Yersinia pestis

Yersinia pestis

Kingdom: Eubacteria
Phylum: Proteobacteria
Class: Gamma Proteobacteria
Order: Enterobacteriales
Genus: Yersinia
Species: Y. pestis

              Yersinia pestis is a Gram-negative facultative anaerobic bipolar-staining (giving it a safety pin appearance) bacillus bacterium belonging to the family Enterobacteriaceae. The infectious agent of bubonic plague, Y. pestis infection can also cause pneumonic and septicemic plague. All three forms have been responsible for high mortality rates in epidemics throughout human history, including the Black Death that accounted for the death of approximately one-third of the European population in 1347 to 1353.
             The genus Yersinia is Gram-negative, bipolar staining coccobacilli, and, similarly to other Enterobacteriaceae, it has a fermentative metabolism. Y. pestis produces an antiphagocytic slime. The organism is motile when isolated, but becomes nonmotile in the mammalian host.

Pathogenicity and immunity

A scanning electron micrograph depicting a mass of Yersinia pestis bacteria
Pathogenicity of Y. pestis is in part due to two anti-phagocytic antigens, named F1 (Fraction 1) and V, both important for virulence.These antigens are produced by the bacterium at 37°C. Furthermore, Y. pestis survives and produces F1 and V antigens within blood cells such as monocytes, but not in polymorphonuclear neutrophils. Natural or induced immunity is achieved by the production of specific opsonic antibodies against F1 and V antigens; antibodies against F1 and V induce phagocytosis by neutrophils.

                   A formalin-inactivated vaccine once was available for adults at high risk of contracting the plague until removal from the market by the FDA. It was of limited effectiveness and may cause severe inflammation. Experiments with genetic engineering of a vaccine based on F1 and V antigens are underway and show promise; however, bacteria lacking antigen F1 are still virulent, and the V antigens are sufficiently variable, that vaccines composed of these antigens may not be fully protective.

Kumkum / safron - Crocus sativus

 Medicinal Plant / herbs

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.....