Antimicrobial peptides as an alternative to relieve antimicrobial growth promoters in poultry

Figures & data

Figure 1. Gut associated lymphoid tissue (GALT): structures and distribution of the primary (Bursa of Fabricius), and secondary lymphoid tissue throughout the gastrointestinal tract

Figure 2. The major classes of avian AMP found in the GI tract

Figure 3. General structure of defensins consists of the signal peptide (yellow), the conserved prosequence (blue), and the cysteine-rich mature peptide (green)

Table 1. Net charges of chicken AvBDs at pH = 7 (Cheng et al. 2015)

Chicken β-defensin	Net charge at pH = 7
AvBD1	+8.00
AvBD2	+4.18
AvBD3	+5.18
AvBD4	+6.08
AvBD5	+3.09
AvBD6	+7.09
AvBD7	+6.00
AvBD8	+0.37
AvBD9	+4.09
AvBD10	+2.09
AvBD11	+6.01
AvBD12	+2.00
AvBD13	+4.46
AvBD14	+7.00

Figure 4. General structure of avian cathelicidins with the signal peptide (purple), the cysteine-rich cathelin-like domain (blue), and the mature peptide sequence (orange) (Zhang and Sunkara 2014)

Figure 5. Amino acid sequences of chicken cathelicidins, with conserved sequences highlighted in red and cysteine residues highlighted in yellow (Zhang and Sunkara 2014)

Figure 6. Amino acid sequences of LEAP-2 in humans, mice, and chickens; with the mature peptide sequences highlighted in red (Townes et al. 2004)

Figure 7. Amino acid sequence of cNKL, with the mature peptide highlighted in red and cysteine residues highlighted in yellow (Lee et al. 2014)

Table 2. Amino acid sequences and properties of cNKL and its synthetic analogues

Peptide	Sequence	Net charge at pH = 7	pI	M.W. (g/mol)
cNKL	GIKCRFCVSL VKKVQKIVGD DPDEDAINNA LNKVCSTGRR QRSICKQLLK KLRQQLSDAL QNNDDPRDVC TTLGLCKG	+5.6	9.15	8,674.01
cNK-2	RRQRSICKQL LKKLRQQLSD ALQNNDD	+3.9	10.85	3,268.71
cNK-3	PDEDAINNAL NKVCSTGRRQ RSICKQLLKK	+3.9	10.43	3,399.91

Cheng, Y., M. D. Prickett, W. Gutowska, R. Kuo, K. Belov, and D. W. Burt. 2015. “Evolution of the Avian β-defensin and Cathelicidin Genes.” BMC Evolutionary Biology 15 (1): 188. doi:https://doi.org/10.1186/s12862-015-0465-3.

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Zhang, G., and L. T. Sunkara. 2014. “Avian Antimicrobial Host Defense Peptides: From Biology to Therapeutic Applications.” Pharmaceuticals 7: 220–247. doi:https://doi.org/10.3390/ph7030220.

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Townes, C. L., G. Michailidis, C. J. Nile, and J. Hall. 2004. “Induction of Cationic Chicken Liver-expressed Antimicrobial Peptide 2 in Response to Salmonella Enterica Infection.” Infection and Immunity 72 (12): 6987–6993. doi:https://doi.org/10.1128/IAI.72.12.6987-6993.2004.

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Lee, M. O., H. Jang, J. Y. Han, and J. E. Womack. 2014. “Chicken NK-lysin Is an Alpha-helical Cationic Peptide that Exerts Its Antibacterial Activity through Damage of Bacterial Cell Membranes.” Poultry Science 93: 864–870. doi:https://doi.org/10.3382/ps.2013-03670.

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