Ichiae are coccoid to pleomorphic and differ in size from tiny (0.four ) to substantial (between 1 and two ) (Popov et al., 1995). E. chaffeensis replicates in an intracellular, membrane-bound vacuole derived from host cell membrane, forming microcolonies called morula for the reason that they resembling mulberries. Morula is derived in the latin word “morum” for mulberry. Each vacuole consists of a single to more than 400 209986-17-4 Purity ehrlichiae (Barnewall et al., 1997). E. chaffeensis exhibits tropism for mononuclear phagocytes, and includes a biphasic developmental cycle which involves two morphologically distinct forms, the smaller (0.four.six ), infectious dense cored cell (DC), plus a bigger replicating reticulate cell (RC, 0.7-0.9 ). Ehrlichiae have a gram unfavorable envelope which include a cytoplasmic membrane and outer membrane separated by periplasmic space; even so, their cell wall lacks peptidoglycan (PG) (Mavromatis et al., 2006). DCs are often coccoid inshape and characterized by an electron dense nucleoid that occupies the majority of the cytoplasm when RCs are pleomorphic in shape and have uniformly dispersed nucleoid filaments and ribosomes distributed all through the cytoplasm (Zhang et al., 2007). E. chaffeensis has one of many smallest bacterial genome (1.3 Mb), encoding as much as 1200 proteins, and about half of these genes have predicted or recognized functions. The genome sequence of Ehrlichia species has revealed low GC content (30 ), a lot of extended tandem repeat sequences (TRs) and on the list of smallest genome to coding ratios, which can be attributed to long noncoding regions (Dunning Hotopp et al., 2006; Frutos et al., 2006). Presence of lengthy non coding regions and low GC content are thought to represent degraded genes inside the final stage of elimination, and improved GC to AT mutations found in connected Rickettsiales members (Andersson and Andersson, 1999a,b). TRs are actively designed and deleted through an unknown mechanism that seems to become compatible with DNA slippage. Generation of TRs in Ehrlichia serves as a mechanism for adaptation for the hosts, not to produce diversity. Even though TRs share similar characteristics, there is certainly no 5-Methoxysalicylic acid Technical Information phylogenetic relationship involving the TRs from various species of Ehrlichia, suggesting TRs evolved soon after diversification of each species (Frutos et al., 2006). The genome sequence of Ehrlichia has revealed quite a few genes potentially involved in host-pathogen interactions like genes coding for tandem and ankyrin-repeat containing proteins, outer membrane proteins, actin polymerization proteins, and also a group of poly(G-C) tract containing proteins, which may be involved in phase variation. Notably, genes encoding proteins linked with biosynthesis of peptidoglycan (PG) and lipopolysaccharide (LPS) are absent from the genome. Considering the fact that, PG and LPS bind to nucleotide-binding oligomerization domain (Nod)-like receptor proteins and toll-like receptor proteins (TLR4) to activate leukocytes, the absence of LPS and PG presumably helps Ehrlichia to evade the innate immune response elicited by these pathogen-associated molecular patterns (PAMPs). E. chaffeensis contains two types of TRs, tiny (12 bp) and substantial (10000 bp) period repeats. These TRs may perhaps play role in regulation of gene expression and phase variation (Frutos et al., 2007). Multiple secretion systems happen to be described in gram adverse bacteria for the delivery of effector proteins. Inside the ehrlichial genome, kind I and IV secretion systems have been identified (Collins et al., 2005; Dunning Hoto.