Advancing the understanding of pathogenesis and virulence of Leptospira interrogans through proteomics, structural, mutagenesis and immunological analyses

Abstract

Leptospirosis is a zoonosis widely distributed in all continents, but prevalent in tropical and sub-tropical regions. The etiological agent is the pathogenic bacteria of the genus Leptospira. In developed countries, the disease in humans is associated with recreational activities with water, while in developing ones, the disease represents a public health problem, with 1 million cases reported being fatal cases around 60 thousands per year. In all countries, leptospirosis has an economic impact because it affects the livestock, causing loss of milk production, failure to thrive and premature death. In urban areas, the rodents, such as Rattus norvegicus, are the main reservoir of the disease. They are asymptomatic carriers of the bacteria, keeping shedding them live through the urine for their lifetime, contaminating soil and water. In Brazil, outbreaks of leptospirosis occur during the rainy season when flooding are frequent. Inundation in association with precarious sanitary conditions favors the contact of humans with contaminated water, spreading the disease. The symptoms of the disease are non-specific flu-like and include fever, headache and myalgia. In some cases, the disease evolves to severe forms, called Well's syndrome and Severe Pulmonary Hemorrhagic Syndrome- SPHS, with mortality rates in adults of 10 to 50% of the cases. There are no efficient diagnostic methods available. Because sanitary measures and rat eradication are difficult to implement, the adoption of prophylactic actions is the best choice to fight the disease. Therefore, different research groups around the world are pursuing the development of vaccine. Understanding the mechanisms of pathogenicity and the identification of virulent factors are crucial to block this pathogen. In this sense, the present project proposes distinctive methodological approaches aiming to advance the knowledge of these bacteria in different aspects: comparative proteomics analysis, structural biochemistry for the recombinant proteins available in our laboratory, mutants knock-in of saprophyte strain and gene silencing of pathogenic strain by CRISPR Cas9 method, scale-up of recombinant protein purification process for diagnostic kit development; to evaluate the involvement of the leptospiral proteins LipL41, LipL21, Lip46 and OmpL37, as potential receptor for endothelial and epithelial cultured cells in vitro. (AU)