Purpose of review: Several alternative mechanisms that cause protease inhibitor resistance have been proposed. A summary of the proposed mechanisms and the status regarding their clinical relevance is given.
Recent findings: At this moment only changes in the cleavage sites of protease (either alone or in the background of protease mutations) have been associated with phenotypic changes in IC50 and virological failure.
Summary: Further studies are necessary to unravel the mechanism, the clinical relevance and potential effect of transmission of these cleavage site changes.
aDepartment of Medical Microbiology, University Medical Center Utrecht, Utrecht, The Netherlands
bInstitute of Virology, University of Cologne, Cologne, Germany
cDepartment of Virology, Erasmus Medical Center, Rotterdam, The Netherlands
Correspondence to Charles Boucher, Department of Medical Microbiology, University Medical Center Utrecht, Heidelberglaan 100 (HP G04.614), 3584 CX Utrecht, The Netherlands Tel: +31 88 755 6526; fax: +31 88 755 5426; e-mail: firstname.lastname@example.org