Immunization with Larrea divaricata Cav. proteins elicits opsonic antibodies against Pseudomonas aeruginosa and induces phagocytic activity of murine macrophages.

Pseudomonas aeruginosa is an opportunistic pathogen implicated in nosocomial infections for which no vaccines have been approved. Larrea divaricata Cav. (Jarilla) is a widely spread plant in America and it is used in folk medicine to treat several pathologies. It has also been shown that antibodies elicited against Jarilla proteins of crude extract (JPCE) cross-react with proteins from gram-negative bacteria. In this study we aim to assess the contribution of anti-JPCE antibodies in the opsonophagocytosis of P. aeruginosa by murine macrophages. Levels of reactivity of anti-JPCE IgG and IgA antibodies against cell and membrane proteins suggest that these proteins induce a response that could favor opsonic bacterial recognition, which is important for the elimination of bacteria on mucous membranes, useful in the early stages of infection. Opsonophagocytosis assays also show that these antibodies could favor bacteria intake. These results together with previous observations that indicate that anti-JPCE antibodies are able to neutralize P. aeruginosa enzymes point L. divaricata proteins as candidates for vaccine development.