Rotavirus VP4 and VP7-Derived Synthetic Peptides as Potential Substrates of Protein Disulfide Isomerase Lead to Inhibition of Rotavirus Infection

• DOI: 10.1007/s10989-012-9314-z
• Publication Date: 2012-07-05T13:28:28Z
• Authors: Martha N. Calderón; Fanny Guzmán; Orlando Acosta; Carlos A. Guerrero
• Keywords: Rotavirus Infections

Rotavirus infection of MA104 cells has been shown to be inhibited by cell membrane-impermeant thiol/disulfide exchange inhibitors and anti-PDI antibodies. To characterise the amino acid sequences of rotavirus structural proteins potentially mediating cell surface PDI–substrate interactions, rotavirus-derived peptides from VP4 and VP7 (RRV) and VP7 (Wa), and their modified versions containing serine instead of cysteine were synthesized. Cysteine-containing VP7 peptides corresponding to residues 189–210 or 243–263 caused an infectivity inhibitory effect of about 64 and 85 %, respectively, when added to cells. Changing cysteine to serine significantly decreased the inhibitory effect. A cysteine-containing peptide corresponding to VP4 residues 200–219 and its scrambled version reduced infectivity by 92 and 80 %, respectively. A cysteine to serine change in the original VP4 200–219 peptide did not affect its inhibitory effect. Non-rotavirus related sequences containing cysteine residues efficiently inhibited rotavirus infectivity. Antibodies against VP7 residues 189–210 or 243–263 significantly inhibited rotavirus infectivity only after virus attachment to cells had occurred, whereas those against VP4 200–219 peptide inhibited infectivity irrespective of whether virus or cell-attached virus was antibody-treated. A direct PDI–peptide interaction was shown by ELISA for cysteine-containing VP7 and VP4 peptides. Virus–cell attachment was unaffected by the peptides inhibiting virus infectivity. The results showed that even though cysteine residues in the peptides tested are important in both virus infectivity inhibition and in vitro PDI–peptide interaction, the accompanying amino acid sequence also plays some role. As a whole, our findings further support our hypothesis that cell surface PDI from MA104 cells might be contributing to rotavirus entry at a post-attachment step.