Protective effect of in ovo treatment with the chicken cathelicidin analog D-CATH-2 against avian pathogenic E. coli

Abstract

Increasing antibiotic resistance and ever stricter control on antibiotic use are a driving force to develop alternatives to antibiotics. One such strategy is the use of multifunctional Host Defense Peptides. Here we examined the protective effect of prophylactic treatment with the D analog of chicken cathelicidin-2 (D-CATH-2) against a respiratory E. coli infection. Chickens were treated with D-CATH-2 in ovo at day 18 of embryonic development or intramuscularly at days 1 and 4 after hatch. At 7 days of age, birds were challenged intratracheally with avian pathogenic E. coli. Protection was evaluated by recording mortality, morbidity (Mean Lesion Score) and bacterial swabs of air sacs at 7 days post-infection. In ovo D-CATH-2 treatment significantly reduced morbidity (63%) and respiratory bacterial load (>90%), while intramuscular treatment was less effective. D-CATH-2 increased the percentage of peripheral blood lymphocytes and heterophils by both administration routes. E. coli specific IgM levels were lower in in ovo treated animals compared to intramuscular D-CATH-2 treatment. In short, in ovo treatment with the Host Defense Peptide derived D-CATH-2 can partially protect chickens from E. coli infection, making this peptide an interesting starting point to develop alternatives to antibiotics for use in the poultry sector.

In ovodelivery of various biological supplements, vaccines and drugs in poultry: current knowledge

“…Results revealed that prophylactic treatment of chickens with D‐CATH‐2 on day 18 of embryonic development through the in ovo method significantly reduced morbidity (63%) and respiratory bacterial load of avian pathogenic E. coli . Such findings support the assumption that the rational use of host defense peptide‐derived D‐CATH‐2 can be a suitable alternative to antibiotics in the poultry sector when used by the in ovo route …”

“…Such findings support the assumption that the rational use of host defense peptide-derived D-CATH-2 can be a suitable alternative to antibiotics in the poultry sector when used by the in ovo route. 163,164 The in ovo route is also used by researchers to assess any toxicity produced by commercially available insecticides; namely, chlorpyrifos, cypermethrin, and spinosad during the development stage in fertilized eggs of Rhode Island Red chickens. Pesticides have been administered via in ovo in a single dose in different concentrations and combinations.…”

Cathelicidins: Immunomodulatory Antimicrobials

“…Additive transgenic expression of porcine cathelicidin PR-39 in normal mice ameliorates the infection’s necrotic phenotype [ 59 ]. In vivo treatment of 18-day-old fertilized chicken eggs with D-chCATH-2 protects chicks from avian Escherichia coli ( E. coli ) infections when they are challenged 7 days after hatching [ 60 ]. The amount of peptide still present in the organs at that time is sufficiently low to conclude that the anti-infective properties of chCATH-2 are likely derived from immunomodulation.…”

Antiviral Activity of Chicken Cathelicidin B1 Against Influenza A Virus

“…Besides having broad antibacterial activity, it can inhibit LPS-induced TLR4 activation and enhance DNA-induced TLR21 activation in macrophages (Coorens et al, 2015;Coorens et al, 2017). Furthermore, CATH-2 treatment in ovo has been described to reduce mortality induced by avian pathogenic E. coli in chicken (Cuperus et al, 2016). Less information is known about the other chicken cathelicidins.…”