High Genomic Variability in Equine Infectious Anemia Virus Obtained from Naturally Infected Horses in Pantanal, Brazil: An Endemic Region Case

• Main Authors: Camila Dantas Malossi, Eduardo Gorzoni Fioratti, Jedson Ferreira Cardoso, Angelo Jose Magro, Erna Geessien Kroon, Daniel Moura de Aguiar, Alice Mamede Costa Marque Borges, Marcia Furlan Nogueira, Leila Sabrina Ullmann, João Pessoa Araujo
• Format: Article
• Language: English
• Published: MDPI AG 2020-02-01
• Series: Viruses
• Subjects: equine infectious anemia virus; molecular characterization; endemic region; rna genome; equine
• Online Access: https://www.mdpi.com/1999-4915/12/2/207

Equine infectious anemia virus (EIAV) is a persistent lentivirus that causes equine infectious anemia (EIA). In Brazil, EIAV is endemic in the Pantanal region, and euthanasia is not mandatory in this area. All of the complete genomic sequences from field viruses are from North America, Asia, and Europe, and only proviral genomic sequences are available. Sequences from Brazilian EIAV are currently available only for <i>gag</i> and LTR regions. Thus, the present study aimed for the first time to sequence the entire EIAV genomic RNA in naturally infected horses from an endemic area in Brazil. RNA in plasma from naturally infected horses was used for next-generation sequencing (NGS), and gaps were filled using Sanger sequencing methodology. Complete viral genomes of EIAV from two horses were obtained and annotated (Access Number: MN560970 and MN560971). Putative genes were analyzed and compared with previously described genes, showing conservation in <i>gag</i> and <i>pol</i> genes and high variations in LTR and <i>env</i> sequences. Amino acid changes were identified in the p26 protein, one of the most common targets used for diagnosis, and p26 molecular modelling showed surface amino acid alterations in some epitopes. Brazilian genome sequences presented 88.6% nucleotide identity with one another and 75.8 to 77.3% with main field strains, such as EIAV Liaoning, Wyoming, Ireland, and Italy isolates. Furthermore, phylogenetic analysis suggested that this Brazilian strain comprises a separate monophyletic group. These results may help to better characterize EIAV and to overcome the challenges of diagnosing and controlling EIA in endemic regions.