Ideal COVID-19 Vaccine May Come from Alpacas, New Study Found

Posted by Ellen Burns on November 3rd, 2021

In response to the COVID-19 caused by the new coronavirus (SARS-CoV-2), there are currently many vaccines on the market worldwide. However, despite the fact that major manufacturers are working hard to produce vaccines, the speed of vaccination still cannot keep up with people\'s needs. At the same time, with the continuous emergence of mutant strains, the effectiveness of vaccines has begun to decline. The development of a COVID-19 vaccine with a larger yield and longer-lasting effect has become a goal that scientists are exploring.

Recently, researchers from the Wellcome Center for Human Genetics, University of Oxford, UK, led an article on Nature Communications, titled \"A potent SARS-CoV-2 neutralising nanobody shows therapeutic efficacy in the Syrian golden hamster model\" of COVID-19\".

In this report, researchers have developed 4 unique nanobodies derived from llamas, which have the potential to prevent COVID-19. In mouse experiments, one of the vaccines was not only injectable, but also showed good preventive effects through nasal inhalation.

Compared with traditional antibodies, nanobodies have a variety of advantages, such as small molecular size and high stability, which enable them to directly achieve local administration by atomization, improve the bioavailability of vaccines and treatment compliance, and advances in technology make the cost of manufacturing nanobodies lower. Based on these factors, the investigators explore the potential of using nanobodies to fight COVID-19.

How to make nanobodies? The researchers set their sights on the alpacas. By injecting the SARS-CoV-2 spike protein into the alpacas’ body to trigger its immune response, a series of single domain heavy chain antibodies (VHH) are obtained.

The researchers selected C1, H3, C5, and F2, the four VHHs with the highest affinity to the receptor binding domain (RBD) of the virus S protein, and produced them, and used surface plasmon resonance (SPR) measurement in a joint competitive binding test. Evaluated the in vitro binding effect of each VHH with Alpha, Beta and other new coronavirus strains of RBD. The test results show that H3, C5 and F2 can effectively neutralize the original SARS-CoV-2 strain and the Alpha mutant strain, while the nanobody that is active against the Beta mutant strain is only C1.

Since C5 performed best in vitro, the researchers chose this nanobody for further research. By injecting C5 nanobody into the peritoneum of 6 Syrian hamster models infected with SARS-CoV-2 with similar symptoms to the human body, the researchers found that this nanobody can significantly reduce the disease symptoms of the infected mice and gain weight 7 days later. The degree of relief was much lower than that of hamsters that did not receive nanobody treatment. In addition, compared with the control group, the hamsters treated with nanobodies also had lower viral loads in the lungs and respiratory tract after 7 days.

In subsequent studies, the researchers also found that not only injections, but even respiratory administration can give full play to the effects of C5 nanobodies.

One of the corresponding authors of the report, James H. Naismith, Professor of Structural Biology, Wellcome Center for Human Genetics, University of Oxford, UK, said: “If our vaccine is finally developed and approved for marketing, then nanobodies will be able to be used worldwide. It provides important treatments for COVID-19 because they are easier to produce than human antibodies and do not need to be stored in cold storage facilities.\"

In conclusion, this study provides an important new form of treatment for COVID-19, indicating that nanobodies derived from alpaca may be an important force in helping people fight the epidemic. It is worth noting that it is not only the prevention and treatment of COVID-19. In this experiment, the researcher\'s technology for developing nanobodies may also help people develop necessary therapies as soon as possible in the future.