Leptospira spp., a genus in the stage of diversity and genomic data expansion

Leptospirosis is a widespread global zoonotic bacterial disease with a noteworthy human-animal-ecosystem interface. The disease presents different clinical manifestations and a high mortality and morbidity rates in humans and animals throughout the world. Characterization and correct classification of Leptospira isolates is essential for a better understanding the epidemiological properties of the disease. In the last ten years, molecular typing tools have been developed and applied to this field. These methods together with the availability of hundreds of new whole genome sequences that belong to known and new described species are shaping the understanding and structure of the entire genus.

Leptospira species molecular epidemiology in the genomic era

Leptospirosis is a zoonotic disease which global burden is increasing often related to climatic change. Hundreds of whole genome sequences from worldwide isolates of Leptospira spp. are available nowadays, together with online tools that permit to assign MLST sequence types (STs) directly from raw sequence data. In this work we have applied R7L-MLST to near 500 genomes and strains collection globally distributed. All 10 pathogenic species as well as intermediate were typed using this MLST scheme. The correlation observed between STs and serogroups in our previous work, is still satisfied with this higher dataset sustaining the implementation of MLST to assist serological classification as a complementary approach. Bayesian phylogenetic analysis of concatenated sequences from R7-MLST loci allowed us to resolve taxonomic inconsistencies but also showed that events such as recombination, gene conversion or lateral gene transfer played an important role in the evolution of Leptospira genus. Whole genome sequencing allows us to contribute with suitable epidemiologic information useful to apply in the design of control strategies and also in diagnostic methods for this illness.

The dynamics of erythrocyte infection in bovine anaplasmosis: a flow cytometry-based analysis

Anaplasma marginale (A. marginale) is an obligate intracellular bacterium that infects bovine erythrocytes causing extravascular hemolysis and anemia. In the present work, we combine SYTO16 labeling of parasitized cells with the statistical power of flow cytometry to study the evolution of erythrocyte infection during bovine anaplasmosis.

Typification of virulent and low virulence Babesia bigemina clones by 18S rRNA and rap-1c

The population structure of original Babesia bigemina isolates and reference strains with a defined phenotypic profile was assessed using 18S rRNA and rap-1c genes. Two reference strains, BbiS2P-c (virulent) and BbiS1A-c (low virulence), were biologically cloned in vitro. The virulence profile of the strains and clones was assessed in vivo. One fully virulent and one low-virulence clone were mixed in identical proportions to evaluate their growth efficiency in vitro. Each clone was differentiated by two microsatellites and the gene gp45. The 18S rRNA and rap-1c genes sequences from B. bigemina biological clones and their parental strains, multiplied exclusively in vivo or in vitro, were compared with strain JG-29. The virulence of clones derived from the BbiS2P-c strain was variable. Virulent clone Bbi9P1 grew more efficiently in vitro than did the low-virulence clone Bbi2A1. The haplotypes generated by the nucleotide polymorphism, localized in the V4 region of the 18S rRNA, allowed the identification of three genotypes. The rap-1c haplotypes allowed defining four genotypes. Parental and original strains were defined by multiple haplotypes identified in both genes. The rap-1c gene, analyzed by high-resolution melting (HRM), allowed discrimination between two genotypes according to their phenotype, and both were different from JG-29. B. bigemina biological clones made it possible to define the population structure of isolates and strains. The polymorphic regions of the 18S rRNA and rap-1c genes allowed the identification of different subpopulations within original B. bigemina isolates by the definition of several haplotypes and the differentiation of fully virulent from low virulence clones.

Prevalence and Genetic Diversity of Anaplasma marginale Strains in Cattle in South Africa

Bovine anaplasmosis, caused by the tick-borne rickettsia Anaplasma marginale, is endemic in South Africa and results in considerable economic loss to the cattle industry. This study was designed to characterize strains of A. marginale at the molecular level from cattle raised in communal and commercial farms in the north-eastern and south-western regions of the Free State Province, South Africa, that varied in rainfall and vegetation. Seroprevalence to A. marginale was determined in 755 cattle by an Anaplasma spp. competitive enzyme-linked immunosorbent assay and ranged from 44% to 98% and was similar in both regions. While Anaplasma centrale was not targeted in this study, A. marginale infections were identified by species-specific msp1alpha polymerase chain reaction in 129 of 215 of the samples studied. Similar genetic diversity of A. marginale strains was found in both the north-eastern and south-western regions. The sequences of 29 A. marginalemsp1alpha amplicons from South African strains revealed considerable genetic diversity providing 14 new repeat sequences. However, 42% of MSP1a repeat sequences were not unique to this region. These results indicated the presence of common genotypes between South African, American and European strains of A. marginale. Cattle movement between different parts of South Africa was suggested by the presence of identical A. marginale MSP1a genotypes in north-eastern and south-western regions of the Free State Province. Control strategies for anaplasmosis in South Africa should therefore be designed to be protective against genetically heterogeneous strains of A. marginale.

Mycobacterium bovis BCG as a delivery system for the RAP-1 antigen from Babesia bovis

Babesia bovis is the causative agent of babesiosis, a tick-borne disease that is a major cause of loss to livestock production in Latin America. Vaccination against Babesia species represents a major challenge against cattle morbidity and mortality in enzootic areas. The aim of this study was to evaluate the capacity of Bacille Calmette-Guerin (BCG) to deliver the rhoptry associated protein (RAP-1) antigen of B. bovis and to stimulate specific cellular and humoral immune responses in mice. Two of five mycobacterial expression vectors efficiently expressed the antigen. These constructs were subsequently studied in vivo following three immunization protocols. The construct with the greatest in vivo stability proved to be the one that induced the strongest immune responses. Our data support the hypothesis that specific T lymphocyte priming by rBCG can be employed as a component of a combined vaccine strategy to induce long-lasting humoral and cellular immune responsiveness towards B. bovis and encourage further work on the application of rBCG to the development of Babesia vaccines.

RANKL expression in a case of follicular lymphoma

The TNF-family molecule, RANKL, is a key regulator of bone remodeling and essential for the development and activation of osteoclasis. Bone involvement signals diesease activity in non-Hodgkin's lymphoma and influences the progenesis. The molecular mechanism and soluble factors involved in osteoclastic activation in haematological malignancies remain unclear except for Multiple Myeloma and Adult T-cell Leukemia. The aim of this paper is to report the first case of Follicular Lymphoma with bone involvement displaying an aberrant expression of RANKL in malignant cells. The detection of RANKL in Follicullar Lymphoma may help to prevent bone lesion in patients by determining an appropriate treatment.

Characterization of the immunophenotype and the metastatic properties of a murine T-lymphoma cell line. Unexpected expression of cytoplasmatic CD4

We report the first characterization of a mouse T-lymphoma cell line that surprisingly expresses cytoplasmatic (cy) yCD4. Phenotypically, LBC cells are CD5+, CD8+, CD16+, CD24+, CD25+, CD2-/dim, CD3-/dim, TCRbeta-/dim, TCRgammadelta, CD154 , CD40-, and CD45R. Coexpress cyTCRbeta, cyCD3, cyCD4, and yet lack surface CD4 expression. Transplantation of LBC cells into mice resulted in an aggressive T-lymphoblastic lymphoma that infiltrated lymph nodes, thymus, spleen, liver, ovary, and uterus but not peripheral blood or bone marrow. LBC cells display a modal chromosome number of 39 and a near-diploid karyotype. Based on the characterization data, we demonstrated that the LBC cell line was derived from an early T-cell lymphocyte precursor. We propose that the malignant cell transformation of LBC cells could coincide with the transition stage from late double-negative, DN3 (CD4- CD8 CD44-/low, CD25+) or DN4 (CD4-low, CD8-/low, CD44-, CD25-) to double-positive (DP: CD4+CD8+) stage of T-cell development. LBC cells provide a T-lymphoblastic lymphoma model derived from a malignant early T-lymphocyte that can be potentially useful as a model to study both cellular regulation and differentiation of T-cells. In addition, LBC tumor provides a short latency neoplasm to study cellular regulation and to perform preclinical trials of lymphoma-relatel clisorders.