Geographical distribution and phylogeny of MERS coronavirus

Abstract

Middle East Respiratory Syndrome Coronavirus (MERS-CoV) is a novel human betacoronavirus first identified in Saudi Arabia in 2012. As of 29th July, 2016, there were 27 countries in Middle East, Africa, Europe, North America and Asia reporting cases of MERS-CoV infection with over 1700 laboratory confirmed cases including 640 deaths. MERS-CoV is a global public health threat. It is vital to investigate the geographical distribution of MERS-CoV in its animal hosts and define viral genetic diversity and host range. Infection in humans is closely correlated with infected dromedaries. However, the transmission route of MERSCoV from dromedary camels to humans is still unclear. Surveillance of MERS-CoV among dromedary camels and defining viral genetic diversity is important to understand areas of the world that are at geographic risk and understand virus epizootiology. Investigation of other potential animals for carriage of MERS-CoV or related viruses is important to define the host range of the virus and provide the basis for disease prevention. Being the natural reservoir of many other coronaviruses, bats are one animal group that are worth studying as a potential natural reservoir of MERS-CoV.

Virological and / or serological studies were carried out on specimens collected from dromedary camels in West (Burkina Faso, Nigeria), North (Morocco) and East (Ethiopia) Africa, from Saudi Arabia and central Asia (Kazakhstan); from Bactrian camels in Kazakhstan and Mongolia and species bats in Egypt and Lebanon. High seroprevalence of MERS-CoV antibodies was detected in dromedary camels in Burkina Faso, Nigeria, Morocco, Ethiopia and Saudi Arabia but not in Kazakhstan. Wherever serological evidence of MERS-CoV was detected, the virus could also be detected in nasal swabs by RT-PCR. MERS-CoV infection was not detected in dromedary camels in Kazakhstan nor in Bactrian camels in Kazakhstan or Mongolia suggesting that camels may not be the natural reservoir of MERS-CoV. No MERSCoV infection was found among 3 species of bats in Egypt and 4 species of bats in Lebanon. However, HKU9-like coronaviruses were found in Rousettus spp bats in these two regions.

In a longitudinal study of dromedary camels in a farm in Saudi Arabia, there was evidence for the introduction and circulation of MERS-CoV over a period of 3 months. It was found that camels can be re-infected in spite of prior MERS-CoV antibody. Co-circulation of 229E related coronavirus, HKU23 coronavirus and MERS-CoV in abattoirs would indicate that there were possibly recombination of viruses happened and caused evolution of viruses.