Sekhavati, M. H. | bioRxiv Science

bioRxiv2021

Design and Computational Analysis of a Chimeric Avian Influenza Antigen: A Yeast-displayed, Universal and Cross-protective Vaccine Candidate

BackgroundA cross-protective avian influenza vaccine candidate can be designed by using a preserved antigen against mutation in various subtypes of influenza. M2e peptide sequence has remained remarkably unchanged in influenza type A isolated since 1918. MethodsA consensus sequence of M2e peptide was obtained from 31 sequences of H5N8, H5N1, H9N2 and H7N9 subtypes of avian influenza virus isolated from 7 avian species in 5 Asian countries. A partial sequence of flagellin was considered as an adjuvant. Subsequently, two chimeric antigens were designed to be virtually cloned and expressed using PYD1 vector and EBY100 yeast strain. The stability and conformational features of these two antigens were assessed through molecular dynamic (MD) simulations. The detectability of vaccine candidates by a specific monoclonal antibody (MAb148) were estimated through docking studies. ResultsIn spite of significant compactness and stability of the first candidate in comparison with the second design, it was less detectable by MAb148. Contrary to the first chimeric antigen, Van der Waals, electrostatic and binding energies of the interaction of the second antigen with MAb148 were significantly closer to the positive control. It is shown that epitopes of the second chimeric antigen could be correctly located in the specific pocket of CDR region of MAb148. ConclusionThe second chimeric antigen could be considered as a yeast-displayed avian influenza vaccine candidate due to the capability of provoking humoral immunity and innate immune system by M2e and flagellin respectively.

bioinformatics↗

bioRxiv2019

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

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

pathology↗