Although they are not environmentally stable, LCVs are infectious

in laboratory settings and pose a risk of causing disease. After differentiation, LCVs then undergo exponential replication for ~4 days (log phase) before beginning an asynchronous conversion back to SCVs at ~6 days post infection (PI) [5, 6]. LCV replication is accompanied by a remarkable expansion of the PV, which eventually occupies the majority of the host cell [2, 7]. Intracellular bacterial pathogens are known to operate by targeting and subverting vital intracellular Go6983 in vivo pathways of the host [8, 9]. Bacterial proteins are a key factor in this subversion of host cell molecular mechanisms [2, 9–11]. Biogenesis and maintenance of the PV, interaction with the autophagic pathway, and inhibition of host cell apoptosis are all dependent on C. burnetii protein synthesis [2, 7, 12–14]. After ingestion

by a host cell, C. burnetii PV maturation experiences a delay when compared to vacuoles carrying latex beads or dead C. burnetii [7, 15]. This delay in phagolysosomal maturation requires ongoing bacterial protein synthesis [7]. C. burnetii protein synthesis is also required for the fusogenicity of C. burnetii containing vacuoles, PV fusion with host vesicles, and in the maintenance of a spacious PV (SPV) during logarithmic bacterial growth [7, 15]. Transient interruption of bacterial protein synthesis results in cessation of SPV-specific vesicle trafficking and SPV collapse [7, 15]. The ABT-737 purchase C. burnetii PV is thought to interact with the autophagic pathway as a means to provide PAK6 metabolites to the bacterium. This interaction is also a pathogen driven buy BV-6 activity [16]. Additionally, an examination of the PV has revealed increased amounts of cholesterol

in the membranes [12]. Interestingly, C. burnetii infected cells have been observed to dramatically increase cholesterol production. During log growth, the PV expands and is accompanied by increased transcription of host genes involved in both cholesterol uptake (e.g. LDL receptor) and biosynthesis (e.g. lanosterol synthase) [2, 12]. Recently, the function of the host cell apoptotic pathway has been shown to be altered during C. burnetii infection. C. burnetii was shown to actively inhibit apoptosis in macrophages exposed to inducers of both the extrinsic and intrinsic apoptotic pathways in a bacterial protein synthesis dependant manner [14]. This antiapoptotic activity causes a marked reduction in activated caspase-3, caspase-9, and poly-ADP (ribose) polymerase (PARP) processing. Other data indicate that C. burnetii mediates the synthesis of host anti-apoptotic proteins A1/Bfl-1 and c-IAP2, which might directly or indirectly prevent release of cytochrome C from mitochondria, interfering with the intrinsic cell death pathway during infection [17]. Moreover, activation of the pro-survival host kinases Akt and Erk1/2 by C. burnetii was shown to protect infected host cells from apoptosis [18].