Biology subjects

So, R. T.

Publications and source records attributed to So, R. T..

3 recordsLinked to original sources

bioRxiv2025

The impact of clade B lineage 5 MERS coronaviruses spike mutations from 2015 to 2023 on virus entry and replication competence

Middle East respiratory syndrome coronavirus (MERS-CoV) is an emerging coronavirus that can cause zoonotic disease in humans with lethal severe viral pneumonia. Dromedary camels are the source of zoonotic infection. As of June 2025, MERS-CoV has resulted in a total of 2626 reported cases, 36% of these being fatal. The number of reported human cases has been on a decreasing trend since 2016 and reached a minimum level during the COVID-19 pandemic. The reason for the reduction of cases is unclear and may be multifactorial. We hypothesized that mutations accumulating in the virus spike protein may have reduced zoonotic potential. Here, we investigate the impact of recently emerged virus spike-protein mutations on virus replication competence using pseudoviruses and replication-competent recombinant viruses. We found that two spike variants detected in 2019 show a reduced cell entry and lower viral replication in human cells. However, spike variants detected in 2023 sequences, did not show significant changes in cell entry and viral replication. All the MERS-CoV spikes tested showed a cell-entry pathway preference via the cell-surface TMPRSS2 route. Our data suggests that spike protein mutations are not a major determinant of the fewer MERS-CoV human cases observed. Author SummaryMERS-CoV is identified by the World Health Organization (WHO) as a potential pandemic candidate. The ability of coronaviruses to mutate and adapt in new hosts raises concerns about the impact of virus genetic changes on human zoonotic potential. There has been a notable decline in human MERS cases reported to the WHO since 2018, but the underlying reasons remain unclear. Here, we focus on investigating whether the recently emerged virus spike mutations may contribute to this observation. We found that while some spike mutations detected in 2019 reduce cell entry and viral replication, more recent viruses do not share this phenotype. This study highlighted a need for comprehensive genomic surveillance and phenotyping of recent MERS-CoV isolates to understand the potential role, if any, of other non-spike virus mutations on viral zoonotic competence and to explore alternate hypothesis, such as cross-reactive immunity from COVID-19 contributing to reduced human MERS-CoV disease.

microbiology↗

bioRxiv2023

Mutation nsp6 L232F associated with MERS-CoV zoonotic transmission confers higher viral replication in human respiratory tract cultures ex-vivo

Middle East respiratory syndrome coronavirus (MERS-CoV) causes zoonotic disease. Dromedary camels are the source of zoonotic infection. We identified a mutation of amino acid leucine to phenylalanine in the codon 232 position of the non-structural protein 6 (nsp6) (nsp6 L232F) that is repeatedly associated with zoonotic transmission. We generated a pair of isogenic recombinant MERS-CoV with nsp6 232L and 232F residues, respectively, and showed that the nsp6 L232F mutation confers higher replication competence in ex-vivo culture of human nasal and bronchial tissues and in lungs of mice experimentally infected in-vivo. Mechanistically, the nsp6 L232F mutation appeared to modulate autophagy and was associated with higher exocytic virus egress, while innate immune responses and zippering activity of the endoplasmic reticulum remained unaffected. Our study suggests that MERS-CoV nsp6 may contribute to viral adaptation to humans. This highlights the importance of continued surveillance of MERS-CoV in both camels and humans. ImportanceViral host adaptation plays an important role in zoonotic transmission of coronaviruses. For MERS-CoV that widely circulates in dromedary camels from Arabian Peninsula, camel-to human transmissions are ongoing, raising the possibility of human adaptive evolution for MERS-CoV. Here, we analysed MERS-CoV sequences and identified an amino acid mutation L232F in nsp6 to occur repeatedly in human MERS-CoV over the years since the first outbreak in 2012. We found the nsp6 L232F confers increase viral replication in-vitro, in ex-vivo upper human respiratory tract cultures and in mice, using a reverse genetics approach. Our results showed the nsp6 L232F may be advantageous for MERS-CoV to replicate in humans. This study highlighted a human adaptation of MERS-CoV and a need for continued surveillance of MERS-CoV to identify any further adaptations in humans, which may be relevant to the pandemic potential of MERS-CoV.

microbiology↗

bioRxiv2022

Age-related seroprevalence trajectories of seasonal coronaviruses in children

Four seasonal coronaviruses, including HCoV-NL63 and HCoV-229E, HCoV-OC43 and HCoV-HKU1 cause approximately 15-30% of common colds in adults. However, the frequency and timing of early infection with four seasonal coronaviruses in the infant are still not well studied. Here, we evaluated the serological response to four seasonal coronaviruses in 1886 children under 18-year-old to construct the viral infection rates. The antibody levels were also determined from the plasma samples of 485 pairs postpartum women and their newborn babies. This passive immunity waned at one year after birth and the resurgence of the IgGs were found thereafter with the increase of the age. Taken together, our results show the age-related seroprevalence trajectories of seasonal coronaviruses in children and provide useful information for deciding vaccine strategy for coronaviruses in the future.

immunology↗