Estimated Comparative Integration Hotspots Identify Different Behaviors of Retroviral Gene Transfer Vectors

Integration of retroviral vectors in the human genome follows non random patterns that favor insertional deregulation of gene expression and may cause risks of insertional mutagenesis when used in clinical gene therapy. Understanding how viral vectors integrate into the human genome is a key issue in predicting these risks. We provide a new statistical method to compare retroviral integration patterns. We identified the positions where vectors derived from the Human Immunodeficiency Virus (HIV) and the Moloney Murine Leukemia Virus (MLV) show different integration behaviors in human hematopoietic progenitor cells. Non-parametric density estimation was used to identify candidate comparative hotspots, which were then tested and ranked. We found 100 significative comparative hotspots, distributed throughout the chromosomes. HIV hotspots were wider and contained more genes than MLV ones. A Gene Ontology analysis of HIV targets showed enrichment of genes involved in antigen processing and presentation, reflecting the high HIV integration frequency observed at the MHC locus on chromosome 6. Four histone modifications/variants had a different mean density in comparative hotspots (H2AZ, H3K4me1, H3K4me3, H3K9me1), while gene expression within the comparative hotspots did not differ from background. These findings suggest the existence of epigenetic or nuclear three-dimensional topology contexts guiding retroviral integration to specific chromosome areas

Sanitary profile in mice and rat colonies in laboratory animal houses in Minas Gerais: I - Endo and ectoparasites Perfil sanitário de colônias de camundongos e ratos de biotérios de Minas Gerais: I - Endo e ectoparasitos

The sanitary conditions of 13 animal houses in nine public institutions in Minas Gerais, and the presence of endo and ectoparasites of mice and rats colonies kept in these facilities were evaluated. Data about barriers to prevent the transmission of diseases and a program of sanitary monitoring were obtained through a questionnaire and local visit. Parasitological methods were performed for diagnosing mite, lice, helminthes, and protozoa parasites in 344 mice and 111 rats. Data have shown that the majority of the animal houses had neither proper physical environment nor protection barriers to prevent the transmission of infections. Parasitological results have shown that only one animal house (7.7%) had parasite free animals, whereas the others have presented infected animals and the prevalences of parasites in the mice colonies were: Myobia musculi (23.1%); Myocoptes musculinus (38.5%); Radfordia affinis (15.4%); Syphacia obvelata (92.3%); Aspiculuris tetraptera (23.1%); Hymenolepis nana (15.4%); Spironucleus muris (46.2%); Giardia muris (46.2%); Tritrichomonas muris (53.8%); Trichomonas minuta (61.5%); Hexamastix muris (7.7%); and Entamoeba muris (84.6%). As for the rat colonies, the prevalences were: Poliplax spinulosa (8.1%); Syphacia muris (46.2%); Trichosomoides crassicauda (28.6%); Spironucleus muris (85.7%); Tritrichomonas muris (85.7%); Trichomonas minuta (85.7%); Hexamastix muris (14.3%) and Entamoeba muris (85.7%).<br>Avaliaram-se as condições sanitárias de 13 biotérios de nove instituições públicas do estado de Minas Gerais, bem como a presença de endo e ectoparasitos nos camundongos e ratos criados nesses biotérios. Os dados sobre barreiras contra infecções e sobre o programa de monitoramento sanitário dos animais foram obtidos por meio de um questionário e de visitas aos biotérios. Métodos parasitológicos foram utilizados para o diagnóstico de ácaros, piolhos, helmintos e protozoários em 344 camundongos e 111 ratos. A maioria dos biotérios não possuía espaços físicos adequados nem barreiras de proteção que pudessem impedir a transmissão de infecções. Os resultados parasitológicos mostraram que em apenas um biotério não foram encontrados animais parasitados. A prevalência de parasitos encontrados em camundongos nos outros biotérios foi: Myobia musculi (23,1%), Myocoptes musculinus (38,5%), Radfordia affinis (15,4%), Syphacia obvelata (92,3%), Aspiculuris tetraptera (23,1%), Hymenolepis nana (15,4%), Spironucleus muris (46,2%), Giardia muris (46,2%), Tritrichomonas muris (53,8%), Trichomonas minuta (61,5%), Hexamastix muris (7,7%) e Entamoeba muris (84,6%). E nas colônias de ratos foram encontrados: Poliplax spinulosa (8,1%), Syphacia muris (46,2%), Trichosomoides crassicauda (28,6%), Spironucleus muris (85,7%), Tritrichomonas muris (85,7%), Trichomonas minuta (85,7%), Hexamastix muris (14,3%) e Entamoeba muris (85,7%)