Retrospective Study of Etiologic Agents Associated with Nonsuppurative Meningoencephalitis in Stranded Cetaceans in the Canary Islands

Abstract

c Nineteen natural cases of etiologically undetermined encephalitides in free-ranging cetaceans were studied retrospectively. Histological examination of the brains revealed variable degrees of nonsuppurative encephalitis or meningoencephalitis, characterized predominantly by perivascular lymphohistiocytic infiltrates. A PCR assay was used on brain and other available tissues to detect the presence of morbillivirus, herpesvirus, West Nile virus, Toxoplasma gondii, and Brucella spp. In addition, immunohistochemical (IHC) staining was performed on selected tissues to determine the presence of morbilliviral antigens. Six animals (5 striped dolphins and 1 common dolphin) showed IHC and/or molecular evidence of morbilliviral antigens and/or genomes, mainly in brain tissue. Conventional nested PCR detected herpesviral DNA in brain tissue samples from two striped dolphins. There was no evidence of West Nile virus, T. gondii, or Brucella spp. in any of the brain tissue samples examined. The information presented here increases the number of confirmed morbillivirus-positive cases within the Canarian archipelago from two previously reported cases to eight. Furthermore, a new nested-PCR method for the detection of morbillivirus is described here. Regarding herpesvirus, the phylogenetic analysis performed in the current study provides valuable information about a possible pathogenic branch of cetacean alphaherpesviruses that might be responsible for some fatal cases worldwide.

HERPESVIRUS-ASSOCIATED GENITAL LESIONS IN A STRANDED STRIPED DOLPHIN (STENELLA COERULEOALBA) IN THE CANARY ISLANDS, SPAIN

“…Although herpesviruses had been described in striped dolphins (Baker 1992;Soto et al 2012;Sierra et al 2014), genital herpesvirus infection in this species had not been recorded. Transmission of genital herpesvirus in cetaceans is likely to be sexual (van Elk et al 2009), as occurs in several herpesviral diseases of humans (Douglas and Kieff 1988) and animals (Kennedy and Miller 1993).…”

“…Alphaherpesviruses have been more commonly associated with skin lesions and systemic infections in cetaceans, whereas gammaherpesviruses were more frequently found in genital wounds. Skin lesions have been attributed to a herpesvirus etiology in cetacean species by three diagnostic criteria: 1) their gross or histologic appearance (Greenwood et al 1974;Baker 1992;Baker and Martin 1992), 2) ultrastructural demonstration of herpeslike viral particles (Martineau et al 1988;Barr et al 1989;Van Bressem et al 1994), and 3) molecular criteria (Smolarek Benson et al 2006;Sierra et al 2014). Genital herpesvirus lesions have been described associated with plaquelike or proliferative wounds in bottlenose and Risso's dolphins (Tursiops truncatus and Grampus griseus; Smolarek Benson et al 2006), two Blainville's beaked whales (Mesoplodon densirostris; Saliki et al 2006;Smolarek Benson et al 2006), and a beluga whale (Delphinapterus leucas; Bellehumeur et al 2015).…”

“…Herpesviruses have also been responsible for more serious diseases, causing encephalitis in a harbor porpoise, a bottlenose dolphin, and a striped dolphin (Stenella coeruleoalba) (Kennedy et al 1992;Esperon et al 2008;Sierra et al 2014). Molecular studies also have described alphaherpesviruses associated with fatal systemic infections in two Atlantic bottlenose dolphins (Blanchard et al 2001), a localized infection of the lymphoid system in a Cuvier's beaked whale (Ziphius cavirostris; Arbelo et al 2010), and acute multifocal necrotizing tubulointerstitial nephritis in a Blainville's beaked whale (Arbelo et al 2012).…”

Fetal distress and in utero pneumonia in perinatal dolphins during the Northern Gulf of Mexico unusual mortality event

“…RNA extraction was conducted on tissues using RNeasy (Qiagen), on 0.5 g of tissue macerate, following the manufacturer's instructions. PCR was carried out by conventional semi-nested retrotranscriptase polymerase chain reaction (RT-PCR), which amplifies a 300 bp within a conserved region in the phosphoprotein gene (P gene) (Sierra et al 2014). Two negative controls (extraction and amplification) and an amplification positive control were used.…”

Evaluation of morbillivirus exposure in cetaceans from the northern Gulf of Mexico 2010-2014

“…RNA was extracted from tissues using the QIAmp cador Pathogen kit (Qiagen), using 0.5 g of tissue macerate, following the manufacturer's instructions. PCR was carried out by conventional semi-nested reverse transcription PCR, which amplifies a 300 bp product within a conserved region in the phosphoprotein gene (P-gene) (Barrett et al 1993, Sierra et al 2014. Partial sequences of the P-gene from the pan-morbillivirus PCR were compared against morbilliviral sequences available in the GenBank database.…”