A Targeted ”Next-Generation” Sequencing-Informatic Approach to Define Genetic Diversity in <i>Theileria orientalis</i> Populations within Individual Cattle: Proof-of-Principle

• Main Authors: Anson V. Koehler, Abdul Jabbar, Ross S. Hall, Robin B. Gasser
• Format: Article
• Language: English
• Published: MDPI AG 2020-06-01
• Series: Pathogens
• Subjects: <i>Theileria orientalis</i>; major piroplasm surface protein (<i>MPSP</i>) gene; multiplicity of infection (MOI); next-generation sequencing (NGS); SeekDeep
• Online Access: https://www.mdpi.com/2076-0817/9/6/448

Oriental theileriosis is an economically important tickborne disease of bovines, caused by some members of the <i>Theileria orientalis</i> complex. Currently, 11 distinct operational taxonomic units (OTUs), or genotypes, are recognized based on their major piroplasm surface protein (<i>MPSP</i>) gene sequences. Two of these genotypes (i.e., <i>chitose</i> and <i>ikeda</i>) are recognized as pathogenic in cattle, causing significant disease in countries of the Asia-Pacific region. However, the true extent of genetic variation and associated virulence/pathogenicity within this complex is unknown. Here, we undertook a proof-of-principle study of a small panel of genomic DNAs (<i>n</i> = 13) from blood samples originating from individual cattle known to harbor <i>T. orientalis</i>, in order to assess the performance of a targeted ”next-generation” sequencing-informatic approach to identify genotypes. Five genotypes (<i>chitose</i>, <i>ikeda</i>, <i>buffeli</i>, <i>type 4,</i> and <i>type 5</i>) were defined; multiple genotypes were found within individual samples, with dominant and minor sequence types representing most genotypes. This study indicates that this sequencing-informatic workflow could be useful to assess the nature and extent of genetic variation within and among populations of <i>T. orientalis</i> on a large scale, and to potentially employ panels of distinct gene markers for expanded molecular epidemiological investigations of socioeconomically important protistan pathogens more generally.