Biology subjects

Jessop, R.

Publications and source records attributed to Jessop, R..

4 recordsLinked to original sources

bioRxiv2025

Genomic and morphological characterisation of a novel iridovirus, bivalve iridovirus 1 (BiIV1), infecting the common cockle (Cerastoderma edule)

1High rates of mortality of the common cockle, Cerastoderma edule, have occurred in the Wash Estuary, UK since 2008. A previous study linked the mortalities to a novel genotype of Marteilia cocosarum, with a strong correlation between cockle moribundity and the presence of M. cocosarum. Here, we characterise a novel iridovirus, identified by chance during metagenomic sequencing of a gradient purification of Marteilia cells, with presence also correlated to cockle moribundity. The novel 179,695 bp iridovirus, bivalve iridovirus 1 (BiIV1), encodes 193 predicted open reading frames and has a 41% G+C content. BiIV1 clusters together with other aquatic invertebrate iridoviruses in phylogenetic analyses and has a similar genome size to other invertebrate iridoviruses. Comparative analysis revealed that BiIV1 has lost three genes that were previously thought to be common amongst all iridoviruses but has also gained genes, potentially from horizontal transfer from its bivalve mollusc host(s). Electron microscopy showed 158 nm icosahedral virions present in the haemocytes of cockles, typical of those observed in host tissues infected with viruses of the family Iridoviridae. Prevalence of BiIV1 in moribund cockles was higher than that in apparently healthy cockles at most sites in the Wash Estuary, with up to 100% PCR prevalence in moribund cockles. Our findings provide the first genome for a bivalve-infecting iridovirus and identify a second bivalve-associated iridovirus in publicly available genomic datasets, adding to the knowledge of invertebrate iridovirus genomics and diversity.

molecular biology↗

bioRxiv2025

Characterisation of Marteilia cocosarum in the Wash Estuary, UK, linked to mass mortalities of cockles (Cerastoderma edule), and its relationship to closely related species

Globally, Marteilia parasites have been associated with significant mass mortality events in populations of commercially important bivalve molluscs, frequently resulting in large-scale fishery collapses and substantial socio-economic impacts. The Wash Estuary, UK, supports several bivalve fisheries, and among these, common cockles Cerastoderma edule have suffered unusually high mortalities since 2008. We investigate potential causes of these mortalities, and confirm infection with Marteilia cocosarum, strongly associated with cockle moribundity, also confirming its presence in archived samples collected in 2009. Molecular and light microscopy screening of samples collected during mortality events in 2021, including healthy (buried) and moribund (weak, unable to bury) cockles, indicated high prevalence of M. cocosarum in moribund cockles (PCR incidence up to 95%) in contrast to healthy cockles (up to 42%), suggesting an association between cockle moribundity and Marteilia infection. Analysis of the full ribosomal RNA array identified consistently different nucleotides between M. cocosarum infections in The Wash (denoted as genotype WE) and those in Wales (denoted genotype BI). 83% of infections in The Wash could be identified as M. cocosarum WE and 12% as M. cocosarum BI, with both genotypes recovered from 5% of infected animals. Histopathologically, M. cocosarum WE infects the gill, mantle and connective tissues, identical to observations of M. cocosarum infecting Welsh cockles. Ongoing cockle mortalities in The Wash raise concerns regarding the sustainability of this resource ecologically and economically. Additional measures may be required to reduce the spread of this pathogen, noting that its distribution beyond The Wash and Wales is currently unknown.

molecular biology↗

bioRxiv2024

Long distance avian migrants fail to bring 2.3.4.4b HPAI H5N1 into Australia for a second year in a row

There is an ongoing and profound burden of lineage 2.3.4.4b high pathogenicity avian influenza (HPAI) H5N1 on wildlife and poultry, globally. Herein we report the continued absence of HPAI and antibodies against lineage 2.3.4.4b HPAI from October - December 2023, in migratory birds shortly after their arrival in Australia. Given the ever-changing phenotype of this virus, worldwide studies on the occurrence, or here absence of the virus, are of critical importance to understand the virus dispersal and incursion risk and development of response strategies.

microbiology↗

bioRxiv2023

Assessment of contaminants, health and survival of migratory shorebirds in natural versus artificial wetlands - the potential of wastewater treatment plants as alternative habitats

The rapid destruction of natural wetland habitats over past decades has been partially offset by an increase in artificial wetlands. However, these also include wastewater treatment plants, which may pose a pollution risk to the wildlife using them. We studied two long-distance Arctic-breeding migratory shorebird species, curlew sandpiper (Calidris ferruginea, n=70) and red-necked stint (Calidris ruficollis, n=100), while on their Australian non-breeding grounds using a natural wetland versus an artificial wetland at a wastewater treatment plant (WTP). We compared pollutant exposure (elements and per- and poly-fluoroalkyl substances/PFASs), disease (avian influenza), physiological status (oxidative stress) of the birds at the two locations from 2011-2020, and population survival from 1978-2019. Our results indicated no significant differences in blood pellet pollutant concentrations between the habitats except mercury (WTP median: 224 ng/g, range: 19-873 ng/g; natural wetland: 160 ng/g, 22-998 ng/g) and perfluorooctanesulfonic acid (WTP median: 52 ng/g, range: <0.01-1280 ng/g; natural wetland: 14 ng/g, <0.01-379 ng/g) which were higher at the WTP, and selenium which was lower at the WTP (WTP median: 5000 ng/g, range: 1950-34400 ng/g; natural wetland: 19200 ng/g, 4130-65200 ng/g). We also measured higher blood o,o-dityrosine (an indicator of protein damage) at the WTP. No significant differences were found for adult survival, but survival of immature birds at the WTP appeared to be lower which could be due to higher dispersal to other wetlands. Interestingly, we found active avian influenza infections were higher in the natural habitat, while seropositivity was higher in the WTP, seemingly not directly related to pollutant exposure. Overall, we found negligible differences in pollutant exposure, health and survival of the shorebirds in the two habitats. Our findings suggest that appropriately managed wastewater treatment wetlands may provide a suitable alternative habitat to these migratory species, curbing the decline of shorebird populations from widespread habitat loss.

ecology↗