Genomic differences between type strain PG1 and field strains of Mycoplasma mycoides subsp. mycoides small-colony type

The recently accomplished complete genomic sequence analysis of the type strain PG1 of Mycoplasma mycoides subsp. mycoides small-colony type revealed four large repeated segments of 24, 13, 12, and 8 kb that are flanked by insertion sequence (IS) elements. Genetic analysis of type strain PG1 and African, European, and Australian field and vaccine strains revealed that the 24-kb genetic locus is repeated only in PG1 and not in other M. mycoides subsp. mycoides SC strains. In contrast, the 13-kb genetic locus was found duplicated in some strains originating from Africa and Australia but not in strains that were isolated from the European outbreaks. The 12- and 8-kb genetic loci were found in two and three copies, respectively, in all 28 strains analyzed. The flanking IS elements are assumed to lead to these tandem duplications, thus contributing to genomic plasticity. This aspect must be considered when designing novel diagnostic approaches and recombinant vaccines.

Clinical signs of deformed wing virus infection are predictive markers for honey bee colony losses.

The ectoparasitic mite Varroa destructor acting as a virus vector constitutes a central mechanism for losses of managed honey bee, Apis mellifera, colonies. This creates demand for an easy, accurate and cheap diagnostic tool to estimate the impact of viruliferous mites in the field. Here we evaluated whether the clinical signs of the ubiquitous and mite-transmitted deformed wing virus (DWV) can be predictive markers of winter losses. In fall and winter 2007/2008, A.m. carnica workers with apparent wing deformities were counted daily in traps installed on 29 queenright colonies. The data show that colonies which later died had a significantly higher proportion of workers with wing deformities than did those which survived. There was a significant positive correlation between V. destructor infestation levels and the number of workers displaying DWV clinical signs, further supporting the mite's impact on virus infections at the colony level. A logistic regression model suggests that colony size, the number of workers with wing deformities and V. destructor infestation levels constitute predictive markers for winter colony losses in this order of importance and ease of evaluation.

A naturally occurring prfA truncation in a Listeria monocytogenes field strain contributes to reduced replication and cell-to-cell spread

Listeria (L.) monocytogenes is an environmental bacterium that may become an intracellular pathogen upon ingestion to cause gastroenteritis, septicaemia, abortions, and/or fatal infections of the central nervous system. We here describe a L. monocytogenes field strain (JF5171) isolated from a bovine placenta in the context of abortion, which exhibited attenuation in bovine brain-slice cultures. The whole genome of strain JF5171 was sequenced, and the invasion, replication, and intercellular spread of JF5171 were further analyzed by quantification of colony forming units and immunofluorescence studies. Phospholipase and hemolysis activity of JF5171 were also quantified along with transcription levels of actA, hly and prfA. The data obtained were compared to those of the widely used L. monocytogenes reference strain, EGD-e. JF5171 exhibited reduced replication and lower levels of phospholipase and hemolysis activity. Invasion and cell-to-cell spread was strongly decreased compared to EGD-e, and actin polymerization was absent. A frame shift deletion was identified in the JF5171 coding region of the major regulator for virulence, prfA. This resulted in a truncated C-terminus sequence (WEN* vs. WGKLN*). In addition, a point mutation resulted in a lysine to arginine substitution at amino acid position 197. Complementation with prfA from EGD-e and with (EGD-e) prfA-K197N increased the replication and spread efficiency of JF5171. In contrast, complementation with the truncated version of prfA had no effect. Taken together, these results suggest that the truncated C-terminus of prfA considerably contributes to the strongly attenuated phenotype observed in vitro.

Outbreak of severe foot rot associated with benign Dichelobacter nodosus in an Alpine ibex colony in the Swiss Prealps.

An outbreak of foot rot occurred in the ibex colony "Vanil Noir" in Switzerland from May to December 2014. This article describes field observations and the analyses carried out on the limbs of 3 animals submitted for postmortem examination. Disease signs observed in the field included lameness, poor body condition and overgrown hooves. Macroscopic examination of selected limbs revealed severe lesions in all of them, including interdigital inflammation with ulceration and malodorous exudation. Histological changes were consistent with chronic laminitis with bone resorption, which was not detected at radiographical examination. Grocott-positive organisms compatible with Dichelobacternodosus were detected in the lesions. Samples collected from the lesions were positive by polymerase chain reaction for benign D. nodosus, which is typically associated with only mild lesions in domestic sheep. Whether D. nodosus is endemic in the colony or had previously been transmitted from sympatric domestic livestock is unclear. The unusual warm and humid weather conditions in 2014 may well have contributed to the outbreak.

Effects, but no interactions, of ubiquitous pesticide and parasite stressors on honey bee (Apis mellifera) lifespan and behaviour in a colony environment

Interactions between pesticides and parasites are believed to be responsible for increased mortality of honey bee (Apis mellifera) colonies in the northern hemisphere. Previous efforts have employed experimental approaches using small groups under laboratory conditions to investigate influence of these stressors on honey bee physiology and behaviour, although both the colony level and field conditions play a key role for eusocial honey bees. Here, we challenged honey bee workers under in vivo colony conditions with sublethal doses of the neonicotinoid thiacloprid, the miticide tau-fluvalinate and the endoparasite Nosema ceranae, to investigate potential effects on longevity and behaviour using observation hives. In contrast to previous laboratory studies, our results do not suggest interactions among stressors, but rather lone effects of pesticides and the parasite on mortality and behaviour, respectively. These effects appear to be weak due to different outcomes at the two study sites, thereby suggesting that the role of thiacloprid, tau-fluvalinate and N. ceranae and interactions among them may have been overemphasized. In the future, investigations into the effects of honey bee stressors should prioritize the use of colonies maintained under a variety of environmental conditions in order to obtain more biologically relevant data.