Effects of cLFchimera, a recombinant antimicrobial peptide, on intestinal morphology, microbiota, and gene expression of immune cells and tight junctions in broiler chickens challenged withC. perfringens

Abstract

24The current study was conducted to investigate the effects of cLFchimera, a recombinant 25 antimicrobial peptide (AMP), on various productive performance and gut health attributes of 26 broilers experimentally challenged with Clostridium perfringens (Cp). Three hundred and sixty 1-27 day-old chickens were randomly allocated to 4 treatments of 6 replicates as follows: T1) 28 unchallenged group fed with corn-soybean meal (CSM) without Cp challenge and additives; T2) 29 challenge group fed with CSM and challenged with Cp without any additives; T3) peptide group 30 challenged with NE supplemented with 20 mg cLF36/kg diet (AMP); T4) antibiotic group 31 challenged with NE and supplemented with 45 mg antibiotic (bacitracin methylene disalicylate)/kg 32 diet (antibiotic). Birds had free access to feed and water, sampling for villi morphology and ileal 33 microbiota were performed on days 10 and 22, while jejunal section was sampled for gene 34 expression of cytokines, tight junctions proteins, and mucin only on day 22. Results showed that 35 AMP ameliorated NE-related lesion in the jejunum and ileum and reduced mortality in challenged 36 birds compared to challenge group with Cp without any additives. Also, supplementing challenged 37 birds with AMP improved growth performance and reconstructed villi morphology. While 38 antibiotic non-selectively reduced the count of bacteria, AMP positively restored ileal microflora 39 in favor of good bacteria (i.e. Bifidobacteria spp. and Lactobacillus spp.). AMP beneficially 40 regulated the expression of cytokines, junctional proteins, and mucin in the jejunum of challenged 41 birds with Cp. Since cLFchimera ameliorated NE lesion score, reduced mortality, improved 42 productive performance and gut health attributes in chickens compared to challenged group and 43 also were mostly similar with those of antibiotics and therefore, it could be concluded that this 44 chimeric peptide can be a worthy candidate to substitute growth promoter antibiotics, while more 45 research is required to unveil the exact mode of action of this synthetic peptide. 46 47 Author summary 48 Necrotic enteritis (NE) is a detrimental enteric disease in the poultry industry worldwide. The 49 etiological factor of this disease is Clostridium perfringens, which is gram-positive anaerobic 50 bacterium. This bacterium is common inhabitant of the intestine in lower counts (105), but it 51 becomes pathogenic in higher counts and can secrete NetB toxin, which is the main cause of 52 inducing NE in broilers. Due to the emergence of antibiotic-resistant bacteria, new generation of 53 antimicrobial additives such as antimicrobial peptides (AMPs) has been introduced to the poultry 54 industry. AMPs are small molecules with 12-50 amino acids having antibacterial activity. 55 Recently, we extracted new AMP from camel milk, expressed in E. coli, refined and lyophilized 56 to produce purified peptides. The current study investigated the effects of this peptide on 57 prevention of NE in broilers. Results showed th...