Cell-Extrinsic Priming Increases Permissiveness of CD4+ T Cells to Human Immunodeficiency Virus Infection by Increasing C-C Chemokine Receptor Type 5 Co-receptor Expression and Cellular Activation Status.

The chemokine receptor CCR5 is expressed on multiple cell types, including macrophages, dendritic cells, and T cells, and is the major co-receptor used during HIV transmission. Using a standard αCD3/CD28 stimulation protocol to render CD4+ T cells from PBMCs permissive to HIV infection, we discovered that the percentage of CCR5 T cells was significantly elevated in CD4+ T cells when stimulated in the presence of peripheral blood mononuclear cells (PBMCs) as compared to when stimulated as purified CD4+ T cells. This indicated that environmental factors unique to the T-PBMCs condition affect surface expression of CCR5 on CD4+ T cells.

Multiple Homozygous Variants in the STING-Encoding Gene in HIV Long-Term Nonprogressors.

Among HIV-infected individuals, long-term nonprogressor (LTNP) patients experience slow CD4 T cell decline and almost undetectable viral load for several years after primary acquisition of HIV. Type I IFN has been suggested to play a pathogenic role in HIV pathogenesis, and therefore diminished IFN responses may underlie the LTNP phenotype. In this study, we examined the presence and possible immunological role of multiple homozygous single-nucleotide polymorphisms in the stimulator of IFN genes (STING) encoding gene involved in IFN induction and T cell proliferation in HIV LTNP patients.

Mucosal stromal fibroblasts markedly enhance HIV infection of CD4+ T cells.

Understanding early events of HIV transmission within mucosal tissues is vital for developing effective prevention strategies. Here, we report that primary stromal fibroblasts isolated from endometrium, cervix, foreskin, male urethra, and intestines significantly increase HIV infection of CD4+ T cells-by up to 37-fold for R5-tropic HIV and 100-fold for X4-tropic HIV-without themselves becoming infected. Fibroblasts were more efficient than dendritic cells at trans-infection and mediate this response in the absence of the DC-SIGN and Siglec-1 receptors.

Generation of a novel chimeric PALFn antigen of Bacillus anthracis and its immunological characterization in mouse model.

Bacillus anthracis chimeric molecule PALFn, comprising the immunodominant domains of protective antigen (PA) and lethal factor (LF), has been developed in the past and has been shown to confer enhanced protection against anthrax in mouse model when challenged with anthrax lethal toxin (LeTx). However, the immunological correlates for this chimeric antigen, both in terms of humoral as well as cell-mediated immune responses, have not been described in detail. To address this gap, we have determined the immunological responses both at humoral as well as cellular levels for the protection conferred by the novel chimeric antigen PALFn constructed in our laboratory in comparison to PA antigen.

Soluble Expression and Characterization of Biologically Active Bacillus anthracis Protective Antigen in Escherichia coli.

Bacillus anthracis secretory protein protective antigen (PA) is primary candidate for subunit vaccine against anthrax. Attempts to obtain large quantity of PA from Escherichia coli expression system often result in the formation of insoluble inclusion bodies. Therefore, it is always better to produce recombinant proteins in a soluble form.

Recombinant expression of Bacillus anthracis lethal toxin components of Indian isolate in Escherichia coli and determination of its acute toxicity level in mouse model.

Bacillus anthracis lethal toxin (LeTx) is the principle factor responsible for toxaemia and anthrax related death. Lethal toxin consist of two proteins viz protective antigen (PA) and lethal factor which combines in a typical fashion similar to other toxins belonging to A-B toxin super family. The amount of LeTx required to kill a particular organism generally differs among strains owing to their geographical distributions and genetic variation.

Rapid Uptake and Inhibition of Viral Propagation by Extracellular OAS1.

The oligoadenylate synthetase (OAS) proteins are traditionally considered intracellular antiviral proteins that mediate antiviral activity through the synthesis of 2'-5'-linked oligoadenylates and subsequent activation of the endoribonuclease RNase L. However, we have recently demonstrated that exogenous recombinant OAS1 is taken up by cells and reduces viral replication both in cell culture and in vivo, independent of RNase L. These results demonstrate a novel paracrine antiviral activity of OAS working in parallel with the classical RNase L pathway.

The 2'-5'-oligoadenylate synthetase 3 enzyme potently synthesizes the 2'-5'-oligoadenylates required for RNase L activation.

Unlabelled: The members of the oligoadenylate synthetase (OAS) family of proteins are antiviral restriction factors that target a wide range of RNA and DNA viruses. They function as intracellular double-stranded RNA (dsRNA) sensors that, upon binding to dsRNA, undergo a conformational change and are activated to synthesize 2'-5'-linked oligoadenylates (2-5As). 2-5As of sufficient length act as second messengers to activate RNase L and thereby restrict viral replication.

Reverse line blot macroarray for simultaneous detection and characterization of four biological warfare agents.

The need for a rapid detection and characterization of biowarfare (BW) agents cannot be over emphasized. With diverse array of potential BW pathogen available presently, rapid identification of the pathogen is crucial, so that specific therapy and control measures can be initiated. We have developed a multiplex polymerase chain reaction based reverse line blot macroarray to simultaneously detect four pathogens of BW importance viz.

Extracellular 2'-5' oligoadenylate synthetase stimulates RNase L-independent antiviral activity: a novel mechanism of virus-induced innate immunity.

The 2'-5' oligoadenylate synthetase (OAS) proteins are traditionally considered intracellular antiviral proteins. However, several studies demonstrate a correlation between the concentration of freely circulating OAS protein in sera from hepatitis C patients and their clinical prognosis. Here we demonstrate that extracellular OAS1 enters into cells and possesses a strong antiviral activity, both in vitro and in vivo, which is independent of RNase L.

Antimicrobial susceptibility and molecular characterization of Vibrio cholerae from cholera outbreaks in Chennai.

The genotype and antibiotic resistance pattern of the toxigenic Vibrio cholerae strains associated with cholera outbreaks vary frequently. Fifty-one V. cholerae strains isolated from cholera outbreaks in Chennai (2002-2005) were screened for the presence of virulence and regulatory genes by multiplex polymerase chain reaction (PCR) assay.