An effective DNA vaccine platform for Middle East respiratory syndrome coronavirus

Middle East respiratory syndrome coronavirus (MERS-CoV) is an ongoing emerging infectious disease across the Arabian Peninsula, with the majority of cases occurring in Saudi Arabia. Through September 23, 2016 the World Health Organization reported about 1,806 total cases, including 643 deaths from 27 countries (http://www.who.int/emergencies/mers-cov/en/). The disease is comprised of a lower respiratory infection wherein individuals exhibit pneumonia-like symptoms that often lead to multi-organ failure and death (1). In addition to close contact with infected camels, transmission from human-to-human most commonly occurs in the hospital setting through close contact between patients and hospital workers (1). MERS-CoV has also been isolated from objects within patient rooms including bed sheets, bed rails, and IV fluid hangers (2), which may all be potential sources of transmission. Several cases of MERS-CoV have been associated with travelers returning home from the Middle East and developing symptoms, including two cases of health care workers returning to the United States (3). The potential for global spread was recently illustrated by a South Korean national returning home from visiting the Arabian Peninsula in May, 2015, and initiating an outbreak that infected 186 people resulting in 20% mortality and a nationwide economic crisis (4). Nonetheless, MERS-CoV is not thought to be sustained in the human population through human-to-human transmission, but may instead be continuously re-introduced into the human population from a zoonotic source, most likely dromedary camels because of high seropositive rates in herds throughout the Middle East (5,6). As camels are integral to the Saudi Arabian culture and economy, nationwide culling of camel herds is not feasible. Consequently, camel vaccination is being considered (7); however, therapeutic strategies have primarily focused on interfering with MERS-CoV infection in humans (3,5).