Research

Researches

Research News

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

02 Nov 2020

T-cell Responses To MERS Coronavirus Infection In People With Occupational Exposure To Dromedary Camels In Nigeria: An Observational Cohort Study

Chris Mok published in The Lancet Infectious Diseases an observational cohort study about MERS infection in people with occupational exposure to dromadery camels in Nigeria, with Malik Peiris, Honorary Director of HKU-Pasteur, and Jincun Zhao, Honorary Professor at HKU-Pasteur and the School of Public Health in the context of a partnership in the Respiratory Diseases Research Center Project in the Greater Bay Area. 

Abstract
Middle East respiratory syndrome coronavirus (MERS-CoV) is recognized as one of eight emerging pathogens of greatest threat to global public health, and dromedary camels are the source of human zoonotic infection. The emergence of SARS-CoV-2 highlights the pandemic potential of zoonotic coronaviruses.

Although this zoonotic disease has been restricted to the Arabian Peninsula, the largest number (>70%) of MERS-CoV infected camels are found in Africa. So far, there was only one MERS outbreak reported in Tunisia initiated by a traveler returning from the Arabian Peninsula but no reports of zoonotic disease in Africa. There were six sero-epidemiological studies of camel-exposed or other humans in Kenya, Egypt, Nigeria, and Morocco and only two (two of 1122 in Kenya and three of 476 tested in Morocco) found any evidence of MERS-CoV infection. Our study aimed to address the question that if workers slaughtering dromedaries in an abattoir in Kano, Nigeria are under the risk of MERS-CoV infection.

We found that 30% of 61 abattoir workers with exposure to dromedaries had MERS-CoV specific T-cell responses, but of 20 abattoir workers without exposure to dromedaries and ten non-abattoir workers from Kano, none had such T-cell responses. Drinking both unpasteurised camel milk and camel urine was significantly and negatively associated with T-cell positivity. Interestingly, no individuals with MERS-CoV T-cell responses had detectable antibody suggesting that the results from the serological studies may not truly reflect the prevalence of MERS-CoV infection in Africa. Our findings indicate that there is substantial zoonotic transmission of MERS-CoV to people with dromedary exposure in parts of Africa. The contribution of MERS-CoV to zoonotic respiratory disease remains to be established. Our findings have implications for global MERS-CoV control policy. There is a need to confirm our findings elsewhere in Africa and to include molecular testing for MERS-CoV in the investigation of patients with severe acute respiratory infections in dromedary-exposed populations in Africa.​

Read the publication online: T-cell Responses To MERS Coronavirus Infection In People With Occupational Exposure To Dromedary Camels In Nigeria: An Observational Cohort Study

 

You can find bellow Professor Stanley Perlman's commentary highlighting the significance of the paper:

02 Nov 2020

COVID-19: Persons Without A Robust Neutralizing Antibody Response Might Be At Risk For SARS-COV-2 Reinfection

Asmaa Hachim and Niloufar Kavian from Sophie Valkenburg's team have published in Emerging Infectious Diseases about reinfection and serologic responses in healthy adult with SARS-CoV-2. Emerging Infectious Diseases, an open access, peer reviewed journal published monthly by the Centers for Disease Control and Prevention, promotes the recognition of new and reemerging infectious diseases around the world and improves the understanding of factors involved in disease emergence, prevention, and elimination.

Details:
Whether SARS-CoV-2 infection induces serologic immunity and the duration of that immunity is unknown. In humans, reinfection with seasonal coronaviruses occurs naturally and in experimental conditions. The group worked on the first SARS-CoV-2 re-infection case that was described world-wide, and that was detected in Hong Kong.
 
In March 2020, a healthy 33-year-old man developed mild signs and symptoms of COVID-19, and was confirmed with a new SARS-CoV-2 infection later in August without symptoms. Their findings show that the first infection did not triggered virus neutralizing antibodies, and that, in the absence of primary neutralizing antibodies, T cells and mucosal immunity might have played a critical role in resolving the infection.
 
Previous studies show that most patients with mild, severe, or asymptomatic SARS-CoV-2 infection produce neutralizing antibodies and antibodies against spike RBD and N proteins. This case was unusual because the patient had low or undetectable levels of neutralizing and binding antibodies against multiple viral proteins during his primary infection and acute stage of asymptomatic reinfection. He was not immunodeficient because he had IgG against measles and varicella zoster viruses and no history of recurrent infections. The virus from the first infection had a truncation in the 58AA open reading frame 8 gene, which mediates immune evasion through downregulation of major histocompatibility complex and interferon responses. However, it is unclear if this mutation contributed to the patient’s lack of antibody production.
 
Reasons for this patient’s unusual response need to be further investigated. He recovered from his primary infection within 3 weeks, and his secondary infection was asymptomatic. These findings indicate that, in the absence of primary neutralizing antibodies, T cells and mucosal immunity might have played a critical role in resolving the infection. Given the unusual antibody response in this patient to his first infection, researchers must be cautious about generalizing more widely from this patient’s experience.