Middle East respiratory syndrome coronavirus neutralising serum antibodies in dromedary camels: a comparative serological study.
BACKGROUND
A new betacoronavirus-Middle East respiratory syndrome coronavirus (MERS-CoV)-has been identified in patients with severe acute respiratory infection. Although related viruses infect bats, molecular clock analyses have been unable to identify direct ancestors of MERS-CoV. Anecdotal exposure histories suggest that patients had been in contact with dromedary camels or goats. We investigated possible animal reservoirs of MERS-CoV by assessing specific serum antibodies in livestock.


METHODS
We took sera from animals in the Middle East (Oman) and from elsewhere (Spain, Netherlands, Chile). Cattle (n=80), sheep (n=40), goats (n=40), dromedary camels (n=155), and various other camelid species (n=34) were tested for specific serum IgG by protein microarray using the receptor-binding S1 subunits of spike proteins of MERS-CoV, severe acute respiratory syndrome coronavirus, and human coronavirus OC43. Results were confirmed by virus neutralisation tests for MERS-CoV and bovine coronavirus.


RESULTS
50 of 50 (100%) sera from Omani camels and 15 of 105 (14%) from Spanish camels had protein-specific antibodies against MERS-CoV spike. Sera from European sheep, goats, cattle, and other camelids had no such antibodies. MERS-CoV neutralising antibody titres varied between 1/320 and 1/2560 for the Omani camel sera and between 1/20 and 1/320 for the Spanish camel sera. There was no evidence for cross-neutralisation by bovine coronavirus antibodies.


CONCLUSIONS
MERS-CoV or a related virus has infected camel populations. Both titres and seroprevalences in sera from different locations in Oman suggest widespread infection.


BACKGROUND
European Union, European Centre For Disease Prevention and Control, Deutsche Forschungsgemeinschaft.
Centre for Infectious Disease Research, Diagnostics and Screening, Division Virology, National Institute for Public Health and the Environment, Bilthoven, Netherlands. Electronic address: Chantal.Reusken@RIVM.nl.
Chantal B E M
CB
Reusken
Bart L
BL
Haagmans
Marcel A
MA
Müller
Carlos
C
Gutierrez
Gert-Jan
GJ
Godeke
Benjamin
B
Meyer
Doreen
D
Muth
V Stalin
VS
Raj
Laura
L
Smits-De Vries
Victor M
VM
Corman
Jan-Felix
JF
Drexler
Saskia L
SL
Smits
Yasmin E
YE
El Tahir
Rita
R
De Sousa
Janko
J
van Beek
Norbert
N
Nowotny
Kees
K
van Maanen
Ezequiel
E
Hidalgo-Hermoso
Berend-Jan
BJ
Bosch
Peter
P
Rottier
Albert
A
Osterhaus
Christian
C
Gortázar-Schmidt
Christian
C
Drosten
Marion P G
MP
Koopmans
D000818:Animals; D057134:Antibodies, Neutralizing / Q000097:blood*; D000914:Antibodies, Viral / Q000097:blood*; D002161:Camelids, New World / Q000097:blood; D002162:Camelus / Q000097:blood*; D002417:Cattle / Q000097:blood; D017934:Coronavirus / Q000145:classification* / Q000276:immunology*; D005260:Female; D006041:Goats / Q000097:blood; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D008297:Male; D012756:Sheep / Q000097:blood
D057134:Antibodies, Neutralizing; D000914:Antibodies, Viral; D007074:Immunoglobulin G