Christopher B. Fox, Mayuresh M. Abhyankar, Feifan Xu, Deborah Chavez, Elda Mendoza, Christopher Chen, Sandra J. Sivananthan, Robert Kinsey, William R. Lykins, Brynn M. Murphy, Andrew R. Martin, Mark A. Tomai, Corey Casper, Karl Pedersen, William A. Petri Jr.  

Despite many years of amebiasis vaccine research using various antigens, adjuvants and model systems, the translation of observations from animals to humans is lacking. Using a lead candidate vaccine composition containing LecA fragment of the Gal-lectin and GLA-3M-052 liposome adjuvant, we immunized rhesus macaques (Macaca mulatta) via intranasal spray or intramuscular injection. Both immunization routes were well tolerated. The vaccine candidate elicited high avidity functional humoral responses as seen by the inhibition of amebic attachment to mammalian target cells by plasma and stool antibodies. Salivary and stool antibody responses were also evident. Importantly, antigen-specific IFN-γ secreting peripheral blood mononuclear cells as well as IgG- and IgA-memory B cells were detected in immunized animals. Antigen-specific antibody and cellular responses were maintained for at least 6 months after the final immunization. Overall, both intranasal and intramuscular immunizations elicited a durable and functional response in systemic and mucosal compartments. These data represent an important step in advancing the LecA + GLA-3M-052 liposome vaccine candidate towards clinical testing.