Abolishment of spawner-isolated mortality virus and where the remaining science leads

In the late 1980s, there was histological and electron microscopy evidence for a parvovirus-like virus in Australian prawns. The data were consistent with infectious hypodermal and haematopoietic necrosis virus (IHHNV). However, these cases did not fit the then current paradigms of the known viruses and sequencing did not find any meaningful sequence homology. The virus was named spawner-isolated mortality virus (SMV; GenBank AF499102.1) in order to allow publication of the information about its occurrence to inform the scientific and aquacultural communities. This virus was present in the early years of mid-crop mortality syndrome (1993-1995). However, as time passed, nucleotide and protein databases have expanded and sequence investigation tools have become more cost effective. The sequence of the entity known as SMV is now shown to be of Carnobacterium divergens (CP016843.1). Therefore, the publications with regard to SMV have been assessed and a recommendation to abolish the name with the still valid science transferred to IHHNV and C. divergens

The effect of viral infection on the relationship between the LOS cells and moulting stages of the black tiger prawn (Penaeus monodon)

The formation of spheroid cells in the lymphoid organ of penaeid prawns has been suggested to be associated with infectious diseases either bacterial or viral. In this study, the abundance of lymphoid organ spheroid (LOS) cells, termed spheroid to total tissue (STT) ratio, in association with the moulting stages in Penaeus monodon that were experimentally infected with presumptive gill associated virus (GAV) was investigated. The experimental prawns were divided into 2 groups: A control group and a GAV infected group. The day post-injection was classified in three categories: (1) 1 5 dpi; (2) 6 10 dpi and (3) 11 onward dpi. The results showed that there were no significant effects of days post-injection, moult stages, lunar phase, and the size of the animals on the STT ratio (P>0.05). The relationship between the LOS cells and lunar phase was being masked by the significant interaction between lunar cycle and the treatments (P<0.05). In the control group, the ratio of STT was lowest at the new moon and highest at the full moon. On the other hand, in the infected (GAV) group, the ratio of STT was lowest at first quarter moon and highest at last quarter moon. The STT ratio was significantly higher in infected group than in the control group (P<0.05). In this study, sex also had a significant effect on the spheroid to total tissue ratio of P. monodon (P<0.05)

Natural infection of the redclaw crayfish Cherax quadricarinatus with presumptive spawner-isolated mortality virus

Crayfish farmers reported reduced tolerance of stress in specimens of Cherax quadricarinatus, which were formerly robust crayfish. Furthermore, one farmer reported a large reduction in yield with final harvest only equaling the stocking weight. Upon trapping, one-third of the crayfish regularly died overnight and a further one-third died on the sorting tray during sexing of juveniles (~3 mo old). Histopathological examination revealed very light (1 or 2 cells per section) infections with Cherax giardiavirus and sometimes mild atrophy of hepatopancreatic cells. Gene probe analysis with a DIG-labeled spawner-isolated mortality virus (SMV) probe demonstrated extensive positive signals in nuclei of many tissues. The hepatopancreas, the midgut, glands associated with the midgut, the epithelium of seminal ducts and follicle cells surrounding oocytes gave the strongest positive signals. Nuclei of the heart, haemocytes, connective tissue and subcutis gave positive signals in some individuals. Although signals were intense and extensive, cytolysis of infected cells was very limited. The possibility of cross infections of SMV between prawns and freshwater crayfish is of international quarantine significance

DOES INTERFERON (IFN)S EXIST IN CRUSTACEA?

The wide exploration of interferon (IFN)s in vertebrates for medical purposes has attracted researchers to investigate the existence of a similar role of interferon in other organisms such as invertebrates, including insects, and crustacea. A review of the literature indicates that there is no evidence of interferon existing either in insects such as D. melanogaster and A. gambiae which have had their genomes fully sequenced or in crustacea. However, a nonspecific antiviral state in crustacean, such as P. monodon can be efficiently triggered by both dsRNA and siRNA. The evidence suggests that anonymous cytokines, similar to interferon and not identical to any vertebrate IFNs, related to antiviral protection, do exist in crustacea. However, how widely spread of interferon immune response inducer or interferon-like molecules in this group is an important issue that remains to be explored

Work–Life Balance in Parent Teachers During COVID-19

Working parents engage in multiple roles. Often, the responsibilities of one role conflicts with the expectations of another role, creating a sense of imbalance. Because of this, working parents often find value in achieving a degree of work-life balance that aligns with their needs and values. Parents employed as teachers may face unique challenges around balancing work and family roles, due to the nature of their jobs. This challenge was heightened by the worldwide change in education during the COVID-19 pandemic. The purpose of this study is to examine the work-life balance of parent teachers during COVID-19. The present study is observational in nature, using a descriptive survey methodology design that includes the Work-Family Conflict Scale and Family-Work Conflict Scale (Netemeyer et al., 1996) followed by four open-ended questions to examine the impact COVID-19 had on the work-life balance of parent teachers. Participants for this study are drawn from a convenience sample of public-school educators of grades kindergarten-12 with one or more dependents in grades kindergarten-12 residing in their home during the 2020-2021 school year

Dietary uptake of green fluorescent protein for delivery of dsRNA to induce RNA interference

Double stranded RNA (dsRNA) is a potent initiator of the RNA interference (RNAi) pathways in a diverse range of organisms including plants, invertebrates and vertebrates. RNAi is increasingly being investigated as an antiviral mechanism, but often the research is hampered by the safe and cost effective delivery of the dsRNA to the target cells. This study uses specifically designed E. coli-expressed plasmids containing green fluorescent protein (gfp), to determine if the plasmids still inside the bacterial cells can be successfully incorporated into host cells of the house cricket (Acheta domesticus), following ingestion of feed or water. This approach was trialled to determine, if using similar designed plasmids containing siRNAs can be effectively administered and provide protection against a target pathogen. Daily exposure through feed is the most effective for gfp expression (78%-91.8%) in A. domesticus, although weekly exposure was statistically equivalent and almost as good (75%-99.9%). Exposure via water gave reasonable uptake either daily or weekly (60%-84%, 14%-56%, respectively), but intensity was reduced and muscles did not demonstrate uptake (P<0.002). Continual or semi-continual exposure to gfp expressing bacteria resulted in increased uptake within cricket tissues, and increasing fluorescence (+++) with increasing exposure. Plasmid-based delivery via bacterial cells is therefore, an effective delivery tool and incorporation into feed allows a cost-effective method of providing continuous exposure for therapeutic purposes

A systematic review of experimental evidence for antiviral effects of ivermectin and an in silico analysis of ivermectin's possible mode of action against SARS-CoV-2

Viral infections remain a major cause of economic loss with an unmet need for novel therapeutic agents. Ivermectin is a putative antiviral compound; the proposed mechanism is the inhibition of nuclear translocation of viral proteins, facilitated by mammalian host importins, a necessary process for propagation of infections. We systematically reviewed the evidence for the applicability of ivermectin against viral infections including SARS-CoV-2 regarding efficacy, mechanisms and selective toxicity. The SARS-CoV-2 genome was mined to determine potential nuclear location signals for ivermectin and meta-analyses for in vivo studies included all comparators over time, dose range and viral replication in multiple organs. Ivermectin inhibited the replication of many viruses including those in Flaviviridae, Circoviridae and Coronaviridae families in vitro. Real and mock nuclear location signals were identified in SARS-CoV-2, a potential target for ivermectin and predicting a sequestration bait for importin β, stopping infected cells from reaching a virus-resistant state. While pharmacokinetic evaluations indicate that ivermectin could be toxic if applied based on in vitro studies, inhibition of viral replication in vivo was shown for Porcine circovirus in piglets and Suid herpesvirus in mice. Overall standardized mean differences; 95% confidence intervals for ivermectin versus controls were: -4.43 (-5.81, -3.04), P < 0.00001. Based on current results, the potential for repurposing ivermectin as an antiviral agent is promising. However, further work is needed to reconcile in vitro studies with clinical efficacy. Developing ivermectin as an additional antiviral agent should be pursued with an emphasis on pre-clinical trials in validated models of infection

Cherax quadricarinatus Resistant to Chequa iflavirus: A Pilot Study

High mortalities of redclaw crayfish (Cherax quadricarinatus) were reported from northern Queensland farms, mainly attributed to two viruses, Chequa iflavirus and Athtab bunyavirus. From a research population of redclaw crayfish with these pre-existing viral infections, five individuals were found uninfected by Chequa iflavirus but infected with Athtab bunyavirus. A pilot study was designed to examine if progeny crayfish from this cohort were resistant to infections by Chequa iflavirus. Two experiments measured changes in viral load with RT-qPCR. Seven donors, four negative controls and six crayfish injected with a purified virus or saline were used. In Experiment 1, the purified viral inoculum was injected into the crayfish, and they were bled 14 days post-injection (dpi). In Experiment 2, haemolymph containing the viruses was injected into the same crayfish and they were bled at 24 hpi, 48 hpi, 7 dpi and 14 dpi. In Exp. 1, the crayfish cleared Chequa iflavirus infections within 14 dpi, while in Exp. 2, it was within 24 hpi. One mortality was observed, but that crayfish had cleared the virus before dying. The number of copies of Athtab bunyavirus and the weights of the crayfish did not differ significantly (p > 0.05) between the control and injected crayfish. Histology of crayfish all showed that the haemolymph vessels were clear of granulomas, suggesting no bacterial involvement. There was no melanisation in the gill tissue of control crayfish, but it was prominent in virus-injected crayfish. Neither group had haemocytic infiltration of the muscle fibres. Anti-viral immune mechanisms of RNA interference and Cherax quadricarinatus Down Syndrome Cell Adhesion Molecule (DSCAM) are hypothesised to be involved in viral clearance. We conclude that these crayfish were resistant to Chequa iflavirus infections and could be commercially exploited by aquaculturists as a nuclear breeding stock if numbers are increased over time

Rediscovery of the Australian strain of infectious hypodermal and haematopoietic necrosis virus

In this study we rediscovered and verified the presence of an infectious hypodermal and haematopoietic necrosis virus (IHHNV) strain amongst cultured penaeid prawns Penaeus monodon from 1993 in Australia on the basis of a PCR analysis with IHHNV specific primers and sequencing of the resulting amplicons. A total of 7 previously published diagnostic primers specific to IHHNV were tested against Australian penaeid prawns and only 1 elicited a positive IHHNV PCR result with 16 out of 20 Australian P. monodon samples examined. In comparison, all 7 primers produced IHHNVpositive amplicons from the New Caledonian control samples. Analysis and comparison of the 392 bp fragment derived from the Australian IHHNV strain (AY590120) with other geographical isolates revealed that the Madagascar isolate shared the highest nucleotide similarity (96.2%) and the Hawaiian and New Caledonian strain the highest nucleotide divergence (90.1 and 90.3% respectively). The high nucleotide variation observed between the Australian and Hawaiian strains provides an explanation for the lack of IHHNV detection amongst Australian prawns with published IHHNV PCRs and commercially available gene probes as they are primarily designed on the basis of the Hawaiian strain (AF218266). Results indicated that IHHNV has been present in Australia for a long (geological and contemporary) time and that the virus is endemic in penaeid prawns in the Australian environment

Systemic infection of freshwater crayfish Cherax quadricarinatus by hymenostome ciliates of the Tetrahymena pyriformis complex

A survey of cultured freshwater crayfish Cherax quadricarinatus in north Queensland revealed systemic infections by hymenostome ciliates in moribund crayfish from one location. The ciliates were identified following protargol impregnation as belonging to the Tetrahymena pyriformis species complex on the basis of their somatic and oral ciliature and morphometric characteristics. Live ciliates were observed in the haemal sinuses of the gills browsing on tissue fragments. Histological examination revealed the ciliates to have invaded most organs and tissues, causing extensive necrosis particularly in the hepatopancreas and antennal gland. Lipid reserves were not depleted in the hepatopancreas, suggesting the rapid development of acute disease. This is the first record of systemic ciliate infections in freshwater decapods