Panton–Valentine leukocidin

Mechanism of action

Panton–Valentine leukocidin is a toxin from the synergohymenotropic family that creates pores in cell membranes. A prophage called Φ-PVL, which is a virus inserted into the Staphylococcus aureus chromosome, carries the genes for this factor. Those genes produce two proteins, LukS-PV and LukF-PV, each 33 and 34 kilodaltons in size.

These two proteins work as subunits, coming together inside the membranes of host defense cells like white blood cells, monocytes, and macrophages. They assemble into a ring with a central hole, allowing cell contents to leak out and also functioning as a superantigen. Some researchers attribute the differing behavior of MRSA subtypes to phenol-soluble modulin peptides rather than to PVL.

Clinical effects

Panton–Valentine leukocidin is a toxin that destroys white blood cells and triggers necrotizing pneumonia, a severe illness with a death rate as high as 75%. In staphylococcal necrotizing pneumonia, 85% of community-acquired cases tested positive for PVL, while hospital-acquired cases showed none.

Despite affecting younger, healthier individuals, community-acquired pneumonia had a worse prognosis, with mortality exceeding 40%. PVL has been linked to multiple fatal outbreak clusters. It may boost staphylococcal protein A, a major pro-inflammatory driver in pneumonia, and also causes boils, abscesses, pyomyositis, and osteomyelitis.

Did You Know?

• PVL was initially discovered by Van deVelde in 1894 due to its ability to lyse leukocytes.
• It was named after Sir Philip Noel Panton and Francis Valentine when they associated it with soft tissue infections in 1932.
• PVL is produced from the genetic material of a bacteriophage that infects Staphylococcus aureus.