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12 Jan 2021

Follow-up: Project On Sewage Helps Uncover Nine Infections In Hong Kong

The University of Hong Kong sewage surveillance project involving HKU-Pasteur research teams will extend its screening capacity after successfully uncovering hidden COVID-19 carriers in two housing blocks in Hong Kong. Standard operating procedure are finalised to trigger mandatory testing of all residents in a block if sewage checks reveal two consecutive positive results or two positive results over three days.

Sponsored by the Health and Medical Research Fund (HMRF) under the Food and Health Bureau, this project allowed the collection of more than 300 domestic sewage samples from sewage collection systems in different areas for nucleic acid tests of the new coronavirus SARS-CoV-2. 
 
Since the beginning of the project in October 2020, the team has been able to demonstrate that sewage surveillance could provide early warning of COVID-19 outbreaks, reflecting the overall spread of virus in the community. It also helps tracking the development trend of community outbreak.
 
 
 
 

12 Jan 2021

SARS-CoV-2 Infection Elicits Robust Neutralizing Antibody Titres In Most Individuals

Prof Leo Poon and Prof Malik Peiris published in Nature Communications the results of their study on neutralizing antibody titres in SARS-CoV-2, concluding that the infection elicits robust neutralizing antibody titres in most individuals.
 
They proceeded by testing 293 sera from an observational cohort of 195 reverse transcription polymerase chain reaction (RT-PCR) confirmed SARS-CoV-2 infections collected from 0 to 209 days after onset of symptoms.
 
Introduction:
Many studies have reported antibody responses in COVID-19 patients using ELISA or other binding assays, but there are fewer reports using virus neutralization tests. Patients with COVID-19 infection develop detectable SARS-CoV-2 neutralizing antibody responses with some having detectable antibody at the end of the 1st week of illness, and almost all having neutralizing antibody after 4 weeks of illness. The magnitude of the antibody responses and the proportion of patients developing antibody responses have varied. Severely ill patients are reported to have higher peak neutralizing antibody titers. 
 
The methods used for detecting neutralizing antibody has also varied. These include the use of pseudoparticle neutralization (ppNT), microneutralization, fluorescent focus reduction assays, microneutralization assays, and plaque reduction neutralization tests (PRNT). Pseudoparticle neutralization tests are convenient and do not require bio-safety level 3 containment, but it is not clear how closely different types of virus pseudoparticles expressing SARS-CoV-2 spike protein mimics authentic virus, or how results from one pseudoparticle assay compares with another. 
 
Even with neutralization of live virus, microneutralization tests were found to be less sensitive than plaque reduction neutralization assays, which are regarded as the “gold-standard” for neutralizing antibody testing. The major outstanding question is the duration of these neutralizing antibody responses. There are reports of rapid waning of antibody with some reports claiming that a third of patients have lost pseudoparticle neutralizing antibody by around 1–2 months after onset of illness. If true, such findings have major implications for the duration of protective immunity from reinfection, and the likely success of vaccination in prevention from reinfection and disease. It is therefore essential that the duration of neutralizing antibody responses are assessed using live virus neutralization assays.
 
 
 
 
Fig. 1: Antibody responses (PRNT90) in COVID-19 patients by days after illness onset and severity, Hong Kong (n = 293 samples).
The black lines showed the fitted values and gray areas showed the 95% confidence intervals. Neutralization tests were carried out in duplicate.
 
Fig. 2: Antibody responses (PRNT50) in COVID-19 patients by days after illness onset and severity, Hong Kong (n = 293 samples).
The black lines showed the fitted values and gray areas showed the 95% confidence intervals. Neutralization tests were carried out in duplicate.

30 Dec 2020

SARS-COV-2: Multidisciplinary Project On Sewage Helps Safeguarding Public Health In Hong Kong

The University of Hong Kong's multidisciplinary team conducting a research for detecting SARS-CoV-2 in sewage has led to improvements in the surveillance of outbreaks in local communities and potential clusters.  

Professor Gabriel Leung, Dean of Medicince (HKUMed) announced on Monday 28 December 2020, that residents of Fung Chak House in Choi Wan Estate, and anyone who visited the building since December 15, will be subject to mandatory testing after four sewage samples taken in the past five days came back positive for coronavirus.

With no confirmed cases so far in Fung Chak House, Professor Leung said the virus found in the sewage is most likely coming from an asymptomatic carrier of SARS-COV-2. The team took those samples after 15 people came down with Covid-19 in the neighboring block of Ming Lai House.

The team includes Professor Leo Poon, Co-Director at HKU-Pasteur, Doctor Hein Min Tun, Principal Investigator at HKU-Pasteur, and is led by Professor Tong Zhang of Department of Civil Engineering.

Sponsored by the Health and Medical Research Fund (HMRF) under the Food and Health Bureau, this project allowed the collection of more than 300 domestic sewage samples from sewage collection systems in different areas for nucleic acid tests of the new coronavirus SARS-CoV-2. 

Since the beginning of the project in October 2020, the team has been able to demonstrate that sewage surveillance could provide early warning of COVID-19 outbreaks, reflecting the overall spread of virus in the community. It also helps tracking the development trend of community outbreak.

>>> Press release from HKU

29 Dec 2020

C&E News 2020 Review To Celebrate Chris Mok’s Paper

In its review largely dominated by SARS-CoV-2 publications, C&E News has selected Chris Mok's paper about antibody CR3022 and SARS-CoV-2 spike structure analysis published in Science earlier this year as a top paper of 2020.

>>> C&EN’s Year in Chemistry 2020

This paper sheds new light into antibody recognition of SARS-CoV-2. To this end, they used the Receptor Binding Domain (RBD) of the Spike protein of SARS-CoV-2, which is the region of the Spike protein that allows virus entry into cells by interacting with its specific receptor.  
 
They took advantage of CR3022, a neutralizing monoclonal antibody previously isolated from a convalescent SARS patient, to determine its crystal structure in complex with the RBD of the SARS-CoV-2 Spike protein. This antibody targets a highly conserved epitope that enables cross-reactive binding with the Spike proteins of both SARS-CoV and SARS-CoV-2. Structural alignment of the CR3022-SARS-CoV-2 RBD complex with the ACE2-SARS-CoV RBD complex further indicates that binding of CR3022 would not clash with ACE2.  
 
This analysis implies that the neutralization mechanism of CR3022 for SARS-CoV does not depend on direct blocking of receptor binding, which is consistent with the observation that CR3022 does not compete with ACE2 for binding to the RBD. Overall, this study provides insight into how SARS-CoV-2 can be targeted by the humoral immune response and revealed a conserved, but cryptic epitope shared between SARS-CoV-2 and SARS-CoV.
 
 

03 Dec 2020

4-Year Research Goup Within The IPIN Call For Application 2020

The Institut Pasteur 2020 call for application for 4-year Research groups is now open ! 

To encourage the development of ambitious research programmes, and to strengthen scientific leadership skills of promising researchers across the Institut Pasteur International Network (IPIN), Institut Pasteur will support the creation of 4-year Research Groups (G4) in these IPIN institutes.

Deadline for application: February 12th , 2021

A G4 is a newly independent structure created for 4 years, within institutes of the IPIN (except Institut Pasteur in Paris) in order to develop or strengthen key research areas of the host institution and to participate in the development of this network by reinforcing research through collaboration and training. The aim is that after the 4 years, a sustainable new research area is initiated at the host institution and and goes on through a permanent structure.

A G4 will be composed by a PI, selected trougth an international call, and scientific staff, including Masters, PhD students, interns and/or postdoctoral researchers.

For more information on eligibility criteria and to download forms for application, please visit Institut Pasteur website.

12 Nov 2020

Evaluation of a SARS-CoV-2 surrogate virus neutralization test for detection of antibody in human, canine, cat and hamster sera

In a recent study published in the Journal of Clinical Microbiology of the American Society for Microbiology, Professor Leo Poon and Professor Malik Peiris, along with the HKU School of Public Health, have evaluated a specific type of SARS-CoV-2 test enabling to detect antibody across human and diverse animal species.

In the global pandemic the world is currently facing, surrogate neutralization assays for SARS-CoV-2 in multiple species are desirable. For sero-epidemiology studies and in outbreak investigations, it is important to detect antibody responses in humans and animals to determine evidence of past infection with SARS-CoV-2. Antibody assays that are transferable across species are desirable because SARS-CoV-2 infects pets and other farmed animals. Such tests are crucial for monitoring antibody responses in experimental animal models and in studies to identify the natural animal reservoir of SARS-CoV-2.

The test evaluated is a recently developed surrogate virus neutralization test (sVNT). The research teams have evaluated the test in comparison to 90% plaque reduction neutralization tests (PRNT90) in human, canine, cat and hamster sera. With PRNT90 as reference, sVNT had sensitivity of 98.9% and specificity of 98.8% respectively.

The study highlights an excellent concordance between the sVNT and the “gold-standard” PRNT90 assays for SARS-CoV-2 antibody detection in humans, dogs, cat and hamster sera. This assay would be of great utility as a species-independent and specific assay for primary testing for antibodies to Sarbecoviruses (SARS-CoV-2, SARS-CoV-1 and closely related viruses) in humans or animals. The sVNT test also has the advantage of technical simplicity, speed (a few hours) and not requiring cell culture facilities or BSL-3 containment.

Read the publication online: “Evaluation of a SARS-CoV-2 surrogate virus neutralization test for detection of antibody in human, canine, cat and hamster sera”, Journal of Clinical Microbiology, 02/11/2020

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