Yellow Fever 17DD Vaccine Virus Infection Causes Detectable Changes in Chicken Embryos

The yellow fever (YF) 17D vaccine is one of the most effective human vaccines ever created. The YF vaccine has been produced since 1937 in embryonated chicken eggs inoculated with the YF 17D virus. Yet, little information is available about the infection mechanism of YF 17DD virus in this biological model. To better understand this mechanism, we infected embryos of Gallus gallus domesticus and analyzed their histopathology after 72 hours of YF infection. Some embryos showed few apoptotic bodies in infected tissues, suggesting mild focal infection processes. Confocal and super-resolution microscopic analysis allowed us to identify as targets of viral infection: skeletal muscle cells, cardiomyocytes, nervous system cells, renal tubular epithelium, lung parenchyma, and fibroblasts associated with connective tissue in the perichondrium and dermis. The virus replication was heaviest in muscle tissues. In all of these specimens, RT-PCR methods confirmed the presence of replicative intermediate and genomic YF RNA. This clearer characterization of cell targets in chicken embryos paves the way for future development of a new YF vaccine based on a new cell culture system.     

A gene cluster required for coordinated biosynthesis of lipopolysaccharide and extracellular polysaccharide also affects virulence of Pseudomonas solanacearum.

Bacterial cell surface components can be important determinants of virulence. At least three gene clusters important for extracellular polysaccharide (EPS) biosynthesis have been previously identified in the plant pathogen Pseudomonas solanacearum. We have found that one of these gene clusters, named ops, is also required for lipopolysaccharide (LPS) biosynthesis. Mutations in any complementation unit of this cluster decreased EPS production, prevented the binding of an LPS-specific phage, and altered the mobility of purified LPS in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. However, restoration of LPS biosynthesis alone was not sufficient to restore virulence to the wild-type level, suggesting that EPS is important for pathogenesis.     

Substitution rates of organelle and nuclear genes in sharks: implicating metabolic rate (again)

Rates of nucleotide substitution for nuclear genes are thought to be governed primarily by the number of germ line replication events (the so-called "generation time" hypothesis). In contrast, rates of mitochondrial DNA evolution appear to be set primarily by DNA damage pathways of mutation mediated by mutagenic by-products of oxidative phosphorylation (the so-called "metabolic-rate" hypothesis). Comparison of synonymous substitution rates estimated for the mitochondrial cytochrome b gene and nuclear-encoded dlx, hsp70, and RAG-1 genes in mammals and sharks shows that rates of molecular evolution for sharks are approximately an order of magnitude slower than those for mammals for both nuclear and mitochondrial genes. In addition, there is significant positive covariation of substitution rate for mitochondrial and nuclear genes within sharks. These results, interpreted in light of the pervasiveness of DNA damage by mutagenic by-products of oxygen metabolism to both nuclear and mitochondrial genes and coupled with increasing evidence for cross-genome activity of DNA repair enzymes, suggest that molecular clocks for mitochondrial and nuclear genes may be set primarily by common mutational mechanisms.      

Bacillus Toyonensis BCT-7112T Spores as Parenteral Adjuvant of BoHV-5 Vaccine in a Murine Model

Probiotics and Antimicrobial Proteins - Bacterial spores of the genus Bacillus are being evaluated as adjuvant molecules capable of improving the immune response to vaccines. In this study, we...