Oral live attenuated polio vaccines induce enhanced T-cell responses with broad antigen recognition compared to inactivated polio vaccines.

Little is known about the immunologic mechanisms responsible for observed differences in mucosal immunity following vaccination with oral live attenuated polio vaccines (OPVs) compared to inactivated polio vaccines (IPVs). Here, we used a flow cytometric activation-induced marker (AIM)-based approach to investigate vaccine-related differences in T cell response using peripheral blood samples from healthy adults enrolled in two polio vaccine trials. Our findings indicate that vaccination with OPVs (1) enhances CD4+ T cell responses, and (2) expands CD4+ and CD8+ antigen recognition of non-structural proteins. Fecal shedding of OPVs was associated with enhanced T cell responses, and primary CD8+ T cell responses appear to correlate with early control of fecal viral shedding. Our results indicate that OPVs induce broad cellular immunity to polioviruses, which may help explain their enhanced ability to stimulate effective pathogen-specific mucosal immunity.