Timing and delivery route effects of cecal microbiome transplants on Salmonella Typhimurium infections in chickens: potential for in-hatchery delivery of microbial interventions.

BACKGROUND: Exposure to microbes early in life has long-lasting effects on microbial community structure and function of the microbiome. However, in commercial poultry settings chicks are reared as a single-age cohort with no exposure to adult birds which can have profound effects on microbiota development and subsequent pathogen challenge. Microbiota manipulation is a proven and promising strategy to help reduce pathogen load and transmission within broiler flocks. However, administration of microbiota transplant products in a hatchery setting may prove challenging. Effective administration strategies are dependent on key factors, such as; the age of chicks receiving interventions and mode of delivery. This study aimed to assess these two aspects to provide supporting evidence towards microbiome manipulation strategies for use in commercial hatcheries. RESULTS: Manipulation of the microbiota between 4 and 72 h of hatch markedly reduced faecal shedding and colonisation with the foodborne pathogen Salmonella enterica serovar Typhimurium (ST4/74). Administration of transplant material via spray or gel drop delivery systems had minimal effect on the protection conferred with fewer birds in transplant groups shown to shed ST4/74 in the faeces compared to PBS-gavaged control birds. Analysis of the microbiome following transplantation demonstrated that all transplant groups had higher diversity and species richness than non-transplant groups during the first week of life and the early stages of infection with ST47/4.The relative abundance of the bacterium Faecalibacterium prausnitzii was significantly higher in CMT groups compared to PBS controls. The presence of F. prausnitzii was also shown to increase in PBS-challenged birds compared to unchallenged birds potentially indicating a role of this bacterium in limiting Salmonella infections. CONCLUSIONS: This study demonstrated that administration of microbiome transplants, using methods that would align with hatchery practices, effectively reduced colonisation and shedding of Salmonella in chickens. Age of chicks at microbiome administration had limited effect on the diversity and composition of the microbiome and conferred protection against Salmonella infections. Traditional hatchery delivery systems, such as spray or gel-drop, are sufficient to transfer donor material, alter the microbiome and confer protection against Salmonella. This study helps highlight the opportunity for use of microbiome modification methods within the hatchery.

Correction to: A role for tetraspanin proteins in regulating fusion induced by Burkholderia thailandensis.

In the original article, incorrect  figures were published with incorrect captions. The correct figures and captions are given below.

A role for tetraspanin proteins in regulating fusion induced by Burkholderia thailandensis.

Burkholderia pseudomallei is the causative agent of melioidosis, a disease with high morbidity that is endemic in South East Asia and northern Australia. An unusual feature of the bacterium is its ability to induce multinucleated giant cell formation (MNGC), which appears to be related to bacterial pathogenicity. The mechanism of MNGC formation is not fully understood, but host cell factors as well as known bacterial virulence determinants are likely to contribute. Since members of the tetraspanin family of membrane proteins are involved in various types of cell:cell fusion, their role in MNGC formation induced by Burkholderia thailandensis, a mildly pathogenic species closely related to B. pseudomallei, was investigated. The effect of antibodies to tetraspanins CD9, CD81, and CD63 in MNGC formation induced by B. thailandensis in infected mouse J774.2 and RAW macrophage cell lines was assessed along with that of recombinant proteins corresponding to the large extracellular domain (EC2) of the tetraspanins. B. thailandensis-induced fusion was also examined in macrophages derived from CD9 null and corresponding WT mice, and in J774.2 macrophages over-expressing CD9. Antibodies to CD9 and CD81 promoted MNGC formation induced by B. thailandensis, whereas EC2 proteins of CD9, CD81, and CD63 inhibited MNGC formation. Enhanced MNGC formation was observed in CD9 null macrophages, whereas a decrease in MNGC formation was associated with overexpression of CD9. Overall our findings show that tetraspanins are involved in MNGC formation induced by B. thailandensis and by implication, B. pseudomallei, with CD9 and CD81 acting as negative regulators of this process.