A persistent giant algal virus, with a unique morphology, encodes an unprecedented number of genes involved in energy metabolism.

Viruses have long been viewed as entities possessing extremely limited metabolic capacities. Over the last decade, however, this view has been challenged, as metabolic genes have been identified in viruses possessing large genomes and virions-the synthesis of which is energetically demanding. Here, we unveil peculiar phenotypic and genomic features of Prymnesium kappa virus RF01 (PkV RF01), a giant virus of the Mimiviridae family. We found that this virus encodes an unprecedented number of proteins involved in energy metabolism, such as all four succinate dehydrogenase (SDH) subunits (A-D) as well as key enzymes in the ß-oxidation pathway. The SDHA gene was transcribed upon infection, indicating that the viral SDH is actively used by the virus- potentially to modulate its host's energy metabolism. We detected orthologous SDHA and SDHB genes in numerous genome fragments from uncultivated marine Mimiviridae viruses, which suggests that the viral SDH is widespread in oceans. PkV RF01 was less virulent compared with other cultured prymnesioviruses, a phenomenon possibly linked to the metabolic capacity of this virus and suggestive of relatively long co-evolution with its hosts. It also has a unique morphology, compared to other characterized viruses in the Mimiviridae family. Finally, we found that PkV RF01 is the only alga-infecting Mimiviridae virus encoding two aminoacyl-tRNA synthetases and enzymes corresponding to an entire base-excision repair pathway, as seen in heterotroph-infecting Mimiviridae These Mimiviridae encoded-enzymes were found to be monophyletic and branching at the root of the eukaryotic tree of life. This placement suggests that the last common ancestor of Mimiviridae was endowed with a large, complex genome prior to the divergence of known extant eukaryotes.IMPORTANCE Viruses on Earth are tremendously diverse in terms of morphology, functionality, and genomic composition. Over the last decade, the conceptual gap separating viruses and cellular life has tightened because of the detection of metabolic genes in viral genomes that express complex virus phenotypes upon infection. Here, we describe Prymnesium kappa virus RF01, a large alga-infecting virus with a unique morphology, an atypical infection profile, and an unprecedented number of genes involved in energy metabolism (such as the tricarboxylic (TCA) cycle and the ß-oxidation pathway). Moreover, we show that the gene corresponding to one of these enzymes (the succinate dehydrogenase subunit A) is transcribed during infection and is widespread among marine viruses. This discovery provides evidence that a virus has the potential to actively regulate energy metabolism with its own gene.

Bacillus cereus biofilm formation on central venous catheters of hospitalised cardiac patients.

Formation of bacterial biofilms is a risk with many in situ medical devices. Biofilm-forming Bacillus species are associated with potentially life-threatening catheter-related blood stream infections in immunocompromised patients. Here, bacteria were isolated from biofilm-like structures within the lumen of central venous catheters (CVCs) from two patients admitted to cardiac hospital wards. Isolates belonged to the Bacillus cereus group, exhibited strong biofilm formation propensity, and mapped phylogenetically close to the B. cereus emetic cluster. Together, whole genome sequencing and quantitative PCR confirmed that the isolates constituted the same strain and possessed a range of genes important for and up-regulated during biofilm formation. Antimicrobial susceptibility testing demonstrated resistance to trimethoprim-sulphamethoxazole, clindamycin, penicillin and ampicillin. Inspection of the genome revealed several chromosomal ß-lactamase genes and a sulphonamide resistant variant of folP. This study clearly shows that B. cereus persisting in hospital ward environments may constitute a risk factor from repeated contamination of CVCs.

Synthesis, characterization, and cellular uptake of magnetic nanocarriers for cancer drug delivery.

HYPOTHESIS: The absence of targetability is the primary inadequacy of conventional chemotherapy. Targeted drug delivery systems are conceptualized to overcome this challenge. We have designed a targetable magnetic nanocarrier consisting of a superparamagnetic iron oxide (SPIO) core and biocompatible and biodegradable poly(sebacic anhydride)-block-methyl ether poly(ethylene glycol) (PSA-mPEG) polymer shell. The idea is that this type of carriers should facilitate the targeting of cancer cells. EXPERIMENTS: PSA-mPEG was synthesized with poly-condensation and the in vitro degradation rate of the polymer was monitored by gel permeation chromatography (GPC). The magnetic nanocarriers were fabricated devoid of any surfactants and were capable of carrying high payload of hydrophobic dye. The successful encapsulation of SPIO within the polymer shell was confirmed by TEM. The results we obtained from measuring the size of SPIO loaded in polymeric NPs (SPIO-PNP) by dynamic light scattering (DLS) and iron content measurement of these particles by ICP-MS, indicate that SPIO is the most suitable carrier for cancer drug delivery applications. FINDINGS: Measuring the hydrodynamic radii of SPIO-PNPs by DLS over one month revealed the high stability of these particles at both body and room temperature. We further investigated the cell viability and cellular uptake of SPIO-PNPs in vitro with MDA-MB-231 breast cancer cells. We found that SPIO-PNPs induce negligible toxicity within a concentration range of 1-2µg/ml. The TEM micrographs of thin cross-sectioned MDA-MBA-231 cells showed internalization of SPIO-PNPs within size range of 150-200nm after 24h. This study has provided a foundation for eventually loading these nanoparticles with anti-cancer drugs for targeted cancer therapy using an external magnetic field.