Novel anellovirus discovered from a mortality event of captive California sea lions

Abstract

A viral metagenomic study was performed to investigate potential viral pathogens associated with a mortality event of three captive California sea lions (Zalophus californianus). This study identified a novel California sea lion anellovirus (ZcAV), with 35 % amino acid identity in the ORF1 region to feline anelloviruses. The double-stranded replicative form of ZcAV was detected in lung tissue, suggesting that ZcAV replicates in sea lion lungs. Specific PCR revealed the presence of ZcAV in the lung tissue of all three sea lions involved in the mortality event, but not in three other sea lions from the same zoo. In addition, ZcAV was detected at low frequency (11 %) in the lungs of wild sea lions. The higher prevalence of ZcAV and presence of the double-stranded replicative form in the lungs of sea lions from the mortality event suggest that ZcAV was associated with the death of these animals.New diseases in marine animals are emerging at an increasing rate and the causative agents of the diseases are mostly unknown (Harvell et al., 1999;Van Bressem et al., 1999). As animals are considered to be the source of .70 % of emerging human infections (Cleaveland et al., 2001), surveillance of pathogens in animals, especially in non-human vertebrates, is important for protecting the health of both humans and wild animal populations (Kruse et al., 2004;Kuiken, 2005).Investigating new viral infections has been difficult due to limitations of current detection methods (reviewed by Delwart, 2007). For example, degenerate PCR and panviral microarrays can detect viruses with close sequence similarity to known viruses, but are limited for discovering novel viruses that share limited similarity with previously sequenced virus genomes. Recent studies have demonstrated the effectiveness of virus-particle purification and shotgun sequencing (viral metagenomics) for describing novel viruses, including those that are unrelated to previously described virus families (Delwart, 2007;Edwards & Rohwer, 2005). The techniques of viral metagenomics were first applied to characterize virus communities present in the environment (Breitbart et al., 2002) One potential application of viral metagenomics is for examination of viral pathogens involved in unusual mortality events of animals. In 2005 and 2006, three California sea lions at the Kansas City Zoo, MO, USA, died in a mortality event of unknown aetiology. Necropsy and histopathology revealed granulomatous, non-suppurative mediastinitis and pleuritis in two of the sea lions, whilst the third sea lion was found to have an accumulation of lymphocytes and macrophages in the upper respiratory submucosa (W. K. Suedmeyer, unpublished results). Chemical toxicity assays using gas chromatography and mass spectroscopy did not detect pesticides, organic toxic compounds or abnormal mineral levels in pool water or gastric contents. All sea lions were negative for pathogenic bacteria, fungi and mycoplasma in culture-based assays and histopathology. The sea lions also tested negative for West Nile virus, ...

Global impact of Torque teno virus infection in wild and domesticated animals

“…TTV became the prototype of a large group of viral agents with similar genomic organization but a low sequence homology, isolated both in humans and in animals. In fact, in the following years, similar viruses were isolated in other species of vertebrates, including nonhuman primates (chimpanzees, macaques, tamarin monkeys, and douroucouli), pets (dogs and cats), livestock (pigs, cattle, sheep, camels, and poultry), and wild boars, badgers, pine martens, tupaias, rodents, bats, sea turtles, and sea lions [3,5,[23][24][25][26][27][28][29]35]. The natural infection of pigs was first described by Leary et al in 1999 [5]; the first complete genome of Torque teno sus virus (TTSuV) was described by Okamoto in 2002 [3].…”

“…Furthermore, a series of closely related TTV-like viruses, and two distinct genera comprising viruses with smaller genome size and similar genetic organization, but only partial sequence homology, designated Torque teno midi virus (TTMDV) and Torque teno mini virus (TTMV), have been characterized [20][21][22]. A large number of AV species has also been reported in wild and domestic animals, including non-human primates, wild boars, badgers, pine martens, tupaias, rodents, bats, sea turtles, sea lions, livestock (pigs, sheep, cattle, camels, and poultry), and companion animals (cats and dogs) [3,5,[23][24][25][26][27][28][29]. Indeed, since to date the presence of TTVs infecting mammalian species has been poorly investigated, it would not be surprising if all mammals were infected with species-specific TTVs.…”

Potential role of viruses in white plague coral disease

“…This is because viruses lack a common phylogenetic marker, and therefore marker-based amplicon sequencing (for example, 16S or 18S ribosomal RNA surveys) cannot necessarily be applied to diverse viral consortia. Some examples of the successful application of viral metagenomics to elucidate the pathogens associated with a disease include the identification of: an astrovirus as the probable cause for shaking mink syndrome (Blomströ m et al, 2010), an anellovirus associated with a California sea lion mortality event (Ng et al, 2009) and a coronavirus that causes human respiratory disease (Bermingham et al, 2012).…”

Infection Dynamics of <i>Torque Teno Sus Virus</i> Types <i>1</i> and <i>2</i> in Serum and Peripheral Blood Mononuclear Cells

“…TTV was first detected in a human patient with post-transfusion hepatitis of unknown aetiology [19], but later detected in many other vertebrate animals including pigs [3,7,10,16,21,22]. In pigs, two distinct species of TTV, Torque teno sus virus (TTSuV), types 1 (TTSuV1) and 2 (TTSuV2) have been described [17,22], and they are currently grouped under the genus Iotatorquevirus of family Anelloviridae [2].…”

“…TTSuV1 and TTSuV2 (TTSuVs) have been detected from serum, plasma, semen, faeces, colostrum, nasal secretion and various tissues [5,8,13,26,29,30] exclusively by Polymerase chain reaction (PCR), and different pig rearing countries have reported prevalence rate ranging from 24 to 100% [4,8,[14][15][16][17][24][25][26]. Limited longitudinal studies employing serum [17,26] and cross-sectional studies employing serum and tissues [1,8,9,27] have shown that TTSuV infection increases with age.…”