The genus Chaetomium fungi are considered to be a rich source of novel and bioactive secondary metabolites of great importance. Up till now, a variety of more than 200 secondary metabolites belonging to diverse structural types of chaetoglobosins, epipolythiodioxopiperazines, azaphilones, xanthones, anthraquinones, chromones, depsidones, terpenoids, and steroids have been discovered. Most of these fungal metabolites exhibited antitumor, cytotoxic, antimalarial, enzyme inhibitory, antibiotic, and other activities. This review covers the extraction, structure elucidation, structural diversity, and biological activities of natural products isolated from about 30 fungi associated with marine- and terrestrial- origins, and highlights some bioactive compounds as well as their mechanisms of action and structure-activity relationships.

Porcine reproductive and respiratory syndrome (PRRS) caused by the PRRS virus (PRRSV) is an important swine disease worldwide. PRRSV has a limited tropism for certain cells, which may at least in part be attributed to the expression of the necessary cellular molecules serving as the virus receptors or factors on host cells for virus binding or entry. However, these molecules conferring PRRSV infection have not been fully characterized. Here we show the identification of non-muscle myosin heavy chain 9 (MYH9) as an essential factor for PRRSV infection using the anti-idiotypic antibody specific to the PRRSV glycoprotein GP5. MYH9 physically interacts with the PRRSV GP5 protein via its C-terminal domain and confers susceptibility of cells to PRRSV infection. These findings indicate that MYH9 is an essential factor for PRRSV infection and provide new insights into PRRSV-host interactions and viral entry, potentially facilitating development of control strategies for this important swine disease.

Here we report the rescue of a recombinant porcine reproductive and respiratory syndrome virus (PRRSV) carrying an enhanced green fluorescent protein (EGFP) reporter gene as a separate transcription unit. A copy of the transcription regulatory sequence for ORF6 (TRS6) was inserted between the N protein and 3′-UTR to drive the transcription of the EGFP gene and yield a general purpose expression vector. Successful recovery of PRRSV was obtained using an RNA polymerase II promoter to drive transcription of the full-length virus genome, which was assembled in a bacterial artificial chromosome (BAC). The recombinant virus showed growth replication characteristics similar to those of the wild-type virus in the infected cells. In addition, the recombinant virus stably expressed EGFP for at least 10 passages. EGFP expression was detected at approximately 10 h post infection by live-cell imaging to follow the virus spread in real time and the infection of neighbouring cells occurred predominantly through cell-to-cell-contact. Finally, the recombinant virus generated was found to be an excellent tool for neutralising antibodies and antiviral compound screening. The newly established reverse genetics system for PRRSV could be a useful tool not only to monitor virus spread and screen for neutralising antibodies and antiviral compounds, but also for fundamental research on the biology of the virus.

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P orcine reproductive and respiratory syndrome virus (PRRSV) is one of the most economically important viruses affecting the swine industry worldwide, resulting in significant economic losses each year (1-3). PRRSV is a small, enveloped, linear, single positive-stranded RNA virus and a member of the order Nidovirales, family Arteriviridae (4). Current vaccination strategies cannot effectively control PRRSV infection because of the high antigenic heterogeneity (5, 6), the replication in and destruction of lung alveolar macrophages (7-9), and the observed antibody-dependent enhancement of PRRSV (10, 11). Therefore, it is imperative to study PRRSV pathogenesis mechanisms so that more effective control measures can be developed.Heme oxygenase-1 (HO-1) is the rate-limiting enzyme of heme degradation, and it functions to catabolize free heme into biliverdin, carbon monoxide, and iron. HO-1 and its end products have antioxidant, anti-inflammatory, and antiviral properties, and it is known to be a pivotal cytoprotective enzyme (12). Upregulation of HO-1 expression suppresses replication of a number of viruses, including hepatitis C virus (HCV), HIV-1, hepatitis B virus (HBV), and influenza virus (13-17). Our previous work showed that PRRSV significantly downregulates HO-1

Microtubule-associated protein tau is considered to play roles in many neurodegenerative diseases including some transmissible spongiform encephalopathies. To address the possible molecular linkage of prion protein (PrP) and tau, a GST-fusion segment of human tau covering the three-repeat region and various PrP segments was used in the tests of GST pull-down and immunoprecipitation. We found tau protein interacted with various style prion proteins such as native prion protein (PrPc) or protease-resistant isoform (PrPSc). Co-localization signals of tau and PrP were found in the CHO cell tranfected with both PrP and tau gene. The domain of interaction with tau was located at N-terminal of PrP (residues 23 to 91). The evidence of molecular interactions between PrP and tau protein highlights a potential role of tau in the biological function of PrP and the pathogenesis of TSEs.

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