Although over 200 serovars of Leptospira have been described, all members of the genus have similar morphology. Leptospira are spiral-shaped bacteria that are 6-20 μm long and 0.1 μm in diameter with a wavelength of about 0.5 μm. One or both ends of the spirochete are usually hooked. Because they are so thin, live Leptospira are best observed by darkfield microscopy.
The bacteria have a number of freedom degrees; when ready to proliferate via binary fission, the bacterium noticeably bends in the place of the future split.
 Cellular structure
Leptospira have a Gram-negative-like cell envelope consisting of a cytoplasmic and outer membrane. However, the peptidoglycan layer is associated with the cytoplasmic rather than the outer membrane, an arrangement that is unique to spirochetes. The two flagella of Leptospira extend from the cytoplasmic membrane at the ends of the bacteria into the periplasmic space and are necessary for the motility of Leptospira.
The outer membrane contains a variety of lipoproteins and transmembrane outer membrane proteins. As expected, the protein composition of the outer membrane differs when comparing Leptospira growing in artificial medium with Leptospira present in an infected animal. Several leptospiral outer membrane proteins have been shown to attach to the host extracellular matrix and to factor H. These proteins may be important for adhesion of Leptospira to host tissues and in resisting complement, respectively.
The outer membrane of Leptospira, like those of most other Gram-negative bacteria, contains lipopolysaccharide (LPS). Differences in the highly immunogenic LPS structure account for the numerous serovars of Leptospira.. Consequently, immunity is serovar specific; current leptospiral vaccines, which consist of one or several serovars of Leptospira endemic in the population to be immunized, protect only against the serovars contained in the vaccine preparation.
Leptospiral LPS has low endotoxin activity.. An unusual feature of leptospiral LPS is that it that it activates host cells via TLR2 rather than TLR4. The unique structure of the lipid A portion of the LPS molecule may acccount for this observation. Finally, the LPS O antigen content of L. interrogans differs in an acutely infected versus a chronically infected animal. The role of O antigen changes in the establishment or maintenance of acute or chronic infection, if any, is unknown.
Kumkum / safron - Crocus sativus
Crocuses belong to the family Iridaceae. The saffron crocus is classified as Crocus sativus, It is a shrub. Leaves are seen towards the base of the stem and are compactly arranged.Read More about safron.....