Induction of immune responses and partial protection in mice after skin immunization with rotavirus VP6 protein and the adjuvant LT(R192G)

Oral or intranasal administration of mice with rotavirus VP6/LT(R192G) vaccine induces between 95 and 99% protection against fecal shedding of rotavirus after challenge. However, mucosal administration of LT(R192G) is controversial. Subcutaneous, intradermal or Biojector injection induced high titers of serum VP6-specific IgG, eliciting only partial to no protection (73, 0 and 26%, respectively), while transcutaneous delivery using gauze pad induced both poor immune responses and no protection (13%). A mixture of VP6-derived synthetic peptides induced >97, 48 and 33% protection after intranasal, gauze pad or Biojector administration, respectively. For needle-free delivery methods to be viable, improvements to these methods must be made to enhance the efficacy of the VP6 vaccine.