Vaccines against Middle East respiratory syndrome coronavirus for humans and camels

Abstract

Middle East respiratory syndrome coronavirus (MERS-CoV) is caused by a novel betacoronavirus that was isolated in late 2012 in Saudi Arabia. The viral infections have been reported in more than 1700 humans, ranging from asymptomatic or mild cases to severe pneumonia with a mortality rate of 40%. It is well documented now that dromedary camels contract the infection and shed the virus without notable symptoms, and such animals had been infected by at least the early 1980s. The mechanism of camel to human transmission is still not clear, but several primary cases have been associated with camel contact. There is no approved antiviral drug or vaccine against MERS-CoV despite the active research in this area. Vaccine candidates have been developed using various platforms and regimens and have been tested in several animal models. Here, this article reviews the published studies on MERS-CoV vaccines with more focus on vaccines tested in large animals, including camels. It is foreseeable that the 1-health approach could be the best way of tackling the MERS-CoV endemic in the Arabian Peninsula, by using the mass vaccination of camels in the affected areas to block camel to human transmission. Camel vaccines can be developed in a faster time with fewer regulations and lower costs and could clear this virus from the Arabian Peninsula if accompanied by efficient public health measures.

A Mini Review of the Zoonotic Threat Potential of Influenza Viruses, Coronaviruses, Adenoviruses, and Enteroviruses

“…With the aim of reducing MERS-CoV transmission to humans, Haagmans et al developed a vaccine for camels using a poxvirus vehicle ( 24 ). This vaccine has significantly reduced virus excretion among camels and conferred cross-immunity to camelpox infections ( 25 ).…”

An Opportunistic Pathogen Afforded Ample Opportunities: Middle East Respiratory Syndrome Coronavirus

“…Successes have been reported, but the approach is challenged by the problem that camels are naturally reinfectable with MERS-CoV, even in the presence of a high titre of neutralising antibodies [ 52 , 74 , 104 ]. To date, camel vaccines reduce viral load but do not prevent virus shedding [ 104 , 105 ]. Human vaccines could target the occupational at-risk groups, which include healthcare, farm, barn, market, and slaughterhouse workers [ 56 , 88 , 106 ].…”

Humoral Immunogenicity and Efficacy of a Single Dose of ChAdOx1 MERS Vaccine Candidate in Dromedary Camels

“…It consists of a receptor-binding domain (RBD)-containing S1 subunit that binds to dipeptidyl peptidase 4 (DPP4) on target cells, and a S2 subunit which contains the fusion peptide involved in viral fusion with target cells 20,21 . Several vaccine candidates have been developed and tested in multiple animal models including mice, rabbits, non-human primates and dromedaries (reviewed in [22][23][24]. While many of these vaccines were designed based on full-length S protein, some others were targeting the S1 subunit or the RBD of the protein to focus the immune response on the critical neutralising epitopes to induce nAbs.…”