Monoclonal antibody therapy for Junin virus infection.

Countermeasures against potential biothreat agents remain important to US Homeland Security, and many of these pharmaceuticals could have dual use in the improvement of global public health. Junin virus, the causative agent of Argentine hemorrhagic fever (AHF), is an arenavirus identified as a category A high-priority agent. There are no Food and Drug Administration (FDA) approved drugs available for preventing or treating AHF, and the current treatment option is limited to administration of immune plasma. Whereas immune plasma demonstrates the feasibility of passive immunotherapy, it is limited in quantity, variable in quality, and poses safety risks such as transmission of transfusion-borne diseases. In an effort to develop a monoclonal antibody (mAb)-based alternative to plasma, three previously described neutralizing murine mAbs were expressed as mouse-human chimeric antibodies and evaluated in the guinea pig model of AHF. These mAbs provided 100% protection against lethal challenge when administered 2 d after infection (dpi), and one of them (J199) was capable of providing 100% protection when treatment was initiated 6 dpi and 92% protection when initiated 7 dpi. The efficacy of J199 is superior to that previously described for all other evaluated drugs, and its high potency suggests that mAbs like J199 offer an economical alternative to immune plasma and an effective dual use (bioterrorism/public health) therapeutic.

Development of a novel multiplex electrochemiluminescent-based immunoassay for quantification of human serum IgG against 10 Staphylococcus aureus toxins.

An electrochemiluminescent (ECL)-based multiplex immunoassay using Meso-Scale Discovery (MSD) technology was developed for detecting antibody response toward 10 Staphylococcus aureus (S. aureus) exotoxins. These 10 antigens included three different groups of toxins: 1) single component pore-forming toxins such as alpha- and delta-hemolysins, 2) the bicomponent pore-forming toxin Panton-Valentine leukocidin (PVL), comprised of LukS-PV and LukF-PV subunits, and 3) enterotoxin/superantigens - Staphylococcal enterotoxins A (SEA), B (SEB), C1 (SEC1), D (SED), K (SEK) and Toxic shock syndrome toxin-1 (TSST-1). Assay development included optimization steps with a conventional SEB ELISA-based serological assay and then optimized parameters were transferred and re-optimized in a singleplex ECL format. Finally, two pentaplex solid-phase ECL formats were developed. As proof of concept, one set of pentaplex ECL data was compared with conventional ELISA results. During the assay development controls were screened and developed for both the singleplex and multiplex assays. ECL-based multiplex assays were more sensitive with a wide dynamic range and proved more time-efficient than conventional ELISAs. Using the newly developed ECL method we showed, for the first time, that delta-hemolysin toxin can induce an immune response as antibody titers could be detected.