Synthetic double-stranded RNA induces innate immune responses similar to a live viral vaccine in humans.

Adjuvants are critical for the success of vaccines. Agonists of microbial pattern recognition receptors (PRRs) are promising new adjuvant candidates. A mechanism through which adjuvants enhance immune responses is to stimulate innate immunity. We studied the innate immune response in humans to synthetic double-stranded RNA (polyinosinic:polycytidylic acid [poly IC] stabilized with poly-L-lysine [poly ICLC]), an agonist for toll-like receptor (TLR) 3, and the cytosolic RNA helicase MDA-5. Transcriptional analysis of blood samples from eight volunteers, after subcutaneous administration of poly ICLC, showed up-regulation of genes involved in multiple innate immune pathways in all subjects, including interferon (IFN) and inflammasome signaling. Blocking type I IFN receptor ex vivo significantly dampened the response to poly IC. Comparative transcriptional analysis showed that several innate immune pathways were similarly induced in volunteers immunized with the highly efficacious yellow fever vaccine. Therefore, a chemically defined PRR agonist like poly ICLC can be a reliable and authentic microbial mimic for inducing innate immune responses in humans.

A microbial community analysis of the octocoral Eunicea fusca

While there is a significant and growing body of knowledge describing the microbial communities of marine invertebrates such as sponges, there are very few such studies focused on octocorals. The octocoral Eunicea fusca is common on reefs in various regions of the Caribbean and has been the subject of natural product investigations. As part of an effort to describe the microbial community associated with octocorals, a culture-independent analysis of the bacterial community of E. fusca was conducted. Specifically, a 16S rDNA clone library analysis was performed to provide baseline data. A total of 40 bacteria members from 11 groups were found. In general, Proteobacteria were the dominant group with a total of 24 species and α-Proteobacteria represented the highest percentage of bacteria associated with E. fusca (27.5 percent). Other prominent groups observed were Acidobacteria, Actinobacteria, Cyanobacteria, Planctomycetes, delta-Proteobacteria, Lentisphaerae and Nitrospirae. This is the first analysis of bacterial populations associated with the gorgonian E. fusca.

The diversity of the bacterial communities associated with the azooxanthellate hexacoral Cirrhipathes lutkeni.

This study examined the symbiotic microbiota of the hexacoral Cirrhipathes lutkeni using traditional plate culture, fluorescence in situ hybridization (FISH) and 16S rDNA characterization. FISH counts for the whole coral (holobiont) showed a major presence of gamma-Proteobacteria (22%) and Actinobacteria (19%), followed by alpha-Proteobacteria (14%), Firmicutes (9%), Cytophaga-Flavobacterium (7%), beta-Proteobacteria (6%) and Chloroflexi (2%). In contrast to the diversity observed by FISH, plate cultures were found to be selective for gamma-Proteobacteria (22 cultures) with the exception of an Actinobacterium. The methods employed in this study detected 76% of all microbes estimated by DAPI staining of C. lutkeni homogenates. The absence of zooxanthellae in this particular hexacoral was confirmed by PCR and spectrophotometry using fresh tissue isolated from the holobiont. This is the first study describing the microbial associations of shallow-water hexacorallia, which opens further insight into coral microbial ecology and may enhance the search for novel natural products in the near future.