Kinetics and role of antibodies against intimin β in colostrum and in serum from goat kids and longitudinal study of attaching and effacing Escherichia coli in goat kids

The presence of antibodies to the intimin β-binding region (Int280-β) of attaching and effacing Escherichia coli (AEEC) in serum from 20 goat kids from 2 herds, as well as in goat colostrum, was investigated by enzyme-linked immunosorbent assay. In addition, the onset and subsequent pattern of shedding of AEEC from the same goat kids over a 6-mo period was investigated. All the colostrum and serum samples tested contained antibodies against Int280-β. The association between the antibody titer and the isolation of AEEC suggests that antibodies to intimin β do not prevent colonization of the intestine by AEEC in goat kids. The AEEC were generally shed only transiently. Most AEEC isolated from the kids belonged to serogroup O26. Three isolates belonged to serogroup O157. These data show that goat kids may be a reservoir of AEEC that are potentially pathogenic for humans.     

Multivariate approach for young bull selection from a performance test using multiple traits of economic importance

This study used multivariate statistics to identify clusters of animals with similar expected progeny difference (EPD) and also identify leading traits that discriminate between bulls. Various linear selection indices based on specific selection criteria were proposed. Records were collected from 880 young Nelore bulls submitted to performance testing in central Brazil between 2001 and 2012. Pre-weaning average daily gain and weights at 210 days with direct and maternal effects were used in the analysis, in addition to post-weaning weight, scrotal circumference at 365 and 450 days, carcass finish and rib eye area. EPDs were classified into three groups, and the EPD means of two of these groups stood out and were considered important based on principal component analysis that associated higher values of direct EPD of weights, average daily weight gain and scrotal circumference. The EPDs for weight at 210, 365 and 450 days, pre- and post-weaning daily gain and scrotal circumference at 365 and 450 days were major causes of variation. Each linear selection index proposed (SI₁, SI₂, SI₃, SI₄ and SI₅) defined a specific approach meaning that a different selection index should be used depending on breeding goals and selection criteria.     

Transmission electron microscopy for characterization of acrosomal damage after Percoll gradient centrifugation of cryopreserved bovine spermatozoa

The objective of this study was to characterize acrosomal ultrastructure following discontinuous Percoll gradient centrifugation of cryopreserved bovine sperm. Semen was collected from six bulls of different breeds and three ejaculates per bull were evaluated. Frozen semen samples were thawed and the acrosomal region of sperm cells was evaluated by transmission electron microscopy (TEM) before (n = 18) and after (n = 18) Percoll centrifugation. The evaluation of 20 sperm heads from each of the 36 samples analyzed ensured that a large number of cells were investigated. The data were subjected to analysis of variance at a level of significance of 5%. Percoll centrifugation reduced the percentage of sperm exhibiting normal acrosomes (from 61.77 to 30.24%), reduced the percentage of sperm presenting atypical acrosome reactions (from 28.38 to 4.84%) and increased the percentage of sperm exhibiting damage in the acrosome (from 6.14 to 64.26%). The percentage of sperm with typical acrosome reactions was not significantly different before (3.70%) and after (0.67%) centrifugation. TEM distinguished four different types of acrosomal status and enabled ultrastructural characterization of acrosomal injuries. The percentage of sperm exhibiting normal acrosomes decreased and damage in the acrosome was the most frequent acrosomal injury with the Percoll gradient centrifugation protocol utilized.     

Cloning, characterization and diagnostic performance of the salivary lipocalin protein TSGP1 from Ornithodoros moubata

The argasid tick Ornithodoros moubata is distributed throughout South and East Africa and Madagascar, where it colonizes wild and domestic habitats and feeds on warthogs, domestic swine, and humans. This argasid transmits the spirochete Borrelia duttonii, causing East African tick-borne relapsing fever in humans, and the African swine fever virus, which causes a highly lethal haemorrhagic disease in pigs. Tick surveillance and the elimination of O. moubata from synanthropic environments (human dwellings and pigsties) would facilitate the control and prevention of these two diseases. Since direct surveillance methods are impractical in this context, the development of an indirect method for the detection of specific antibodies against tick salivary proteins in samples taken from animal or human hosts living in the area under study would provide a more convenient surveillance and diagnostic tool. Previous work has indicated that the 20A1 salivary antigen of O. moubata could be an optimal candidate for the development of a specific serological test and identified it as an orthologue of the Ornithodoros savignyi TSGP1 lipocalin. The objectives of the present work were to clone, sequence, and molecularly characterize the O. moubata TSGP1, as well as its production as a recombinant protein in order to assess its usefulness as a diagnostic antigen in an ELISA test for tick surveillance. Our results show that O. moubata TSGP1 (OmTSGP1) conserves the tertiary structure of lipocalins and contains the biogenic amine-binding motif. We also show that OmTSGP1 shares 65% sequence identity with the O. savignyi TSGP1, demonstrating that they represent orthologous proteins and suggesting they share identical function as biogenic amine scavengers. A recombinant form of OmTSGP1 was produced, showing 100% sensitivity and 99.4% specificity in an ELISA test for the detection of anti-O. moubata antibodies in pig sera. This recombinant antigen represents a promising epidemiological tool for O. moubata surveillance that may help to implement control measures against O. moubata-borne diseases.     

Risk-based surveillance for avian influenza control along poultry market chains in South China: The value of social network analysis

Over the past two decades, the poultry sector in China went through a phase of tremendous growth as well as rapid intensification and concentration. Highly pathogenic avian influenza virus (HPAIV) subtype H5N1 was first detected in 1996 in Guangdong province, South China and started spreading throughout Asia in early 2004. Since then, control of the disease in China has relied heavily on wide-scale preventive vaccination combined with movement control, quarantine and stamping out. This strategy has been successful in drastically reducing the number of outbreaks during the past 5years. However, HPAIV H5N1 is still circulating and is regularly isolated in traditional live bird markets (LBMs) where viral infection can persist, which represent a public health hazard for people visiting them. The use of social network analysis in combination with epidemiological surveillance in South China has identified areas where the success of current strategies for HPAI control in the poultry production sector may benefit from better knowledge of poultry trading patterns and the LBM network configuration as well as their capacity for maintaining HPAIV H5N1 infection. We produced a set of LBM network maps and estimated the associated risk of HPAIV H5N1 within LBMs and along poultry market chains, providing new insights into how live poultry trade and infection are intertwined. More specifically, our study provides evidence that several biosecurity factors such as daily cage cleaning, daily cage disinfection or manure processing contribute to a reduction in HPAIV H5N1 presence in LBMs. Of significant importance is that the results of our study also show the association between social network indicators and the presence of HPAIV H5N1 in specific network configurations such as the one represented by the counties of origin of the birds traded in LBMs. This new information could be used to develop more targeted and effective control interventions.     

Serotype distribution and production of muramidase-released protein, extracellular factor and suilysin by field strains of Streptococcus suis isolated in the United States

Streptococcus suis is an important swine pathogen and a zoonotic agent. Differences in virulence have been noted among the 33 described serotypes, serotype 2 being considered the most virulent. In this study, we aimed at assessing the serotype distribution and the production of virulence-associated markers by strains recovered from diseased pigs in the United States (U.S.). Results showed that among the 100 strains evaluated, serotype 3 (20% of the isolates) and serotype 2 (17%) were the most prevalent. We then investigated the presence in these isolates of the genes sly, epf and mrp, encoding the virulence-associated markers suilysin (SLY), extracellular factor (EF) and muramidase-released (MRP) protein, respectively. The effective production of the markers by the strains was also verified. Results showed that the presence of the gene did not always correlate with actual expression of the respective protein. In the case of MRP, this was due, in most cases, to frameshift mutations at the 5′ end of the gene resulting in premature stop codons. The most prevalent phenotypes among U.S. strains were MRP⁺EF⁻SLY⁻ (40%) and MRP⁻EF⁻SLY⁺ (35%). Serotype distribution greatly differed from that reported in several European countries, as did the production of virulence markers, particularly for serotype 2. On the other hand, our results for the U.S. S. suis isolates are similar to those reported for Canadian strains, suggesting a common status in North America.     

The horizontal barrier effect of stems on the foraging behaviour of cattle grazing five tropical grasses

The rate of nutrient intake (RNI) is a primary determinant of animal performance in grazing cattle and depends on both diet quality and instantaneous intake rate (IIR). In turn, diet quality and IIR are a function of the foraging behaviour of the animal (selectivity, bite mass and bite rate) and the characteristics of the sward. In this study we evaluated the effect of the stem density and the tensile resistance of stems on the foraging behaviour of cattle grazing tropical pasture species. The methodology involved the use of small sown microswards offered to tethered cattle. The experiment consisted of a factorial combination of five tropical grasses [Bothriochloa pertusa (Bp), Chloris barbata (Cb), Chloris gayana (Cg), Cynodon dactylon (Cd) and Heteropogon contortus (Hc)] and three stem densities (0, 400 and 800 stems m^− 2). Bp and Cd had stems of significantly lower tensile resistance (19 and 15 N respectively) (Group 1) than those of Cb, Cg and Hc (110, 211 and 167 N respectively) (Group 2). The steers avoided stems of Group 2 and thus, reduced bite area, bite mass, IIR and RNI as stem density increased. However, the animals did not avoid stems of Group 1 and there was no effect of stem density on any of the foraging behaviour variables when cattle grazed species in Group 1. These results confirm that RNI and plant part selection is closely associated with the tensile resistance of the stem.     

Purification and characterization of a 45-kDa concealed antigen from the midgut membranes of Ornithodoros erraticus that induces lethal anti-tick immune responses in pigs

Ornithodoros erraticus is an argasid tick that can transmit severe diseases such as human relapsing fever and African swine fever. In the search for a vaccine against this parasite, a crude extract of tick midgut membranes (GME) was obtained that in pigs and mice induced a protective response able to kill up to 80% of the nymphs in the first 72 h post-feeding and to reduce the fecundity of females by more than 50%. To identify the protective antigens, the GME was subjected to successive biochemical fractionations and the resulting simpler protein fractions were inoculated in pigs. A 45-kDa antigen, the so-called Oe45, was detected, purified and demonstrated to be responsible for the protection induced by the GME. Oe45 seems to be a membrane protein that is presumably expressed on the luminal membrane of midgut epithelial cells. Oe45 consists of at least two differently charged bands (cationic and neutral), which show antigenic cross-reactivity. The possibility that these bands might be different isoforms of the same protein is discussed. Although Oe45 is constitutively expressed at low levels throughout the trophogonic cycle, its expression is up-regulated by the ingestion of blood, as suggested by the higher levels observed between 6 and 72 h post-feeding.     

Epidemiologic investigation of an outbreak of goose parvovirus infection in Sweden

An outbreak of goose parvovirus (GPV) infection on a Swedish goose farm in the spring of 2004 increased the mortality rates from 2% in the early unaffected hatches to 90% and 99% respectively in the two hatches following virus introduction and 40% in goslings hatched later in the same breeding season. In this paper we describe the clinical observations, diagnostic procedures, and epidemiologic investigation carried out to elucidate the source of the infection. The diagnosis was confirmed by serology, virus isolation, and sequence analysis of a 493-bp-long fragment of the VP1 gene. Phylogenetically the causative virus was closely related to pathogenic GPV strains isolated in 2003 and 2004 from Poland and the United Kingdom, respectively. The Swedish isolate exhibited less homology with pathogenic strains from Hungary and Asia and with attenuated vaccine strains. The epidemiologic investigation showed that the virus was first introduced to a contract farm (farm A) and then was transferred with newly hatched goslings to the farm that had submitted the birds for necropsy (index farm). The exact time and source of the virus introduction to farm A could not be determined with absolute certainty. Possible sources of the infection included backyard goose eggs that had been delivered to farm A for subcontract incubation and hatching, wild geese that frequented the flock of breeding geese on pasture on farm A, and a clutch of Canada goose eggs (Branta canadensis) that had been produced by wild geese and was hatched in the same machine as the eggs produced by farm A.     

Canine bartonellosis: serological and molecular prevalence in Brazil and evidence of co-infection with Bartonella henselae and Bartonella vinsonii subsp. berkhoffii

The purpose of this study was to determine the serological and molecular prevalence of Bartonella spp. infection in a sick dog population from Brazil. At the S?o Paulo State University Veterinary Teaching Hospital in Botucatu, 198 consecutive dogs with clinicopathological abnormalities consistent with tick-borne infections were sampled. Antibodies to Bartonella henselae and Bartonella vinsonii subsp. berkhoffii were detected in 2.0% (4/197) and 1.5% (3/197) of the dogs, respectively. Using 16S-23S rRNA intergenic transcribed spacer (ITS) primers, Bartonella DNA was amplified from only 1/198 blood samples. Bartonella seroreactive and/or PCR positive blood samples (n=8) were inoculated into a liquid pre-enrichment growth medium (BAPGM) and subsequently sub-inoculated onto BAPGM/blood-agar plates. PCR targeting the ITS region, pap31 and rpoB genes amplified B. henselae from the blood and/or isolates of the PCR positive dog (ITS: DQ346666; pap31 gene: DQ351240; rpoB: EF196806). B. henselae and B. vinsonii subsp. berkhoffii (pap31: DQ906160; rpoB: EF196805) co-infection was found in one of the B. vinsonii subsp. berkhoffii seroreactive dogs. We conclude that dogs in this study population were infrequently exposed to or infected with a Bartonella species. The B. henselae and B. vinsonii subsp. berkhoffii strains identified in this study are genetically similar to strains isolated from septicemic cats, dogs, coyotes and human beings from other parts of the world. To our knowledge, these isolates provide the first Brazilian DNA sequences from these Bartonella species and the first evidence of Bartonella co-infection in dogs.