New Evidences of the Anti-SARS-CoV-2 Vaccine Candidate FINLAY-FR-02 Effects on Immune System Using Morphometric Techniques

Abstract

Introduction: As a part of a repeated dose toxicity and local tolerance study of the anti-Severe acute respiratory syndrome-Coronavirus-2 vaccine candidate FINLAY-FR-02, a morphometric histopathological analysis was carried out to obtain a more detailed understanding of its effects on organs within the immune system. Materials and Methods: Sprague Dawley rats were divided into three groups: those vaccinated with three doses of the vaccine candidate (37.5 μg receptor binding domain), the placebo group, and controls. Tissue samples of the spleen, deep inguinal lymph node, and popliteal lymph node from five animals in each group were obtained at 3, 7, and 21 days after completing the vaccination schedule. Paraffin tissue sections for histological examination were prepared using standard procedures and stained with hematoxylin and eosin. Results: In the spleen, there was an increase in the density of the Malpighian corpuscles. In the deep inguinal and popliteal lymph nodes, there was an increase in the density of subcapsular secondary lymphoid follicles and paracortical secondary lymphoid follicles, as well as the presence of apoptosis, plasmocytes, macrophages, and mast cells in vaccinated animals. Conclusion: The histopathological and morphometric observations in the spleen and lymph nodes confirmed the development of an intense immune response against the vaccine candidate FINLAY-FR-02. The morphometric methods developed in this study could be valuable for future research studies related to the evaluation of new vaccine candidates.

Keywords

• covid-19
• finlay-fr-02
• morphometry
• immunotoxicology
• vaccines