ABSTRACT
Leptospirosis is a widespread zoonosis caused by pathogenic Leptospira spp. It is an important infectious disease that affects humans and animals. The disease causes economic losses as it affects livestock, with decreased milk production and death. Our group is investigating the genome sequences of L. interrogans targeting surface-exposed proteins because, due to their location, these proteins are capable to interact with several host components that could allow establishment of the infection. These interactions may involve adhesion of the bacteria to extracellular matrix (ECM) components and, hence, help bacterial colonization. The bacteria could also react with the host fibrinolytic system and/or with the coagulation cascade components, such as, plasminogen (PLG) and fibrinogen (Fg), respectively. The binding with the first system generates plasmin (PLA), increasing the proteolytic power of the bacteria, while the second interferes with clotting in a thrombin-catalyzed reaction, which may promote hemorrhage foci and increase bacterial dissemination. Interaction with the complement system negative regulators may help bacteria to evade the host immune system, facilitating the invasion. This work compiles the main described leptospiral proteins that could act as adhesins, as PLG and fibrinogen receptors and as complement regulator binding proteins. We present models in which we suggest possible mechanisms of how leptospires might colonize and invade host tissues, causing the disease. Understanding leptospiral pathogenesis will help to identify antigen candidates that would contribute to the development of more effective vaccines and diagnostic tests.
Subject(s)
Host-Pathogen Interactions , Leptospira/pathogenicity , Adhesins, Bacterial/physiology , Animals , Complement System Proteins/physiology , Extracellular Matrix Proteins/metabolism , Fibrinogen/physiology , Humans , Immune Evasion , Leptospira/immunology , Plasminogen/metabolismABSTRACT
Um surto de leptospirose foi observado em bovinos leiteiros em Santo Antônio do Monte, Minas Gerais. O rebanho apresentava reações positivas anti-leptospira sorovar Hardjo no teste de microaglutinação (MAT) e havia sido vacinado anteriormente com vacina experimental contendo a sorovariedade Hardjo. O MAT revelou 48,06% dos bovinos positivos para sorovariedade Hardjo genótipo Hardjobovis, 36,82% para sorovariedade Hardjo genótipo Hardjoprajitno. Os animais apresentavam aborto e mastite com presença de sangue no leite. A presente pesquisa teve como objetivos isolar as sorovariedades existentes a partir da urina de vacas sorologicamente positivas, elaborar uma vacina experimental com as sorovariedades isoladas no rebanho, avaliar a eficiência do programa de vacinação por um período de dois anos por meio da sorologia do rebanho. Foi isolada Leptospira spp. a partir da urina de duas vacas com sinais sugestivos da doença. As amostras isoladas foram identificadas pela sorologia com anticorpos monoclonais e seqüenciamento do gene 16S rRNA como pertencentes à espécie Leptospira interrogans, sorogrupo Sejroe, sorovariedade Hardjo e genótipo Hardjoprajitno. O uso da vacina autógena foi eficaz no controle da leptospirose no rebanho no período de dois anos. Os resultados da sorologia revelaram ausência de animais positivos na última prova realizada no rebanho.
An outbreak of leptospirosis in dairy cattle was observed in Santo Antonio do Monte, Minas Gerais. The herd had positive reactions in anti-Leptospira serovar Hardjo agglutination test (MAT) and had been previously vaccinated with a vaccine containing serovars Hardjo. The MAT showed 48.06% of cattle positive for serovars Hardjo genotype Hardjobovis, 36.82% for serovars Hardjo genotype Hardjoprajitno. The animals had abortions and mastitis with blood in the milk. This study aimed to isolate the existing serovars from the urine of serologically positive cows, produce an experimental vaccine with the serovars isolated in the herd, evaluating the effectiveness of the vaccination program for a period of two years through the herd serology. Leptospira spp. was isolated from the urine of two cows with signs suggestive of the disease. The strains were identified by serology with monoclonal antibodies and 16S rRNA gene sequencing as belonging to the Leptospira interrogans species Sejroe serogroup Hardjo serovars and Hardjoprajitno genotype. Use of the autochthonous vaccine was effective in leptospirosis controlling in the herd in two years. The serology results showed the absence of positive animals in the last race held in the herd.
