Peptides analogous to regions of the Nterminus or the pre - transmembrane domain of the S2 subunit inhibited SARS - CoV plaque formation by 40 - 70 % at concentrations of 15 - 30 M . Interestingly , peptides analogous to the SARS - CoV or MHV loop region inhibited viral plaque formation by > 80 % at similar concentrations .