No evidence for clonal transmission of urogenital carcinoma in California sea lions (Zalophus californianus)

Leathlobhair, Máire Ní; Gulland, Frances M. D.; Murchison, Elizabeth P.

doi:10.12688/wellcomeopenres.11483.1

Cited by 7 publications

(5 citation statements)

References 43 publications

(48 reference statements)

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“…The coexistence of a transmissible cancer with non-transmissible cancers, warn for the systematic use of molecular markers to verify the transmissible nature of DN. More generally, wildlife cancer research needs to consider a more general use of molecular markers (Leathlobhair et al 2017).…”

Section: Discussionmentioning

confidence: 99%

Prevalence and polymorphism of a mussel transmissible cancer in Europe

et al. 2021

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Transmissible cancers are parasitic malignant cell lineages that acquired the ability to infect new hosts from the same species, or sometimes related species. First described in dogs and Tasmanian devils, transmissible cancers were later discovered in some marine bivalves affected by a leukemia-like disease. In Mytilus mussels, two lineages of Bivalve Transmissible Neoplasia (BTN) have been described to date (MtrBTN1 and MtrBTN2), both emerged in a M. trossulus founder individual. Here, we performed an extensive screening of genetic chimerism, a hallmark of transmissible cancer, by genotyping 106 SNPs of 5907 European Mytilus mussels. The genetic analysis allowed us to simultaneously obtain the genotype of hosts -M. edulis, M. galloprovincialis or hybrids -and the genotype of tumors of heavily infected individuals. In addition, a subset of 222 individuals were systematically genotyped and analysed by histology in order to screen for possible non-transmissible cancers. We detected MtrBTN2 at low prevalence in M.edulis, and also in M. galloprovincialis and hybrids although at a much lower prevalence. No MtrBTN1 or new BTN were found, but 8 individuals with non-transmissible neoplasia were observed at a single polluted site on the same sampling date. We observed a diversity of MtrBTN2 genotypes that appeared more introgressed or more ancestral than MtrBTN1 and reference healthy M. trossulus individuals. The observed polymorphism is most likely due to somatic null alleles caused by structural variations or point mutations in primer-binding sites leading to enhanced detection of the host alleles. Despite low prevalence, two sublineages divergent by 10% fixed somatic null alleles and one non-synonymous mtCOI substitution, are co-spreading in the same geographic area, suggesting a complex diversification of MtrBTN2 since its emergence and host species shift.

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Section: Discussionmentioning

confidence: 99%

Prevalence and polymorphism of a mussel transmissible cancer in Europe

et al. 2021

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“…The coexistence of a transmissible cancer with non-transmissible cancers, warn for systematic use of molecular markers to verify the transmissible nature of DN. More generally, wildlife cancer research needs to consider a more general use of molecular markers to address the issue (Leathlobhair et al 2017).…”

Section: Discussionmentioning

confidence: 99%

Prevalence and polymorphism of a mussel transmissible cancer in Europe

Hammel

Simon

Arbiol

et al. 2021

Preprint

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Transmissible cancers are parasitic malignant cell lineages that acquired the ability to infect new hosts from the same species, or sometimes related species. First described in dogs and Tasmanian devils, transmissible cancers were later discovered in some marine bivalves affected by a leukemia-like disease. In Mytilus mussels, two lineages of Bivalve Transmissible Neoplasia (BTN), both emerged in a M. trossulus founder individual, have been described to date (MtrBTN1 and MtrBTN2). Here, we performed an extensive screening of genetic chimerism, a hallmark of transmissible cancer, by genotyping hundred SNPs of thousands of European Mytilus mussels. The genetic analysis allowed us to simultaneously obtain the genotype of hosts -M. edulis, M. galloprovincialis or hybrids- and the genotype of tumors of heavily infected individuals. In addition, a subset of individuals were systematically genotyped and analysed by histology in order to screen for possible non-transmissible cancers. We detected MtrBTN2 at low prevalence in M. edulis, and also in M. galloprovincialis and hybrids although at a much lower prevalence. No MtrBTN1 or new BTN were found but a few individuals with non-transmissible neoplasia were observed at a single polluted site on the same sampling date. We observed a diversity of MtrBTN2 genotypes that appeared more introgressed or more ancestral than MtrBTN1 and reference healthy M. trossulus individuals. The observed polymorphism is most likely due to somatic null alleles caused by structural variations or point mutations in primer-binding sites leading to enhanced detection of the host alleles. Despite low prevalence, two divergent sublineages, confirmed by mtCOI sequences, are co-spreading in the same geographic area, suggesting a complex diversification of MtrBTN2 since its emergence and host species shift.

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“…Although transmissible cancer clones are thought to emerge rarely, their numbers and distributions in wildlife populations are difficult to assess 68 , 69 . The current work, together with a previous study of urogenital carcinoma in California sea lions, argues against transmissible cancer aetiologies for three well-recognised animal cancers 8 .…”

Section: Discussionmentioning

confidence: 59%

“…However, in the latter case, the causative infectious agent often remains elusive 1 , 2 . One infectious modality that may be more frequent than previously assumed is the transmissible cancer cell 7 , 8 . Transmissible cancers are somatic cell lineages that are spread between hosts by the physical transfer of living cancer cells.…”

Section: Introductionmentioning

confidence: 99%

Genotype data not consistent with clonal transmission of sea turtle fibropapillomatosis or goldfish schwannoma

et al. 2021

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Recent discoveries of transmissible cancers in multiple bivalve species suggest that direct transmission of cancer cells within species may be more common than previously thought, particularly in aquatic environments. Fibropapillomatosis occurs with high prevalence in green sea turtles (Chelonia mydas) and the geographic range of disease has increased since fibropapillomatosis was first reported in this species. Widespread incidence of schwannomas, benign tumours of Schwann cell origin, reported in aquarium-bred goldfish (Carassius auratus), suggest an infectious aetiology. We investigated the hypothesis that cancers in these species arise by clonal transmission of cancer cells. Through analysis of polymorphic microsatellite alleles, we demonstrate concordance of host and tumour genotypes in diseased animals. These results imply that the tumours examined arose from independent oncogenic transformation of host tissue and were not clonally transmitted. Further, failure to experimentally transmit goldfish schwannoma via water exposure or inoculation suggest that this disease is unlikely to have an infectious aetiology.

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No evidence for clonal transmission of urogenital carcinoma in California sea lions (Zalophus californianus)

Cited by 7 publications

References 43 publications

Prevalence and polymorphism of a mussel transmissible cancer in Europe

Prevalence and polymorphism of a mussel transmissible cancer in Europe

Prevalence and polymorphism of a mussel transmissible cancer in Europe

Genotype data not consistent with clonal transmission of sea turtle fibropapillomatosis or goldfish schwannoma

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