Evaluation of monkeypox- and vaccinia-virus neutralizing antibodies before and after smallpox vaccination: A sero-epidemiological study.

Since May 2022, several countries outside of Africa experienced multiple clusters of monkeypox virus (MPXV)-associated disease. In the present study, anti-MPXV and anti-vaccinia virus (VACV) neutralizing antibody responses were evaluated in two cohorts of subjects from the general Italian population (one half born before the WHO-recommended end of smallpox vaccination in 1980, the other half born after). Higher titers (either against MPXV or VACV) were observed in the cohort of individuals born before the interruption of VACV vaccination. An association between VACV and MPXV antibody levels was observed, suggesting that the smallpox vaccination may confer some degree of cross-protection against MPXV infection. Results from this study highlight low levels of immunity toward the assessed Orthopoxviruses, especially in young adults, advocating the introduction of a VACV- or MPXV-specific vaccine in case of resurgence of monkeypox disease outbreaks.

Rectal Administration of Leishmania Cells Elicits a Specific, Th1-Associated IgG2a Response in Mice: New Perspectives for Mucosal Vaccination against Leishmaniasis, after the Repurposing of a Study on an Anti-Viral Vaccine Candidate.

The mucosal immune system plays a pivotal role in the control of infections, as it represents the first line of defense against most pathogens, from respiratory viruses to intestinal parasites. Mucosal vaccination is thus regarded as a promising strategy to protect animals, including humans, from infections that are acquired by ingestion, inhalation or through the urogenital system. In addition, antigens delivered at the mucosal level can also elicit systemic immune responses. Therefore, mucosal vaccination is potentially effective also against systemic infections acquired through non-mucosal routes, for example, through the bite of hematophagous insects, as in the case of leishmaniasis, a widespread disease that affects humans and dogs. Here, we explored the potential of antigen rectal administration for the generation of anti-Leishmania immunity. Mice were immunized through rectal administration of whole cells of the model parasite Leishmania tarentolae (using a clone engineered to express the spike protein of the SARS-CoV-2 virus generated in a previous study). A specific anti-Leishmania IgG antibody response was detected. In addition, the recorded IgG2a/IgG1 ratio was higher than that of animals injected subcutaneously; therefore, suggesting a shift to a Th1-biased immune response. Considering the importance of a Th1 polarization as a protective response against Leishmania infections, we suggest that further investigation should be focused on the development of novel types of vaccines against these parasites based on rectal immunization.