A novel Bursin-like peptide as a potential virus inhibitor and immunity regulator in SPF chickens infected with recombinant ALV

Abstract

BackgroundAvian leukosis viruses (ALVs) are important contagious suppressive factors of chicken immunity and growth performance, resulted in enormous economic loss. Although virus eradication programs are applied in breeder flocks, ALVs are still widespread globally. Therefore, other valuable adjunct to reduce the negative effect of ALVs should be considered. Bursin-like peptide (BLP) showed remarkable immunomodulatory effects, whereas their influence on ALV-infected avian groups has not been reported. Here, a designed hybrid BLP was expressed in E. coli. The purified BLP was injected subcutaneously weekly in SPF chickens congenitally infected with a natural ALV strain. Then the influences of this BLP on the growth performance, immune response and virus titer of ALV-infected chickens were determined.ResultsThis BLP injection significantly improved the body weights of ALV-infected birds (P < 0.05). BLP injection significantly enhanced organ index in the BF in ALV-infected birds (P < 0.05). The weekly injection of BLP significantly lengthened the maintenance time of antibodies against Newcastle disease virus (NDV) attenuated vaccine of ALV-infected birds (P < 0.05) and boosted the antibody titer against avian influenza virus (AIV) H5 inactive vaccine of mock chicken (P < 0.05). BLP injection in mock chickens enhanced the levels of serum cytokines (IL-2, IL-4 and interferon-γ) (P < 0.05). Surprisingly, the novel BLP significantly inhibited expression of the ALV gp85 gene in the thymus (P < 0.05), kidney (P < 0.05) and bursa of Fabricius (BF) (P < 0.01) of ALV-infected chickens. Both viral RNA copy number and protein level decreased significantly with BLP (50 μg/mL) inoculation before ALV infection in DF1 cells (P < 0.05).ConclusionsThis is the first report investigating the influence of BLP on the growth and immunity performance of chickens infected by ALV. It also is the first report about the antiviral effect of BLP in vivo and in vitro. This BLP expressed in E. coli showed potential as a vaccine adjuvant, growth regulator and antiretroviral drug in chickens to decrease the negative effects of ALV infection.

Review of antiviral peptides for use against zoonotic and selected non-zoonotic viruses

“…This virus is also a naturally occurring avian virus that affects poultry worldwide causing enormous economic issues in the poultry industry since its emergence [80]. In this sense programs for virus eradication should be applied to reduce economic damage caused by ALVs [81].…”

“…Zeng et al (2019) evaluated a novel recombinant hybrid polypeptide based on bursin peptide. It was previously demonstrated that bursin, a tripeptide (Lys-His-Gly-NH2) hormone selectively stimulates avian B cell differentiation [81] and promotes immune-globulin (Ig) switching from IgM to IgG [9]. Furthermore, a novel stabilized bursin mimetics, Gagnon's tetrapeptide (Lys-Asn-Pro-Tyr), induces the selective expansion of B cells as well as the stimulation of cytotoxic T lymphocytes [10].…”

“…On the other hand, BLP treatment subsequently applied to virus inoculation did not significantly reduce virus infection. Overall the authors stated that peptide BLP showed potential as an antiretroviral drug in chickens diminishing the effects of ALV infection [81].…”

Transcriptomic analysis of spleen B cell revealed the molecular basis of bursopentin on B cell differentiation

“…Bursin is the first active factor with a clear tripeptide structure Lys-His-Gly-NH2 derived from BF, and selectively induces B-cell-differentiation [ 4 , 5 ]. Bursin-like peptide (BLP) is reported to have the potential as a virus inhibitor and immunity regulator to decrease the negative effects of ALV infection in SPF chickens [ 6 ]. BP-IV induces a strong humoural and cellular immune response for the epitope peptide vaccine for H9N2 subtype AIV [ 7 ].…”