In the race to find an effective prophylactic for the novel coronavirus, a 4-year-old llama could emerge as the victor. Named Winter, she has chocolate-colored skin, spindly legs and lopsided ears, the New York Times reported. She also has tiny antibodies that scientists believe could prove efficient in blocking the entry of Covid19 into human cells.
Researchers from Belgium picked Winter at random from a group of 130 llamas at a research farm, where they tested the ability of her unique antibodies, called nanobodies, in a series of studies involving the SARS and MERS viruses. They found Winter’s nanobodies proved effective in staving off infections, leading them to test the same antibodies against the coronavirus in cell cultures. While animal or human trials using llama antibodies have not begun yet, the research, published in the journal Cell, shows llama nanobodies could be pathbreaking in the fight against the coronavirus pandemic.
While the world waits for a vaccine, scientists have already made headway in studying antibody therapy for Covid19, which they say is providing immediate results. One such option is convalescent plasma therapy, which injects antibodies from patients recovered from Covid19 into infected patients. Scientists are also manufacturing artificial antibodies in laboratories to aid in antibody therapy. The coronavirus has spiky proteins on its outside that help the virus invade human cells. These antibodies can bind to the spiky protein, therefore neutralizing its ability to infect human cells.
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The Belgian researchers state llama nanobodies provide a third antibody therapy option, which could be much more effective in this binding process that human antibodies could. Humans produce one kind of antibody, made up of both heavy and light protein chains, that forms a Y shape. This combination makes the resulting Y structure large and clunky, which makes its ability to fully bind to the spike protein questionable. Llamas, on the other hand, produce two types of antibodies — one that resembles the heavy human kind, and another that’s 25% smaller because it doesn’t have any light-chain proteins. This smaller antibody, researchers say, is much more effective in binding to spike proteins on the coronavirus, because it can get into its nooks and crannies and achieve complete neutralization.
Llamas have long been used in researching therapies to neutralise HIV and influenza. One reason is that these nanobodies are extremely stable and can withstand manipulations, molecular virologist, and author of the Cell study, Dr. Xavier Saelens, tells the New York Times, which makes it easier to experiment with fusing them with other antibodies, even humans’. While these nanobodies are also available in other camelids, such as alpacas, and are also present in sharks, accessing those from unfriendly mammals is not possible. They “are not a great experimental model, and are a lot less cuddly than llamas,” co-author of the study, Daniel Wrapp, tells the New York Times.
Researchers hope pursuing this line of inquiry through clinical trials can establish llama nanobodies as a prophylactic treatment (preventative measure) for people at risk of contracting the coronavirus. The fact that these antibodies are stable also means they can be delivered via inhaler, study authors say. “There is still a lot of work to do to try to bring this into the clinic,” Dr. Saelens tells the New York Times. “If it works, llama Winter deserves a statue.”
