Contamination with MERS-CoV causes lethal pneumonia in the common marmoset. animals to uncovered or infected patients. The vast majority of, if not all, camels in the Middle East have been infected with MERS-CoV, and some contain high titers of antibody to the computer virus. Here, we show that this antibody is usually protective if delivered either prophylactically or therapeutically to mice infected with MERS-CoV, indicating that this may be a useful intervention in infected patients. TEXT A decade after the emergence of the severe acute respiratory syndrome (SARS), a novel beta coronavirus was isolated from a patient with a fatal viral pneumonia in Saudi Arabia in 2012 (1). The disease is now designated Middle East respiratory syndrome (MERS), and the causative computer virus is usually MERS coronavirus (MERS-CoV). So far (as of 7 February 2015), 971 confirmed cases, 356 of them fatal, have been reported to the World Health Business (http://www.who.int/csr/disease/coronavirus_infections/mers-5-february-2015.pdf?ua=1). Main human cases have been reported from a number of countries in the Arabian peninsula and the Middle East region, but travel-associated cases and limited human-to-human transmission from such cases have been reported from other countries in Europe, Africa, and Asia. While clusters of human cases with limited human-to-human transmission within health care facilities or families have been reported (2), index cases in the transmission chains remain of presumed zoonotic origin. MERS-CoV-like viruses are common in dromedary camels, with seroepidemiological studies indicating seroprevalence of >90% in adult animals (3). Viruses isolated from dromedaries are genetically and phenotypically closely related to viruses isolated from humans and retain the capacity to infect cultures of the human airways (4). Other domestic livestock in affected areas, including cattle, goats, sheep, and equids, have no evidence of MERS-CoV contamination. There is no convincing evidence of MERS-CoV in bats, although a genetically related computer virus, albeit with a divergent spike protein, has been detected in bats from Africa (5). Contamination in dromedaries has been reported to precede human contamination in a few instances (6). Given the ubiquitous nature of contamination in dromedaries, human exposure to MERS-CoV must be common; however, human disease remains rare (7). Furthermore, MERS-CoV remains endemic in dromedaries in East and North Africa (3), although locally acquired human cases have not been reported in countries in these regions. It is unclear whether this represents a lack of recognition or a true absence of disease. Thus, while dromedaries are recognized as a natural host of MERS-CoV, the modes of transmission to humans remain unclear. SR-17018 The apparent case fatality of MERS appears to be high (approximately 37%), with age and underlying disease conditions, including SR-17018 diabetes, respiratory or cardiovascular diseases, and immunocompromised status, being risk factors (8). When human case clusters have been intensively investigated, it has become apparent that milder cases are not uncommon and that such cases are probably undiagnosed in the general population (2). Thus, the overall severity of MERS may be milder than reflected from hitherto-diagnosed cases. The repeated emergence of clusters of human-to-human MERS transmission is reminiscent of the emergence of SARS in late 2002, when clusters of human cases from the animal reservoir emerged and then went extinct, until the computer virus finally adapted to acquire the capacity for sustained human-to-human transmission. Computer virus then spread globally to infect more than 8,000 persons in >28 countries or territories (examined in reference 9). Within the past 200 years, other animal coronaviruses have adapted to humans and have spread globally, < 0.05 compared to the no-treatment group. (B) A 200-l portion of camel serum 2 diluted in phosphate-buffered saline (PBS) SR-17018 was transferred into Ad5-hDPP4-transduced 6- to 8-week-old BALB/c mice, as explained for panel A. Computer virus titers were measured at day 3 p.i. There were 3 mice/group/time point. (C). A 200-l portion of camel serum 2 diluted in PBS was transferred intraperitoneally into 6- to 10-week-old Ad5-hDPP4-transduced IFNAR?/? mice 1 day after intranasal contamination with 1 105 PFU MERS-CoV. Titers were measured Mouse monoclonal to HDAC4 at days 3 and 5 p.i. There were 3 mice/group/time point. (D) A 200-l portion of camel serum 2 was transferred intraperitoneally into Ad5-hDPP4 transduced IFNAR?/? mice 1 day after MERS-CoV contamination. Mice were monitored daily for mortality (there was none) and excess weight loss. There were 5 mice per group. SR-17018 If camel serum is to be useful in patients, it will need to be delivered therapeutically. Since Ad5-hDPP4-transduced mice SR-17018 lacking expression of the IFN-/ receptor (IFNAR?/?) are more susceptible to MERS-CoV than immunocompetent mice, we treated IFNAR?/? mice with serum from camel 2 at 24 h after contamination. Under these conditions, treatment with undiluted serum accelerated the kinetics of computer virus.