Swine breeding has achieved a high development based on genetic improvement, nutrition, management, and sanity. However, due to intensive breeding methods, swine have become more susceptible to a higher number of infectious diseases. Among the most important pathogens that affect the swine world industry is the Porcine Circovirus 2 (PCV2), a small, icosahedral, non-enveloped virus, ambisense single-stranded circular DNA, composed by 1,766-1,768 nucleotides. This virus is highly resistant to environmental variations and disinfecting agents, endemic worldwide and has been associated with several distinct clinical manifestations that entail important economic losses to the producers. The transport of the PCV2 to the cell nucleus involves the importins (Importin ± (Imp±) and Importin ² (Imp²)), which are specialized proteins that recognize proteins with Nuclear Localization Sequences (NLSs). Site-directed mutagenesis experiments demonstrated that the 41 amino acid residues from the N-terminal segment of the PCV2 capsid protein (protein Cap) and, therefore, they necessarily enclose the NLS sequence of this virus. Despite this information, the interactions of the Imp±/PCV2 NLS complex have not been yet characterized. Thus, the objective of this project is to get insights on this complex based on the co-crystallization of the recombinant Mus musculus Imp± with the PCV2 NLS and verify the affinity of these molecules by isothermal titration calorimetry experiments. The obtained crystals will be submitted to X-ray diffraction experiments and the data generated will be processed to solve the Imp±/PCV2 NLS crystallographic structure of complexed with the peptide. The results of this project could contribute to a better comprehension of the PCV2 biology and potentially for the future development of antiviral drugs for the treatment of porcine circoviruses and/or other biotechnological products.
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