RESUMEN

Efficacies of a handheld thermal fogger (Patriot™) and a backpack ultra-low volume (ULV) sprayer (Twister™) with combinations of 2 different adulticides (pyrethrin, deltamethrin) and an insect growth regulator (pyriproxyfen) were field-tested and compared for their impact on reducing indoor Aedes aegypti populations in Thailand. The effectiveness of the indoor space sprays was evaluated by sampling the natural Ae. aegypti population in houses and determining their physiological status, by monitoring mortality of sentinel caged mosquitoes (AFRIMS strain) and by assessing larval mortality in laboratory bioassays using water exposed to the spray. A total of 14,742 Ae. aegypti were collected from Biogents Sentinel traps in this study. The combination of ULD® BP-300 (3% pyrethrin) and NyGuard® (10% pyriproxyfen) sprayed either by the Patriot or Twister significantly reduced some Ae. aegypti populations up to 20 days postspray relative to the control clusters. The addition of pyriproxyfen to the adulticide extended how long household mosquito populations were suppressed. In 2 of the 4 products being compared, the Twister resulted in higher mortality of caged mosquitoes compared with the Patriot. However, neither machine was able to achieve high mortality among Ae. aegypti placed in hidden (protected) cages. The larval bioassay results demonstrated that the Twister ULV provided better adult emergence inhibition than the Patriot (thermal fogger), likely due to larger droplet size.

Asunto(s)

RESUMEN

The primary aim of this study was to evaluate the antitumor efficacy of the bromodomain inhibitor JQ1 in pancreatic ductal adenocarcinoma (PDAC) patient-derived xenograft (tumorgraft) models. A secondary aim of the study was to evaluate whether JQ1 decreases expression of the oncogene c-Myc in PDAC tumors, as has been reported for other tumor types. We used five PDAC tumorgraft models that retain specific characteristics of tumors of origin to evaluate the antitumor efficacy of JQ1. Tumor-bearing mice were treated with JQ1 (50 mg/kg daily for 21 or 28 days). Expression analyses were performed with tumors harvested from host mice after treatment with JQ1 or vehicle control. An nCounter PanCancer Pathways Panel (NanoString Technologies) of 230 cancer-related genes was used to identify gene products affected by JQ1. Quantitative RT-PCR, immunohistochemistry and immunoblots were carried out to confirm that changes in RNA expression reflected changes in protein expression. JQ1 inhibited the growth of all five tumorgraft models (P<0.05), each of which harbors a KRAS mutation; but induced no consistent change in expression of c-Myc protein. Expression profiling identified CDC25B, a regulator of cell cycle progression, as one of the three RNA species (TIMP3, LMO2 and CDC25B) downregulated by JQ1 (P<0.05). Inhibition of tumor progression was more closely related to decreased expression of nuclear CDC25B than to changes in c-Myc expression. JQ1 and other agents that inhibit the function of proteins with bromodomains merit further investigation for treating PDAC tumors. Work is ongoing in our laboratory to identify effective drug combinations that include JQ1.

Asunto(s)

RESUMEN

Rift Valley fever (RVF) continues to be a significant problem in Kenya as well as in Egypt, Yemen, and Saudi Arabia. In order to determine the ability of Kenyan mosquitoes to transmit RVF virus (RVFV), we collected mosquitoes in the Lake Naivasha region of Kenya and evaluated them for their potential to transmit RVFV under laboratory conditions. After feeding on a hamster (Mesocricetus auratus) with a viremia of 10(9.7) plaque-forming units of virus/ml of blood, Culex zombaensis were highly susceptible to infection with RVFV, with 89% becoming infected. In contrast, Cx. quinquefasciatus that were fed on the same hamsters were marginally susceptible, with only 20% becoming infected. Differences in percentages of mosquitoes that developed a disseminated infection were equally disparate, with 55% and 8%, for Cx. zombaensis and Cx. quinquefasciatus, respectively. Forty-eight percent of the Cx. zombaensis with a disseminated infection that fed on a susceptible hamster transmitted virus by bite, indicating a moderate salivary gland barrier. However, the presence of a salivary gland barrier could not be determined for Cx. quinquefasciatus because none of the 18 mosquitoes that took a 2nd blood meal had a disseminated infection. These studies illustrate the need to identify the ability of individual mosquito species to transmit RVFV so that correct decisions can be made concerning the application of appropriate control measures during an outbreak.

Asunto(s)

RESUMEN

Fluorescence in situ hybridisation (FISH) was employed to identify the chromosomal integration site of the human T-cell lymphotropic virus, type 1 (HTLV-1) present in T-cell clones derived from HTLV-1-infected individuals and a virally transformed cell line, C8166-45. Proviral sequences were detected in C8166-45 but not uninfected Jurkat cells. Integration sites were reliably detected in T-cell clones determined previously to be infected with HTLV-1. The results indicated that the transformed cell line and some of the T-cell clones possessed more than one proviral integration site. This hybridisation system is useful for determining the number of integration events and for localising proviruses to specific chromosomal regions.

Asunto(s)

RESUMEN

Human T-cell leukaemia virus type I (HTLV-I) is the aetiological agent of adult T-cell leukaemia/lymphoma and tropical spastic paraparesis/HTLV-I-associated myelopathy (TSP/HAM). The trans-activating protein (Tax) of HTLV-I is strongly implicated in cellular proliferation. We examined the tax gene and 5' long terminal repeat (LTR) sequences in eight naturally infected T-cell clones derived from TSP/HAM-affected individuals who were either productively (proliferate spontaneously) or silently (do not proliferate spontaneously) infected. In two silently infected clones point mutations within the proviruses resulted in truncation of the Tax protein. One clone harboured both a deleterious tax gene mutation and a point mutation in an enhancer element of the 5' LTR. Sequence changes, immunological escape mutation, integration site context and host cell phenotype may all contribute to the high proportion of latently or silently infected T-cells found in vivo in virus carriers.

Asunto(s)

RESUMEN

A bicistronic human immunodeficiency virus type 1 (HIV-1)-based vector is described in which the expression of a selectable marker and a second gene of interest are forcibly coupled by means of an internal ribosome entry site. The vector provides high-level expression of the coselected gene in approximately 90% of transduced cells and has been used to express an endoplasmic reticulum-targeted single-chain antibody (intrabody) directed against a subunit of the interleukin-2 receptor, IL-2R alpha. In the established T cell line Kit225 and also in primary human T cells stably transduced with the intrabody vector, the cell surface expression of IL-2R alpha could be reduced to a low or undetectable level. Responsiveness to IL-2 was reduced 10-fold in the IL-2R alpha-negative cells, consistent with a lack of high-affinity IL-2 receptors. Pseudotyping of the HIV-1 core with the vesicular stomatitis virus G protein improved particle stability by two- to three-fold and enhanced vector entry into established T cell lines up to 230-fold. Vector entry into primary human T cells was most efficient when the amphotropic murine leukemia virus envelope was used. The forced, high-expression capability of the bicistronic vector, together with the capacity of HIV-1 vectors to infect nondividing cells, make this an attractive tool for the genetic manipulation of primary cell types.

Asunto(s)

Asunto(s)

RESUMEN

Adult T cell leukemia (ATL) is an aggressive malignancy that is associated with HTLV-I infection and characterized by constitutive expression of the high-affinity interleukin-2 receptor. The alpha subunit of the high-affinity receptor (IL-2Ralpha), which is normally present only on activated T cells, is specifically upregulated by HTLV-I and constitutively expressed on fresh leukemic cells from ATL patients as well as cell lines transformed by HTLV-I in vitro. Here we directly address the functional significance of IL-2Ralpha expression in HTLV-I transformed cell lines by using an endoplasmic reticulum-targeted single-chain antibody to inhibit the cell surface expression of IL-2Ralpha. Using constitutive and tetracycline-repressible systems to express the ER-targeted antibody against IL-2Ralpha, we have reduced cell surface expression of IL-2Ralpha by more that 2 logs of mean fluorescence intensity to virtually undetectable levels in the IL-2-independent HTLV-I-transformed cell lines C8166-45 and HUT102. No toxicity was associated with the intracellular retention of IL-2Ralpha, and the growth rate of the IL-2Ralpha-negative cells was in each case comparable to that of the parental cell line. We conclude that cell surface expression of IL-2Ralpha is dispensable for the in vitro growth of these HTLV-I-transformed cells.

Asunto(s)

RESUMEN

Human T-cell leukemia virus type I (HTLV-I)-infected T cells expanded in vitro by single-cell cloning provide a unique system for investigating virus-cell interactions in nonimmortalized T cells. By analysis of clones generated randomly from the blood of virus carriers, we confirm that CD4 T cells are the major reservoir of HTLV-I in vivo and show that most infected cells contain a single integrated provirus. Contrary to the situation in HTLV-I immortalized cell lines, the HTLV-I provirus was found to be transcriptionally silent in a high proportion of randomly generated T-cell clones and could not be reactivated by mitogenic stimulation. The spontaneous proliferation previously documented in HTLV-I-infected T-cell clones was not observed in silently infected cells, and therefore correlates directly with the expression of tax and other viral genes. The only cytokine mRNA found to be significantly elevated in the virus-producing clones was interleukin-6; however, receptor-blocking experiments argue against a role for IL-6 in the virus-induced cell proliferation. We observed a striking variation in the ability of individual HTLV-I-producing clones to immortalize fresh peripheral blood lymphocytes. This ability did not correlate with the levels of viral mRNA expression, gag p24 production, spontaneous proliferation, or tax-transactivation, possibly suggesting a role for host cell factors as determinants of viral infectivity or immortalization. Studies to elucidate the basis of this phenotypic heterogeneity should enhance our understanding of viral spread and pathogenesis.

Asunto(s)

RESUMEN

A total of 530 oviposition trap samples were collected within a 10-km radius of Clemson University between March 30 and October 19, 1993. From 19,664 larvae reared from collected eggs, 7 species were identified: Aedes albopictus (89%), Ae. triseriatus (6.5%), Culex restuans (2.7%), Cx. territans (0.6%), Cx. pipiens complex (0.7%), Toxorhynchites rutilus septentrionalis (0.2%), and Orthopodomyia signifera (0.1%). This is the first record of Ae. albopictus in Clemson. Aedes aegypti was not found. Of the 41 ovitrap locations, 100% were positive for Ae. albopictus.

Asunto(s)

RESUMEN

We have previously described a series of human immunodeficiency virus type 1-based vectors in which efficient RNA encapsidation appeared to correlate with the presence of a 1.1-kb env gene fragment encompassing the Rev-responsive element (RRE). In this report, we explore in detail the role of the RRE and flanking env sequences in vector expression and RNA encapsidation. The analysis of a new series of vectors containing deletions within the env fragment failed to identify a discrete packaging signal, although the loss of certain sequences reduced packaging efficiency three- to fourfold. Complete removal of the env fragment resulted in a 100-fold decrease in the vector transduction titer but did not abolish RNA encapsidation. We conclude that the RRE and 3' env sequences are not essential for human immunodeficiency virus type 1 vector encapsidation but may be important in vectors in which a heterologous gene has been placed adjacent to the 5' packaging signal, potentially disrupting its structure.

Asunto(s)

RESUMEN

Single-chain antibodies, synthesized by the cell and targeted to a particular cellular compartment, can be used to interfere in a highly specific manner with cell growth and metabolism. Recent applications of this technology include the phenotypic knockout of growth-factor receptors, the functional inactivation of p21ras and the inhibition of HIV-1 replication. Intracellular antibodies are likely to have a widespread impact in biological research as a simple and effective alternative to other forms of gene inactivation; they demonstrate clear potential as reagents for cancer therapy and for the control of infectious diseases.

Asunto(s)

RESUMEN

The experimental manipulation of peptide growth hormones and their cellular receptors is central to understanding the pathways governing cellular signaling and growth control. Previous work has shown that intracellular antibodies targeted to the endoplasmic reticulum (ER) can be used to capture specific proteins as they enter the ER, preventing their transport to the cell surface. Here we have used this technology to inhibit the cell surface expression of the alpha subunit of the high-affinity interleukin 2 receptor (IL-2R alpha). A single-chain variable-region fragment of the anti-Tac monoclonal antibody was constructed with a signal peptide and a C-terminal ER retention signal. Intracellular expression of the single-chain antibody was found to completely abrogate cell surface expression of IL-2R alpha in stimulated Jurkat T cells. IL-2R alpha was detectable within the Jurkat cells as an immature 40-kDa form that was sensitive to endoglycosidase H, consistent with its retention in a pre- or early Golgi compartment. A single-chain antibody lacking the ER retention signal was also able to inhibit cell surface expression of IL-2R alpha although the mechanism appeared to involve rapid degradation of the receptor chain within the ER. These intracellular antibodies will provide a valuable tool for examining the role of IL-2R alpha in T-cell activation, IL-2 signal transduction, and the deregulated growth of leukemic cells which overexpress IL-2R alpha.

Asunto(s)

RESUMEN

Recombinant vectors based on the type 1 human immunodeficiency virus (HIV-1) can be used to deliver genes into cells expressing the HIV receptor, CD4. We have used a transient RNA packaging system to compare the safety and efficacy of HIV-1 vector transduction by wild-type and replication-deficient helper viruses. Helper virus-free vector transfer was consistently achieved when the helper virus gag-pol and env genes were expressed from separate plasmids such that two recombination events were required to form an infectious genome. Other forms of attenuation, such as deletion of the 5' phi region, were inadequate to prevent helper virus transmission. Vector transduction by the wild-type and non-replicating helper viruses occurred with comparable efficiency except in instances where efficient vector RNA expression was dependent upon transactivating factors supplied by the helper virus. These data demonstrate the feasibility of safe gene transfer using HIV-1 vectors.

Asunto(s)

RESUMEN

The location of HTLV-I (human T-cell leukemia virus type 1) proviral sequences in the genome of infected human cells was explored by hybridization of a viral probe with compositional fractions of host-cell DNAs. In the twelve cases examined, HTLV-I sequences were absent from the GC-poorest 40% of the host genome (namely, from isochores that are below 39% GC). Transcriptionally inactive proviral sequences were localized in GC-poor isochores (comprised between 39% and 42-44% GC) of the human genome, which are characterized by a constant and low gene concentration. In contrast, transcriptionally active proviral sequences were found in the GC-rich and very GC-rich isochores, which are gene rich, transcriptionally and recombinationally active, and endowed with an open chromatin structure. Since GC-rich isochores are present in R'-bands and very GC-rich isochores form T-bands, these results also provide information on the location of HTLV-I proviral sequences in human chromosomes. The results obtained with HTLV-I are in agreement with the non-random, compartmentalized integration of animal retroviral sequences that had been previously observed in other viral-host systems. They provide, however, much more detailed information on the regional location of proviral sequences in the host genome and on the correlation between their transcription and their location.

Asunto(s)

RESUMEN

cis elements required for the encapsidation of human immunodeficiency virus type 1 (HIV-1) RNA have been investigated by using a replication-competent helper virus to package a series of HIV-1-based vectors which had been stably transfected into human CD4 T-cell lines. A previously identified packaging signal in the 5' leader region was not sufficient for the encapsidation of small vectors containing heterologous genes. In contrast, vectors containing additional gag and env sequences were packaged with high efficiency and transduced into CD4-expressing target cells with titers exceeding 10(4) CFU/ml. The presence of gag sequences did not enhance vector packaging efficiency. A 1.1-kb env gene fragment encompassing the Rev-responsive element was absolutely required for the expression and encapsidation of vectors containing cis-acting repressive sequences and appeared also to contain an important packaging signal. Vectors as small as 2.6 kb were successfully packaged in this system. The presence of abundant, packageable vector RNA did not appear to interfere with encapsidation of the wild-type HIV-1 genome, suggesting that HIV-1 RNA packaging capacity is not saturated during acute infection.

Asunto(s)

RESUMEN

A unique feature of both human T-cell leukemia virus type I (HTLV-I) carriers and subjects with HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP), a chronic inflammatory disease of the nervous system, is the presence of large numbers of activated T cells that spontaneously proliferate in vitro. We have investigated the mechanisms of T-cell activation by HTLV-I in freshly isolated blood T cells and in naturally infected T-cell clones obtained by direct single-cell cloning from patients with HAM/TSP. Both CD4+ and CD8+ HTLV-I-infected T-cell clones showed the unusual ability to proliferate in the absence of exogenous interleukin 2 (IL-2). Nevertheless, HTLV-I-infected clones were not transformed, as they required periodic restimulation with phytohemagglutinin and feeder cells for long-term growth. Irradiated or fixed HTLV-I-infected clones were found to induce the proliferation of blood T cells when cocultured, which we refer to as THTLV-1-T cell activation. This THTLV-1-T cell-mediated activation was blocked by monoclonal antibodies (mAbs) against CD2/lymphocyte function-associated molecule 3 (LFA-3), LFA-1/intercellular cell-adhesion molecule (ICAM), and the IL-2 receptor but not by mAbs against class I or class II major histocompatibility complex molecules, HTLV-I gp46, or a high-titer HAM/TSP serum. Spontaneous proliferation of blood T cells from HAM/TSP patients could also be inhibited by mAbs to CD2/LFA-3, LFA-1/ICAM and to the IL-2 receptor (CD25). These results show at the clonal level that HTLV-I infection induces T-cell activation and that such activated T cells can in turn stimulate noninfected T cells by cognate THTLV-1-T cell interactions involving the CD2 pathway.

Asunto(s)

Asunto(s)

Asunto(s)

RESUMEN

The biological safety cabinet is the one piece of laboratory and pharmacy equipment that provides protection for personnel, the product, and the environment. Through the history of laboratory-acquired infections from the earliest published case to the emergence of hepatitis B and AIDS, the need for health care worker protection is described. A brief description with design, construction, function, and production capabilities is provided for class I and class III safety cabinets. The development of the high-efficiency particulate air filter provided the impetus for clean room technology, from which evolved the class II laminar flow biological safety cabinet. The clean room concept was advanced when the horizontal airflow clean bench was manufactured; it became popular in pharmacies for preparing intravenous solutions because the product was protected. However, as with infectious microorganisms and laboratory workers, individual sensitization to antibiotics and the advent of hazardous antineoplastic agents changed the thinking of pharmacists and nurses, and they began to use the class II safety cabinet to prevent adverse personnel reactions to the drugs. How the class II safety cabinet became the mainstay in laboratories and pharmacies is described, and insight is provided into the formulation of National Sanitation Foundation standard number 49 and its revisions. The working operations of a class II cabinet are described, as are the variations of the four types with regard to design, function, air velocity profiles, and the use of toxins. The main certification procedures are explained, with examples of improper or incorrect certifications. The required levels of containment for microorganisms are given. Instructions for decontaminating the class II biological safety cabinet of infectious agents are provided; unfortunately, there is no method for decontaminating the cabinet of antineoplastic agents.

Asunto(s)