Once transmitted from infected ticks to hosts, the spirochetes colonize target tissuesa process supported by the preferential expression of certain gene products that help them adapt to challenges specific to various microenvironments [7, 8]. changes take place in the gut, where the spirochetes encounter host-derived molecules present in the blood meal, including ingested antibodies. Thus, in a limited number of cases, including after receipt of the former OspA-based Lyme vaccine [15, 16], host antibodies generated against specific borrelial antigens have been shown to inhibit microbial transmission from ticks to host . Some of these gene products, such as BBA52 and OspCassist spirochetes in migrating from ticks to mice and/or establishing host infection and may play a prominent role in pathogenesis [18C20]. However, given the remarkable genetic diversity of  and the ability of the spirochete to alter its surface proteome throughout the enzootic cycle, it is difficult to find single protective antigens. Thus, one goal of our ongoing studies is to identify additional stable and conserved borrelial antigens, particularly those that are expressed during tick feeding or mammalian infection and that serve essential roles in infectivity. The enzootic cycle of Lyme disease spirochetes provides opportunities to target the bacteria either in the mammalian host or the arthropod vector. An advantage of targeting bacteria in the host is that a potential vaccine would only have to induce a memory B-cell response , with the infection serving as a proxy booster immunization to induce sufficient antibody levels for neutralization. On the other hand, a benefit of strategies aimed at neutralizing spirochetes in the arthropod vector is that the bacteria’s antigenic profile has not been subjected to the evolutionary selective pressure of the mammalian host’s immune response [23, 24]. In fact, antigens expressed in the vector are mostly conserved , and antigenic variation mechanisms appear to be minimally used in the vector . With this strategy, however, the host’s antibodies should be maintained at high L-873724 levels and stable (over a long duration) without requiring frequent booster immunizations. BB0405 was previously identified as one of the differentially expressed and surface-exposed spirochete antigens that are possible vaccine targets . Here we show that BB0405 supports spirochete infection in mammals and L-873724 that the antigen is a promising candidate for transmission-blocking vaccines against Lyme disease. MATERIALS AND METHODS infectious isolate B31 A3 was used throughout the present study . Spirochete cultures were grown in Barbour-Stoenner-Kelly H (BSK-H) medium with or without 350 g/mL kanamycin. ticks were reared in the laboratory as described elsewhere . Female C3H/HeN mice aged 4C6 weeks were purchased from the National Institutes Rabbit Polyclonal to ARRC of Health. All animal experiments were performed in accordance with the guidelines of the Institutional Animal Care and Use Committee and Institutional Biosafety Committee of the University of Maryland, College Park. Polymerase Chain Reaction (PCR) Analysis The oligonucleotide sequences for each of the primers used in specific PCR reactions are listed in Supplementary Table 1. Total RNA was isolated using TRIzol reagent (Invitrogen) and reverse transcribed to complementary DNA (cDNA; AffinityScript, Stratagene/Invitrogen), and reverse transcriptionCPCR (RT-PCR) or quantitative RT-PCR (qRT-PCR) analyses were performed as described elsewhere [19, 28]. Expression of was analyzed in various tissues of L-873724 C3H/HeN mice (3 animals/group) 14 days after infection (105 spirochetes/mouse) or in naive or infected nymphal ticks that fed on infected mice or naive mice (20 ticks/mouse), respectively,.