Electron beam-killed Staphylococcus vaccine reduced lameness in broiler chickens

Authors: ASSUMPCAO, ANNA - University Of Arkansas; Jesudhasan, Palmy; Arsi, Komala; ALHARBI, KHAWLA - University Of Arkansas; ASNAYANTI, ANDI - University Of Arkansas; TRIEU, ANH - University Of Arkansas; Read, Quentin; PERERA, RUVINDU - University Of Arkansas; SHWANI, ABDULKARIM - Orise Fellow; HASAN, AMER - University Of Arkansas; PILLAI, SURESH - Texas A&M University; Anderson, Robin; Donoghue, Ann - Annie; RHOADS, DOUGLAS - University Of Arkansas; ALRUBAYE, ADNAN - University Of Arkansas

Submitted to: Vaccine
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/20/2024
Publication Date: N/A
Citation: N/A

Interpretive Summary: Broiler chicken lameness caused by Bacterial Chondronecrosis with Osteomyelitis (BCO) was first reported in 1972 and is presently amongst the top-most economic and animal welfare issues faced by the poultry industry. BCO lameness results hundreds of millions of dollars in lost revenue annually in the United States and worldwide due to bird condemnation at the marketing age. BCO is caused by multiple opportunistic bacterial pathogens in the respiratory and gastro-intestinal (GI) tracts. Moreover, inhaled bacterial pathogens from the aerosol of chicken houses may leak from the respiratory system to the blood and eventually colonize the growth plates of long bones leading to lameness. Similarly, bacterial species ingested with the diet can leak from the GI tract to the bloodstream via compromised intestinal tight junctions and colonize the growth plates of long bones. Necrosis of cartilage and bone tissue by such colonized bacteria (typically in the femoral and tibial heads) ultimately causes the birds to be lame. Subclinical BCO lameness infections are widespread and can adversely impact animal well-being and meat quality, which is in turn detrimental to the sustainability and financial profitability of the broiler industry. The regular lameness rate in broiler chickens varies from 3% up to 15%, resulting in mortality rates ranging from 5% to 10%. In the early 2010s, 12.5 billion broiler chickens were estimated to experience leg-related disorders worldwide. However, the latest unpublished report presented by the Tyson Foods industry mentions that current regular loss due to lameness runs up to 6%, nevertheless possessing the potential to reach 15% in case of an outbreak. Considering the broiler production value of $50.4 billion of the United States in 2022, the current estimate of the regular economic loss in chicken meat production due to lameness in the US ranges from $900 million to $1.8 billion. Therefore, the aforementioned impact on the poultry industry added to the absence of efficacious mitigatory measures, vehemently necessitates the development of a successful commercial vaccine for the control of BCO lameness worldwide. To date, there has been no successful vaccine or any intervention method to help reduce the incidence of BCO lameness in Arkansas or the United States or worldwide. There is, therefore, a critical need to develop a vaccine to reduce the financial as well as the health impact of BCO lameness on the poultry industry. Bacterial chondronecrosis with osteomyelitis (BCO) lameness in broiler is caused by several bacterial pathogens including Enterococcus cecorum, Streptococcus spp., Staphylococcus spp, E. coli. BCO is often caused by several species of Staphylococcus and vaccines are known to enhance immunity, thereby reducing colonization, and preventing diseases. It is known that electron beam (eBeam)-killed-Salmonella, and eBeam-killed-Clostridium perfringens prevented colonization in chicken. To prove if the eBeam-killed-Staphylococcus vaccine would reduce BCO lameness, we developed eBeam-killed-Staphylococcus using eBeam technology and conducted bird studies with eBeam-killed-Staphylococcus in broiler chickens. We used formalin-killed-Staphylococcus as a control vaccine in these studies. We vaccinated day-18 broiler chicken embryos (in ovo vaccination). The vaccinated and non-vaccinated birds were housed on floor pens on the hatch day and challenged the birds with S. agnetis (~1x104 CFU/mL) on day 20 and day 21 through the water. We have collected blood samples before and after the challenge to determine the immune parameters. The birds were scored for lameness regularly every day after 22 days post-hatch. All birds were killed on day 56. We found that approximately 50% of the birds in the eBeam vaccinated group was free of lameness compared to the other groups (Formalin-killed vaccine group and positive c

Technical Abstract: Broiler chicken lameness caused by Bacterial Chondronecrosis with Osteomyelitis (BCO) is presently amongst the top-most economic and animal welfare issues faced by the poultry industry. The estimated economic loss in chicken meat production due to lameness in the United States ranges from $900 million to $1.8 billion USD. BCO lameness is caused by multiple opportunistic bacterial pathogens inhabiting the respiratory and gastrointestinal tracts. In cases of immune deficiency by stress, injury, or inflammation of the tissue, opportunistic pathogens, mainly Staphylococcus spp., can infiltrate the respiratory or gastrointestinal mucosa, migrate through the bloodstream to eventually colonize the growth plates of long bones, causing necrosis that leads to lameness. This is the first report of developing a Staphylococcus vaccine against BCO lameness disease in broiler chickens. Our results showed a 50% reduction in the incidence of lameness in chickens treated with the electron Beam (eBeam), which killed the Staphylococcus vaccine compared to the control. Additionally, the eBeam-vaccinated chickens present higher titer of IgA anti-Staphylococcus, signifying the development of an efficient and more specific humoral immune response. Our data establish the eBeam-killed Staphylococcus vaccine as a highly effective approach to reducing the incidence of lameness in broiler chickens.