Serological MERS-CoV tests
Serological tests have been developed for the detection of antibodies against MERS-CoV (Middle East respiratory syndrome coronavirus) in humans and in camels. MERS-CoV is an emerging pathogen which is responsible for an outbreak of severe acute respiratory illness predominantly in the Arabian Peninsula with a high number of fatalities. Camels are known hosts of the virus. The Anti-MERS-CoV indirect immunofluorescence test (IIFT) is an established, highly sensitive screening test for anti-MERS-CoV antibodies in human sera. The assay utilizes virus-infected cells as the antigenic substrate, with non-infected cells serving as a control. Positive samples yield a distinct fluorescence pattern on the infected cells. The EUROIMMUN Anti-MERS-CoV ELISA is the first commercially available anti-MERS-CoV ELISA. The assay microplates are coated with purified recombinant MERS-CoV spike protein S1 domain, which provides high sensitivity and specificity and reduces cross reactions with other human coronaviruses. Nevertheless, cross reactivity with other coronaviruses cannot be excluded with either the ELISA or the IIFT. For this reason, positive screening results should always be confirmed by a neutralization test, as stipulated by the World Health Organisation. The Anti-MERS-CoV IIFT Camel and the Anti-MERS-CoV ELISA Camel are based on the same test principles as the human tests and are suitable for determining antibody levels in camels. The human and camel serological assays have been used in numerous published studies on MERS-CoV infection mechanisms. Notably, it was found that there are no significant levels of anti-MERS-CoV antibodies in human subjects from Saudi Arabia. This implies that the virus has not been circulating in humans for long and that the majority of the population remains susceptible to infection. Studies in dromedary camels, on the other hand, have revealed high seropositivity in animals from the Arab region and Eastern Africa, even in samples that are decades old. Thus, MERS-CoV appears to have been circulating widely in dromedaries for some time. Since the virus can sporadically pass from camels to humans, dromedaries represent a significant risk factor for infection in people.
