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Here we report the discovery of Yaravirus, a lineage of amoebal virus with a puzzling origin and evolution. Yaravirus presents 80-nm-sized particles and a 44,924-bp dsDNA genome encoding for 74 predicted proteins. Yaravirus genome annotation showed that none of its genes matched with sequences of known organisms at the nucleotide level; at the amino acid level, six predicted proteins had distant matches in the nr database. Complimentary prediction of three-dimensional structures indicated possible function of 17 proteins in total. Furthermore, we were not able to retrieve viral genomes closely related to Yaravirus in 8,535 publicly available metagenomes spanning diverse habitats around the globe. The Yaravirus genome also contained six types of tRNAs that did not match commonly used codons. Proteomics revealed that Yaravirus particles contain 26 viral proteins, one of which potentially representing a divergent major capsid protein (MCP) with a predicted double jelly-roll domain. Structure-guided phylogeny of MCP suggests that Yaravirus groups together with the MCPs of Pleurochrysis endemic viruses. Yaravirus expands our knowledge of the diversity of DNA viruses. The phylogenetic distance between Yaravirus and all other viruses highlights our still preliminary assessment of the genomic diversity of eukaryotic viruses, reinforcing the need for the isolation of new viruses of protists.

Tropheryma whipplei , is an actinobacterium that causes different infections in humans, including Whipple's disease. The bacterium infects and replicates in macrophages, leading to a Th2-biased immune response. Previous studies have shown that T. whipplei harbors complex surface glycoproteins with evidence of sialylation. However, the exact contribution of these glycoproteins for infection and survival remains obscure. To address this, we characterized the bacterial glycoprofile and evaluated the involvement of human β-galactoside-binding lectins, Galectin-1 (Gal-1) and Galectin-3 (Gal-3) which are highly expressed by macrophages as receptors for bacterial glycans. Tropheryma whipplei glycoproteins harbor different sugars including glucose, mannose, fucose, β-galactose and sialic acid. Mass spectrometry identification revealed that these glycoproteins were membrane- and virulence-associated glycoproteins. Most of these glycoproteins are highly sialylated and N-glycosylated while some of them are rich in poly-N-acetyllactosamine (Poly-LAcNAc) and bind Gal-1 and Gal-3. In vitro, T. whipplei modulates the expression and cellular distribution of Gal-1 and Gal-3. Although both galectins promote T. whipplei infection by enhancing bacterial cell entry, only Gal-3 is required for optimal bacterial uptake. Finally, we found that serum levels of Gal-1 and Gal-3 were altered in patients with T. whipplei infections as compared to healthy individuals, suggesting that galectins are also involved in vivo . Among T. whipplei membrane-associated proteins, poly-LacNAc rich-glycoproteins promote infection through interaction with galectins. T. whipplei modulates the expression of Gal-1 and Gal-3 both in vitro and in vivo . Drugs interfering with galectin-glycan interactions may provide new avenues for the treatment and diagnosis of T. whipplei infections.

Ivermectin has emerged as very promising pediculicide, particularly in cases of resistance to commonly used pediculicides. Recently, however, the first field-evolved ivermectin-resistance in lice was reported. To gain insight into the mechanisms underlying ivermectin-resistance, we both looked for mutations in the ivermectin-target site (GluCl) and searched the entire proteome for potential new loci involved in resistance from laboratory susceptible and ivermectin-selected resistant body lice. Polymorphism analysis of cDNA GluCl showed no non-silent mutations. Proteomic analysis identified 22 differentially regulated proteins, of which 13 were upregulated and 9 were downregulated in the resistant strain. We evaluated the correlation between mRNA and protein levels by qRT-PCR and found that the trend in transcriptional variation was consistent with the proteomic changes. Among differentially expressed proteins, a complexin i.e. a neuronal protein which plays a key role in regulating neurotransmitter release, was shown to be the most significantly down-expressed in the ivermectin-resistant lice. Moreover, DNA-mutation analysis revealed that some complexin transcripts from resistant lice gained a premature stop codon, suggesting that this down-expression might be due, in part, to secondary effects of a nonsense mutation inside the gene. We further confirmed the association between complexin and ivermectin-resistance by RNA-interfering and found that knocking down the complexin expression induces resistance to ivermectin in susceptible lice. Our results provide evidence that complexin plays a significant role in regulating ivermectin resistance in body lice and represents the first evidence that links complexin to insecticide resistance., Competing Interests: The authors have declared that no competing interests exist.

Tropheryma whipplei, the agent of Whipple's disease, is a gram-positive rod-shaped bacterium that belongs to the group of actinobacteria. In order to produce monoclonal antibodies (MAbs) against this bacterium, we inoculated mice with two different strains, Slow2 and Endo5. We produced 13 and 10 MAbs against Slow2 and Endo5, respectively. Nine of the Slow2 MAbs and seven of the Endo5 MAbs recognized a 58-kDa epitope. In addition, three other Endo5 MAbs detected a unique 84-kDa epitope. These MAbs were species specific, as they did not react with a selection of 22 different bacterial species, but they were not strain specific, as they did react with six other strains of T. whipplei. Two-dimensional gel electrophoresis (2-DE) was combined with mass spectrometry (MS) to identify the 58-kDa and 84-kDa epitopes recognized by MAbs. After trypsin in-gel digestion of the spot, the 58-kDa protein was identified as an ATP synthase F1 complex beta chain, whereas the 84-kDa protein was identified as a polyribonucleotide nucleotidyltransferase by MS with matrix-assisted laser desorption ionization-time of flight. In an in vitro model, one of these MAbs allowed good detection of T. whipplei in stool samples, contrary to a rabbit polyclonal antibody, which led to high fluorescent background. In the prospective studies, the produced MAb will be tested for detection of T. whipplei in clinical samples, and the gene coding for identified 58-kDa and 84-kDa antigens will be tentatively cloned and then tested for its use in a diagnostic enzyme-linked immunosorbent assay for Whipple's disease.