Thermus caliditerrae sp. nov., a novel thermophilic species isolated from a geothermal area.

Two thermophilic bacterial strains, designated YIM 77925(T) and YIM 77777, were isolated from two hot springs, one in the Hydrothermal Explosion (Shuirebaozhaqu) area and Frog Mouth Spring in Tengchong county, Yunnan province, south-western China. The taxonomic positions of the two isolates were investigated by a polyphasic approach. Cells of the two strains were Gram-stain-negative, aerobic and rod-shaped. They were able to grow at 50-70 °C, pH 6.0-8.0 and with a NaCl tolerance up to 0.5% (w/v). Colonies are circular, convex, non-transparent and produce yellow pigment. Phylogenetic analyses based on 16S rRNA gene sequences comparison clearly demonstrated that strains YIM 77925(T) and YIM 77777 represent members of the genus Thermus, and they also detected low-level similarities of 16S rRNA gene sequences (below 97%) compared with all other species in this genus. Their predominant menaquinone was MK-8. The genomic DNA G+C contents of strains YIM 77925(T) and YIM 77777 were 65.6 mol% and 67.2 mol%, respectively. Based on the results of physiological and biochemical tests and phylogenetic analyses, strains YIM 77925(T) and YIM 77777 could not be classified as representing any species of the genus Thermus with a validly published name. Thus the two strains are considered to represent a novel species of the genus Thermus, for which the name Thermus caliditerrae sp. nov. is proposed. The type strain is YIM 77925(T) ( = DSM 25901(T) = CCTCC 2012061(T)).

The 40 kDa Linear Polyethylenimine Inhibits Porcine Reproductive and Respiratory Syndrome Virus Infection by Blocking Its Attachment to Permissive Cells.

Porcine reproductive and respiratory syndrome (PRRS) is one of the most economically devastating infectious diseases in pigs worldwide. The causative agent is the PRRS virus (PRRSV). In this study, we explored polyethylenimine (PEI), a cationic polymer with different forms (linear or branched), to inhibit the replication of PRRSV. Our results demonstrate that the linear but not the 40 kDa branched PEI, or the 25 kDa linear PEI, were well tolerated in cultured cells and exhibited a broad-spectrum inhibition of heterogeneous PRRSV-2 isolates in both MARC-145 cells and primary porcine pulmonary alveolar macrophages (PAMs). Further analysis suggests that PEI could prevent the attachment of PRRSV virions to the susceptible cells. Notably, PEI had a minimal effect on PRRSV internalization in MARC-145 cells, whereas PEI promoted the internalization of PRRSV virions in PAMs, which suggests that these two types of cells might have different internalization processes of PRRSV virions. In conclusion, our data demonstrate that PEI could be used as a novel inhibitor against PRRSV.

Development and use of a biotinylated 3ABC recombinant protein in a solid-phase competitive ELISA for the detection of antibodies against foot-and-mouth disease virus.

A biotinylated 3ABC recombinant protein was developed and used in a competitive ELISA (cELISA) to detect foot-and-mouth disease virus (FMDV) antibodies in cattle, sheep and pigs. In this report, we describe the cloning and expression of 3ABC protein in Escherichia coli cells as fusion protein with 6xHis and biotin. This cELISA uses streptavidin to capture bacterially expressed and in vivo biotinylated 3ABC antigen. The antigen capture strategy provides a simple and reliable method, which does not require purification of recombinant antigen before the serological assay. An hyperimmune guinea pig antiserum produced against purified 6xHis-3ABC was used as competitor in the test. The potential use of this cELISA for the identification of antibodies induced by FMD virus infection from those induced by vaccination is discussed.