바이오스펙테이터

by yoonseok Suh

Covid-19 vaccine candidate study in human ACE2 (hACE2) expressing mice..Confirmed neutralizing antibody, T cell immune response, virus defense effect.."Phase 1/2 application planned for this month"

Eubiologics announced on the 7th that it has confirmed the formation of neutralizing antibodies, T-cell immune responses, and virus defense effects in the evaluation of efficacy of the COVID-19 vaccine candidate material at the pre-clinical; it is under development with the Korea Mouse Phenotyping Center (KPMC).

Developed with KMPC, humanized mouse (K18-hACE2 TG) expressing human ACE2 was utilized for Eubiologic’s inoculation of COVID-19 vaccine candidate materials, from September to November, for twice every two weeks with three dosages: low dose (0.2μg), medium dose (1μg), and high dose (5μg). ACE2 is a protein used when a new type of coronavirus is infected within the cell.

As a result, Eubiologics reported that neutralizing antibodies were 200-3400 times more potent depending on the dose of the vaccine, and that cellular immune responses such as IFN-γ, TNF-α and IL-2 were observed as the dose increased from lower doses. In addition, showing higher Th1 response than Th2 response, it is expected that there would be no adverse reaction from antibody-dependent enhancement (AED). The Th1 response is activated by bacterial or viral infection and plays a role in removing foreign pathogens by promoting the secretion of cytokines. Th2 response plays a role in promoting antibody formation; excess formation of antibody caused by excessive Th2 response can lead to antibody-dependent adverse reaction (AED) that rather worsens symptoms after vaccination.

In addition, Eubiologics and KMPC conducted an attack experiment to analyze the defense effects of vaccines by injecting COVID-19 virus (NCCP 43326) with more than 10^5 PFU into the vaccinated mouse. The result showed no change in weight and body temperature in vaccinated group and that the amount of injected virus inside body was reduced to about 1/1000 on the fifth day of virus injection.

In histopathology analysis, when observing the lungs, spleen, duodenum of mice after injecting virus, various lesions were induced in the virus group (control), but the vaccinated group showed a significant decrease in lesions, indicating that the preventive effect was observed.

Sung Je-kyung, head of KMPC, said, "We have found satisfying results in this attack, and we are pleased to contribute to the development of the Covid-19 vaccine in Korea," adding, "We are also looking forward to the clinical phase 1/2 that Eubiologics will soon carry out."

Eubiologics official said, "We will proceed with clinical research with confidence along with positive pre-clinical results. We will apply for the phase 1/2 of clinical trials in Korea this month, complete the third phase by next year, and present excellent and safe vaccines."

On the other hand, this research by Eubiologics and KMPC is the result of a study using the government's project called, "Research on the establishment of non-clinical test infrastructure for infectious disease treatment and vaccine" supported through the 3rd supplementary budget. Eubiologics and KMPC plan to disclose the results of this research in detail in future journals.