Endogenous interleukin 6 is a resistance factor for cis-diamminedichloroplatinum and etoposide-mediated cytotoxicity of human prostate carcinoma cell lines.

Hormonal treatment of advanced prostatic cancer patients generally results in an initially beneficial response, but the treated patients develop hormonally resistant disease in which no curative therapy is currently available. Recent studies have revealed that interleukin 6 (IL-6) is a growth factor for myeloma, renal cell carcinoma, and certain T-cell lymphomas. Further, IL-6 has been shown to block apoptosis induced by p53, transforming growth factor beta, and certain cancer chemotherapeutic compounds.

Interaction of Sendai viral F, HN, and M proteins with host cytoskeletal and lipid components in Sendai virus-infected BHK cells.

We have studied the interaction of Sendai viral fusion (F), hemagglutinin/neuraminidase (H/N), and matrix (M) proteins with host cytoskeletal and lipid components in Sendai virus-infected BHK cells using two nonionic detergents Triton X-100 (TX-100) and octyl glucoside (OG). Our results show that while M protein acquired resistance to both TX-100 and OG extraction, F and HN exhibited insolubility only to TX-100 but not to OG. Furthermore, in the presence of high salt (1 M NaCl), M, but not F or HN, became TX-100 soluble.

Deletion mutation in the signal anchor domain activates cleavage of the influenza virus neuraminidase, a type II transmembrane protein.

Influenza virus neuraminidase (NA) is a type II integral membrane protein with a long hydrophobic domain [29 amino acids (aa)] at the N terminus that functions as an uncleaved signal for translocation into the endoplasmic reticulum and anchors the protein in the membrane. The function of the transmembrane domain in intracellular transport was investigated by deletion mutagenesis. Expression of the mutated NA in eukaryotic cells and by in vitro translation in the presence of membranes showed that the deletion of eight amino acids (aa 28 to 35) from the carboxy end of the signal anchor domain resulted in cleavage, probably by the signal peptidase and secretion of NA into the culture medium.

Mutational analysis of the conserved motifs of influenza A virus polymerase basic protein 1.

Influenza virus polymerase complex is a heterotrimer consisting of polymerase basic protein 1 (PB1), polymerase basic protein 2 (PB2), and polymerase acidic protein (PA). Of these, only PB1, which has been implicated in RNA chain elongation, possesses the four conserved motifs (motifs I, II, III, and IV) and the four invariant amino acids (one in each motif) found among all viral RNA-dependent RNA or RNA-dependent DNA polymerases. We have modified an assay system developed by Huang et al.

The alpha 3 domain of the Qa-2 molecule is defective for CD8 binding and cytotoxic T lymphocyte activation.

Qa-2 is a nonclassical class I molecule encoded by the Q7 gene within the mouse major histocompatibility complex (MHC). Results from previous experiments on Qa-2, and on a chimeric Ld molecule (LQ3) in which the alpha 3 domain is encoded by Q7b, suggested that the alpha 3 domain of Qa-2 does not carry out the functions typical of the alpha 3 domains in other classical and nonclassical class I antigens. Class I molecules that contain the Qa-2 alpha 3 domain are poorly recognized by primary cytotoxic T lymphocytes (CTLs), and do not function normally in either positive or negative selection in vivo.

Molecular determinants of macrophage tropism and viral persistence: importance of single amino acid changes in the polymerase and glycoprotein of lymphocytic choriomeningitis virus.

This study documents that the immunosuppressive lymphocytic choriomeningitis virus (LCMV) variant, clone 13, shows a specific predilection for enhanced infection of macrophages both in vitro and in vivo and that single amino acid changes in the viral polymerase and glycoprotein are responsible for macrophage tropism. The growth difference seen between variant clone 13 and the parental Armstrong strain was specific for macrophages, since both clone 13 and Armstrong grew equally well in fibroblasts and neither isolate infected lymphocytes efficiently. Complete sequencing of the clone 13 genome, along with genetic analysis, showed that a single amino acid change in the polymerase (K-->Q at position 1079) was the major determinant of virus yield in macrophages.

Elevated IFN-gamma and decreased IL-2 gene expression are associated with HIV infection.

Because cytokines have a central role in the regulation and function of the human immune system, expression of several key cytokine genes in HIV infection was compared by quantitative polymerase chain reaction studies in lymphocytes from HIV-seronegative and -seropositive subjects. Elevated levels of IFN-gamma mRNA and lowered IL-2 mRNA were found in the PBMC of eight seropositive men with CD4 T cells over 500/mm3 (mean, 647/mm3), whereas IL-4 and IL-10 mRNA were not changed significantly. PBMC obtained 2 yr later from four of these patients with stable disease status (unchanged CD4 T cell number) showed median mRNA levels that were nearer normal for IFN-gamma and for IL-2.

Identification of the cleavage site and determinants required for poliovirus 3CPro-catalyzed cleavage of human TATA-binding transcription factor TBP.

Host cell RNA polymerase II-mediated transcription is inhibited by poliovirus infection. We have shown previously that the human TATA-binding protein (TBP), a general transcription factor required for transcription of all RNA polymerase II genes, is directly cleaved both in vitro and in vivo by the virus-coded protease 3CPro. 3CPro specifically cleaves glutamine-glycine bonds in the viral polyprotein.

Nuclear retention of M1 protein in a temperature-sensitive mutant of influenza (A/WSN/33) virus does not affect nuclear export of viral ribonucleoproteins.

We investigated the properties of ts51, an influenza virus (A/WSN/33) temperature-sensitive RNA segment 7 mutant. Nucleotide sequence analysis revealed that ts51 possesses a single nucleotide mutation, T-261----C, in RNA segment 7, resulting in a single amino acid change. Phenylalanine (position 79) in the wild-type M1 protein was substituted by serine in ts51.

Synthesis and processing of the influenza virus neuraminidase, a type II transmembrane glycoprotein.

The influenza virus neuraminidase (NA), a type II transmembrane glycoprotein, is expressed at the surface of infected cells and is a major structural component of the virion. The kinetics of biosynthesis of NA, including modification of N-linked sugar chains, association with GRP78-BiP, oligomerization, and transport to the cell surface, were examined in A/WSN/33 influenza-infected BHK cells. Prior to gaining endoglycosidase H (endo H) resistance, NA was found to transiently associate with GRP78-BiP (t1/2 approximately 5 min).

Acute lymphoid changes and ongoing immune activation in SIV infection.

Two features of simian immunodeficiency virus (SIV) infection are emphasized: a transitory decrease in CD4 T cells in the first 2 weeks of infection followed by CD8 T-cell rise, and immune cell activation occurring by 4 weeks and persisting throughout the illness. The short-term changes included a fall in CD4 T cells by 2 weeks with partial recovery by 4 weeks and a CD8 rise that starts at 2 weeks. Subsequent characterization of CD4 T cells showed reduced expression of HLA-DR and CD25 (IL-2 receptor alpha chain) antigens later in SIV infection.

A latent, nonpathogenic HSV-1-derived vector stably expresses beta-galactosidase in mouse neurons.

A genetically engineered herpes simplex virus variant was constructed for use as a stable gene vector for neurons. To inhibit replication, the agent possessed a deletion in the immediate early gene ICP4, and to minimize reactivation from the latent state, the gene encoding the latency-associated transcript was deleted. The E.

Function of two discrete regions is required for nuclear localization of polymerase basic protein 1 of A/WSN/33 influenza virus (H1 N1).

Polymerase basic protein 1 (PB1) of influenza virus (A/WSN/33), when expressed from cloned cDNA in the absence of other viral proteins, accumulates in the nucleus. We have examined the location and nature of the nuclear localization signal of PB1 by using deletion mutants and chimeric constructions with chicken muscle pyruvate kinase, a cytoplasmic protein. Our studies showed some novel features of the nuclear localization signal of PB1.

Latent infections in spinal ganglia with thymidine kinase-deficient herpes simplex virus.

A herpes simplex virus type 1 variant [C239(TK-)] harboring a deletion in the thymidine kinase (TK) gene was assessed for capacity to establish latent infections. Outbred Swiss Webster mice were inoculated on both hind footpads, and numbers of neurons expressing latency-associated transcript and amounts of viral DNA in latently infected lumbosacral spinal ganglia were scored. C239(TK-) established levels of latent infection that were only slightly lower than those found for either a TK rescued variant of this agent or the parent wild-type KOS.

T4+ T helper cell function in vivo: differential requirement for induction of antiviral cytotoxic T-cell and antibody responses.

This study documents the differential requirements of T4+ T helper cells in the induction of virus-specific cytotoxic T-lymphocyte (CTL) and antibody responses during acute lymphocytic choriomeningitis virus infection. Two monoclonal antibodies (GK1.5 and RL172.