A COVID-19 vaccine candidate currently undergoing early-stage human trials in China can produce a “robust” immune response against the novel coronavirus in mice and macaques, a new study says.
The researchers, including those from Tsinghua University in China, noted that the vaccine candidate, called ARCoV, elicited both antibody as well as cell mediated immune response against the novel coronavirus SARS-CoV-2 in mice and non-human primates.
According to the study, published in the journal Cell on Friday, ARCoV is currently being evaluated in phase I human trials to assess whether it is safe and generates an immune response in humans.
ARCoV, which is an mRNA vaccine, is based on the genetic material of SARS-CoV-2, and enables host cells to to produce the RBD protein used by the virus to enter cells, the researchers said.
The RBD produced from these cells elicit an immune response from the host, the study noted.
“Our results demonstrated that two doses of immunisation of ARCoV vaccine have induced high levels of antibodies with broad neutralising capabilities against SARS-CoV-2 in mice,” the scientists wrote in the study.
This technology, according to the study, is similar to the one used by the US biotechnology company Moderna for its vaccine candidate mRNA-1273.
In the current study, the researchers showed that the mRNA vaccine candidate can be delivered into host cells using ultra small lipid molecules as carriers.
“Here, we developed a lipid-nanoparticle-encapsulated mRNA (mRNA-LNP) encoding the receptor binding domain (RBD) of SARS-CoV-2 as a vaccine candidate (termed ARCoV),” the scientists wrote in the study.
In humans, the researchers said the vaccine can be delivered as an injection into the muscle.
They said a single dose or two doses of ARCoV generated “robust antibody and T cell responses in mice and non-human primates against multiple epidemic SARS-CoV-2 strains.”
According to the study, the vaccine formulation remained stable and efficient for delivery at 25 degrees Celsius for at least one week.
“These unique features of ARCoV make it a promising COVID-19 vaccine candidate with universal availability and global accessibility,” the study noted.
Citing a limitation of the study, the researchers said the immunised mice were tested only with a “mouse-adapted strain of SARS-CoV-2.”
They said further experiments challenging vaccinated animals with virus strains prevalent in the ongoing pandemic will provide more data about the protective efficacy.
The scientists added that the duration of neutralising antibody response induced by ARCoV is yet to be determined.
“Future studies are needed to evaluate the long-term immune response in animal models and the effectiveness of ARCoV in humans,” the study noted.