Llama antibodies hold clue to Covid-19 treatment

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Llama antibodies hold clue to Covid-19 treatment

Llama antibodies hold clue to Covid-19 treatment

May 09, 2020 10:39:43 AM (IST)

Llama antibodies hold clue to Covid-19 treatment-1New Delhi: Winter, a four-year-old chocolate brown female llama in a Belgian farm, may hold clues to mitigating the Covid-19 crisis, according to scientists.

Researchers at the University of Texas at Austin linked two copies of a special kind of antibody produced by llamas to create a new antibody that binds to a key protein on Sars-CoV-2, the virus that causes the coronavirus disease. Initial test results to be published in the journal Cell on May 28 indicate that this antibody blocks viruses that display the spike protein - including Sars-CoV-2 - from entering and infecting cells.

The inspiration to do this research came from a study conducted on Winter by the same team in 2016.

Back then, when Winter was nine months old, researchers were studying two earlier coronaviruses: Sars-CoV-1 (which caused the Severe Acute Respiratory Syndrome outbreak in 2003), and Mers-CoV (which caused the Middle East Respiratory Syndrome in 2012). Winter was injected with spike proteins from those viruses over six weeks. Researchers then collected a blood sample and isolated antibodies that bound to each version of the spike protein. One of them showed promise in stopping the virus from infecting cells.

“That was exciting to me because I’d been working on this for years. But there wasn’t a big need for a coronavirus treatment then. This was just basic research. Now, this can potentially have some translational implications too,” said Daniel Wrapp, a graduate student in McLellan Lab and co-first author of the paper in a statement published on University of Austin website.

“This is one of the first antibodies known to neutralise Sars-CoV-2,” said Jason McLellan, associate professor of molecular biosciences at UT Austin and co-senior author.

The University of Texas team is now preparing to conduct preclinical studies in animals such as hamsters or primates. Unlike vaccines that have to be given in advance to provide protection, antibodies can be given to people who are already sick to reduce severity of disease. They start working immediately, the authors said.

When the immune systems of llamas or other camelids detect bacteria and viruses, they produce two types of antibodies: one that is similar to human antibodies, and another so tiny that they’re called nanobodies. Aravind Penmatsa, scientist at Indian Institute of Science has been studying this unique quality, and his group isolated camel antibodies with help from National Research Centre on Camel, Bikaner.

“Camels and llamas have a unique antibody structure that lacks the light chain that is conventionally present in other species including humans. Conventional antibodies have both the heavy and light chains and resemble a “Y” shaped molecule. Despite lacking the light chain, camelid antibodies retain the neutralising ability of the large antibodies within a single domain called the VHH or nanobodies. Due to their small size, the camelid or llama antibodies have unique advantages, for instance, ease of production, and greater ability to interact with deep cavities and pockets on target surfaces,” said Penmatsa, responding to the University of Texas study over email.

Penmatsa has an ongoing study on the effectiveness of camel antibodies in treating antimicrobial resistance.

Camelid antibodies are being studied for their potential in monitoring and treatment of tumors, therapies for inflammatory and neurodegenerative diseases, drug delivery and passive immunotherapy according to an article in Frontiers journal.

But experts warned that it may take a long time before such findings develop into therapy.

“It’s still a long way to go. The paper has shown the potential of these antibodies in inhibiting coronavirus from entering mammalian cells. Further pre-clinical experiments are needed in relevant animal models to see if antibodies are stable and neutralise the virus inside animals. Generally pre-clinical studies take years but considering the pandemic challenge this can be done in months to a year,” said Amit Singh, associate professor, Centre for Infectious Disease Research, Indian Institute of Science.

Hindustan Times