Characterization of Nucleosomal Histone Protein(s) of L. donovani for its potential as a vaccine target against Visceral Leishmaniasis

Abstract

Leishmaniasis (cutaneous, mucocutaneous, and visceral) is caused by an intracellular protozoan parasite complex by the invasion of the reticuloendothelial system (spleen, liver and bone marrow). Leishmaniasis is a zoonotic parasitic disease caused by a protozoan parasite of genus Leishmania (Schuster and Sullivan, 2002) and accounts for approximately 40,000 deaths per year (Guerin et al., 2002). It is a poverty-related disease affecting the poorest of the poor and is associated with malnutrition, displacement, poor housing, and illiteracy, and gender discrimination, weakness of the immune system and lack of resources. Leishmaniasis is an ancient disease that may have been historically portrayed in figures, papyrus, statues and ceramics, and has been discussed from analysis of mummified human remains and archaeological findings (Altamirano-Enciso et al., 2003). The discovery of a chronic ulcer that heals over time has been cited under several names; however, the description of Visceral Leishmaniasis (VL) from historical papers is absent. Nevertheless, the identification of New World Leishmaniasis was facilitated by descriptions of a typical mucosa lesion, which was common among pre-Colombian inhabitants. Leishmania belongs to the phylum Euglenozoa and class Kinetoplastida, which lacks a fossil record. Molecular studies have shown that kinetoplastids are probably related to the euglenids (Dooijes et al., 2000). Both belong to the eukaryote supergroup Excavata, whose fossils suggest their appearance during the Ordovician period (Roger and Hug, 2006). In the Old World, Indian physicians applied the Sanskrit term kala-azar (meaning ‘black fever’) to an ancient disease later defined as VL. It was first noticed in Jessore in India in 1824, when patients suffering from fevers that were thought to be due to malaria failed to respond to quinine. In 1901, Sir William Boog Leishman (1865–1926) identified certain organisms in smears taken from the spleen of a patient who had died from "dum-dum fever". Initially, these organisms were considered to be trypanosomes, but in 1903 Charles Donovan (1863–1951) described them as being new. The link between these organisms and kala azar was eventually discovered by Ronald Ross, who named them Leishmania donovani in memory of these two researchers. In 1921, brothers Edouard and Etienne Sergent succeeded in proving that the vector for transmission of Leishmania parasites to mammals is the sand fly of the genus Phlebotomus. Swaminath et al (Swaminath et al., 2006) proved using human volunteers that the Leishmania parasite could be transmitted by Phlebotomus sandflies in the Old World. In 1922, it was found that Lutzomyia is the vector of New World Leishmaniasis by Ralph Lainson and his colleagues (Cox, 2002).