As experts all over the world search for ways to halt the spread of COVID-19, an effective treatment may be available in a very unlikely source. A preliminary study led by the University of Texas at Austin has revealed that antibodies from llamas have the potential to wipe out COVID-19 infection.
The research team has engineered a new weapon against SARS-CoV-2 using a llama antibody that was tested to treat the first SARS coronavirus. The experts previously demonstrated that the antibody bound tightly to spike proteins on SARS-CoV-1 to stop them from spreading infection.
When a llama’s immune system detects a pathogen such as a virus, the animal produces two types of antibodies – one that is similar to a human antibody and another that is about a quarter of the size. The smaller ones, called single-domain antibodies or nanobodies, can be nebulized and used in an inhaler.
“That makes them potentially really interesting as a drug for a respiratory pathogen because you’re delivering it right to the site of infection,” said study co-first author Daniel Wrapp.
A four-year-old llama named Winter who lives on a Belgian farm became the focus of coronavirus studies in 2016 at the age of nine months.
In an effort to identify preventive substances for SARS-CoV-1 and MERS-CoV, researchers injected Winter with stabilized spike proteins from the viruses over the course of about six weeks.
The experts isolated antibodies in blood samples, and identified one antibody called VHH-72 that prevented the SARS coronavirus from infecting cells in culture.
“That was exciting to me because I’d been working on this for years,” said Wrapp. “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.”
When the researchers tested VHH-72 against the new coronavirus, it did not bind as tightly to the spike proteins. The experts crossed-linked two copies of the antibody and got much better results.
The initial tests conducted with the modified antibody show that it attaches itself tightly to SARS-Cov-2 spike proteins, and is capable of preventing the virus from infecting cells in culture.
Study co-senior author Professor Jason McLellan said this is “one of the first antibodies known to neutralize SARS-CoV-2.”
Next, the team will test the antibody in animals such as nonhuman primates before hopefully conducting tests in humans. The goal is to develop an antibody that can treat people soon after SARS-Cov-2 infection.
“Vaccines have to be given a month or two before infection to provide protection,” said Professor McLellan. “With antibody therapies, you’re directly giving somebody the protective antibodies and so, immediately after treatment, they should be protected. The antibodies could also be used to treat somebody who is already sick to lessen the severity of the disease.”
This type of treatment would be particularly helpful for high-risk individuals or for people who have an increased risk of exposure, such as health care workers.
The study is published in the journal Cell.