Porcine reproductive and respiratory syndrome (PRRS) is a severe viral disease in pigs, causing great economic losses worldwide each year. The causative agent of the disease, PRRS virus (PRRSV), is a member of the family Arteriviridae. Here we report our investigation of the unparalleled large-scale outbreaks of an originally unknown, but so-called “high fever” disease in China in 2006 with the essence of PRRS, which spread to more than 10 provinces (autonomous cities or regions) and affected over 2,000,000 pigs with about 400,000 fatal cases. Different from the typical PRRS, numerous adult sows were also infected by the “high fever” disease. This atypical PRRS pandemic was initially identified as a hog cholera-like disease manifesting neurological symptoms (e.g., shivering), high fever (40–42°C), erythematous blanching rash, etc. Autopsies combined with immunological analyses clearly showed that multiple organs were infected by highly pathogenic PRRSVs with severe pathological changes observed. Whole-genome analysis of the isolated viruses revealed that these PRRSV isolates are grouped into Type II and are highly homologous to HB-1, a Chinese strain of PRRSV (96.5% nucleotide identity). More importantly, we observed a unique molecular hallmark in these viral isolates, namely a discontinuous deletion of 30 amino acids in nonstructural protein 2 (NSP2). Taken together, this is the first comprehensive report documenting the 2006 epidemic of atypical PRRS outbreak in China and identifying the 30 amino-acid deletion in NSP2, a novel determining factor for virulence which may be implicated in the high pathogenicity of PRRSV, and will stimulate further study by using the infectious cDNA clone technique.

The Bacillus subtilis protein YtvA is related to plant phototropins in that it senses UVA-blue-light by means of the flavin binding LOV domain, linked to a nucleotide-binding STAS domain. The structural basis for interdomain interactions and functional regulation are not known. Here we report the conformational analysis of three YtvA constructs, by means of size exclusion chromatography, circular dichroism (CD) and molecular docking simulations. The isolated YtvA-LOV domain (YLOV, aa 25-126) has a strong tendency to dimerize, prevented in full-length YtvA, but still observed in YLOV carrying the N-terminal extension (N-YLOV, aa 1-126). The analysis of CD data shows that both the N-terminal cap and the linker region (aa 127-147) between the LOV and the STAS domain are helical and that the central beta-scaffold is distorted in the LOV domains dimers. The involvement of the central beta-scaffold in dimerization is supported by docking simulation of the YLOV dimer and the importance of this region is highlighted by light-induced conformational changes, emerging from the CD data analysis. In YtvA, the beta-strand fraction is notably less distorted and distinct light-driven changes in the loops/turn fraction are detected. The data uncover a common surface for LOV-LOV and intraprotein interaction, involving the central beta-scaffold, and offer hints to investigate the molecular basis of light-activation and regulation in LOV proteins.

Porcine reproductive and respiratory syndrome (PRRS) has a major negative economic impact on the swine industry worldwide. During the investigation of PRRS virus (PRRSV) in mainland China, European genotype (EU, type 1) PRRSV isolates were detected in swine herds both with and without clinical symptoms. Two complete genome sequences for Chinese type 1 PRRSV isolates were identified from viruses isolated from lung tissue and sera. The two viruses, designated BJEU06-1 and NMEU09-1, produced cytopathic effects in primary porcine alveolar macrophages but not in Marc-145 cells, and had a mean diameter of 55 nm, as measured by transmission electron microscopy . Comparative sequence analysis revealed that they shared 87.0-91.5 % and 58.0-58.2 % identity with the EU and North American genotype (NA, type 2) prototypic strains LV and VR-2332, respectively. Remarkably, these isolates, characterized by concomitant deletions within non-structural protein 2 (Nsp2) and ORF3 hypervariable regions, have never been described. Phylogenetic trees showed that all of the novel Chinese isolates of European genotype are in the pan-European subtype 1 that is predominant in Europe. However, they evolved from different ancestors. These novel viruses are predicted to be products of the divergent evolution of ancestor PRRSV isolates introduced from Europe. This is the first report of type 1 PRRSV wild isolates being in mainland China. Our findings confirm that the Chinese type 1 PRRSV isolates originated from diverse progenitors and the type 1 and type 2 PRRSV isolates, having different biological properties, have coexisted on the Chinese mainland for several years. INTRODUCTIONPorcine reproductive and respiratory syndrome (PRRS) emerged in North America in 1987(Keffaber, 1989 and in western Europe in 1990(Wensvoort et al., 1991, and is now one of the most economically significant swine diseases worldwide. The aetiological agent of the disease, PRRS virus (PRRSV), was isolated in the Netherlands in 1991 (Wensvoort et al., 1991) and subsequently in the United States (Collins et al., 1992). Even though the PRRSV isolates on the two continents emerged almost simultaneously, caused similar disease symptoms and shared the same virion morphology, European and North American PRRSV isolates were antigenically and genetically very different (Forsberg et al., 2002;Ropp et al., 2004;Rossow, 1998). Thus, two genotypes of PRRSV have been defined: the European (EU genotype, type 1) and the North American (NA genotype, type 2) strains (Meng et al., 1995;Nelsen et al., 1999). Originally, EU PRRSV was restricted to Europe, while NA PRRSV was restricted to North America and Asia. Nowadays however, coexistence of the two genotypes has been identified in Europe, North America and Asia, complicating PRRSV differential diagnosis, disease prevention and control (Amonsin et al., 2009; Balka et al., 2008;Bøtner et al., 1997;Dewey et al., 2000; Fang et al., 2007;Kim et al., 2009b;Ropp et al., 2004; Thanawongnuwech et al., 2004;van Vugt et al., 2001).PRRSV is an en...

Potassium channels participate in many critical biological functions and play important roles in a variety of diseases. In recent years, many significant discoveries have been made which motivate us to review these achievements. The focus of our review is mainly on three aspects. Firstly, we try to summarize the latest developments in structure determinants and regulation mechanism of all types of potassium channels. Secondly, we review some diseases induced by or related to these channels. Thirdly, both qualitative and quantitative approaches are utilized to analyze structural features of modulators of potassium channels. Our analyses further prove that modulators possess some certain natural-product scaffolds. And pharmacokinetic parameters are important properties for organic molecules. Besides, with in silico methods, some features that can be used to differentiate modulators are derived. There is no doubt that all these studies on potassium channels as possible pharmaceutical targets will facilitate future translational research. All the strategies developed in this review could be extended to studies on other ion channels and proteins as well.

The open reading frame PSPTO2896 from the plant pathogen Pseudomonas syringae pv. tomato encodes a protein of 534 amino acids showing all salient features of a blue light-driven two-component system. The N-terminal LOV (light, oxygen, voltage) domain, potentially binding a flavin chromophore, is followed by a histidine kinase (HK) motif and a response regulator (RR). The full-length protein (PST-LOV) and, separately, the RR and the LOV+HK part (PST-LOV(DeltaRR)) were heterologously expressed and functionally characterized. The two LOV proteins showed typical LOV-like spectra and photochemical reactions, with the blue light-driven, reversible formation of a covalent flavin-cysteine bond. The fluorescence changes in the lit state of full-length PST-LOV, but not in PST-LOV(DeltaRR), indicating a direct interaction between the LOV core and the RR module. Experiments performed with radioactive ATP uncover the light-driven kinase activity. For both PST-LOV and PST-LOV(DeltaRR), much more radioactivity is incorporated when the protein is in the lit state. Furthermore, addition of the RR domain to the fully phosphorylated PST-LOV(DeltaRR) leads to a very fast transfer of radioactivity, indicating a highly efficient HK activity and a tight interaction between PST-LOV(DeltaRR) and RR, possibly facilitated by the LOV core itself.