Supplemental magnolol or honokiol attenuates adverse effects in broilers infected with Salmonella pullorum by modulating mucosal gene expression and the gut microbiota

Background:Salmonella pullorum is one of the most harmful pathogens to avian species.Magnolol and honokiol,natural compounds extracted from Magnolia officinalis,exerts anti-inflammatory,anti-oxidant and antibacterial activities.This study was conducted to evaluate the effects of dietary supplemental magnolol and honokiol in broilers infected with S.pullorum.A total of 360 one-day-old broilers were selected and randomly divided into four groups with six replicates:the negative control group(CTL),S.pullorum-infected group(SP),and the S.pulloruminfected group supplemented with 300 mg/kg honokiol(SPH)or magnolol(SPM).Results:The results showed that challenging with S.pullorum impaired growth performance in broilers,as indicated by the observed decreases in body weight(P<0.05)and average daily gains(P<0.05),along with increased spleen(P<0.01)and bursa of Fabricus weights(P<0.05),serum globulin contents,and the decreased intestine villus height and villus/crypt ratios(P<0.05).Notably,supplemental magnolol and honokiol attenuated these adverse changes,and the effects of magnolol were better than those of honokiol.Therefore,we performed RNA-Seq in ileum tissues and 16S rRNA gene sequencing of ileum bacteria.Our analysis revealed that magnolol increased the α-diversity(observed species,Chao1,ACE,and PD whole tree)and β-diversity of the ileum bacteria(P<0.05).In addition,magnolol supplementation increased the abundance of Lactobacillus(P<0.01)and decreased unidentified Cyanobacteria(P<0.05)both at d 14 and d 21.Further study confirmed that differentially expressed genes induced by magnolol and honokiol supplementation enriched in cytokine-cytokine receptor interactions,in the intestinal immune network for IgA production,and in the cell adhesion molecule pathways.Conclusions:Supplemental magnolol and honokiol alleviated S.pullorum-induced impairments in growth performance,and the effect of magnolol was better than that of honokiol,which could be partially due to magnolol’s ability to improve the intestinal microbial and mucosal barrier.

Construction and Characterization of a Novel Bacmid AcBac-Syn Based on a Synthesized Baculovirus Genome

Baculoviruses are large DNA viruses which have been widely used as expression vectors and biological insecticides.Homologous recombination and Bac-to-Bac system have been the main methods for manipulating the baculovirus genome.Recently, we generated a synthetic baculovirus Ac MNPV-WIV-Syn1 which fully resembled its parental virus Autographa californica multiple nucleopolyhedrovirus(Ac MNPV). Here, we report the modification of Ac MNPV-WIV-Syn1 into a novel bacmid, Ac Bac-Syn, which can be used as a backbone for Bac-to-Bac system. To achieve this, a vector contained a Lac Z:att Tn7 and egfp cassette was constructed, and recombined with a linearized Ac MNPV-WIV-Syn1 genome by transformation-associated recombination in yeast to generate bacmid Ac Bac-Syn. The bacmid was then transfected to insect cells and the rescued virus showed similar biological characteristics to the wild-type virus in terms of the kinetics of budded virus production, the morphology of occlusion bodies, and the oral infectivity in insect larvae. For demonstration, a red fluorescent protein gene Dsred was transposed into the att Tn7 site by conventional Bac-to-Bac method, and the transfection and infection assays showed that Ac Bac-Syn can be readily used for foreign gene insertion and expression.Ac Bac-Syn has several advantages over the conventional Ac MNPV bacmids, such as it contains an egfp reporter gene which facilitates visualization of virus propagation and titration;its DNA copy numbers could be induced to a higher level in E. coli;and the retaining of the native polyhedrin gene in the genome making it an attractive system for studying the functions of gene related to occlusion body assembly and oral infection.