Genetic diversity of Orf virus isolated from sheep in Uruguay.

Orf virus (ORFV) is the etiological agent of contagious ecthyma, a disease widely spread in the world that occasionally causes zoonotic infections. This work is the first molecular characterization of ORFV in Uruguay, where we analyzed twenty-one sheep samples, eighteen of which were recovered from thirteen ORFV outbreaks that occurred during 2004 to 2011 as well as three strains from a national vaccine. Phylogenetic analysis and the derived amino acid sequences from the B2L gene suggest that the Uruguayan virus do not form a unique cluster, with most of them displaying similarities with worldwide ORFV isolates as well as our vaccine strains.

Prevalence of Escherichia coli adhesion-related genes in neonatal calf diarrhea in Uruguay.

INTRODUCTION: Neonatal calf diarrhea (NCD), one of the most important diseases of neonatal dairy and beef calves in Uruguay, has become relevant in association with intensive systems. This disease generates substantial economic losses every year worldwide as a result of increased morbidity and mortality. Escherichia coli, one of the pathogens associated with NCD, can express several fimbrial and afimbrial adhesins. The objective of this study was to assess the presence of clpG, f5, f17A, f17G(II), and f17G(I) genes that encode three important adhesins expressed in diarrheagenic E. coli: F5, F17 and CS31A, isolated from feces of calves in Uruguay. METHODOLOGY: Feces of 86 (70 diarrheic and 16 healthy) calves, from 15 animal facilities in Uruguay, were collected between 2012 and 2013. Biochemical and molecular identification were performed to finally obtain 298 E. coli isolates. Partial amplification of adhesion-related genes was performed by polymerase chain reaction. RESULTS: The most prevalent gene was f17A (31.2%), followed by f17G(II), clpG, f17G(I) and f5 (25.8%, 17.5%, 3.7% and 0.7%, respectively). All genes were present in diarrheic and healthy animals except f5 and f17G(I); these genes were present only in affected calves, although in low numbers. CONCLUSIONS: This is the first report of the presence of F5, F17, and CS31A genes in E. coli strains from NCD cases in Uruguay. Prevalence values of the genes, except f5, were in accordance with regional findings. It is expected that further characterization of locally transmitted strains will contribute to control a problem of regional and international magnitude.

Identification of Leukotoxin and other vaccine candidate proteins in a Mannheimia haemolytica commercial antigen.

Bovine Respiratory Disease is the most costly disease that affects beef and dairy cattle industry. Its etiology is multifactorial, arising from predisposing environmental stress conditions as well as the action of several different respiratory pathogens. This situation has hindered the development of effective control strategies. Although different type of vaccines are available, many currently marketed vaccines are based on inactivated cultures of the main viral and bacterial agents involved in this pathology. The molecular composition of commercial veterinary vaccines is a critical issue. The present work aims to define at the proteomic level the most relevant valence of a line of commercial respiratory vaccines widely used in Central and South America. Since Mannheimia haemolytica is responsible for most of the disease associated morbid-mortality, we focused on the main proteins secreted by this pathogen, in particular Leukotoxin A, its main virulence factor. By Western blot analysis and mass spectrometry, Leukotoxin A was identified as a major component of M. haemolytica culture supernatants. We also identified other ten M. haemolytica proteins, including outer membrane proteins, periplasmic transmembrane solute transporters and iron binding proteins, which are relevant to achieve protective immunity against the pathogen. This work allowed a detailed molecular characterization of this vaccine component, providing evidence of its quality and efficacy. Furthermore, our results contributed to the identification of several proteins of interest as subunit vaccine candidates.