Veterinary Research Forum

Abstract Newcastle disease (ND) is a highly contagious and severe disease that affects birds, including domestic poultry, causing significant economic losses to the poultry industry. The disease is caused by the ND virus (NDV). Despite extensive vaccination efforts against NDV, controlling the disease remains challenging, primarily due to the emergence of new genotypes. Recent attention has focused on calcium phosphate nanoparticles (CaP NPs) as promising adjuvants for vaccines. This study aimed to design and construct CaP NPs containing inactivated NDV genotype VII and evaluate their safety and humoral immunogenicity in chickens. Following virus propagation in specific-pathogen-free eggs and inactivation with formalin, CaP NPs containing inactivated NDV were prepared using in situ and adsorption methods. The NPs were characterized for shape, size, polydispersity index and surface charge. Chickens were immunized subcutaneously with CaP NPs containing inactivated NDV and the humoral immune response against NDV was assessed using HI and enzyme-linked immunosorbent assays. Results showed a significant increase in the mean antibody titer against NDV in chickens treated with both NP structures compared to control groups. No significant difference was observed between the two NP preparation methods. The safety of CaP NPs containing inactivated NDV was confirmed. However, mucosal immunization with these NPs did not yield satisfactory results indicating the need for further research. Overall, this study confirmed the positive role of CaP as an adjuvant in enhancing the humoral immune response against NDV via injection and highlighted the need for continued research on mucosal immunization with the NPs.

Abstract Characterization of isolated pigeon paramyxovirus-1 (PMV-1) and its pathogenicity in broiler chickens were studied. Two hundred and thirty-two samples collected from 50 unvaccinated pigeons lofts suspected to Newcastle disease from private houses and bird markets from Ahvaz‌, Iran. Swab samples from cloaca and oropharynx of live pigeons and from trachea, lung, liver, spleen, kidney, brain, proventriculus and cecal tonsil of dead pigeons suspected to ND were collected. Isolation of the PPMV-1 was performed through intra-allantoic inoculation of 9- to 11- day-old embryonated chicken eggs. The RNA extraction and cDNA synthesis were conducted. With PCR, multiplication of cleavage site of F gene was carreid out and PCR products were sequenced and phylogenetic comparison on isolates was performed. For pathogenecity study of isolated PPMV-1, one hundred sixty day-old broiler chicks were divided into four equal groups. Groups 1 and 2 chicks vaccinated against ND by B1 vaccine at nine days. Groups 3 and 4 were kept as unvaccinated control groups. Groups 1 and 4 chicks were challenged with 10⁵EID₅₀ of highest virulent isolated PPMV-1 by ocular route at day 29. The results indicated PPMV-1 is enzootic in Ahvaz pigeons and all isolates were virulent Newcastle disease virus with 112KRQKR*F117 motif. For study pathogenicity of pigeon isolate in chickens, they challenged with most virulent isolate, showed respiratory signs, conjunctivitis and in some cases depression and lethargy. In conclusion, isolated PPMV-1 is a virulent NDV and can infect chickens and produce mild ND in unvaccinated chickens.

Abstract Increased susceptibility of birds to avian pathogens in intensive husbandry system has emphasized on necessity of improvement of innate and specific immune responses of birds by the fast establishment of a beneficial microflora and immune stimulator factors to guarantee healthy and low-price products. During this study, 192 one-day-old broiler chicks (Ross-380) in four groups with three replicates per group were used to investigate effectiveness of synbiotic Biomin Imbo on immune responses of the chickens following routine vaccination against Newcastle disease (ND), avian influenza (AI), infectious bronchitis (IB) and infectious bursal disease (IBD). The results of this study indicated that supplementation of Biomin Imbo in diet enhanced humoral immune responses significantly in the case of ND, IB, IBD (p = 0.049, p = 0.020, p = 0.036, respectively), but insignificantly in the case of AI (p = 0.160) following vaccination of the chickens against these most common important viral poultry diseases. It was more effective following vaccination with live than killed vaccines. In conclusion, application of synbiotic Biomin Imbo, as a feed-additive adjuvant promotes acquired humoral immune responses of broiler chickens.