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Middle East respiratory syndrome coronavirus (MERS-CoV) targets the epithelial cells of the respiratory tract both in humans and in its natural host, the dromedary camel. Virion attachment to host cells is mediated by 20-nm-long homotrimers of spike envelope protein S. The N-terminal subunit of each S protomer, called S1, folds into four distinct domains designated S1A through S1D. Binding of MERS-CoV to the cell surface entry receptor dipeptidyl peptidase 4 (DPP4) occurs via S1B. We now demonstrate that in addition to DPP4, MERS-CoV binds to sialic acid (Sia). Initially demonstrated by hemagglutination assay with human erythrocytes and intact virus, MERS-CoV Sia-binding activity was assigned to S subdomain S1A. When multivalently displayed on nanoparticles, S1 or S1A bound to human erythrocytes and to human mucin in a strictly Sia-dependent fashion. Glycan array analysis revealed a preference for α2,3-linked Sias over α2,6-linked Sias, which correlates with the differential distribution of α2,3-linked Sias and the predominant sites of MERS-CoV replication in the upper and lower respiratory tracts of camels and humans, respectively. Binding is hampered by Sia modifications such as 5-N-glycolylation and (7,)9-O-acetylation. Depletion of cell surface Sia by neuraminidase treatment inhibited MERS-CoV entry of Calu-3 human airway cells, thus providing direct evidence that virus–Sia interactions may aid in virion attachment. The combined observations lead us to propose that high-specificity, low-affinity attachment of MERS-CoV to sialoglycans during the preattachment or early attachment phase may form another determinant governing the host range and tissue tropism of this zoonotic pathogen.

Middle East respiratory syndrome coronavirus (MERS-CoV) infections have led to an ongoing outbreak in humans, which was fueled by multiple zoonotic MERS-CoV introductions from dromedary camels. In addition to the implementation of hygiene measures to limit further camel-to-human and human-to-human transmissions, vaccine-mediated reduction of MERS-CoV spread from the animal reservoir may be envisaged. Here we show that a modified vaccinia virus Ankara (MVA) vaccine expressing the MERS-CoV spike protein confers mucosal immunity in dromedary camels. Compared with results for control animals, we observed a significant reduction of excreted infectious virus and viral RNA transcripts in vaccinated animals upon MERS-CoV challenge. Protection correlated with the presence of serum neutralizing antibodies to MERS-CoV. Induction of MVA-specific antibodies that cross-neutralize camelpox virus would also provide protection against camelpox.

Human coronavirus-EMC (hCoV-EMC) is a new coronavirus that has killed around half of the few humans infected so far; this study now identifies DPP4 as the receptor that this virus uses to infect cells. Human receptor for emerging coronavirus The emerging pathogenic coronavirus hCoV-EMC, first identified in September 2012, has been fatal in about half of the few humans infected so far. Bart Haagmans and colleagues have now identified the receptor that this virus uses to infect cells. In contrast to the related virus SARS-CoV, which uses angiotensin converting enzyme 2, the functional receptor for hCoV-EMC is dipeptidyl peptidase 4 (DPP4, also known as CD26), an exopeptidase found on non-ciliated cells in the lower respiratory tract. This enzyme is highly conserved across different species, and hCoV-EMC can also use bat DPP4 as a functional receptor — a possible clue as to the host range and epidemiological history of this new virus. The findings may also be important for the development of intervention strategies. Most human coronaviruses cause mild upper respiratory tract disease but may be associated with more severe pulmonary disease in immunocompromised individuals 1 . However, SARS coronavirus caused severe lower respiratory disease with nearly 10% mortality and evidence of systemic spread 2 . Recently, another coronavirus (human coronavirus-Erasmus Medical Center (hCoV-EMC)) was identified in patients with severe and sometimes lethal lower respiratory tract infection 3 , 4 . Viral genome analysis revealed close relatedness to coronaviruses found in bats 5 . Here we identify dipeptidyl peptidase 4 (DPP4; also known as CD26) as a functional receptor for hCoV-EMC. DPP4 specifically co-purified with the receptor-binding S1 domain of the hCoV-EMC spike protein from lysates of susceptible Huh-7 cells. Antibodies directed against DPP4 inhibited hCoV-EMC infection of primary human bronchial epithelial cells and Huh-7 cells. Expression of human and bat ( Pipistrellus pipistrellus ) DPP4 in non-susceptible COS-7 cells enabled infection by hCoV-EMC. The use of the evolutionarily conserved DPP4 protein from different species as a functional receptor provides clues about the host range potential of hCoV-EMC. In addition, it will contribute critically to our understanding of the pathogenesis and epidemiology of this emerging human coronavirus, and may facilitate the development of intervention strategies.

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. 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. 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. MERS-CoV or a related virus has infected camel populations. Both titres and seroprevalences in sera from different locations in Oman suggest widespread infection. European Union, European Centre For Disease Prevention and Control, Deutsche Forschungsgemeinschaft.

A novel human coronavirus (HCoV-EMC/2012) was isolated from a man with acute pneumonia and renal failure in June 2012. This report describes the complete genome sequence, genome organization, and expression strategy of HCoV-EMC/2012 and its relation with known coronaviruses. The genome contains 30,119 nucleotides and contains at least 10 predicted open reading frames, 9 of which are predicted to be expressed from a nested set of seven subgenomic mRNAs. Phylogenetic analysis of the replicase gene of coronaviruses with completely sequenced genomes showed that HCoV-EMC/2012 is most closely related to Tylonycteris bat coronavirus HKU4 (BtCoV-HKU4) and Pipistrellus bat coronavirus HKU5 (BtCoV-HKU5), which prototype two species in lineage C of the genus Betacoronavirus . In accordance with the guidelines of the International Committee on Taxonomy of Viruses, and in view of the 75% and 77% amino acid sequence identity in 7 conserved replicase domains with BtCoV-HKU4 and BtCoV-HKU5, respectively, we propose that HCoV-EMC/2012 prototypes a novel species in the genus Betacoronavirus . HCoV-EMC/2012 may be most closely related to a coronavirus detected in Pipistrellus pipistrellus in The Netherlands, but because only a short sequence from the most conserved part of the RNA-dependent RNA polymerase-encoding region of the genome was reported for this bat virus, its genetic distance from HCoV-EMC remains uncertain. HCoV-EMC/2012 is the sixth coronavirus known to infect humans and the first human virus within betacoronavirus lineage C. IMPORTANCE Coronaviruses are capable of infecting humans and many animal species. Most infections caused by human coronaviruses are relatively mild. However, the outbreak of severe acute respiratory syndrome (SARS) caused by SARS-CoV in 2002 to 2003 and the fatal infection of a human by HCoV-EMC/2012 in 2012 show that coronaviruses are able to cause severe, sometimes fatal disease in humans. We have determined the complete genome of HCoV-EMC/2012 using an unbiased virus discovery approach involving next-generation sequencing techniques, which enabled subsequent state-of-the-art bioinformatics, phylogenetics, and taxonomic analyses. By establishing its complete genome sequence, HCoV-EMC/2012 was characterized as a new genotype which is closely related to bat coronaviruses that are distant from SARS-CoV. We expect that this information will be vital to rapid advancement of both clinical and vital research on this emerging pathogen. Coronaviruses are capable of infecting humans and many animal species. Most infections caused by human coronaviruses are relatively mild. However, the outbreak of severe acute respiratory syndrome (SARS) caused by SARS-CoV in 2002 to 2003 and the fatal infection of a human by HCoV-EMC/2012 in 2012 show that coronaviruses are able to cause severe, sometimes fatal disease in humans. We have determined the complete genome of HCoV-EMC/2012 using an unbiased virus discovery approach involving next-generation sequencing techniques, which enabled subsequent state-of-the-art bioinformatics, phylogenetics, and taxonomic analyses. By establishing its complete genome sequence, HCoV-EMC/2012 was characterized as a new genotype which is closely related to bat coronaviruses that are distant from SARS-CoV. We expect that this information will be vital to rapid advancement of both clinical and vital research on this emerging pathogen.

A 31-year-old woman who was 10 weeks pregnant contracted Zika virus infection in Suriname; this led to fetal loss. ZIKV was detected in the woman's blood for at least 21 days. To the Editor: Data linking Zika virus (ZIKV) infection to fetal death have been reported in only a handful of cases to date. 1 , 2 Here, we present a case of ZIKV infection in a woman who had a miscarriage. ZIKV was detected in the fetal tissue, and ZIKV viremia lasted for at least 21 days. In January 2016, a 31-year-old woman who was 10 weeks pregnant visited an outpatient clinic in Rotterdam, the Netherlands, because of a 2-day history of headache, mild arthralgia in both wrists and the left knee, and a pruritic, macular rash. The symptoms had begun the . . .

The Middle-East respiratory syndrome coronavirus (MERS-CoV) is a zoonotic virus that causes severe and often fatal respiratory disease in humans. Efforts to develop antibody-based therapies have focused on neutralizing antibodies that target the receptor binding domain of the viral spike protein thereby blocking receptor binding. Here, we developed a set of human monoclonal antibodies that target functionally distinct domains of the MERS-CoV spike protein. These antibodies belong to six distinct epitope groups and interfere with the three critical entry functions of the MERS-CoV spike protein: sialic acid binding, receptor binding and membrane fusion. Passive immunization with potently as well as with poorly neutralizing antibodies protected mice from lethal MERS-CoV challenge. Collectively, these antibodies offer new ways to gain humoral protection in humans against the emerging MERS-CoV by targeting different spike protein epitopes and functions.

A new type of coronavirus has been identified as the causative agent underlying Middle East Respiratory Syndrome (MERS). The MERS coronavirus (MERS-CoV) has spread in the Middle East, but cases originating in the Middle East have also occurred in the European Union and the USA. Eight hundred and thirty-seven cases of MERS-CoV infection have been confirmed to date, including 291 deaths. MERS-CoV has infected dromedary camel populations in the Middle East at high rates, representing an immediate source of human infection. The MERS-CoV spike (S) protein, a characteristic structural component of the viral envelope, is considered as a key target of vaccines against coronavirus infection. In an initial attempt to develop a MERS-CoV vaccine to ultimately target dromedary camels, we constructed two recombinant adenoviral vectors encoding the full-length MERS-CoV S protein (Ad5.MERS-S) and the S1 extracellular domain of S protein (Ad5.MERS-S1). BALB/c mice were immunized with both candidate vaccines intramuscularly and boosted three weeks later intranasally. All the vaccinated animals had antibody responses against spike protein, which neutralized MERS-CoV in vitro. These results show that an adenoviral-based vaccine can induce MERS-CoV-specific immune responses in mice and hold promise for the development of a preventive vaccine that targets the animal reservoir, which might be an effective measure to eliminate transmission of MERS-CoV to humans.

The mechanism by which ZIKV causes a range of neurological complications, especially congenital microcephaly, is not well understood. The fact that congenital microcephaly is associated with Asian lineage ZIKV strains raises the question of why this was not discovered earlier. One possible explanation is that Asian and African ZIKV strains differ in their abilities to infect cells of the CNS and to cause neurodevelopmental problems. Here, we show that Asian ZIKV strains infect and induce cell death in human neural progenitor cells—which are important target cells in the development of congenital microcephaly—less efficiently than African ZIKV strains. These features of Asian ZIKV strains likely contribute to their ability to cause chronic infections, often observed in congenital microcephaly cases. It is therefore likely that phenotypic differences between ZIKV strains could be, at least in part, responsible for the ability of Asian ZIKV strains to cause congenital microcephaly. Recent Zika virus (ZIKV) infections have been associated with a range of neurological complications, in particular congenital microcephaly. Human neural progenitor cells (hNPCs) are thought to play an important role in the pathogenesis of microcephaly, and experimental ZIKV infection of hNPCs has been shown to induce cell death. However, the infection efficiency and rate of cell death have varied between studies, which might be related to intrinsic differences between African and Asian lineage ZIKV strains. Therefore, we determined the replication kinetics, including infection efficiency, burst size, and ability to induce cell death, of two Asian and two African ZIKV strains. African ZIKV strains replicated to higher titers in Vero cells, human glioblastoma (U87MG) cells, human neuroblastoma (SK-N-SH) cells, and hNPCs than Asian ZIKV strains. Furthermore, infection with Asian ZIKV strains did not result in significant cell death early after infection, whereas infection with African ZIKV strains resulted in high percentages of cell death in hNPCs. The differences between African and Asian lineage ZIKV strains highlight the importance of including relevant ZIKV strains to study the pathogenesis of congenital microcephaly and caution against extrapolation of experimental data obtained using historical African ZIKV strains to the current outbreak. Finally, the fact that Asian ZIKV strains infect only a minority of cells with a relatively low burst size together with the lack of early cell death induction might contribute to its ability to cause chronic infections within the central nervous system (CNS). IMPORTANCE The mechanism by which ZIKV causes a range of neurological complications, especially congenital microcephaly, is not well understood. The fact that congenital microcephaly is associated with Asian lineage ZIKV strains raises the question of why this was not discovered earlier. One possible explanation is that Asian and African ZIKV strains differ in their abilities to infect cells of the CNS and to cause neurodevelopmental problems. Here, we show that Asian ZIKV strains infect and induce cell death in human neural progenitor cells—which are important target cells in the development of congenital microcephaly—less efficiently than African ZIKV strains. These features of Asian ZIKV strains likely contribute to their ability to cause chronic infections, often observed in congenital microcephaly cases. It is therefore likely that phenotypic differences between ZIKV strains could be, at least in part, responsible for the ability of Asian ZIKV strains to cause congenital microcephaly.

Ferrets are widely used as a small animal model for a number of viral infections, including influenza A virus and SARS coronavirus. To further analyze the microbiological status of ferrets, their fecal viral flora was studied using a metagenomics approach. Novel viruses from the families Picorna-, Papilloma-, and Anelloviridae as well as known viruses from the families Astro-, Corona-, Parvo-, and Hepeviridae were identified in different ferret cohorts. Ferret kobu- and hepatitis E virus were mainly present in human household ferrets, whereas coronaviruses were found both in household as well as farm ferrets. Our studies illuminate the viral diversity found in ferrets and provide tools to prescreen for newly identified viruses that potentially could influence disease outcome of experimental virus infections in ferrets.