A novel cardiovirus in wild rats

Abstract

BackgroundCardioviruses cause severe illnesses in rodents and humans. In recent years, novel cardioviruses have been frequently found, which promoted further studies of the genetic diversity of cardioviruses. Using viral metagenomics, we genetically characterized a novel cardiovirus (named SX1) from wild rat feces. The genomic structure of SX1 shared similar features with those of the Theiler’s murine encephalomyelitis viruses, including a leader protein, four structural proteins and seven non-structural proteins. Phylogenetic analysis based on both structural proteins and non-structural proteins coding regions showed that SX1 was formed into a separate branch, being located between the branches of Theiler’s murine encephalomyelitis viruses and Thera viruses. Variable resides presented in the Ser/Thr rich domain of L protein, VP1 loops, and VP2 puffs distinguished SX1 from Theiler’s murine encephalomyelitis viruses, suggesting the different antigenicity and pathogenicity of SX1.

Viral Metagenomics Revealed a Novel Cardiovirus in Feces of Wild Rats

“…Cardioviruses have been thought to only infect rodents rather than humans, but the potential presence of some human cardioviruses has been reported over the years. In 2007, a novel human cardiovirus, characterized as Saffold virus (SAFV), was found in a stool sample of a girl with a fever of unknown origin (FUO) [1, 6, 9]. Cardioviruses are further divided into three species: Cardiovirus A (encephalomyocarditis virus, EMCV), Cardiovirus B (theilovirus), and Cardiovirus C [4, 10].…”

“…Although rodents are natural host for this virus, EMCV has also been found in many other hosts like mammals, birds, and invertebrates [11, 12]. Cardiovirus C has two types of novel cardioviruses (Boone cardiovirus 1 and 2) and was discovered in laboratory rats ( Rattus norvegicus ) [9, 13]. Cardiovirus B consists of 16 different viruses: Theiler’s murine encephalomyelitis virus (TMEV), Vilyuisk human encephalomyelitis virus (VHEV), Thera virus (TRV), SAFV 1–11, Genet fecal theilovirus (GFTV), and rat cardiovirus 1 (RCV-1) [14].…”

“…Fecal samples were suspended in Dulbecco’s phosphate-cushioned saline (DPBS) solution, subjected to vigorous vortex and then centrifuged (12,000 g for 2 min). Supernatants were filtered through a 0.45-mm filter (Millipore) to remove eukaryotic and bacterial cell-sized particles, and 200 mL of each pool was then subjected to a mixture of nuclease enzymes to reduce the concentration of free (non-viral encapsidated) nucleic acids [9, 24]. The remaining total nucleic acid was then isolated using QiaAmp Mini Viral RNA kit (Qiagen) according to the manufacturer’s protocol.…”

“…Library preparation and computational analysis were performed as previously described [9]. Briefly, 20 fecal samples were pooled into four pools which included 5 fecal samples each.…”

“…Cardioviruses are further divided into three species: Cardiovirus A (encephalomyocarditis virus, EMCV), Cardiovirus B (theilovirus), and Cardiovirus C [4, 10]. Cardiovirus A consists of only single virus (EMCV), which can cause the demyelinating diseases myocarditis, encephalitis, or type 1 diabetes in rodents [6, 9]. Although rodents are natural host for this virus, EMCV has also been found in many other hosts like mammals, birds, and invertebrates [11, 12].…”