The Panton-Valentine leukocidin vaccine protects mice against lung and skin infections caused by Staphylococcus aureus USA300.

Methicillin-resistant Staphylococcus aureus is increasingly responsible for staphylococcal infections in the community. A large percentage of the community-acquired methicillin-resistant (CA-MRSA) strains in the USA produce Panton-Valentine leukocidin (PVL), which is associated with severe infections. The virulence of the clinical CA-MRSA strain USA300 was compared to that of its isogenic pvl-deleted mutant, and it was shown that PVL contributes to lung and muscle tissue destruction, respectively, in murine necrotizing pneumonia and skin infection models. Mice infected with the USA300 strain developed a dominant anti-PVL response. The PVL subunits were therefore tested as vaccinogens against this isolate, and their vaccine efficacy correlated with both the route of vaccination and infection. These data suggest that PVL is a virulence factor in murine CA-MRSA infections.

Risk factors for encephalitis from West Nile Virus: a matched case-control study using hospitalized controls.

We conducted a case-control study to determine risk factors for developing encephalitis among West Nile virus cases when compared with age-, gender and race/ethnicity-matched hospitalized controls. In the multivariable conditional logistic regression analysis, we identified the following independent risk factors associated with being an encephalitis case: hypertension (OR 4.0; P = 0.005), immunosuppressing conditions (OR 5.6; P = 0.001) and cardiovascular disease (OR = 28.3; P < 0.001). Individuals with these comorbidities should be targeted for education on protecting themselves from mosquito exposures.