Progress and problems in vaccination against necrotic enteritis in broiler chickens

Abstract

Necrotic enteritis in broilers is caused by Clostridium perfringens type A strains that produce the NetB toxin. Necrotic enteritis is one of the gastrointestinal diseases in poultry that has gained worldwide importance during the last decade due to efforts to improve broiler performance. Prevention strategies include avoiding predisposing factors, such as coccidiosis, and in-feed supplementation with a variety of feed additives. However, vaccination with modified toxin or other secreted immunogenic proteins seems a logical preventive tool for protection against a toxin-producing bacterium. Formalin-inactivated crude supernatant has been used initially for vaccination. Several studies have been carried out recently to identify the most important immunogenic and protective proteins that can be used for vaccination. These include the NetB toxin, as well as a number of other proteins. There is evidence that immunization with single proteins is not protective against severe challenge and that combinations of different antigens are needed. Most published studies have used multiple dosage vaccination regimens that are not relevant for practical use in the broiler industry. Single vaccination regimens for 1-day-old chicks appear to be non-protective. This review describes the history of vaccination strategies against necrotic enteritis in broilers and gives an update on future vaccination strategies that are applicable in the field. These may include breeder hen vaccination, in ovo vaccination and live attenuated vectors to be used in feed or in drinking water

Design and Expression Optimization of a Chimeric Derivative of NetB, Alpha-Toxin and Metallopeptidase Proteins as a Subunit Vaccine Against Clostridium perfringens

“…The designation of fusion subunit vaccine encompassing the immunogenic segments from individual toxin against NE is a promising recent approach [8]. Mot et al and Uzal et al, have shown for protection against NE, administration of multiple antigens like Alpha-toxin and NetB toxin could elicit better immunogenicity and protection than each antigen alone [16,32]. Rostami et al, designed a fusion protein consisting of immunogenic parts of three virulence factors of NetB-Alpha toxin-Tpel(NAT) to be used as vaccine against necrotic enteritis [27].…”

Recent breakthroughs have unveiled the many knowledge gaps inClostridium perfringens-associated necrotic enteritis in chickens: the first International Conference on Necrotic Enteritis in Poultry

“…Although NetB has been identified as a key toxin involved in disease (Keyburn et al, 2008), this has still not led to the development of a vaccine for broilers (Mot et al, 2014). Several antigens in addition to NetB seem to be important in immunoprotection.…”

Spotlight on avian pathology: untangling contradictory disease descriptions of necrotic enteritis and necro-haemorrhagic enteritis in broilers

“…Originally, alpha toxin was considered to be the main virulence factor for NE, until the NetB toxin was identified as a crucial factor in disease pathogenesis (Keyburn et al, 2008;. Since then, a lot of research has been conducted on the identification of risk factors, pathogenesis, and preventive measures of NetB-associated NE (Mot et al, 2014;Moore, 2016;Prescott et al, 2016;Wade et al, 2016Wade et al, , 2020Calik et al, 2019). However, despite the overwhelming evidence of the importance of NetB-producing type G strains in NE pathogenesis, this is still a matter of debate in the scientific community, with some research groups describing the isolation of netB-negative type A strains from diseased birds (Yin et al, 2017;Li et al, 2018;Zhang et al, 2019).…”