The effect of infectious bursal disease virus infection on gut microbiota of broiler chicken and the role of prebiotics and probiotics on correction of gut dysbiosis using analysis of 16s rRNA gene sequencing

Abstract

The infectious bursal disease (IBD) virus (IBDV) causes intestinal inflammation and dysbiosis of the gut microbiota by replicating in the bursa of Fabricius and gut associated lymphoid tissues (GALT), to cause gut dysbiosis that results in poor productivity associated with high morbidity and mortality in the susceptible birds. The aim of the work was to study the gut dysbiosis associated with IBD infection and how prebiotic and probiotic prophylaxis could overcome this dysbiosis. Thus, a total of 108-day-old chicks were divided into 6 groups (18 birds each) and 4 groups were administered prophylaxis treatments for 5 days namely Enterococcus faecium (P1), Saccharomyces cerevisiae (P2), organic acids (OAs) (P3) and synbiotic (P4) before IBDV inoculation; the remaining 2 groups were control negative (CN) and control positive (CP). At 14 days of age, all groups except for CN were challenged via eye drop with IBDV (strain MK088026). The clinical signs, postmortem lesions (PM), mortality, bursal index (BI), immune response, body weight gain (BWG), feed intake (FI), feed conversion rate (FCR), caecum villi morphometry and gut microbiome profile were studied. At 3 days post infection (dpi), significant decrease in caecum total mucosal thickness (P<0.05) were observed in CP group (204±12.6 µm) compared to CN group (266±16 µm) while it was corrected in infected prophylaxis groups P1 (310±10.5 µm), P2 (320±13.4 µm), P3 (267±13.9 µm) and P4 (265±10.6 µm). Caecal microbiome profile was studied by sequencing of 16S rRNA and metagenomic analysis at 14 days of age and by the 3rd dpi. The CP group showed signs and PM lesions of IBDV with total mortality of 11.1% while other infected prophylaxis groups showed mild signs with no mortality except for S. cerevisiae treated group (mortality 5.6%). At 3 dpi, the IBDV caused significant increase (P<0.05) in the relative abundance of phylum Cyanobacteria and phylum Proteobacteria with non-significant increase in Enterobacteriaceae, Campylobacteracea and Lachnospiraceae with decrease in phylum Bacteroidetes, family Ruminococcaceae, Enterococcaceae, and Lactobacillaceae compared to CN group. The prophylaxis infected groups differed from CP as they showed increase in the relative abundance of phylum Bacteroidetes, family Ruminococcaceae, Enterococcaceae, and family Lactobacillaceae. S. cerevisiae and OAs prophylaxis groups could overcome the increase of family Campylobacteriacea caused by IBDV infection. IBDV infection caused a decrease in total BWG and poorer FCR than the CN, while prophylaxis infected groups showed higher total BWG, and improved FCR. It was concluded that prophylaxis with prebiotic, probiotic and synbiotic are effective and recommended to avoid negative impact of Gumboro vaccination and/or field infection.