Biomedical subjects

D Guzo

Publications and source records attributed to D Guzo.

6 recordsLinked to original sources

PubMed1996

Transformation of gypsy moth (Lymantria dispar) cell lines by infection with Glyptapanteles indiensis polydnavirus.

Glyptapanteles indiensis, a species of braconid parasitic wasp, infects its host Lymantria dispar (gypsy moth) with a polydnavirus (GiPDV) to suppress the host immune system during parasitization. Here it is shown that GiPDV can infect L. dispar cell lines and that a portion of the GiPDV genome is stably maintained in infected cells. Results of Southern hybridization analyses suggested that this portion of the GiPDV genome is integrated into the L. dispar cellular genome. This is the first report of an insect viral DNA molecule that can apparently integrate into lepidopteran insect cells.

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PubMed1992

Viral and host cellular transcription in Autographa californica nuclear polyhedrosis virus-infected gypsy moth cell lines.

Infection of two gypsy moth cell lines (IPLB-Ld652Y and IPLB-LdFB) by the Autographa californica multiple-enveloped nuclear polyhedrosis virus (AcMNPV) is characterized by extremely attenuated viral protein synthesis followed by a total arrest of all viral and cellular protein production. In this study, AcMNPV- and host cell-specific transcription were examined. Overall levels of viral RNAs in infected gypsy moth cells were, at most measured times, comparable to RNA levels from an infected cell line (TN-368) permissive for AcMNPV replication. Northern blot (RNA) analyses using viral and host gene-specific probes revealed predominantly normal-length virus- and cell-specific transcripts postinfection. Transport of viral RNAs from the nucleus to the cytoplasm and transcript stability in infected gypsy moth cells also appeared normal compared with similar parameters for AcMNPV-infected TN-368 cells. Host cellular and viral mRNAs extracted from gypsy moth and TN-368 cells at various times postinfection and translated in vitro yielded similar spectra of host and viral proteins. Treatment of infected gypsy moth cells with the DNA synthesis inhibitor aphidicolin eliminated the total protein synthesis shutoff in infected IPLB-LdFB cells but had no effect on protein synthesis inhibition in infected IPLB-Ld652Y cells. The apparent selective block in the translation of viral transcripts early in infection and the absence of normal translation or transcription of host cellular genes at later times is discussed.

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PubMed1991

Effect of an Autographa californica nuclear polyhedrosis virion component(s) on DNA synthesis and growth in several insect cell lines.

Thirteen different insect cell lines representing three different orders were infected with Autographa californica nuclear polyhedrosis virus (AcMNPV) whose genome had been inactivated in situ by photochemical means or by short wave UV irradiation. Changes in rates of cellular DNA synthesis, as measured by [3H]thymidine incorporation, and cell growth were subsequently measured at various times post infection. Seven cell lines exhibited a significant decline in [3H]thymidine incorporation (compared to control levels) during an initial 12 h period post infection, while three cell lines showed substantial declines in [3H]thymidine incorporation over a 4 day period post infection. All cell lines which showed a significant decline in [3H]thymidine over the duration of the experiment (4 days) also exhibited reduced cell growth rates. The role of a putative AcMNPV virion associated factor(s) in influencing these cellular events is discussed.

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PubMed1991

DNA-binding proteins of baculovirus-infected cells during permissive and semipermissive replication.

Certain insect cell lines have been shown to be permissive (TN-368) or semipermissive (IPLB-LD-652Y) for Autographa californica nuclear polyhedrosis virus (AcMNPV) replication (McClintock et al., 1986b). In this report DNA-binding proteins were identified in such cell:virus systems by hybridizing Western blots containing uninfected and infected cell proteins with AcMNPV or host DNA probes. In the AcMNPV-infected TN-368 permissive cell system, 8 virus-induced DNA-binding proteins with molecular weights ranging from 67.5K to 18.75K were observed under the highest conditions of stringency. When these DNA-binding proteins were compared to structural proteins of AcMNPV, several appeared to be similar to those observed in SDS-PAGE protein profiles of nonoccluded virus (NOV) and occlusion body (PIBs) preparations. Using an AcMNPV occlusion negative mutant (L1GP-gal3) and an anti-AcMNPV-polyhedrin monoclonal antibody, a major DNA-binding protein (33.0K), observed in the permissive system, corresponded to polyhedrin and to a comigrating virus-induced DNA-binding protein. In the AcMNPV-infected IPLB-LD-652Y semipermissive cell system, no virus-induced DNA-binding proteins were detected. However, several host DNA-binding proteins were present but their ability to bind DNA decreased significantly following infection.

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PubMed1991

Changes in macromolecular synthesis of gypsy moth cell line IPLB-Ld652Y induced by Autographa californica nuclear polyhedrosis virus infection.

The aberrant replication of the Autographa californica multiple-enveloped nuclear polyhedrosis virus (AcMNPV) in the Lymantria dispar cell line IPLB-Ld652Y was used as a model system for the investigation of factors regulating baculovirus host specificity. A previous study of this system indicates that viral gene expression in infected cells is extremely attenuated and subsequently all cellular and viral protein synthesis is inhibited. In the present study, infection of IPLB-Ld652Y cells with AcMNPV photochemically inactivated in situ resulted in a rapid reduction in cell mitotic indices and cell growth, as well as inducing a series of distinct morphological changes in these cells. At the molecular level, infection with inactivated virus, followed by pulse labelling with [3H]thymidine, resulted in a rapid [0 to 2 h post-infection (p.i.)] and permanent inhibition of host cellular DNA synthesis. Assays of cellular DNA polymerases in isolated IPLB-Ld652Y nuclei confirmed the reduction in cellular DNA synthesis observed in intact cells and indicated an initial (0 to 2 h p.i.) reduction in the activity of aphidicolin-sensitive DNA polymerases. Activity of all cellular DNA polymerases was inhibited at later times p.i. Host cell protein synthesis was completely inhibited after 48 h p.i. Treatment of inactivated virus and virus-infected cells with various chemical and physical factors (i.e. pH and temperature) or lysosomotropic agents revealed that virus entry into cells and fusion of endocytic vesicles (containing virus) with lysosomes were essential for suppression of cellular macromolecular synthesis. The possible involvement of structural components of the AcMNPV virion in these effects is discussed.

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PubMed1986

Studies on polydnavirus transmission.

Polydnaviruses are thought to replicate only in the ovaries of certain hymenopteran species. Nevertheless, in the present study, polydnaviral DNA was found to exist in males of the braconid parasitoid species Cotesia melanoscela and in both male and female non-ovarian tissue of an ichneumonid, Hyposoter fugitivus; preliminary results suggest that viral DNA may be present in an unintegrated form, but whether or not it is encapsidated is unknown. Using interstrain genetic crosses, we demonstrated that C. melanoscela males can apparently transmit at least some viral DNA to female progeny. We suggest that polydnavirus DNAs may be present in most if not all tissues of certain parasitoid species, and are probably maintained within parasitoid populations by vertical transmission through the germ line. In parallel experiments, manually injected eggs of the ichneumonid parasitoid (H. fugitivus) survived and hatched in Malacosoma americanum larvae in the apparent absence of exogenous polydnavirus; female parasitoids reared in this manner nevertheless carried virus in their ovaries. Experiments utilizing different strains of C. melanoscela also suggest that per os transmission of polydnaviruses (to parasitoid larvae) does not occur, despite the fact that inoculum viral DNA can be shown to persist for several days in the tissues of parasitized host larvae.

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