Effect of experimental Ornithobacterium rhinotracheale infection along with live infectious bronchitis vaccination in broiler chickens

Abstract

Ornithobacterium rhinotracheale (ORT), a bacterium causing respiratory tract infection, has led to a significant problem in the intensive poultry production in Egypt. Polymerase chain reaction-amplified 784bp specific ORT DNA fragments were found in 7 ORT isolates from lungs, air sacs, and tracheas of commercial broilers or layers in Egypt in 2015. The objective of this study was to investigate the role of the live variant IBV 4/91 with ORT infection. A total of 120 14-d-old broiler chickens (Cobb 500) were equally divided into 4 groups for experimental infection in a complete randomized design. Group 1 was infected with ORT strain and live infectious bronchitis vaccine (IBV 4/91) simultaneously; group 2 was infected with the bacterial strain alone; group 3 was vaccinated only with IBV 4/91, and group 4 was the non-vaccinated and non-infected control group. The respiratory signs, post-mortem lesions (tracheitis and pneumonia) and histopathological findings of lungs, trachea, and air sacs in the experimentally infected broiler chickens appeared to be more prominent in the chickens of group 1 than group 2. With respect to body weight, weight gain, feed conversion rate, and Ornithobacterium re-isolation, there was a difference (P ≤ 0.05) among the chickens of group 1 and the other groups. This reveals that the use of live infectious bronchitic vaccines, which is a common practice in the local Egyptian field of production, may concomitantly increase the pathogenicity of ORT in broiler chickens.

Ornithobacterium rhinotracheale: An Update Review about An Emerging Poultry Pathogen

“…Generally, an attenuated vaccine is not recommended due to ORT pathogenicity. In Egypt, Ellakany et al investigated the role of a live variant IVB 4/91 vaccine in ORT infection and revealed that its use can simultaneously increase the pathogenicity of ORT [93]. However, one study evaluated the use of a live, temperature-sensitive mutant vaccine administered by oculonasal instillation in one-day-old turkey.…”

Research Note: Serological investigation of Ornithobacterium rhinotracheale infection in China

“…ORT can cause retarded growth, decreased egg production, and increased mortality and has been associated with avian respiratory disease. Viral infections caused by avian metapneumovirus, infectious bronchitis virus, and Newcastle disease virus and bacterial infections caused by Avibacterium paragallinarum , Bordetella avium , and Escherichia coli can cause severe clinical symptoms when coinfected with ORT ( Ellakany et al., 2019 ). The severity of ORT depends on the strain pathogenicity and other factors such as age, coinfections, and management practices.…”

Microscopic changes in the organs of broiler chickens with Ornithobacterium rhinotra-cheale infection

“…Similar microscopic changes were observed in the trachea of 60-day-old quails with ornithobacteriosis, which were characterized by slight degeneration and desquamation of the mucosal epithelium, edema of the lamina propria, edema and congestion, hemorrhages of varying severity and incendiary cell infiltration (Kapakin et al, 2013). Other studies three days after experimental infection of broiler chickens aged 14 days with the causative agent of ornithobacteriosis established: tracheal mucosa with signs of catarrhal tracheitis, goblet cell hyperplasia, lymphocyte infiltration, loss of cilia, hyperplasia of the mucous membrane and glandular epithelium, stagnant phenolmena and infiltration by mononuclear cells (Ellakany et al, 2019). In the spleen, diffuse parenchymal edema and a decrease in the number of lymphocytes in lymphoid follicles were noted.…”

“…Bacteriological studies are essential for the diagnosis, since microscopic changes in a number of diseases can be similar. In particular, studies by Hany Ellakany and Hatem Hamid have established that similar microscopic changes occur for mycoplasmosis and ornithobacteriosis, and the causative agents of these disea-ses can develop together, mutually reinforcing the pathogenic effect (Ellakany et al, 2019).…”

“…The causative agent Ornithobacterium rhinotracheale often acts as a secondary bacterial infection, which aggravates the course of other viral and bacterial diseases. It is diagnosed in cases of infectious bronchitis, laryngotracheitis, hemophilia, metapneumovirus infection, escherichiosis and aspergillosis (Morales-Erasto et al, 2016;Chu et al, 2017;Ellakany et al, 2019).…”