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Background and Objectives: Severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) serosurveys are typically analysed by applying a fixed threshold for seropositivity ('conventional approach'). However, this approach underestimates the seroprevalence of anti‐nucleocapsid (N) in vaccinated individuals—who often exhibit a difficult‐to‐detect anti‐N response. This limitation is compounded by delays between the onset of infection and sample collection. To address this issue, we compared the performance of four immunoassays using a new analytical approach ('ratio‐based approach'), which determines seropositivity based on an increase in anti‐N levels. Materials and Methods: Two groups of plasma donors and four immunoassays (Elecsys total anti‐N, VITROS total anti‐N, Architect anti‐N Immunoglobulin G (IgG) and in‐house total anti‐N) were evaluated. First‐group donors (N = 145) had one positive SARS‐CoV‐2 polymerase chain reaction (PCR) test result and had made two plasma donations, including one before and one after the PCR test (median = 27 days post‐PCR). Second‐group donors (N = 100) had made two plasma donations early in the Omicron wave. Results: Among first‐group donors (97.9% vaccinated), sensitivity estimates ranged from 60.0% to 89.0% with the conventional approach, compared with 94.5% to 98.6% with the ratio‐based approach. Among second‐group donors, Fleiss's κ ranged from 0.56 to 0.83 with the conventional approach, compared with 0.90 to 1.00 with the ratio‐based approach. Conclusion: With the conventional approach, the sensitivity of four immunoassays—measured in a predominantly vaccinated population based on samples collected ~1 month after a positive test result—fell below regulatory agencies requirement of ≥95%. The ratio‐based approach significantly improved the sensitivities and qualitative agreement among immunoassays, to the point where all would meet this requirement. [ABSTRACT FROM AUTHOR]

The largest mucosal surface in the body is in the gastrointestinal tract, a location that is heavily colonized by microbes that are normally harmless. A key mechanism required for maintaining a homeostatic balance between this microbial burden and the lymphocytes that densely populate the gastrointestinal tract is the production and transepithelial transport of poly-reactive IgA (ref. 1). Within the mucosal tissues, B cells respond to cytokines, sometimes in the absence of T-cell help, undergo class switch recombination of their immunoglobulin receptor to [IgA.sup.+], and differentiate to become plasma cells (2). However, [IgA.sup.+]-secreting plasma cells probably have additional attributes that are needed for coping with the tremendous bacterial load in the gastrointestinal tract. Here we report that mouse [IgA.sup.+] plasma cells also produce the antimicrobial mediators tumour-necrosis factor-α (TNF-α) and inducible nitric oxide synthase (iNOS), and express many molecules that are commonly associated with monocyte/granulocytic cell types. The development of iNOS-producing [IgA.sup.+] plasma cells can be recapitulated in vitro in the presence of gut stroma, and the acquisition of this multifunctional phenotype in vivo and in vitro relies on microbial co-stimulation. Deletion of TNF-α and iNOS in B-lineage cells resulted in a reduction in [IgA.sup.+] production, altered diversification of the gut microbiota and poor clearance of a gut-tropic pathogen. These findings reveal a novel adaptation to maintaining homeostasis in the gut, and extend the repertoire of protective responses exhibited by some B-lineage cells., Most class switch recombination (CSR) to IgA+ takes place in the Peyer's patches and requires encounters between B cells and cytokine-secreting T cells within germinal centres. However, IgA+ CSR can [...]

European Green Crab (EGC; Carcinus maenas) is a voracious aquatic invasive species (AIS) that threatens Canada's Atlantic and Pacific marine and estuarine ecosystems. It preys on and competes with commercial and recreational shellfish, negatively impacts commercial fisheries, and destroys ecologically- and biologically-significant habitat for native species. Fisheries and Oceans Canada (DFO) has developed substantial knowledge of EGC, particularly regarding trapping for early detection, monitoring, research, and physical removal for control. Information on trapping method considerations (deployment, environment, behaviour, catch) and goalfocussed protocols for different objectives including control measures and mitigation strategies has been compiled to provide advice on detection and control of EGC. Trapping EGC is critical for early detection, determining impacts on native species and habitat, and rapid response and control efforts to prevent ecosystem degradation and commercial fishery loss. A review of 69 peer reviewed studies and unpublished projects on EGC trapping were reviewed to examine trap types used in Canada (46 studies) and elsewhere (23 studies). Fifteen traps were categorized by type and usage in Canada and 13 additional traps that were used in North America and other parts of the world. The Fukui collapsible crab trap was the most utilized trap in Canada based on the review. Other traps have proven effective and direct trap type comparisons have been conducted in several regions. Trap selection must consider the trapping objective, in particular, the targeted portion of the EGC population, as some trap types can disproportionately catch large adult EGC due to trap design and intraspecific EGC behaviours. Several factors are key in selecting an appropriate trap type based on trapping objectives, which can include habitat type, depth and site location, deployment method, life stage of targeted population, bycatch considerations and available resources. Trapping is an effective methodology for monitoring relative changes in EGC abundances and population dynamics, including changes in co-occurring native species (e.g., rock crab, lobster, and some fish depending on the trap type) that may be impacted by the invasion. Trapping for rapid response and control can effectively reduce EGC numbers and alter population dynamics. Outcomes could include reduction of EGC mean body size and recovery of impacted native species and habitat, but trapping efforts may need to be sustained to maintain low impacts of EGC on ecosystem components. Knowledge gaps identified include a lack of information on trapping juvenile EGC and determining effective threshold levels or numbers for control to prevent environmental and fishery impacts. This EGC trapping advice could be incorporated by managers into a decisionmaking tool for guiding action related to early detection, rapid response, and control management activities. [ABSTRACT FROM AUTHOR]

Abstract Background Infectious salmon anemia (ISA) virus (ISAV) is a pathogen of marine-farmed Atlantic salmon (Salmo salar); a disease first diagnosed in Norway in 1984. This virus, which was first characterized following its isolation in cell culture in 1995, belongs to the family Orthomyxoviridae, genus, Isavirus. The Isavirus genome consists of eight single-stranded RNA segments of negative sense, each with one to three open reading frames flanked by 3' and 5' non-coding regions (NCRs). Although the terminal sequences of other members of the family Orthomyxoviridae such as Influenzavirus A have been extensively analyzed, those of Isavirus remain largely unknown, and the few reported are from different ISAV strains and on different ends of the different RNA segments. This paper describes a comprehensive analysis of the 3' and 5' end sequences of the eight RNA segments of ISAV of both European and North American genotypes, and evidence of quasispecies of ISAV based on sequence variation in the untranslated regions (UTRs) of transcripts. Results Two different ISAV strains and two different RNA preparations were used in this study. ISAV strain ADL-PM 3205 ISAV-07 (ADL-ISAV-07) of European genotype was the source of total RNA extracted from ISAV-infected TO cells, which contained both viral mRNA and cRNA. ISAV strain NBISA01 of North American genotype was the source of vRNA extracted from purified virus. The NCRs of each segment were identified by sequencing cDNA prepared by three different methods, 5' RACE (Rapid amplification of cDNA ends), 3' RACE, and RNA ligation mediated PCR. Sequence analysis of five clones each derived from one RT-PCR product from each NCR of ISAV transcripts of segments 1 to 8 revealed significant heterogeneity among the clones of the same segment end, providing unequivocal evidence for presence of intra-segment ISAV quasispecies. Both RNA preparations (mRNA/cRNA and vRNA) yielded complementary sequence information, allowing the simultaneous identification and confirmation of the 3' and 5' NCR sequences of the 8 RNA genome segments of both genotypes of ISAV. The 3' sequences of the mRNA transcripts of ADL-ISAV-07 terminated 13-18 nucleotides from the full 3' terminus of cRNA, continuing as a poly(A) tail, which corresponded with the location of the polyadenylation signal. The lengths of the 3' and 5' NCRs of the vRNA were variable in the different genome segments, but the terminal 7 and 11 nucleotides of the 3' and 5' ends, respectively, were highly conserved among the eight genomic segments of ISAV. The first three nucleotides at the 3' end are GCU-3' (except in segment 5 with ACU-3'), whereas at the 5' end are 5'-AGU with the polyadenylation signal of 3-5 uridines 13-15 nucleotides downstream of the 5' end terminus of the vRNA. Exactly the same features were found in the respective complementary 5' and 3' end NCR sequences of the cRNA transcripts of ADL-ISAV-07, indicating that the terminal sequences of the 8 RNA genome segments are highly conserved among the two ISAV genotypes. The 5' NCR sequences of segments 1, 2, 3, 5, and 7, and the 3' NCR sequences of segments 3 and 4 cRNA were 100% identical in the two genotypes, and the 3' NCR sequences of segment 5 cRNA was the most divergent, with a sequence identity of 77.2%. Conclusions We report for the first time, the presence of intra-segment ISAV quasispecies, based on sequence variation in the NCR sequences of transcripts. In addition, this is the first report of a comprehensive unambiguous analysis of the 3' and 5' NCR sequences of all 8 RNA genome segments from two strains of ISAV representing the two genotypes of ISAV. Because most ISAV sequences are of cDNA to mRNA, they do not contain the 3' end sequences, which are removed during polyadenylation of the mRNA transcripts. We report for the first time the ISAV consensus sequence CAT/ATTTTTACT-3' (in the message sense 5'-3') in all segments of both ISAV genotypes.

We report new observations of two invasive ascidian species, the solitary Ascidiella aspersa and the colonial Diplosoma listerianum, from Eastern Canada, which include some records from new sites. Because these species share many superficial characteristics with native and non-native species in the region, identifications based on detailed taxonomic studies of internal structures--and not only on external features--are essential and can complement molecular methods. In this report, specimens of A. aspersa collected from Nova Scotia in 2013 and D. listerianum from New Brunswick and Quebec in 2017 were described morphologically to confirm species identity. Specimens of both were collected one year after initial discoveries in Nova Scotia and New Brunswick, respectively. Specimens of D. listerianum from Quebec were collected after a six-year hiatus. This report contributes a new record of A. aspersa 30 km (by sea) north of the site of the first record in Canada. It also confirms the first record of D. listerianum and documents its rapid spread in New Brunswick. This report is the first time that A. aspersa from Eastern Canada and D. listerianum from New Brunswick and the second time that D. listerianum from Quebec was explicitly identified based on an examination of internal features. Species confirmation of these easily overlooked or misidentified taxa contributes a time-stamp on current invasion fronts and suggests that the risk of further introductions and spread of these invasive species is present at un-invaded sites throughout Eastern Canada. [ABSTRACT FROM AUTHOR]

In eastern Canada, the initial suspected discovery of the non-indigenous colonial ascidian Diplosoma listerianum in Quebec was followed by species identification and increased awareness for its detection in the neighbouring provinces of Nova Scotia and Prince Edward Island. A phylogenetic analysis was conducted based on sequences generated from the 18S ribosomal DNA gene isolated from tissues of two Canadian samples (Quebec and Nova Scotia) and samples from several species belonging to the Diplosoma genus, which confirmed the species identity of the eastern Canadian specimens. Colonies of D. listerianum found in Quebec (2008) and Nova Scotia (2012) are currently the only tissue records of this species in eastern Canada. Water samples of concentrated plankton collected in Quebec (2010 and 2011) and in Prince Edward Island (2011) tested PCR positive for D. listerianum DNA, but colonies were not observed concurrently. As a case study for early detection, this paper documents how D. listerianum was detected in eastern Canada by different groups (government monitoring, academic research) and with different methods (dive surveys, genetic analysis of water samples, collector plates). This case study suggests that the co-operation between groups and the breadth of the methods used contributed to the early detection of this species in three eastern Canadian provinces. In particular, we show that (i) partnerships between government, academia, and industry, (ii) a national capacity for species-specific molecular detection tools, and (iii) the recognition that the effectiveness and limitations of different monitoring methods may be site-specific can have positive early detection and monitoring outcomes. [ABSTRACT FROM AUTHOR]