There have been increased reports of outbreaks of enteric redmouth disease (ERM) caused by Yersinia ruckeri in previously vaccinated salmonids in Europe, with some of these outbreaks being attributed to emergent non-motile, Tween 80-negative, biotype 2 isolates. To gain information about their likely origins and relationships, a geographically and temporally diverse collection of isolates were characterised by serotyping, biotyping, pulsed-field gel electrophoresis (PFGE) and outer membrane protein (OMP) profiling. A total of 44 pulsotypes were identified from 160 isolates by PFGE, using the restriction enzyme Not I. Serotype O1 isolates responsible for ERM in rainbow trout in both the US and Europe, and including biotype 2 isolates, represented a distinct subgroup of similar pulsotypes. Biotype 2 isolates, responsible for outbreaks of the disease in rainbow trout in the UK, Denmark and Spain, had different pulsotypes, suggesting that they represented different clones that may have emerged separately. Danish biotype 2 isolates recovered since 1995 were indistinguishable by PFGE from the dominant biotype 1 clone responsible for the majority of outbreaks in Denmark and the rest of mainland Europe. In contrast, US biotype 2 isolate YRNC10 had an identical pulsotype and OMP profile to UK biotype 2 isolates, suggesting that there had been exchange of these isolates between the UK and the US in the past. UK Atlantic salmon isolates were genetically and serologically diverse, with 12 distinct pulsotypes identified among 32 isolates.KEY WORDS: Yersinia ruckeri · Pulsed-field gel electrophoresis · PFGE · Enteric redmouth disease · ERM · Biotype · Emerging strain Resale or republication not permitted without written consent of the publisherDis Aquat Org 84: [25][26][27][28][29][30][31][32][33] 2009 monovalent killed whole cell commercial vaccines, generally based on the Hagerman type strain (Horne & Barnes 1999). However, reports of ERM vaccine breakdown have emerged in Europe and the USA, which are attributed to biotype 2 (Tween 80-negative, nonmotile) isolates of Y. ruckeri (Austin et al. 2003, Fouz et al. 2006, Arias et al. 2007. Biotype 2 isolates were first described as having caused the disease in UK rainbow trout by Davies & Frerichs (1989).Farmers have also reported increasing mortalities due to yersiniosis of UK Atlantic salmon Salmo salar (L.); however, there are limited published studies regarding yersiniosis of this species (Bullock et al. 1976, Bruno & Munro 1989. Nevertheless, farmed Atlantic salmon fry in the major production areas of Europe (Scotland, Ireland and Norway) and Chile are routinely vaccinated with commercial rainbow trout ERM vaccines or autologous preparations (Bravo & Midtlyng 2007, L. A. Laidler pers. comm.). In Chile alone, up to 140 million salmon yr -1 were vaccinated against yersiniosis between and 2003(Bravo & Midtlyng 2007.Yersinia ruckeri is a highly clonal and biochemically homogeneous species (Schill et al. 1984, Stevenson & Airdrie 1984, Daly et al. 1986, Pyle et al...

Biotype 2 (BT2) variants of the bacterium Yersinia ruckeri are an increasing disease problem in U.S. and European aquaculture and have been characterized as serovar 1 isolates that lack both peritrichous flagella and secreted phospholipase activity. The emergence of this biotype has been associated with an increased frequency of enteric redmouth disease (ERM) outbreaks in previously vaccinated salmonid fish. In this study, four independent specific natural mutations that cause the loss of both motility and secreted lipase activity were identified in BT2 strains from the United States, United Kingdom, and mainland Europe. Each of these was a unique mutation in either fliR, flhA, or flhB, all of which are genes predicted to encode essential components of the flagellar secretion apparatus. Our results demonstrate the existence of independent mutations leading to the BT2 phenotype; thus, this phenotype has emerged separately at least four times. In addition, BT2 strains from the United Kingdom were shown to have the same mutant allele found in U.S. BT2 strains, suggesting a common origin of this BT2 lineage. This differentiation of distinct BT2 lineages is of critical importance for the development and validation of alternative vaccines or other treatment strategies intended for the control of BT2 strains.

Abstract. We investigate the relative role of volcanic eruptions, El Niño-Southern Oscillation (ENSO), and the quasibiennial oscillation (QBO) in the quasi-decadal signal in the tropical stratosphere with regard to temperature and ozone commonly attributed to the 11 yr solar cycle. For this purpose, we perform transient simulations with the Whole Atmosphere Community Climate Model forced from 1960 to 2004 with an 11 yr solar cycle in irradiance and different combinations of other forcings. An improved multiple linear regression technique is used to diagnose the 11 yr solar signal in the simulations. One set of simulations includes all observed forcings, and is thereby aimed at closely reproducing observations. Three idealized sets exclude ENSO variability, volcanic aerosol forcing, and QBO in tropical stratospheric winds, respectively. Differences in the derived solar response in the tropical stratosphere in the four sets quantify the impact of ENSO, volcanic events and the QBO in attributing quasi-decadal changes to the solar cycle in the model simulations. The novel regression approach shows that most of the apparent solar-induced lower-stratospheric temperature and ozone increase diagnosed in the simulations with all observed forcings is due to two major volcanic eruptions (i.e., El Chichón in 1982 and Mt. Pinatubo in 1991). This is caused by the alignment of these eruptions with periods of high solar activity. While it is feasible to detect a robust solar signal in the middle and upper tropical stratosphere, this is not the case in the tropical lower stratosphere, at least in a 45 yr simulation. The present results suggest that in the tropical lower stratosphere, the portion of decadal variability that can be unambiguously linked to the solar cycle may be smaller than previously thought.

Several strains of Gram-pos bacilli)-shaped bacteria were cultured turbot, Scophthalmi North of Spai treptoc is. The a-hae olytic reptoc lS-lik( : identified b] physiological, biochemical and 16S rRNA sequence analysis as Streptococcus parauberis. T the First report of S. parauberis associated wit!