Detection of a respiratory coronavirus from tissues archived during a pneumonia epizootic in  free-ranging Pacific harbor seals Phoca vitulina richardsii

Abstract

In June 2000, 21 adult harbor seals Phoca vitulina richardsii were found dead along a localized section of the central California coast. Necropsy of 5 fresh carcasses revealed pulmonary congestion, consolidation, and hemorrhage. Histopathological changes in lungs from 2 of these seals included a necrotizing lymphocytic and histocytic lobar pneumonia with intra-lesional bacteria. A coronavirus (CoV) was detected in archived tissues from 1 of the 5 seals via a degenerate PCR for nidoviral RNA-dependent RNA polymerase (RdRp), and was subsequently confirmed via specific PCR. Based on the partial RdRp sequence, the CoV was identified as a novel, divergent member of the CoV group 1a. The virus is tentatively named harbor seal coronavirus (HSCoV). The clinical significance of HSCoV and its involvement in the etiology of the epizootic pneumonia and deaths of the harbor seals is uncertain. KEY WORDS: Harbor seal · Phoca vitulina richardsii · Coronavirus · Pneumonia Resale or republication not permitted without written consent of the publisherDis Aquat Org 90: [113][114][115][116][117][118][119][120] 2010 crochiropteran bat hosts; and Group 2d, from megachiropteran bat hosts (Woo et al. 2007). It has been proposed that Group 3 be divided as follows: Groups 3a, from avian hosts; Group 3b, which contains a coronavirus from a beluga whale Delphinapterus leucas, the only coronavirus identified in a marine mammal to date; and Group 3c, which contains viruses from diverse avian hosts as well as one from an Asian leopard cat Prionailurus bengalensis that may represent recent host switching (Woo et al. 2009).In late May and early June 2000, 21 adult harbor seals Phoca vitulina richardsii were found dead along a localized 10 mile (16 km) section of the central California coast at Point Reyes National Seashore. Upon postmortem examination of 5 relatively fresh carcasses, all seals had grossly abnormal lungs, and histological examination of 3 cases revealed severe pneumonia. A similar event with similar gross necropsy findings had occurred in 1997, when approximately 90 seals were found dead in the same area, but no conclusive etiology for the event was identified. In both events, a viral infection with secondary bacterial pneumonia was suspected. CoVs are recognized causes of enteric and respiratory infections that are often fatal in young animals. Here we report on the identification of a novel respiratory coronavirus from one of these harbor seals. This novel coronavirus of wildlife is a novel member of Group 1a and is distinct from, but most closely related to the CoVs of ferrets, cats, dogs, and swine. MATERIALS AND METHODS Animals and samples.On 26 May 2000, a harbor seal (HS D62) was found dead at McClure's Beach, Point Reyes National Seashore, in central California, and a field necropsy was conducted. Tonsil, stomach, cerebellum, brain stem, and lymph node were collected in 10% formalin for histological analysis. An additional 4 adult harbor seals were found dead on 6 June 2000. Two harbor seals, designated as H...

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“…Histologically, the bacterium causes vasculitis with characteristic "swarms" of Gram-negative bacilli (Gaffney et al, 2008). P. aeruginosa infection has also been associated with hemorrhagic pneumonia in a cluster of deaths in adult free-ranging harbor seals (Nollens et al, 2010).…”