Repeat-Dose Toxicity Study Using the AFPL1-Conjugate Nicotine Vaccine in Male Sprague Dawley Rats

Characterization of stability, safety and immunogenicity of the mRNA lipid nanoparticle vaccine Iribovax® against COVID-19 in nonhuman primates

mRNA-lipid nanoparticle (mRNA-LNP) vaccines have proved their efficacy, versatility and unprecedented manufacturing speed during the COVID-19 pandemic. Here we report on the physicochemical properties, thermostability, immunogenicity, and protective efficacy of the nucleoside-modified mRNA-LNP vaccine candidate Iribovax® (also called SNEG2c). Injection of BALB/c mice, rabbits and nonhuman primates with two doses of SNEG2c induced production of high-titers of SARS-CoV-2 spike-specific and receptor-binding domain (RBD)-neutralizing antibodies in immunized animals. In addition to the strong humoral response, SNEG2c elicited substantial Th1-biased T-cell response. Sera from rhesus macaques immunized with a low dose of the vaccine showed robust spike-specific antibody titers 3-24× as high as those in convalescent sera from a panel of COVID-19 patients and 50% virus neutralization geometric mean titer of 1024 against SARS-CoV-2. Strikingly, immunization with SNEG2c completely cleared infectious SARS-CoV-2 from the upper and lower respiratory tracts of challenged macaques and protected them from viral-induced lung and trachea lesions. In contrast, the non-vaccinated macaques developed moderate to severe pulmonary pathology after the viral challenge. We present the results of repeat-dose and local tolerance toxicity and thermostability studies showing how the physicochemical properties of the mRNA-LNPs change over time and demonstrating that SNEG2 is safe, well tolerated and stable for long-term. These results support the planned human trials of SNEG2c.

Repeat-dose and local tolerance toxicity of SARS-CoV-2 FINLAY-FR-02 vaccine candidate in Sprague Dawley rats

This study evaluates safety of FINLAY-FR-02, a vaccine candidate against SARS-CoV-2 based on the recombinant receptor binding domain conjugated to tetanus toxoid, in a preclinical, repeat-dose toxicity and local tolerance study. Sprague Dawley rats were randomly allocated to three experimental groups: control (receiving physiological saline solution); placebo (receiving all vaccine components except antigens) and vaccine group (receiving three doses of the vaccine candidate, 37.5 µg of RBD) administered intramuscularly in hind limbs at 24 h intervals during three days. We evaluated physiological condition, pain, food and water consumption, body temperature, dermal irritability, injection site temperature and inflammation, immunological response, blood chemistry, relative organ weight, histopathology and immunotoxicology. The product was well tolerated; no clinically relevant changes, pain, local effects or adverse systemic toxicological changes or deaths were observed. These preliminary results permitted the Cuban regulatory authorities to authorize clinical trials in humans.

Assessing Neutralized Nicotine Distribution Using Mice Vaccinated with the Mucosal Conjugate Nicotine Vaccine

Tobacco smoking continues to be a global epidemic and the leading preventable cause of cancer and cardiovascular disease. Nicotine vaccines have been investigated as an alternative to currently available smoking cessation strategies as a means to increase rates of success and long-term abstinence. Recently, we demonstrated that a mucosal nicotine vaccine was able to induce robust mucosal and systemic antibodies when delivered heterologously using intranasal and intramuscular routes. Herein, we investigated the neutralization ability of the anti-nicotine antibodies using both intranasal and intracardiac nicotine challenges. Combining the extraction of lyophilized organ samples with RP-HPLC methods, we were able to recover between 47% and 56% of the nicotine administered from the blood, brain, heart, and lungs up to 10 min after challenge, suggesting that the interaction of the antibodies with nicotine forms a stable complex independently of the route of vaccination or challenge. Although both challenge routes can be used for assessing systemic antibodies, only the intranasal administration of nicotine, which is more physiologically similar to the inhalation of nicotine, permitted the crucial interaction of nicotine with the mucosal antibodies generated using the heterologous vaccination route. Notably, these results were obtained 6 months after the final vaccination, demonstrating stable mucosal and systemic antibody responses.