Vaccine development is an interesting and dynamic field of study, due in part to the variety of approaches used for antigen discovery.  A recent publication in the Journal of Parasitology International by Gong et al. showcased this.  Researchers sought to gain a deeper understanding of the mechanism behind how the parasite Toxoplasma gondii invades host cells.  More specifically, these researchers were interested in a T. gondii protein called MAR domain-containing protein 4a (TgMCP4a).  MAR domains within proteins are known to mediate the interaction between parasite and host cell, as well as aiding in the formation of the binding complex.  This group was interested in the binding mechanism of this protein and began their experiments by performing FACS analysis on a recombinant TgMCP4a protein combined with various types of eukaryotic cells.  The results from these experiments showed binding of TgMCP4a to Vero, CHO, and 293T cells.  This group then wanted to further investigate and determine what exactly the TgMCP4a proteins were binding to.  They performed a pull-down assay followed by mass spectrometry analysis and identified the proteins binding to TgMCP4a were heat shock proteins (HSP) – more specifically – HSC70 and HSP70.  In order to confirm these results, the TgMCP4a plasmid was transfected into 293T cells for use in an immunoprecipitation experiment.  The resulting protein precipitate was identified, as expected, as HSC70 and HSP70.  This investigation sheds light on a possible mechanism for the parasitic TgMCP4a protein.  In a previous publication, it was shown that certain types of viruses will exploit HSPs and use them for virus replication.  It is possible that the T. gondii parasite uses HSP70/HSC70 for similar reasons.  For example, HSPs could facilitate parasite-host binding, and aid with parasitic growth.  An essential step towards vaccine development is first understanding the mechanism behind infection, as well as, understanding the invader-host relationship.  T. gondii affects 34% of the world today, making the development of a vaccine very significant.

The anti-HSC70 antibody used in the western blot for this experiment was purchased from StressMarq Biosciences (catalog # SPC-102).

The original research paper was published in:

Gong H, Kobayashi K, Sugi T, Takemae H, Ishiwa A, et al.  Characterization and binding analysis of a microneme adhesive repeat domain-containing protein from Toxoplasma gondii.  Parasitol Int. 2013 Dec 18;63(2):381-388. doi: 10.1016/j.parint.2013.12.006. [Epub ahead of print]