Members of the team that first mapped the spike protein of SARS-CoV-2 have now created a new antibody that binds to this key protein and prevents it infecting cells in culture. If proven successful in future trials this could become an effective way to immediately protect people from the disease Covid-19. But the researchers on this study had a helping hand from an unlikely ally – Winter the Llama. Back in 2016, the researchers injected the then 9-month-old Winter with stabilized spike proteins from two earlier coronaviruses: SARS-CoV-1 and MERS-CoV, in a process similar to human vaccination. Like we see in humans, this triggered Winter’s immune system to produce antibodies against the infection. When isolating these antibodies from blood samples, they discovered one in particular, called VHH-72, showed real promise in preventing the viruses displaying spike proteins from infecting cells in culture. Fast-forward to a few months ago when SARS-CoV-2, the virus that causes Covid-19, emerged, and the team from the University of Texas at Austin, the National Institutes of Health, and Ghent University, wondered whether the VHH-72 antibody from Winter, could also prove effective against this new coronavirus. On its own, the antibody weakly bound to SARS-CoV-2’s spike protein, however, by engineering two copies of the VHH-72 antibody together the researchers produced a new antibody that could efficiently neutralize SARS-CoV-2. The newly produced antibody (blue) binds tightly to the spike protein on SARS-CoV-2 (pink, green and orange), stopping it from attaching to cells and infecting them. University of Texas at Austin “This is one of the first antibodies known to neutralize SARS-CoV-2,” Jason McLellan, associate professor of molecular biosciences at UT Austin said in a statement. McLellan is a co-senior author of the “pre-proof” study, which has been peer-reviewed and undergoing final formatting changes before being published in Cell on May 5. Although currently only shown to block SARS-CoV-2’s spike protein from infecting cells in culture, the team are preparing to conduct pre-clinical trials in animals such as hamsters or non-human primates, before hopefully testing their creation in humans. If these tests come to fruition, the team hope their antibodies could be used a treatment to help people soon after they become infected with the novel coronavirus, and even provide immediate protection for those in vulnerable groups and those with an increased risk of exposure to the virus such as health care workers. “Vaccines have to be given a month or two before infection to provide protection,” McLellan explained. “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.” One other point of interest of using llama antibodies (or for that matter other camelids such as alpacas) is that they come in two sizes – a human-sized one, and one that’s around a quarter of the size, called single-domain antibodies or nanobodies. These are small enough to be nebulized and used in an inhaler; a promising method of antibody transport. “That makes them potentially really interesting as a drug for a respiratory pathogen because you're delivering it right to the site of infection,” Daniel Wrapp, a graduate student in McLellan's lab and co-first author of the paper, remarked in the statement. As for the study’s leading lady, Winter, she continues to live on a farm in the Belgian countryside with around 130 other llamas and alpacas, oblivious to the fact that she could well have played a part in saving humanity. Winter, we salute you. Source
