Comparative histopathologic and viral immunohistochemical studies on CeMV infection among Western Mediterranean, Northeast-Central, and Southwestern Atlantic cetaceans

PLoS One. 2019 Mar 20;14(3):e0213363. doi: 10.1371/journal.pone.0213363. eCollection 2019.

Abstract

Cetacean morbillivirus (CeMV) is a major natural cause of morbidity and mortality in cetaceans worldwide and results in epidemic and endemic fatalities. The pathogenesis of CeMV has not been fully elucidated, and questions remain regarding tissue tropism and the mechanisms of immunosuppression. We compared the histopathologic and viral immunohistochemical features in molecularly confirmed CeMV-infected Guiana dolphins (Sotalia guianensis) from the Southwestern Atlantic (Brazil) and striped dolphins (Stenella coeruleoalba) and bottlenose dolphins (Tursiops truncatus) from the Northeast-Central Atlantic (Canary Islands, Spain) and the Western Mediterranean Sea (Italy). Major emphasis was placed on the central nervous system (CNS), including neuroanatomical distribution of lesions, and the lymphoid system and lung were also examined. Eleven Guiana dolphins, 13 striped dolphins, and 3 bottlenose dolphins were selected by defined criteria. CeMV infections showed a remarkable neurotropism in striped dolphins and bottlenose dolphins, while this was a rare feature in CeMV-infected Guiana dolphins. Neuroanatomical distribution of lesions in dolphins stranded in the Canary Islands revealed a consistent involvement of the cerebrum, thalamus, and cerebellum, followed by caudal brainstem and spinal cord. In most cases, Guiana dolphins had more severe lung lesions. The lymphoid system was involved in all three species, with consistent lymphoid depletion. Multinucleate giant cells/syncytia and characteristic viral inclusion bodies were variably observed in these organs. Overall, there was widespread lymphohistiocytic, epithelial, and neuronal/neuroglial viral antigen immunolabeling with some individual, host species, and CeMV strain differences. Preexisting and opportunistic infections were common, particularly endoparasitism, followed by bacterial, fungal, and viral infections. These results contribute to understanding CeMV infections in susceptible cetacean hosts in relation to factors such as CeMV strains and geographic locations, thereby establishing the basis for future neuro- and immunopathological comparative investigations.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Bottle-Nosed Dolphin / virology
  • Central Nervous System / pathology
  • Central Nervous System / virology
  • Cetacea / virology*
  • Dolphins / virology
  • Female
  • Lung / pathology
  • Lung / virology
  • Lymphoid Tissue / pathology
  • Lymphoid Tissue / virology
  • Male
  • Morbillivirus Infections / immunology
  • Morbillivirus Infections / pathology
  • Morbillivirus Infections / veterinary*
  • Morbillivirus*
  • Species Specificity
  • Stenella / virology

Supplementary concepts

  • Cetacean morbillivirus

Grants and funding

'Projeto de Monitoramento de Praias da Bacia de Santos' (PMP-BS) (MAQUA/UERJ, CTA Meio Ambiente, Instituto Boto Cinza, Petrobras) and Programa de Conservação dos botos-cinza (Sotalia guianensis) e outros cetáceos' from Ilha Grande and Sepetiba bay (MAQUA/UERJ, Associação Cultural e de Pesquisa Noel Rosa, INEA, Transpetro) support cetacean research in this region. PMP-BS is a monitoring program demanded by the federal environmental licensing conducted by IBAMA. AFA and JL-B have research grants from CNPq (PQ-1D), FAPERJ (JCNE) and UERJ (Prociência).EBS-N had support from Qualitec/UERJ scholarship (Edital 2014). This research was supported by Coordination for the Improvement of Higher Education Personnel (CAPES) and São Paulo Research Foundation (FAPESP), grants #2015/00735-6; 2017/24335-2. CNPq/FAPESP also support the post-doctoral fellows JDD (grants #2017/02223-8; #2018/01876) and KRG (grants #2014/24932-2; #2015/05043-5). JLCD is a recipient of a fellowship from the Brazilian National Council for Scientific and Technological Development (CNPq; grant # 305349/2015-5).