A new study published in Emerging Infectious Diseases reinforces the urgent need for surveillance of Middle East respiratory syndrome coronavirus (MERS-CoV) and phenotypic studies to monitor MERS-CoV spillover, adaptation, and pandemic potential.
MERS-CoV circulates in dromedary camels in the Arabian Peninsula and occasionally causes spillover infections in humans. Since 2012, a total of 2,626 cases of MERS-CoV, including 953 deaths, have been reported by health authorities worldwide.
Since the beginning of the COVID-19 pandemic, few human cases of MERS-CoV have been reported in Saudi Arabia, in stark contrast to the large epidemic outbreaks reported during 2012–2019. The small number of reported MERS-CoV infections might be because of limited MERS-CoV surveillance and nonpharmaceutical interventions that were in place during the COVID-19 pandemic or because of phenotypic changes in circulating MERS-CoV. 1
Since the beginning of 2024, and as of 2 December 2024, five MERS-CoV cases, including four fatalities, have been reported in Saudi Arabia with date of onset in 2024.2
Researchers in the current study collected 558 swabs from camels in Saudi Arabia over approximately 1-year period. They found 39% were positive for MERS-CoV RNA. Sequencing results were most similar to B5 lineage sequences and harbored unique genetic features, including novel amino acid polymorphisms in the spike protein.
“The distinct sublineages in clade B5-2023 did not cluster geographically, indicating that dromedary camels are maintaining virus diversity across different sites within the central Arabian Peninsula,” noted the study authors.
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Clinical overview of Middle East Respiratory Syndrome
CDC – Updated 4 Dec 2024
Although MERS cases have been reported among children and adults of all ages, most reported MERS cases have been in older adults. Most hospitalized MERS patients have had pre-existing medical conditions that likely increased their risk for severe illness. Among global cases reported to date, the mortality rate of MERS cases reported to the World Health Organization (WHO) is approximately 35%.
How to conduct a cross-sectional study of MERS-CoV infection in populations occupationally exposed to dromedary camels
WHO Technical Document – 19 Dec 2024
This protocol describes a one-time cross-sectional investigation with a (highly recommended) One Health approach, which may be implemented at any time in regions with persons who are occupationally-exposed, through contact with dromedary camels, to MERS-CoV. This investigation will inform MERS-CoV estimates of seroprevalence, prevalence (current infection) and viral shedding, as well as the geographical extent of these, among occupationally exposed populations and their dromedary camels. Within this protocol there are detailed study procedures (e.g. recruitment, follow-up, laboratory), other study-specific guidance (e.g. ethical considerations, statistical analysis), and implementation tips.
MERS-CoV internalization does not rely on DPP4 cytoplasmic tail signaling
NPJ Viruses – 30 Dec 2024
MERS-CoV infects respiratory epithelial cells in humans and camels by binding to dipeptidyl peptidase 4 (DPP4) as its entry receptor. This study suggests that, although MERS-CoV binds to DPP4, other host factors may need to interact with DPP4 or the spike protein to trigger internalization. The presence and distribution of the MERS-CoV receptor in the respiratory tract correlate with virus transmission, implying that frequent spillovers from this species to humans may occur in the near future. Further studies should focus on identifying additional host factors involved in the internalization process, which might provide insights into novel therapeutic targets.
Newcastle disease virus displaying an ectodomain of MERS-CoV spike protein elicited robust immunity in mice
Vaccines – 24 Dec 2024
The Newcastle disease virus (NDV) vector is a well-established, safe, and effective platform for vaccine development. With recent advancements in stabilizing coronavirus spike proteins to enhance their antigenicity, this study aimed to determine whether modifications to the MERS-CoV spike protein could improve its presentation on NDV particles, allowing the resulting virus to be used as an inactivated vaccine.
Protein nanoparticle vaccines induce potent neutralizing antibody responses against MERS-CoV
Cell Reports – 24 Dec 2024
Here researchers develop MERS-CoV vaccines utilizing a computationally designed protein nanoparticle platform that has generated safe and immunogenic vaccines against various enveloped viruses, including a licensed vaccine for SARS-CoV-2. Two-component nanoparticles displaying spike (S)-derived antigens induce neutralizing responses and protect mice against challenge with mouse-adapted MERS-CoV.
REFERENCES
- Ongoing Evolution of Middle East Respiratory Syndrome Coronavirus, Saudi Arabia, 2023–2024. Emerging Infectious Diseases. Dec 2024
- MERS-CoV Worldwide Overview. European Centre for Disease Prevention and Control. 12 Dec 2024.