Protein characterization of Babesia equi piroplasms isolated from infected horse erythrocytes.

This study characterizes the proteins present in Babesia equi piroplasms, which are isolated from infected horse erythrocytes, to aid in the understanding of this organism’s biology, potentially helping to develop more precise diagnostic methods or treatments down the line.

Protein Characterization

• The researchers focused on characterizing the proteins found in Babesia equi piroplasms. Piroplasms are a stage in the lifecycle of certain parasitic organisms, including B. equi, a parasite that can infect horses.
• They purified these piroplasms by means of lysis, a process that ruptures the cell membrane, performed on infected horse erythrocytes (red blood cells) using what’s known as N2 gas cavitation. Following this, Percoll density-gradient centrifugation was used to further isolate the piroplasms. This is a method that separates components based on density.

Identification of Proteins

• The proteins were then analyzed using two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis (2D-SDS-PAGE), a method often used in biochemistry and molecular biology to separate proteins by mass (which are inferred based on the proteins’ molecular weights) and charge.
• The process of 2D-SDS-PAGE revealed the presence of multiple proteins, which were measured by their relative molecular weights (Mr). The major proteins identified had different mass values of 18, 28, 30, 41, 43, 54, 66.5, and 96 kilo Daltons (kDa).

Immunoblot Analysis

• Next, an immunoblot analysis was conducted. This is a technique used to detect specific proteins in a sample which relies on the binding of antibodies to the proteins of interest.
• This analysis was performed using serum from a horse that had been experimentally infected with the B. equi parasite. The immunoblot revealed six immunodominant proteins (those which elicit a stronger immune response) with molecular weights of 15, 18, 28, 30, 41, and 96 kDa.
• Further analysis showed that two of these immunodominant proteins, the ones weighing 18 and 28 kDa, were found to be membrane-bound proteins, which was determined by a process known as Triton X-114 phase partitioning. This is a method used to separate proteins based on their hydrophobicity or affinity for water.

Implications of the Study

• Identifying and understanding the proteins of B. equi could be key in developing future diagnostic methods or treatment options against this horse-infecting parasite.
• The data this research generated about the proteins present in B. equi piroplasms, including their molecular weights and whether they are membrane-bound, provides valuable data that can be used in future studies.