Panton-Valentine leukocidin (PVL) is a virulence factor associated with severe necrotizing pneumonia and skin abscesses caused by community-acquired MRSA. What is the mechanism of action of PVL?

• A Formation of pores in the neutrophil cell membrane causing lysis ✓
• B ADP-ribosylation of elongation factor 2
• C Inhibition of peptidoglycan cross-linking in the cell wall
• D Stimulation of massive IL-1 and TNF release from macrophages

Explanation

PVL is a two-component cytotoxin (LukS-PV and LukF-PV) that assembles into pores in the membranes of neutrophils and monocytes, causing cell lysis and tissue necrosis. It is strongly associated with the USA300 CA-MRSA clone. Diphtheria toxin ADP-ribosylates EF-2. TSST-1 acts as a superantigen stimulating cytokine release. PVL directly kills leukocytes rather than stimulating cytokine release.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.