Veterinary Research Forum

Abstract The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus is the causative agent of the emerging zoonotic respiratory disease. One of the most important prerequisites for combating emerging diseases is the development of vaccines within a short period of time. In this study, antigen-irradiated, inactivated SARS-CoV-2 viruses and the disaccharide trehalose were used to enhance immune responses in the Syrian hamster. The SARS-CoV-2 virus was isolated from tracheal swabs, confirmed by Real-Time Polymerase Chain Reaction (RT-PCR), and propagated on Vero cells. For inactivation, it was irradiated with 14.00 kGy gamma radiation. Evaluation of the antigenic properties of the spike protein subunit S1 showed that the antigens were intact after gamma irradiation. The gamma-irradiated and formalin-treated viruses were used to immunize hamsters in four vaccine formulations. Neutralizing antibodies increased significantly in all vaccinated groups three weeks after the second and third vaccinations. The concentration of secretory immunoglobulin A in the irradiated vaccine plus trehalose increased significantly in nasal lavage and nasopharyngeal-associated lymphoid tissue fluids three weeks after the second and third vaccinations. The lymphocyte proliferation test in the spleen showed a significant increase in all vaccinated hamsters, but the increase was greater in irradiated vaccine plus trehalose and irradiated vaccine plus alum. We can recommend the irradiated inactivated vaccine SARS-CoV-2 plus trehalose (intra-nasal) and another irradiated inactivated vaccine SARS-CoV-2 plus alum (subcutaneous) as safe vaccines against coronavirus disease of 2019 (COVID-19), which can stimulate mucosal, humeral, and cellular immunities. However, the protectivity of the vaccine against COVID-19 in vaccinated hamsters must be investigated in a challenge test to assess the potency and efficiency of vaccine.

Abstract Purification is an important step in the production of viral vaccines that strongly affects product recovery and subsequent immune responses. The present study was carried out with the aim of improving the purification of infectious bursal disease virus (IBDV) by the tangential flow filtration (TFF) method. Then, the effect of the purified virus on the induction of immune responses against IBDV in specific pathogen free (SPF) chickens was investigated. The IBD07IR strain was propagated in embryonated SPF eggs. The virus was purified using a 100 kDa cassette. The quality of the recovered viruses was evaluated by titration. A total number of 60 SPF chickens were randomly divided into three groups (n = 20) and received the concentrated viral antigen, commercial live IBDV vaccine and phosphate-buffered saline at the age of 3 weeks by eye drop method. The bursa of Fabricius was examined histopathologically for possible changes. Sera were collected at 1-week intervals from day 0 until the end of 6 weeks after vaccination. The IBDV-specific antibody levels, induction of cell-mediated immunity and mRNA expression levels of cytokines were evaluated. The results showed that despite a relative raise in virus titer from 7.66 to 8.17 embryo infectious dose (EID)₅₀ mL^-1 following purification, both the purified IBDV and commercial vaccine are able to induce strong immune responses against the virus. Within a context of egg-based IBDV vaccine production, a single-step TFF can be applied for the relatively purification. This platform requires a further study in the selection of multiple membranes to optimize the operating conditions and final product.

Abstract The objective of the present study was to evaluate the alterations in selected indicators of immune responses and oxidative stress of broilers fed with nano-manganese. One hundred-sixty 1-day-old broiler chicks were randomly assigned into four groups with three replicates. Birds were fed the same basal diet supplemented with nano-manganese oxide, as 0.00 (control group), 50.00, 100, or 150 mg kg^-1 of diet. The birds were vaccinated against avian influenza (AI), Newcastle disease (ND), infectious bronchitis (IB) and infectious bursal disease (IBD) as the standard vaccination schedule. Blood sample was taken from the brachial vein of birds on 42^th day. A significant decrease in antibody titer against sheep RBC was revealed in the nano-manganese 100 and 150 groups compared to the control group. In addition, the antibody titers against IB and ND were significantly lower in the all nano-manganese groups compared to the control group. No significant difference was observed for the antibody titer against AI and oxidative stress indices among the experimental groups. The findings in the present study suggested that nano-manganese at 50.00, 100 and 150 mg kg^-1 levels might suppress humoral immune response in broilers which should be taken into consideration in supplementation.