Cetaceans as marine ecosystem health sentinels

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Evaluation of morbillivirus and herpesvirus infection in cetaceans stranded along the portuguese coastline

Publication . Bento, Maria Carolina Rocha de Medeiros; Duarte, Ana Isabel Simões Pereira; Eira, Catarina Isabel Costa Simões

ABSTRACT - Cetacean strandings are frequent along the Portuguese coastline and stranded specimens provide a unique opportunity to study disease and infectious disease agents in cetacean populations. Morbillivirus is particularly important in cetaceans for its ability to cause disease and for its high mortality rates. Herpesviruses are also particularly interesting since they are known to have close co-evolutionary paths with their hosts and for establishing latent infections that can resurge with any stressors of the immune system. This work aimed at investigating the epidemiology and pathophysiology of cetacean morbillivirus and herpesvirus. Furthermore, we aimed at establishing a profile of cytokine genes expression in healthy common dolphins and evaluate the possibility of using that tool to assess immunological shifts in this species. A molecular survey for dolphin morbillivirus revealed striped dolphins stranded in the Portuguese and Galician coasts have a prevalence of approximately 20% of positive individuals, higher than prevalence found for common dolphins (1%). A phylogeographic pattern was detected in the phylogenetic analysis with viral sequences from the Canary Islands more similar to those from the Mediterranean than samples from Portugal and Galicia. Herpesvirus infection was also detected in cetaceans, and both alpha and gammaherpesvirus were detected. Our work reported infection by herpesvirus in common dolphins for the first time. Co-infection with different strains of herpesvirus was detected, as well as co-infection with morbillivirus and Toxoplasma gondii. Relative expression of cytokine genes (IL1β, IL6, TNFα, IL12, IL4,IL10, and IFN-γ) was also determined for a group of healthy common dolphins. Relative expression was also determined in two sick common dolphins. Our results showed that IL1β, TNFα and IFN-γ were the cytokines with higher relative expression in healthy individuals and that Il-10 was the most expressed gene in the two sick animals, with a downregulation of all other cytokines. This work clarified the epidemiology of morbillivirus in cetacean species stranded along the Portuguse coastline, contributed to the variability of herpesvirus sequences in the gamma and alphaherpesvirus subfamilies and supports the evidence that profiling cytokine markers may serve as a tool to assess immunological shifts in stranded cetaceans

2023-02-06Tese de doutoramento

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Entidade financiadora

Fundação para a Ciência e a Tecnologia

Programa de financiamento

5876-PPCDTI

Número da atribuição

RECI/AAG-GLO/0470/2012