As mitochondria are negatively charged organelles, penetrating cations are used as parts of chimeric molecules to deliver specific compounds into mitochondria. In other words, they are used as electrophilic carriers for such chemical moieties as antioxidants, dyes, etc., to transfer them inside mitochondria. However, unmodified penetrating cations affect different aspects of cellular physiology as well. In this review, we have attempted to summarise the data about the side effects of commonly used natural (e.g., berberine) and artificial (e.g., tetraphenylphosphonium, rhodamine, methylene blue) penetrating cations on cellular physiology. For instance, it was shown that such types of molecules can (1) facilitate proton transport across membranes; (2) react with redox groups of the respiratory chain; (3) induce DNA damage; (4) interfere with pleiotropic drug resistance; (5) disturb membrane integrity; and (6) inhibit enzymes. Also, the products of the biodegradation of penetrating cations can be toxic. As penetrating cations accumulate in mitochondria, their toxicity is mostly due to mitochondrial damage. Mitochondria from certain types of cancer cells appear to be especially sensitive to penetrating cations. Here, we discuss the molecular mechanisms of the toxic effects and the anti-cancer activity of penetrating cations.

Background/Objectives: The World Health Organization (WHO) recommends the use of attenuated Sabin strains for the production of inactivated poliovirus vaccine (IPV), offering improved biosafety while retaining immunogenicity. To better characterize the antigenic composition of Sabin strain-based IPV (sIPV), including both the protective D-antigen and the non-protective H-antigen forms, we developed a method for purifying D- and H-antigens forms. Methods: D- and H-antigens of poliovirus Sabin strains types 1, 2, and 3 were purified using gradient ultracentrifugation and used to generate antigen-specific polyclonal antibodies. Results: The generated polyclonal antibodies demonstrated high specificity with neutralizing titers of antibodies against Sabin type 1 poliovirus—1:2048, against Sabin type 2 poliovirus—more than 1:2048, against Sabin type 3 poloivirus—1:2048. Conclusions: This antigen-specific antibody approach provides a valuable tool for routine quality control in sIPV manufacturing, enabling accurate quantification of immunogenic components and detection of potentially immunogenic degradation products during vaccine storage and distribution. Antibodies to the D-antigen allow assessment of immunogenic, neutralizing epitopes, while antibodies to the H-antigen provide a tool for detecting non-neutralizing components. This antigen-specific antibody approach offers a valuable tool for studying the antigenic structure of sIPV and for improving the accuracy of ELISA-based antigen quantification.

Various types of COVID-19 vaccines, including adenovirus, mRNA, and inactivated ones, have been developed and approved for clinical use worldwide. Inactivated vaccines are produced using a proven technology that is widely used for the production of vaccines for the prevention and control of infectious diseases, including influenza and poliomyelitis. The development of inactivated whole-virion vaccines commonly includes several stages: the production of cellular and viral biomass in cell culture; inactivation of the virus; filtration and ultrafiltration; chromatographic purification of the viral antigen; and formulation with stabilizers and adjuvants. In this study, the suitability of four resins for Size-Exclusion Chromatography was investigated for the purification of a viral antigen for the human COVID-19 vaccine.

SARS-CoV-2, which causes COVID-19, continues to circulate around the world, making it necessary to study the impact of rapidly emerging mutations on escape from neutralizing antibodies and pathogenesis. While RBD mutations are well characterized, mutations in the N-terminal domain (NTD) of the spike protein remain comparatively understudied despite their relevance to antibody recognition. This study investigates two phenotypically distinct SARS-CoV-2 mutants, which exhibited differences in plaque morphology on Vero cells. Whole-genome sequencing via Illumina identified a novel 12-nucleotide insertion in the spike NTD. This insertion induced a frameshift, introducing five new amino acids potentially altering viral behavior, receptor interactions, and antibody detection in ELISAs. The study further explores the pathogenicity of these variants in a hamster model. These findings underscore the importance of monitoring NTD mutations, which may contribute to immune evasion and influence therapeutic antibody efficacy, highlighting gaps in current research on SARS-CoV-2 evolution.

As mitochondria are negatively charged organelles, penetrating cations are used as a part of the chimeric molecules to deliver the specific compounds into mitochondria. However, unmodified penetrating cations affect different aspects of cellular physiology as well. In this review we have attempted to summarize the data about side effects of the commonly used natural (e.gberberine) and artificial (e.g. tetraphenylphosphonium, rhodamine, methylene blue) penetrating cations on cellular physiology. For instance, it was shown that such types of molecules can (1) facilitate proton transport across membranes; (2) react with redox groups of respiratory chain; (3) induce DNA damage; (4) interfere with pleiotropic drug resistance; (5) disturb membrane integrity (6) inhibit the enzymes. Also, the products of the biodegradation of penetrating cations can be toxic. As penetrating cations accumulate in mitochondria, their toxicity is mostly due to the mitochondrial damage. Mitochondria of certain types of cancer cells appear to be especially sensitive to penetrating cations. Here we discuss the molecular mechanisms of the toxic effects and the anti-cancer activity of the penetrating cations.

Vaccination remains the primary strategy for poliomyelitis prevention. The D-antigen of poliovirus is a critical component of inactivated polio vaccines, as it induces the production of neutralizing antibodies and provides protective immunity. Therefore, the development of quantitative immunoassays for monitoring D-antigen content during vaccine production is an important task. In this study, we generated recombinant camelid single-domain antibodies (VHHs) specific for the D-antigen of Sabin poliovirus type 1 and evaluated their antigen specificity. The obtained VHH antibodies demonstrated strong binding to the native D-antigen of Sabin type 1 poliovirus. Furthermore, the use of clone S1-C7 as a capture antibody in combination with Sabin type 1-specific polyclonal antibodies for detection revealed differential recognition of the vaccine-derived Sabin type 1 and homologous wild-type Mahoney strains. Notably, such discrimination was not observed when polyclonal antibodies were used alone, indicating that incorporation of VHH S1-C7 into the assay enhances strain-specific antigen recognition. In a neutralization assay, clone S1-C7 exhibited in vitro neutralizing activity against Sabin type 1 poliovirus. One clone, S1-D9, demonstrated cross-reactivity with all three poliovirus serotypes, suggesting recognition of a conserved epitope in the capsid and potential utility as a universal detection antibody. The generated VHH antibodies represent promising analytical tools for poliovirus antigen characterization. Together with S1-C7, they enable the discrimination of both D- and C-antigen forms as well as vaccine-derived and wild-type strains.