Biology subjects

Paley, R.

Publications and source records attributed to Paley, R..

3 recordsLinked to original sources

bioRxiv2024

Laboratory in vitro replication of Ostreid Herpes Virus (OsHV-1) using Pacific oyster tissue explants

Pacific oysters (Crassostrea or Magallana gigas) are one of the most economically important aquaculture species globally. Over the past two decades, ostreid herpesvirus (OsHV-1), has become a major pathogen of cultured Pacific oysters resulting in widespread mortality with a global distribution. Experimental use of OsHV-1 is challenging for many reasons, including both complexity and relative obscurity of host pathogen dynamics, and a lack of functioning model systems. The goal of this study was to improve the tools available for working with OsHV-1 in both whole animals and in tissue explants established ex vivo from oysters and maintained in controlled laboratory conditions. Tissue explants were taken from oysters originating from two different sources that have different levels of mortality in OsHV-1 challenges and were used in disease challenges alongside whole animals for comparison. Quantitative PCR, histology and electron microscopy were used to confirm that the explants were capable of replicating OsHV-1. Furthermore, the quantitative PCR results suggests that the source of the oysters was significant in determining the outcome of infection in the explants, supporting the validity of the explant model for OsHV-1 infection. This approach for studying OsHV-1 allows for the control of confounding factors in disease outcome that is not possible in whole animal challenges, providing a new tool for studying OsHV-1 in Pacific oysters.

microbiology↗

bioRxiv2023

In field use of water samples for genomic surveillance of ISKNV infecting tilapia fish in Lake Volta, Ghana

Viral outbreaks are a constant threat to aquaculture, limiting production for better global food security. A lack of diagnostic testing and monitoring in resource-limited areas hinders the capacity to respond rapidly to disease outbreaks and to prevent viral pathogens becoming endemic in fisheries productive waters. Recent developments in diagnostic testing for emerging viruses, however, offers a solution for rapid in situ monitoring of viral outbreaks. Genomic epidemiology has furthermore proven highly effective in detecting viral mutations involved in pathogenesis and assisting in resolving chains of transmission. Here, we demonstrate the application of an in-field epidemiological tool kit to track viral outbreaks in aquaculture on farms with reduced access to diagnostic labs, and with non-destructive sampling. Inspired by the "lab in a suitcase" approach used for genomic surveillance of human viral pathogens and wastewater monitoring of COVID19, we evaluated the feasibility of real-time genome sequencing surveillance of the fish pathogen, Infectious spleen and kidney necrosis virus (ISKNV) in Lake Volta. Viral fractions from water samples collected from cages holding Nile tilapia (Oreochromis niloticus) with suspected ongoing ISKNV infections were concentrated and used as a template for whole genome sequencing, using a previously developed tiled PCR method for ISKNV. Mutations in ISKNV in samples collected from the water surrounding the cages matched those collected from infected caged fish, illustrating that water samples can be used for detecting predominant ISKNV variants in an ongoing outbreak. This approach allows for the detection of ISKNV and tracking of the dynamics of variant frequencies, and may thus assist in guiding control measures for the rapid isolation and quarantine of infected farms and facilities.

genomics↗

bioRxiv2022

Molecular epidemiology of Infectious Spleen and Kidney Necrosis Virus (ISKNV) in Ghanaian cultured tilapia

1Infectious Spleen and Kidney Necrosis Virus (ISKNV) is increasingly gaining more attention globally, due to its highly significant economic impact on the aquaculture industry. In late 2018, unusually high levels of mortality (60-90%) was reported in some intensive tilapia cage culture systems in Ghana. Preliminary investigations confirmed the involvement of ISKNV, a viral pathogen noted for fatal systemic infections in many fish species. As a follow-up on the outbreak situation, and post-mass vaccination of affected fish farms, the need to investigate further the molecular epidemiology and phylogeography of the virus across Lake Volta became paramount. In this study, a multiplexed PCR assay and MinION nanopore sequencing of the Major Capsid Protein (MCP) were performed to investigate the presence and genotype of ISKNV in tilapia collected from 30 randomly selected farms spread across Lake Volta. Fish with and without clinical signs were included in the molecular detection of the virus from brain, kidney and spleen tissues. ISKNV was detected at 80% prevalence with fry and juvenile fish being most affected. Phylogenetic analysis of the MCP revealed that all 35 isolates from 14 different farms were ISKNV genotype I with near- 100% homology to the 2018 outbreak strain. Vaccination and heat shock treatment; the main specific interventions currently employed to control the viral pathogen have not achieved much success and ISKNV remains a threat to the growth of the aquaculture industry in Ghana. The outcome of this study can be useful in improving fish health management and biosecurity policies in the aquaculture industry.

molecular biology↗