Oxford vaccine boosts immunity in pigsDate: 26 June 2020 Tags: Biotechnology
A study in pigs has found that two doses of Oxford vaccine (ChAdOx1 nCoV-19) given as prime-boost produce greater antibody responses than a single dose.
This has important implications for COVID-19 vaccine development as virus-specific T cells are thought to play an important role in SARS-CoV-2 infection.
The researchers found that even a single dose was sufficient in inducing antigen-specific antibody and T cells responses in pigs, the booster dose elevated the antibody responses, with a significant increase in neutralizing antibody levels. There was no significant increase in antibody responses in mice after the booster dose.
A single dose of the vaccine-induced a humoral and cellular immune response in rhesus macaques. While the vaccinated rhesus macaques did not develop pneumonia, the vaccination was unable to prevent infection when exposed to the virus.
They found that the vaccinated animals that were infected when exposed to the virus had “significantly reduced” viral load in bronchoalveolar lavage fluid and respiratory tract tissue compared with control animals.
While a single dose of the vaccine-induced antigen-specific antibody and T cells responses in both mice and pigs, the booster dose enhanced the antibody responses significantly in just one mouse strain. But in the case of pigs, the booster dose significantly enhanced the antibody responses.
The animals that received the booster dose exhibited significantly greater levels of neutralizing antibodies two weeks after the second dose compared with animals that received only one dose.
T cell responses were higher in pigs that received two doses of the vaccine compared with animals that received only one dose, thus demonstrating that the prime-boost regimen trended toward a higher response.
Phase-3 will assess the efficacy of the vaccine in a large number of people over 18 years of age. The researchers will assess how well the vaccine helps prevent people from becoming infected and unwell with COVID-19.