Small heat shock proteins (sHSPs) are oligomeric stress proteins characterized by an α-crystallin domain (ACD) surrounded by a N-terminal arm and C-terminal extension. Publications on sHSPs have reported that they exist in prokaryotes and eukaryotes but, to our knowledge, not in viruses. Here we show that sHSPs are present in some cyanophages that infect the marine unicellular cyanobacteria, Synechococcus and Prochlorococcus. These phage sHSPs contain a conserved ACD flanked by a relatively conserved N-terminal arm and a short C-terminal extension with or without the conserved C-terminal anchoring module (CAM) L-X-I/V, suggested to be implicated in the oligomerization. In addition, cyanophage sHSPs have the signature pattern, P-P-[YF]-N-[ILV]-[IV]-x(9)-[EQ], in the predicted β2 and β3 strands of the ACD. Phylogenetically, cyanophage sHSPs form a monophyletic clade closer to bacterial class A sHSPs than to cyanobacterial sHSPs. Furthermore, three sHSPs from their cellular host, Synechococcus, are phylogenetically close to plants sHSPs. Implications of evolutionary relationships between the sHSPs of cyanophages, bacterial class A, cyanobacteria, and plants are discussed.

The gypsy moth, Lymantria dispar L., is one of the most destructive forest pests in the world. While the subspecies established in North America is the European gypsy moth (L. dispar dispar), whose females are flightless, the two Asian subspecies, L. dispar asiatica and L. dispar japonica, have flight-capable females, enhancing their invasiveness and warranting precautionary measures to prevent their permanent establishment in North America. Various molecular tools have been developed to help distinguish European from Asian subspecies, several of which are based on the mitochondrial barcode region. In an effort to identify additional informative markers, we undertook the sequencing and analysis of the mitogenomes of 10 geographic variants of L. dispar, including two or more variants of each subspecies, plus the closely related L. umbrosa as outgroup. Several regions of the gypsy moth mitogenomes displayed nucleotide substitutions with potential usefulness for the identification of subspecies and/or geographic origins. Interestingly, the mitogenome of one geographic variant displayed significant divergence relative to the remaining variants, raising questions about its taxonomic status. Phylogenetic analyses placed this population from northern Iran as basal to the L. dispar clades. The present findings will help improve diagnostic tests aimed at limiting risks of AGM invasions.

Background: Manipulative parasites are thought to liberate molecules in their external environment, acting as manipulation factors with biological functions implicated in their host’s physiological and behavioural alterations. These manipulation factors are part of a complex mixture called the secretome. While the secretomes of various parasites have been described, there is very little data for a putative manipulative parasite. It is necessary to study the molecular interaction between a manipulative parasite and its host to better understand how such alterations evolve. Methods: Here, we used proteomics to characterize the secretome of a model cestode with a complex life cycle based on trophic transmission. We studied Schistocephalus solidus during the life stage in which behavioural changes take place in its obligatory intermediate fish host, the threespine stickleback (Gasterosteus aculeatus). We produced a novel genome sequence and assembly of S. solidus to improve protein coding gene prediction and annotation for this parasite. We then described the whole worm’s proteome and its secretome during fish host infection using LC–MS/MS. Results: A total of 2290 proteins were detected in the proteome of S. solidus, and 30 additional proteins were detected specifically in the secretome. We found that the secretome contains proteases, proteins with neural and immune functions, as well as proteins involved in cell communication. We detected receptor-type tyrosine-protein phosphatases, which were reported in other parasitic systems to be manipulation factors. We also detected 12 S. solidus-specific proteins in the secretome that may play important roles in host–parasite interactions. Conclusions: Our results suggest that S. solidus liberates molecules with putative host manipulation functions in the host and that many of them are species-specific. Graphical

Glycoside hydrolase family 32 (GH32) enzymes cleave the glycosidic bond between two monosaccharides or between a carbohydrate and an aglycone moiety. GH32 enzymes have been studied in prokaryotes and in eukaryotes but not in viruses. This is the first analysis of GH32 enzymes in Bacillus subtilis phage SP10, ϕNIT1 and SPG24. Phylogenetic analysis, molecular docking and secretability predictions suggest that phage GH32 enzymes function as levan (fructose homopolysaccharide) fructotransferase. We showed that viruses also contain GH32 enzymes and that our analyses in silico strongly suggest that these enzymes function as levan fructotransferase.

Spike (S) protein is a key protein in coronaviruses life cycle. SARS-CoV-2 Omicron BA.1 variant of concern (VoC) presents an exceptionally high number of 30 substitutions, 6 deletions and 3 insertions in the S protein. Recent works revealed major changes in the SARS-CoV-2 Omicron biological properties compared to earlier variants of concern (VoCs). Here, these major changes could be explained, at least in part, by the mutations N764K and/or N856K in S2 subunit. These mutations were not previously detected in other VoCs. N764K and N856K generate two potential cleavage sites for SKI-1/S1P serine protease, known to cleave viral envelope glycoproteins. The new sites where SKI-1/S1P could cleave S protein might impede the exposition of the internal fusion peptide for membrane fusion and syncytia formation. Based on the human protein atlas, SKI-1/S1P protease is not found in lung tissues (alveolar cells type I/II and endothelial cells), but present in bronchus and nasopharynx. This may explain why Omicron has change of tissue tropism. Viruses have evolved to use several host proteases for cleavage/activation of envelope glycoproteins. Mutations that allow viruses to change of protease may have a strong impact in host range, cell and tissue tropism, and pathogenesis.