases that causes medical as well as economic problems especially in tropical countries. The illness has no specific pathognomonic signs; therefore, the rapid and accurate diagnosis of the disease has a very important role in preventing the Brucella spillover and treatment. The purpose of this study was to design a new indirect ELISA test for detection of human brucellosis based on using recombinant Brucella abortus outer membrane protein 16.00 kDa (rOMP16) as an antigen. OMP16 gene of B. abortus was initially synthesized and cloned in pET-21d vector and then expressed in Escherichia coli cells. The expression was confirmed by the SDS-PAGE, western blotting and dot blotting. The purified protein was coated in ELISA plates and an indirect ELISA was performed on 70 human serum samples. The results were evaluated with a commercial IgG ELISA kit and Rose Bengal plate agglutination tests as reference tests. Diagnostic performance of designed OMP16 ELISA test in comparison with Rose Bengal plate test revealed 100% of sensitivity, 95.00% of specificity and good Fleiss kappa agreement, whereas, where it was compared to commercial ELISA kit, it revealed very good kappa agreement with 100% of sensitivity and 100% of specificity in cut-off value of 0.13. It was concluded that OMP 16.00 kDa could be acceptable alternative antigen for detecting Brucella IgG antibody with high accuracy.

Abstract The purpose of this study was to determine the prevalence of bovine leukemia virus (BLV) in Khorasan Razavi and Khorasan Shomali provinces which are the main provinces located in the northeast of Iran. Total number of 429 blood samples were collected from industrial dairy herds. The samples were categorized based on province, age (2-3, 4-6, and 7-10 years old), calving (≤ 2, 3-5, and > 5) and herd size (≤ 100, 101-250, and > 250) and examined by indirect ELISA. The results of this study showed that 109 (25.4%) out of 429 serum samples were BLV seropositive. The BLV prevalence among cattle of dairy herds of Khorasan Razavi and Khorasan Shomali provinces were 29.8% and 1.5%, respectively. The results showed that the number of seropositive animals was increased significantly with the age (p < 0.05). The infection rate in animals 2-3, 4-6 and 7-10 years old were 12.1%, 26.7% and 45.6%, respectively. It was shown that BLV prevalence according to calving ≤ 2, 3-5 and > 5 was 15.5%, 33.0% and 42.9%, respectively, with a significant difference between calving ≤ 2 and > 5 (p < 0.001). The prevalence of BLV among herd size of ≤ 100, 101-250 and > 250 was 19.7%, 14.3% and 42.1%, respectively, which was significantly higher in herds with more than 250 cattle (p < 0.05). This study revealed that BLV infection in dairy herds of northeast of Iran was influenced by geographical location (province), age, calving and herd size.