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Morbillivirus in live stranded cetaceans from Brazilian coast: immunohistochemical evidence
Groch, Kátia R.1, 2; Carvalho, Vitor L.3; Meirelles, Ana Carolina O.3; Gonzales-Viera, Omar4; Kolesnikovas, Cristiane K. M.5; Groch, Karina R.6; Zucca, Daniele7; Fernández, Antonio7; Catão-Dias, José Luiz1
(1) Laboratório de Patologia Comparada de Animais Selvagens, FMVZ, Universidade de São Paulo, Av. Orlando Marques de Paiva 87, São Paulo, SP, 05508-270, Brazil
(2) NGO Projeto Biopesca, Av. Presidente Castelo Branco, Praia Grande, SP, 11700 800, Brazil
(3) Aquasis - Associação de Pesquisa e Preservação de Ecossistemas Aquáticos, Rua José de Alencar 150. Praia de Iparana., Caucaia, CE, 61627-010, Brazil
(4) Laboratório de Histologia, Embriologia y Patologia Veterinaria, FMV, Universidad Nacional Mayor de San Marcos, Av. Circunvalacion 2800, Lima, San Borja, 41, Peru
(5) Associação R3 Animal, Rua dos Coroas, 469, Florianópolis, SC, 88061-600, Brazil
(6) Projeto Baleia Franca, Av. Atlântica s/nº. Caixa Postal 201., Imbituba, SC, 88780-000, Brazil
(7) División de Histología y Patología Animal, IUSA, Universidad de Las Palmas de Gran Canaria, Autov. Bañaderos-Las Palmas, KM 6,5, Arucas, Gran Canaria, 35415, Spain
Corresponding author: kgroch@terra.com.br
Morbilliviruses are associated with mortality outbreaks in marine mammals in the northern hemisphere. One single fatal case has been confirmed in Australia although serologic surveys indicate the presence of morbillivirus worldwide. This work investigated the occurrence of morbillivirus in nine cetaceans stranded alive along the Brazilian coast: a sperm whale calf (Physeter macrocephalus) in southern Brazil; a short-finned pilot whale calf (Globicephala macrorhynchus), a Guiana dolphin calf (Sotalia guianensis), a juvenile melon-headed whale (Peponocephala electra), an adult spinner dolphin (Stenella longirostris), an adult striped dolphin (Stenella coeruleoalba), an adult Fraser’s dolphin (Lagenodelphis hosei) and two humpback whales (Megaptera novaeangliae) in the northeastern coast. The animals stranded between February/2007 and February/2011 presenting neurologic/behavior changes and subsequently died or were euthanized. Necropsies were performed and sampled tissues were processed for histopathology and immunohistochemistry utilizing a monoclonal antibody against the nucleoprotein antigen of Canine Distemper Virus known to cross-react with cetacean morbilliviruses. Viral antigen was detected in neurons in the brain (3/3), spinal cord (2/3) and enteric nervous system (5/9) of five animals: P. macrocephalus, G. macrorhynchus, S. guianensis, P. electra and S. longirostris. Main microscopic lesions in positive animals included non-suppurative meningitis/encephalitis (2/3), neuronophagia (2/3), pneumonia (5/5), necrotic hepatitis (4/5), myocardial necrosis (2/5), lymphoid depletion (4/5) and reactive hyperplasia (3/5), splenitis (4/5), lymphadenitis (3/5), and colitis (4/5). There was no evidence of syncytia or viral inclusion bodies. This is the first report of morbillivirus antigen detected in marine mammals from South America and the first report in P. macrocephalus, S. guianensis and S. longirostris. RT-PCR tests are currently underway to confirm and genetically characterize the virus strain. This finding alerts for the occurrence of this potentially lethal disease in the South Atlantic Ocean and opens new venues for the understanding of origin and epidemiology of morbillivirus in cetaceans. (FAPESP 2011/08357-0; 2010/500094-3).