The donor had a relatively weak neutralizing serum titer, and, indeed, only one of 4,600 B-cell supernates showed neutralizing activity. to protect contacts and front-line workers. What might medicine have to NSC-23026 offer? And in what time frame could prophylactics and therapeutics be discovered and made available? In PNAS, Corti et al. (8) describe the discovery of a potent human neutralizing mAb against a novel beta coronavirus, Middle East Respiratory Syndrome (MERS) virus, 4 mo after conception of the project. They demonstrate prophylactic and postexposure efficacy in an animal model of MERS virus infection. Their study supports the Rabbit Polyclonal to ADAMDEC1 notion that the generation of passive NSC-23026 antibodies might be a general, rapid strategy to counter emerging pathogens, at least until effective small-molecule drugs and vaccines can be developed. In April 2012, six hospital workers in Jordan were diagnosed with acute respiratory failure of unknown origin. Discovery of the causative agent, MERS virus, occurred in September 2012 (9). Over the next 2 y, additional cases were noted in the Middle East (Oman, Saudi Arabia, United Arab Emirates, and Iran), Asia (Malaysia, Philippines, and Indonesia), Europe (France, Greece, Italy, Spain, and United Kingdom), and the United States. Those individuals infected in Asia, Europe, and the United States were either travelers to the Middle East, nontraveling family members, or medical workers who Corti et al. describe the discovery of a potent human neutralizing mAb against a novel beta coronavirus, Middle East Respiratory Syndrome (MERS) NSC-23026 virus, 4 mo after conception of the project. cared for infected patients. One person hospitalized in the same European hospital room as an infected traveler became infected. The 184 laboratory-confirmed cases in a recent outbreak in South Korea are believed to have originated from one or two South Korean travelers to the Middle East. Clearly, this virus can spread by human-to-human contact. There have now been more than 1,300 documented cases and over 500 deaths from MERS worldwide, involving sporadic cases, small clusters, and large outbreaks (10, 11), most notably in Saudi Arabia following contact with camels, with the camels presumably infected by bats. Multiple genomic variants have been detected in domesticated camels in the Middle East, suggesting that the virus has been circulating for some time. Antibodies have been delivered passively to protect against infection for millions of years in breast milk, ever since we became mammals. The first medical transfer of antibody, however, occurred 125 y ago by von Behring and Kitasato (12). Convalescent sera has been transfused into patients with hopes of improving survival in a number of infections (13C15), but such sera are limited in quantity, variable in potency, and offer safety concerns. Specific mAbs, however, allow scale-up, consistency, and safety (15). Corti et al. (8) immortalized memory B cells from a MERS-convalescent donor several months after he recovered from infection, and tested supernates from single antibody-producing B cells for virus neutralization. The donor had a relatively weak neutralizing serum titer, and, indeed, only one of 4,600 B-cell supernates showed neutralizing activity. The mAb produced by the corresponding B-cell clone, dubbed LA60, was shown to neutralize a number of MERS virus strains potently at concentrations in the range of 0.1 to a few nanomolar. LA60 showed efficacy when given before or 1 d following exposure to virus in a mouse model of MERS infection. Doses of 1C15 mg/kg of body weight of mAb led to a reduction in viral titers of 2C4 logs on day 3, and to undetectable virus NSC-23026 on day 5. Much smaller doses of 0.12 mg/kg were effective when delivered intranasally in controlling this respiratory pathogen. Replication and pathology are limited in this model, and the animal typically clears the virus by day 7, so efficacy in humans remains to.