ABSTRACT
VlsE is a surface exposed lipoprotein of the Lyme disease spirochete, Borrelia burgdorferi. Spirochetes are able to generate many antigenic variants of VlsE by DNA recombination at the vlsE locus. Novel VlsE antigenic variants are readily observed in mice infected with B. burgdorferi. We followed a clonal population of spirochetes through a tick transmission cycle and report that unlike in vertebrates, the vlsE locus is stable in ticks.
Subject(s)
Antigens, Bacterial/genetics , Arthropod Vectors/microbiology , Bacterial Proteins/genetics , Borrelia burgdorferi/genetics , Genetic Variation , Ixodes/microbiology , Lipoproteins/genetics , Animals , Borrelia burgdorferi/physiology , Female , Larva/microbiology , Mice , Polymorphism, Restriction Fragment Length , Sequence Analysis, DNAABSTRACT
Protozoal parasites of the genus Leishmania are transmitted to their vertebrate host within the saliva of the sand fly during a blood meal. The saliva of the sand fly Lutzomyia longipalpis contains maxadilan, a potent vasodilator and immunomodulator. Maxadilan has been shown to enhance the virulence of L. major in all strains of laboratory mice when injected along with the organism. Increased haematopoiesis has been associated with enhanced susceptibility to Leishmania organisms. Here, we show that maxadilan alone stimulates bone marrow haematopoiesis through its ability to stimulate interleukin-6 production by bone marrow stromal cells. Moreover, these effects of maxadilan are mediated through the interaction of maxadilan with the pituitary adenylate cyclase activating polypeptide receptor. These data suggest that increasing haematopoiesis may be yet another way that maxadilan enhances susceptibility of mice to Leishmania infection.
