High Rate of Circulating MERS-CoV in Dromedary Camels at Slaughterhouses in Riyadh, 2019.

Taibah A Aljasim,Naif Khalaf Alharbi,Abdulrahman Almasoud,Mohamed W Alenazi,Asma N Alsaleh,Haya A Aljami,Suliman A Alsagaby

doi:10.3390/v12111215

Abstract

MERS-CoV is a zoonotic virus that has emerged in humans in 2012 and caused severe respiratory illness with a mortality rate of 34.4%. Since its appearance, MERS-CoV has been reported in 27 countries and most of these cases were in Saudi Arabia. So far, dromedaries are considered to be the intermediate host and the only known source of human infection. This study was designed to determine the seroprevalence and the infection rate of MERS-CoV in slaughtered food-camels in Riyadh, Saudi Arabia. A total of 171 nasal swabs along with 161 serum samples were collected during the winter; from January to April 2019. Nasal swabs were examined by Rapid test and RT-PCR to detect MERS-CoV RNA, while serum samples were tested primarily using S1-based ELISA Kit to detect MERS-CoV (IgG) antibodies and subsequently by MERS pseudotyped viral particles (MERSpp) neutralization assay for confirmation. Genetic diversity of the positive isolates was determined based on the amplification and sequencing of the spike gene. Our results showed high prevalence (38.6%) of MERS-CoV infection in slaughtered camels and high seropositivity (70.8%) during the time of the study. These data indicate previous and ongoing MERS-CoV infection in camels. Phylogenic analysis revealed relatively low genetic variability among our isolated samples. When these isolates were aligned against published spike sequences of MERS-CoV, deposited in global databases, there was sequence similarity of 94%. High seroprevalence and high genetic stability of MERS-CoV in camels indicating that camels pose a public health threat. The widespread MERS-CoV infections in camels might lead to a risk of future zoonotic transmission into people with direct contact with these infected camels. This study confirms re-infections in camels, highlighting a challenge for vaccine development when it comes to protective immunity.

Highlights

Middle East Respiratory Syndrome (MERS), caused by MERS Coronavirus (MERS-CoV) is one of three recently emerged human coronaviruses that cause severe respiratory infections and were associated with major outbreaks worldwide
In order to determine the rate of MERS-CoV in camels slaughtered for food in Riyadh during the winter of 2019, 171 camels were sampled from three large official abattoirs in Riyadh city
The Ct values of all tested samples ranged from 14.377 to 40. This finding indicates an ongoing circulation of MERS-CoV in camels in Saudi Arabia, as tested in camels brought from different locations into slaughterhouses for food production

Summary

Introduction

Middle East Respiratory Syndrome (MERS), caused by MERS Coronavirus (MERS-CoV) is one of three recently emerged human coronaviruses that cause severe respiratory infections and were associated with major outbreaks worldwide. MERS-CoV has infected around 2900 people and caused 858 deaths in 27 countries. The majority of the cases were reported from Saudi Arabia (2102 cases; 72%), including 780 related deaths [1]. The virus was first detected in Saudi Arabia in 2012, from a patient with severe respiratory illness and subsequent multi-organ failure and death [3]. Camels were confirmed as intermediate animal host showing high proportions of MERS-CoV circulation especially in young calves (

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