A multidisciplinary research team from the LKS Faculty of Medicine (HKUMed) and the Faculty of Engineering of the University of Hong Kong (HKU) has successfully developed an innovative screening platform to rapidly assess the impact of SARS-CoV-2 mutations on disease severity. Compared to traditional methods, this platform has achieved a speed improvement of up to 39 times. Additionally, the researchers focused on understanding how mutations affect syncytium formation, a process known as cell fusion in which infected cells fuse with uninfected cells. This research helps identify emerging viral variants that could pose a significant risk to public health. The team has also identified two FDA-approved drugs that can ease disease severity. The findings were published in Nature Biomedical Engineering [link to publication], and a patent application has been filed based on the research.

Background
The SARS-CoV-2 virus, which caused the worldwide COVID-19 pandemic, has been continuously evolving since its emergence. Spike protein mutations can lead to different degrees of infectivity and lethality. The spike protein plays a crucial role in viral infection by binding to human ACE2 receptors and merging with neighbouring uninfected cells to form syncytia, which contribute to virus spread and disease severity. Scientists have discovered that severe COVID-19 cases often exhibit syncytium cells in the lungs, providing evidence of the connection between spike-driven cell fusion and infection severity.

Large-scale screening to assess cell-cell fusion is challenging, as it requires a rapid way to measure the fusion process. Previous studies individually constructed and monitored spike variants to assess their potential to form syncytia, which was both technically demanding and costly. To address this, the research team used innovative screening methods and advanced genetic techniques to identify the specific genetic and cellular factors responsible for promoting syncytia formation. This research is crucial for developing effective interventions and treatments to block the fusion and potentially restrict virus spread.

Research findings
The team used a special system involving split green fluorescent protein (GFP), which produces detectable signals when cells fuse together. They combined it with a microfluidics-based system and large-scale mutagenesis to create a new platform for rapid screening and analysis of a wide range of spike protein variants and their fusion capabilities.

By studying the spike protein and its mutations, researchers have found that certain variants, such as the Delta strain, form larger syncytia than the original strain of the virus. They discovered that a single K854H mutation can transform the Omicron variant into a strain that forms fusions from a low rate to a high rate. Furthermore, some mutations found in the study were predicted to be as mutable as those seen in the previous variants, such as Omicron and Delta, revealing that these new mutations should be kept under surveillance as they could emerge in future viral evolution.

To enhance the efficiency of the screening process, the team developed a new strategy using size-exclusion selection to sort fused and unfused cells on a large scale, which enabled speedy screening. This method achieved over 80% in accuracy rate, comparing with the traditional approach.

Employing the size-exclusion selection strategy, the team conducted a genome-wide CRISPR screen and identified two cellular factors, AP2M1 and FCHO2, involved in cellular uptake mechanism, which contributes to syncytium formation. The researchers then tested two FDA-approved drugs, chlorpromazine and fluvoxamine, currently used for antipsychotic purposes, to inhibit cellular uptake. Experiments on hamster models showed that these drugs could inhibit syncytium formation induced by the spike protein and potentially alleviate disease severity.

Significance of the study
The significance of this study lies in its interdisciplinary approach, combining high-throughput CRISPR screening, large-scale mutagenesis, droplet microfluidics, and virology. The droplet microfluidics system enabled the study of cell-cell interactions in a high-throughput manner and provided high-resolution data. The paired-cell system has the potential to systematically profile the fusogenicity of various viruses, including HIV, RSV, Herpesviridae, SARS-CoV-2 and other coronaviridae that induce syncytium formation. The combination of high-throughput profiling systems and CRISPR screening led to the discovery of a potential therapeutic target to combat syncytium formation and reduce the severity of SARS-CoV-2 infections.

Professor Alan Wong Siu-lun, Associate Professor in the School of Biomedical Sciences, HKUMed, who led the research, stated, ‘These innovative systems enable us to rapidly track SARS-CoV-2 mutations on a larger scale and identify treatment options; they can also be broadly applied in the study of various pathological and physiological cell fusion conditions relevant to biomedical research, including cancer immunotherapy.’

Looking forward, he added, ‘The methods and knowledge gained from this study have the potential to contribute to public health efforts and provide insights into the development of therapeutic interventions for COVID-19 and other diseases involving cell fusion.’

About the research team
The HKU collaborative research team was led by Professor Alan Wong Siu-lun and Dr Gigi Choi Ching-gee from the School of Biomedical Sciences, and Professor Chu Hin from the Department of Microbiology, School of Clinical Medicine, HKUMed; together with Professor Anderson Shum Ho-cheung, Department of Mechanical Engineering, Faculty of Engineering. The collaborative research team also includes Charles Chan Wai-fong, Wang Bei and Dr Chu Hoi-yee from the School of Biomedical Sciences, and Dr Huang Xiner and Luo Cuiting from the Department of Microbiology, School of Clinical Medicine, HKUMed; and Dr Lang Nan and Mao Tianjiao from the Department of Mechanical Engineering, Faculty of Engineering.

Acknowledgements
This research was supported by the National Natural Science Foundation of China (Excellent Young Scientists Fund); the Centre for Oncology and Immunology, and the Advanced Biomedical Instrumentation Centre, under the Health@InnoHK Initiative funded by the Innovation and Technology Commission, the Government of Hong Kong SAR; and the Collaborative Research Fund under the Hong Kong Research Grants Council.

Media enquiries
Please contact LKS Faculty of Medicine of The University of Hong Kong by email (medmedia@hku.hk).

CHAMPAIGN, Ill. — Public policies blocked many families of Mexican descent living in the U.S. from accessing vital services such as food and mental health care during the COVID-19 pandemic, even though these communities experienced some of the highest infection and mortality rates.

Thirty-eight perinatal women and mothers of young children were interviewed about the challenges they faced during the pandemic and proposed solutions to better meet the needs of their communities during future large-scale crises in a study led by University of Illinois Urbana-Champaign kinesiology and community health professor Sandraluz Lara-Cinisomo.

Co-authors of the study are molecular anthropologist Amy L. Non of the University of California-San Diego; Kimberly D-Anna-Hernandez, a professor of psychology at Marquette University; and U. of I. graduate student Mary Ellen Mendy and undergraduate students Jessica Avalos and Jacqueline Marquez.

The women in the study discussed the stressors they encountered during the pandemic, including their difficulties accessing mental health treatment, child care and food. Their suggestions and insights were used to identify actionable policies and programs that could help meet the needs of Latino communities during future emergencies.

The participants, who were interviewed between September 2021 and December 2022, were part of a longitudinal study that recruited them from a clinic in San Diego, one of the U.S. cities with large Latino populations of Mexican heritage.

The women were about 36 years old on average. Although about 81% of them were born in Mexico, many had resided in the U.S. for 17 years or more. About 31% reported having an annual household income of less than $21,000, while a similar percentage earned $40,000 or more, according to the study.

Lara-Cinisomo said participants faced complex stressors during the pandemic. Half of the women in the study said their families had challenges obtaining food due to loss of income and subsidies such as school lunches, as well as supply chain shortages and consumer stockpiling.

“While early in the pandemic various federal and state programs and policies were deployed to mitigate people’s risks for exposure and enhance families’ economic security, millions of tax-paying families of Mexican descent and other Latino backgrounds were excluded because of restrictions and exclusions set by those programs,” Lara-Cinisomo said.

The researchers found that more than twice as many Spanish speakers reported food-related issues compared with their English-speaking counterparts.

“Policymakers should consider how language barriers increase the risks of Spanish-speaking families losing out on benefits designed to meet their needs, such as CalFresh,” California’s iteration of the federal SNAP food assistance program for low-income people, Lara-Cinisomo said.

“Communicating food and health and safety information in linguistically appropriate media, such as texts, videos or commercials, is vital to ensure accessibility to people with differing literacy and technological skills and should be carefully considered by policymakers.”

Involving trusted sources in disseminating relevant and critical information was also recommended by the participants. For marginalized communities that have experienced historical discrimination and anti-immigrant propaganda, trust in these sources is vital, Lara-Cinisomo said.

“Research has shown that community engagement is critical in emergency preparedness and increases the likelihood of meeting the needs of marginalized communities,” Lara-Cinisomo said. Accordingly, she and her team recommended developing a contingency plan to train culturally and linguistically competent community health workers to cultivate networks of trusted community members to assist in crisis communication efforts.

Some women discussed feeling anxiety about the uncertainties associated with the pandemic, such as lockdowns and conflicting health information. These feelings were exacerbated by employment disruptions, pregnancy, and food access problems, and their concerns extended to family members residing in other households and those living in Mexico, participants told the researchers.

The majority of those interviewed advocated broadening access to food subsidy programs such as WIC and SNAP to offset income losses and food shortages during large-scale crises, along with providing public awareness campaigns about local food banks and assistance programs.

Even though California provides more services for undocumented immigrants — including paid family leave and one year of emergency coverage with mental health services under Medi-Cal, the state’s Medicaid plan, for pregnant women — caring for their mental health needs was a significant problem for many participants. Fifteen women reported needing mental health care, but twice as many of the English-speaking women mentioned these issues compared with their Spanish-speaking counterparts, the researchers found.

The researchers hypothesized that this difference may have been associated with cultural beliefs, with Spanish-speaking women feeling less comfortable disclosing mental health problems because of stigmatization compared with those who spoke English. Or, it may have been that those who spoke Spanish were more resilient or more concerned about immediate needs such as food assistance, the team said.

Participants recommended broadening access to mental health services for mothers and their families, promoting awareness with providers and patients, and disseminating mental health information and resources through videos and other media and via programs such as WIC.

Many of the women — largely those who spoke only Spanish — reported difficulties obtaining personal protective equipment and sanitization supplies because of shortages, consumer stockpiling, and price gouging, in keeping with other studies that showed low-income and marginalized communities were disproportionately affected.

Although the study sample was small, Lara-Cinisomo said it highlighted critical needs for responsive, culturally appropriate policies and programs to ensure the well-being of Mexican-descent perinatal women and mothers of young children during public health crises.

Lara-Cinisomo discussed the team’s findings and study participants’ recommendations during a virtual Briefing on Perinatal Health and Well-being on April 3 hosted by the journal Health Affairs, which published the study.