A gene coding for a thermostable esterase was isolated by functional screening of Escherichia coli cells that had been transformed with fosmid environmental DNA libraries constructed with metagenomes from thermal environmental samples. The gene conferring esterase activity on E. coli grown on tributyrin agar was composed of 936 bp, corresponding to 311 amino acid residues with a molecular mass of 34 kDa. The enzyme showed significant amino acid similarity (64%) to the enzyme from a hyperthermophilic archaeon, Pyrobaculum calidifontis . An amino acid sequence comparison with other esterases and lipases revealed that the enzyme should be classified as a new member of the hormone-sensitive lipase family. The recombinant esterase that was overexpressed and purified from E. coli was active above 30°C up to 95°C and had a high thermal stability. It displayed a high degree of activity in a pH range of 5.5 to 7.5, with an optimal pH of approximately 6.0. The best substrate for the enzyme among the p -nitrophenyl esters (C ₄ to C ₁₆ ) examined was p -nitrophenyl caproate (C ₆ ), and no lipolytic activity was observed with esters containing an acyl chain length of longer than 10 carbon atoms, indicating that the enzyme is an esterase and not a lipase.

Severe acute respiratory syndrome coronavirus (SARS-CoV) is the etiological agent of a newly emerged disease SARS. The SARS-CoV nucleocapsid (N) protein is one of the most abundant structural proteins and serves as a diagnostic marker for accurate and sensitive detection of the virus. Using a SELEX (systematic evolution of ligand by exponential enrichment) procedure and recombinant N protein, we selected a high-affinity RNA aptamer capable of binding to N protein with a dissociation constant of 1.65 nM. Electrophoretic mobility shift assays and RNA competition experiments showed that the selected aptamer recognized selectively the C-terminal region of N protein with high specificity. Using a chemiluminescence immunosorbent assay and a nanoarray aptamer chip with the selected aptamer as an antigen-capturing agent, we could sensitively detect N protein at a concentration as low as 2 pg/ml. These aptamer–antibody hybrid immunoassays may be useful for rapid, sensitive detection ofSARS-CoV N protein.

Viruses alter cellular physiology and function to establish cellular environment conducive for viral proliferation. Viral immune evasion is an essential aspect of viral persistence and proliferation. The multifaceted mitochondria play a central role in many cellular events such as metabolism, bioenergetics, cell death, and innate immune signaling. Recent findings accentuate that viruses regulate mitochondrial function and dynamics to facilitate viral proliferation. In this review, we will discuss how viruses exploit mitochondrial dynamics to modulate mitochondria-mediated antiviral innate immune response during infection. This review will provide new insight to understanding the virus-mediated alteration of mitochondrial dynamics and functions to perturb host antiviral immune signaling.

Immunosuppression associated with ovarian cancer (OC) and resultant peritoneal carcinomatosis (PC) hampers the efficacy of many promising treatment options, including immunotherapies. It is hypothesized that oncolytic virus-based therapies can simultaneously kill OC and mitigate immunosuppression. Currently, reovirus-based anticancer therapy is undergoing phase I/II clinical trials for the treatment of OC. Hence, this study was focused on characterizing the effects of reovirus therapy on OC and associated immune microenvironment. Our data shows that reovirus efficiently killed OC cells and induced higher expression of the molecules involved in antigen presentation including major histocompatibility complex (MHC) class I, β2-microglobulin (β2M), TAP-1, and TAP-2. In addition, in the presence of reovirus, dendritic cells (DCs) overcame the OC-mediated phenotypic suppression and successfully stimulated tumor-specific CD8+ T cells. In animal studies, reovirus targeted local and distal OC, alleviated the severity of PC and significantly prolonged survival. These therapeutic effects were accompanied by decreased frequency of suppressive cells, e.g., Gr1.1+, CD11b+ myeloid derived suppressor cells (MDSCs), and CD4+, CD25+, FOXP3+ Tregs, tumor-infiltration of CD3+ cells and higher expression of Th1 cytokines. Finally, reovirus therapy during early stages of OC also resulted in the postponement of PC development. This report elucidates timely information on a therapeutic approach that can target OC through clinically desired multifaceted mechanisms to better the outcomes.