Genetic Diversity of Theileria equi From Horses In Different Regions of Brazil Based On the 18S rRNA Gene.

The research article discusses the study conducted to understand the genetic diversity of the parasite Theileria equi, which causes equine piroplasmosis, in different regions of Brazil using the 18S rRNA gene. The study identified two distinct genotypes of T. equi present in Brazil and identified regions within the 18S rRNA sequence that showed considerable genetic variability.

Objective of the Study

• The study focuses on the molecular characterization of Theileria equi, a protozoa that causes equine piroplasmosis, a significant disease affecting equines in Brazil and globally.

Methodology

• Equine blood samples were collected from the five geographical regions of Brazil.
• The samples were subjected to real-time PCR to test for the presence of T. equi.
• The researchers also sequenced and analyzed the 18S rRNA sequences obtained from 23 samples taken from naturally infected horses. This analysis was carried out to identify the genotypes and sites of genetic variability.

Findings

• Thirteen different T. equi 18S rRNA sequences and two distinct genotypes were identified, suggesting a significant genomic diversity of T. equi present in Brazil.
• Three hypervariable regions (V2, V4, and V8) were discovered in the 18S rRNA sequence of T. equi through alignment entropy analysis. The V4 region showed the most genetic variability.
• Phylogenetic analysis, which was based on the 18S rRNA sequences, revealed the formation of 3 distinct clades (groups – A, B, and C). Samples from Brazil were present in two of these clades (A and C).

Conclusion

• The study presents the characterization and heterogeneity of the circulating T. equi 18S rRNA sequences in Brazil for the first time. It acknowledges Brazil as an endemic area for equine piroplasmosis with at least two distinct T. equi genotypes naturally infecting equines.