A Rare Case of Panton-Valentine Leukocidin-Related Cervical Empyema.

Staphylococcus aureus is found in the normal skin and mucosa of approximately 30% of healthy populations and is the most common pathogen in human disease associated with bacteria. They are divided into methicillin-sensitive S . aureus (MSSA) and methicillin-resistant S. aureus (MRSA). The S. aureus strains carrying the Panton-Valentine leukocidin genes (SA-PVL) were initially believed to belong to the MRSA group; however, recent reports showed they also belonged to the MSSA group (MSSA-PVL). SA-PVL is common in skin and soft-tissue infections but rare in musculoskeletal infections, especially in spondylodiscitis. We are reporting a case suffering from cervical spondylodiscitis and epidural abscess associated with MSSA carrying the Panton-Valentine leukocidin genes.

Use of a synthetic biosensor for neutralizing activity-biased selection of monoclonal antibodies against atroxlysin-I, an hemorrhagic metalloproteinase from Bothrops atrox snake venom.

BACKGROUND: The snake Bothrops atrox is responsible for the majority of envenomings in the northern region of South America. Severe local effects, including hemorrhage, which are mainly caused by snake venom metalloproteinases (SVMPs), are not fully neutralized by conventional serum therapy. Little is known about the immunochemistry of the P-I SVMPs since few monoclonal antibodies (mAbs) against these molecules have been obtained. In addition, producing toxin-neutralizing mAbs remains very challenging. METHODOLOGY/PRINCIPAL FINDINGS: Here, we report on the set-up of a functional screening based on a synthetic peptide used as a biosensor to select neutralizing mAbs against SVMPs and the successful production of neutralizing mAbs against Atroxlysin-I (Atr-I), a P-I SVMP from B. atrox. Hybridomas producing supernatants with inhibitory effect against the proteolytic activity of Atr-I towards the FRET peptide Abz-LVEALYQ-EDDnp were selected. Six IgG1 Mabs were obtained (named mAbatr1 to mAbatr6) and also two IgM. mAbatrs1, 2, 3 and 6 were purified. All showed a high specific reactivity, recognizing only Atr-I and B. atrox venom in ELISA and a high affinity, showing equilibrium constants in the nM range for Atr-I. These mAbatrs were not able to bind to Atr-I overlapping peptides, suggesting that they recognize conformational epitopes. CONCLUSIONS/SIGNIFICANCE: For the first time a functional screening based on a synthetic biosensor was successfully used for the selection of neutralizing mAbs against SVMPs.