Identification of a novel equine infectious anemia virus field strain isolated from feral horses in southern Japan

Abstract

Although equine infectious anemia (EIA) was described more than 150 years ago, complete genomic sequences have only been obtained from two field strains of EIA virus (EIAV), EIAV Wyoming and EIAV Liaoning . In 2011, EIA was detected within the distinctive feral Misaki horse population that inhabits the Toi-Cape area of southern Japan. Complete proviral sequences comprising a novel field strain were amplified directly from peripheral blood of one of these EIAVinfected horses and characterized by nucleotide sequencing. The complete provirus of Miyazaki2011-A strain is 8208 bp in length with an overall genomic organization typical of EIAV. However, this field isolate possesses just 77.2 and 78.7 % nucleotide sequence identity with the EIAV Wyoming and EIAV Liaoning strains, respectively, while similarity plot analysis suggested all three strains arose independently. Furthermore, phylogenetic studies using sequences obtained from all EIAV-infected Misaki horses against known viral strains strongly suggests these Japanese isolates comprise a separate monophyletic group.

Phylogenetic Analysis of Russian Eiav Isolates Using an Optimized Nested PCR

“…The EIA etiological agent is of viral nature (Equine infectious anemia virus -EIAV) and belongs to the genus Lentivirus in the family Retroviridae [4,5]. The EIA viral genome consists of two positive-sense identical single-stranded linear RNA molecules [4,[6][7][8] and includes three major structural genes arranged (in 53) as gag (encode virion core proteins required for intracellular assembly and virus release from the cells), pol (encodes polypeptides with revertase, specific RNA-ase and DNA-endonuclease activity) and env (encodes surface virion glycoproteins involved in the formation of the virion envelope, in specific recognition of host cell and in virus penetration through its membrane) [4,8,9]. Furthermore, the EIA viral genome contains three additional open reading frames, the tat, rev, and S2, from which small accessory proteins involved in the viral RNA synthesis regulation and processing are expressed.…”

“…Furthermore, the EIA viral genome contains three additional open reading frames, the tat, rev, and S2, from which small accessory proteins involved in the viral RNA synthesis regulation and processing are expressed. The auxiliary protein S2 is an important determinant of the EIA virus replication and pathogenic properties in vivo [4,6,[8][9][10]. The nucleotide sequence of the viral genome has long terminal repeats (LTR) at both ends that are necessary for the integration of proviral DNA (pDNA) into the cell genome [8,11].…”

“…As seen in the dendrogram, strain K-3-VNIITIBP-VIEV is included into the same cluster as strains V70 and V26 (with the nucleotide identity of 98 %). According to published data, strains V70 and V26 were isolated in Japan by passaging North American EIAV Wyoming strain on naturally susceptible animals, and belong to the same genetic group [8,9] with the intragroup differences not exceeding 5 %. Nucleotide sequence homology of the gag gene regions in strains 3-K-VNIITIBP-VIEV and EIAV Wyoming was also 98 %.…”

Antiviral potency and functional analysis of tetherin orthologues encoded by horse and donkey

“…Equine infectious anemia virus (EIAV), which belongs to the Retroviridae family, is a non-primate enveloped virus that has been reported to infect all members of the Equidae family [18, 19]. The clinical cases and virus evolution have been well documented in horses, ponies, donkey and mules.…”

Equine infectious anemia virus in Japan: Viral isolates V70 and V26 are of North American not Japanese origin

“…This conclusion is derived from statements published in Japanese scientific journals that declare V70 and V26 are serial horse passaged variants of the North America EIAV Wyoming strain (Kobayashi and Kono, 1967;Kono et al, 1970) and on comparative nucleotide sequence analysis. Examination of complete genomic sequences demonstrate V70 and V26 possess 98.0% and 97.5% respectively, nucleotide sequence identity with EIAV Wyoming (AF033820, isolated in North America) (Petropoulos, 1997), but less than 80.3% with the other three non-laboratory adapted field strains: EIAV Liaoning (AF327877, isolated in China) (Tu et al, 2007), EIAV Miyazaki2011-A (JX003263, isolated in Japan) (Dong et al, 2013) and EIAV Ireland (JX480631, isolated in Ireland) (Quinlivan et al, 2013) that have been characterized to date. Furthermore, phylogenetic analysis of these sequences reveals V70 and V26 cluster with EIAV Wyoming and known derivatives of this virus (Fig.…”