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Abstract The vaccine Mycobacterium bovis Bacillus Calmette-Guérin (BCG) elicits an immune response that is protective against certain forms of tuberculosis (TB); however, because BCG efficacy is limited it is important to identify alternative TB vaccine candidates. Recently, the BCG deletion mutant and vaccine candidate BCGΔBCG1419c was demonstrated to survive longer in intravenously infected BALB/c mice due to enhanced biofilm formation, and better protected both BALB/c and C57BL/6 mice against TB-induced lung pathology during chronic stages of infection, relative to BCG controls. BCGΔBCG1419c-elicited protection also associated with lower levels of proinflammatory cytokines (i.e. IL6, TNFα) at the site of infection in C57BL/6 mice. Given the distinct immune profiles of BCG- and BCGΔBCG1419c-immunized mice during chronic TB, we set out to determine if there are early immunological events which distinguish these two groups, using multi-dimensional flow cytometric analysis of the lungs and other tissues soon after immunization. Our results demonstrate a number of innate and adaptive response differences between BCG- and BCGΔBCG1419c-immunized mice which are consistent with the latter being longer lasting and potentially less inflammatory, including lower frequencies of exhausted CD4+ T helper (TH) cells and higher frequencies of IL10-producing T cells, respectively. These studies suggest the use of BCGΔBCG1419c may be advantageous as an alternative TB vaccine candidate.

Platycladus orientalis leaves are rich in flavonoids and polysaccharides, which offer high medicinal and nutritional benefits. This study aimed to investigate the impact of P. orientalis leaf extract (PLE) on the growth performance, fur quality, serum parameters, and intestinal microbiota of raccoon dogs. Sixty healthy male black raccoon dogs, aged 85 (±5) days, were randomly assigned to four groups and fed a basal diet supplemented with 0, 0.25, 0.50, and 1.00 g/kg PLE for 125 days (designated as groups P0, P1, P2, and P3, respectively). The results revealed that the raccoon dogs in group P1 exhibited increased average daily gain and underfur length while showing a decreased feed/gain ratio compared to group P0 (p < 0.05). However, the heart index in group P2 was significantly lower than in group P0 (p < 0.05), and the kidney index and serum alanine aminotransferase activities in group P3 were higher than in groups P2 and P0 (p < 0.05), suggesting potential adverse effects at higher PLE dosages. Notably, dietary PLE supplementation led to a reduction in serum glucose concentrations (p < 0.05), which may have implications for glucose regulation. Furthermore, the study explored the impact of dietary supplementation with 0.25 g/kg PLE on the raccoon dogs’ intestinal microbiota using high-throughput sequencing. The results showed significant alterations in the microbial community structure, with a notable decrease in the abundance of Prevotella copri in response to 0.25 g/kg PLE supplementation (p < 0.05). In conclusion, supplementing raccoon dogs’ diet with 0.25 g/kg PLE can lead to improved growth performance and a positive influence on the intestinal microbiota. However, caution should be exercised regarding higher dosages, as they may have adverse effects on certain parameters. As a result, PLE holds promise as a potential feed additive for fur animal production.