Comparative Efficacy of Parenteral and Mucosal Recombinant Probiotic Vaccines Against SARS-CoV-2 and Infections in Animal Models.

Background: The accumulation of specific IgG antibodies in blood serum is considered a key criterion for the effectiveness of vaccination. For several vaccine-preventable infections, quantitative indicators of the humoral response have been established, which, when reached, provide a high probability of protection against infection. The presence of such a formal correlate of vaccine effectiveness is crucial, for example, in organizing preventive measures and validating newly developed vaccines.

Evaluation of Immune Response to Mucosal Immunization with an Oral Probiotic-Based Vaccine in Mice: Potential for Prime-Boost Immunization against SARS-CoV-2.

Following the conclusion of the COVID-19 pandemic, the persistent genetic variability in the virus and its ongoing circulation within the global population necessitate the enhancement of existing preventive vaccines and the development of novel ones. A while back, we engineered an orally administered probiotic-based vaccine, L3-SARS, by integrating a gene fragment that encodes the spike protein S of the SARS-CoV-2 virus into the genome of the probiotic strain L3, inducing the expression of viral antigen on the surface of bacteria. Previous studies demonstrated the efficacy of this vaccine candidate in providing protection against the virus in Syrian hamsters.

SARS-CoV-2 Spike Protein-Expressing Enterococcus for Oral Vaccination: Immunogenicity and Protection.

The declaration of the conclusion of the COVID-19 pandemic notwithstanding, coronavirus remains prevalent in circulation, and the potential emergence of novel variants of concern introduces the possibility of new outbreaks. Moreover, it is not clear how quickly and to what extent the effectiveness of vaccination will decline as the virus continues to mutate. One possible solution to combat the rapidly mutating coronavirus is the creation of safe vaccine platforms that can be rapidly adapted to deliver new, specific antigens in response to viral mutations.

Live Influenza Vaccine Provides Early Protection against Homologous and Heterologous Influenza and May Prevent Post-Influenza Pneumococcal Infections in Mice.

Influenza and infections are a significant cause of morbidity and mortality worldwide. Intranasal live influenza vaccine (LAIV) may prevent influenza-related bacterial complications. The objectives of the study are to estimate resistance against early influenza infection and post-influenza pneumococcal pneumonia after LAIV in mice.

Associated virus-bacterial vaccine based on seasonal LAIV and chimeric peptide provide protection against post-influenza pneumococcal infection in mouse model.

Severe influenza complications are often caused by infection, which presents the most common cause of community-acquired pneumonia. We evaluated in a mouse model an associated virus-bacterial vaccine based on seasonal live influenza vaccines (LAIV) and chimeric protein comprising flagellin (PSPF). Intranasal immunization of mice with a complex of trivalent LAIV and PSPF caused an increased release of early cytokines in the lungs of mice.