Intravacc, announced that it has obtained positive preclinical results for its SARS-CoV-2 Outer Membrane Vesicle (OMV) based recombinant Spike protein (rSp) candidate nose spray vaccine.
For the preclinical study four groups of mice and four groups of hamsters received two intranasal immunizations on day one and day 21. One group of mice and hamsters received a vaccine based on OMV’s mixed with rSp (CovOMV) and the other a vaccine based on OMV’s coupled to rSp based on Intravacc’s proprietary OMV click technology (CovOMVclick). Control animals received respectively only OMV’s or only rSp. On day 35 the mice blood samples were tested for virus neutralizing antibodies. The hamsters were challenged with SARS-CoV-2 on day 42 after blood collection. Over a period of seven days after challenges, their bodyweight loss was measured and on day seven the animals were pathologically examined for lung lesions.
In the mice that received the CovOMV- and CovOMVclick vaccines, respectively 30% and 90% virus neutralizing antibodies were detected. In all the hamsters both candidate vaccines induced neutralizing antibodies, but the level of antibodies in hamsters that received CovOMVclick was slightly higher compared to the other group. In the group receiving rSp only, one animal showed a low virus neutralizing antibody titer. Intranasal vaccination with both OMV-rSp vaccine candidates resulted in complete protection after challenge, as no lung lesions were detected by histopathology, seven days after the hamsters were challenged. Furthermore, all hamsters that received the CovOMV- and CovOMVclick vaccines showed reduced systemic weight loss after challenge, whereas unvaccinated animals or animals vaccinated with OMV’s or rSp lost more than 10% of their bodyweight.
